CA1207058A - Plant oriented control system - Google Patents
Plant oriented control systemInfo
- Publication number
- CA1207058A CA1207058A CA000440920A CA440920A CA1207058A CA 1207058 A CA1207058 A CA 1207058A CA 000440920 A CA000440920 A CA 000440920A CA 440920 A CA440920 A CA 440920A CA 1207058 A CA1207058 A CA 1207058A
- Authority
- CA
- Canada
- Prior art keywords
- temperature
- task
- greenhouse
- zone
- output section
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- A—HUMAN NECESSITIES
- A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01G—HORTICULTURE; CULTIVATION OF VEGETABLES, FLOWERS, RICE, FRUIT, VINES, HOPS OR SEAWEED; FORESTRY; WATERING
- A01G9/00—Cultivation in receptacles, forcing-frames or greenhouses; Edging for beds, lawn or the like
- A01G9/24—Devices or systems for heating, ventilating, regulating temperature, illuminating, or watering, in greenhouses, forcing-frames, or the like
- A01G9/246—Air-conditioning systems
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A40/00—Adaptation technologies in agriculture, forestry, livestock or agroalimentary production
- Y02A40/10—Adaptation technologies in agriculture, forestry, livestock or agroalimentary production in agriculture
- Y02A40/25—Greenhouse technology, e.g. cooling systems therefor
Abstract
Plant Oriented Control System Abstract A system for controlling environmental conditions in greenhouses having a plurality of crop beds. The system comprises sensors stationed over crop beds comprising an aspirated enclosure and means therein for generating analog electrical signals indicative of wet bulb and dry bulb temperatures.
The system comprises a microcomputer located within the greenhouse having a central processing unit with associated scratch memory and program memory sections; an analog to digital input section for receiving the analog electrical signals from the sensors; an output section for converting the computer logic signals to electrical signals at power levels to operate electromechanical apparatus; and serial digital pathway means for connecting the central processing unit, input section and output section. The system further comprises a memory programmed with a task for inputting digital data from the input section indicative of wet bulb and dry bulb temperatures and for calculating the moisture content of the atmosphere over each bed;
a task for comparing the temperature and said moisture content with preselected command levels; and a task which in response to said comparison generates commands to the output section capable of initiating therethrough electromechanical action to move the temperature and moisture content toward the preselected command levels.
The system comprises a microcomputer located within the greenhouse having a central processing unit with associated scratch memory and program memory sections; an analog to digital input section for receiving the analog electrical signals from the sensors; an output section for converting the computer logic signals to electrical signals at power levels to operate electromechanical apparatus; and serial digital pathway means for connecting the central processing unit, input section and output section. The system further comprises a memory programmed with a task for inputting digital data from the input section indicative of wet bulb and dry bulb temperatures and for calculating the moisture content of the atmosphere over each bed;
a task for comparing the temperature and said moisture content with preselected command levels; and a task which in response to said comparison generates commands to the output section capable of initiating therethrough electromechanical action to move the temperature and moisture content toward the preselected command levels.
Description
r~3 Description Plant Oriented Control System Field of the Invention This invention pertains to a plant oriented system for controlling 5 environmental conditions in greenhouses.
Background Automatic control of temperature in a greenhouse by regulating heating and ventilation is old in the art. In fact, other factors affecting the growth and health of the crops being grown in the greenhouse have been 10 automatically controlled. However, in the past control has been directed to maintaining the overall greenhouse environment based upon a small number of sensors and traditional control devices such as single thermostats.
Microprocessor control of greenhouse environment has been mllch discussed in various papers. However, attempts to use computers to control the 15 greenhouse environment, to applicants' knowledge, have not been totally suecessful. One problem has been the inherently noisy (electronically speaking) environment of the greenhouse causing distortion of small mag-nitude signals. Another has been the necessity to keep the computers outside of the greenhouse itself. Thus prior greenhouse control systems have not 20 been plant or crop oriented control systems. They have not addressed the problems of controlling growth and plant health conditions directly at the growing bed or plant level. Unfortunately, the control of the overall greenhouse conditions, while providing adequate plant growth and health conditions at one bed, may not provide the proper conditions at another bed.
25 This may be due to the nonuniformity of a condition, say temperature, throughout the greenhouse or the fact that different beds are planted with different crops or even that difeerent beds planted with the same crop are at different stages in the growing cycle. Prior greenhouse control systems have not provided adequate individualized control of bed areas based upon 30 feedback of temperature, light, and humidity conditions directly over the beds.
7~8 Summary of the Invention It is an object of this invention to provide a computerized plant oriented control system for control of the greenhouse environment including, for example, temperature, light, moisture, and/or carbon dioxide concentra-tion.
It is a further object to provide a computerized plant oriented control system for minimizing the amount of electrical or fuel energy required by the greenhouse and to maintain the temperature over the crop beds relative to a control point, say, maximum temperature, minimum temperature, and/or lD dew point.
It is a still further object to provide a computerized plant oriented control system which anticipates changes in the conditions over the crop beds by sensing remote conditions such as light above shades, external tempera-tures, wind velocity and direction.
It is yet another object of this invention to provide a plant oriented control system for programming growth rates by maintaining one or more conditions such as temperature, mist, irrigation, and carbon dioxide con-centration in the atmosphere over the beds as a function of the available light and/or a controlled amount of light incident the crop bed.
It is an object of one embodiment of this invention to provide a computerized plant oriented control system that as a function of light, temperature, and humidity over the beds and the age of the crops provides the amount of mist or irrigation necessary to insure healthful propagation and growth of the crop.
It is a feature according to this invention that a greenhouse has a plurality of sensing zones and a plurality of control zones which are not contiguous and wherein each sensing zone is provided individualized environ-mental control based upon its particular needs. According to an especially sophisticated embodiment of this invention where control conditions are changed from time to time, the control algorithms in the microcomputer witl7in the greenhouse may be changed by downloading from a host computer located external to the greenhouse and, for example, serving more than one greenhouse.
It is a still further advantage according to this invention to provide a plant oriented crop ~ontrol system that is extremely versatile in its accommodation to the type of heating and cooling and other environmental '7Q~i~
control systems already in place in a majority of existing greenhouses notwithstanding the diversity of the existing systems.
The plant oriented control system makes proper decisions based upon the needs of the plants or crops and will give the grower a more energy efficient method of control over the greenhouse environment. The system includes components that collect data such as temperature, light, humidity, wind speed and direction. A central microcomputer unit uses the data obtained to make decisions and act upon them. The microcomputer is programmed with one or more algorithms to mal~e the decisions. The algorithms may be modified depending upon the nature of the crop and the greenhouse system being controlled. The plant oriented control system provides a fully automated greenhouse environment with the ability to monitor and control all applicable conditions.
In it broadest expression, the computerized plant oriented control system comprises structure defining a plurality of sensing zones, structure defining a plurality of control zones and a microcomputer within the greenhouse programrned with algorithms or tasks for maintaining at least one environmental condition in the control zones to promote the health and growth of the crop or crops. For those embodiments which relate to anticipatory control condition, sensors remote from the bed such as external temperature, wind speed and wind direction sensors are required. For those embodiments involving programmed plant growth wherein conditions above the erop bed are controlled as a function of the crop age, the microcomputer must include a real time clock.
As the terms are used herein, a "sense zone" or "sensing zone" is a bed area, preferably not in excess of about 3,000 square feet all planted with the same crop at about the same time having at least two spaced temperature sensors positioned directly over and near ~within about three feet) of the bed, a light sensor directly over and near the bed and an aspirated humidity sensor directly over and near the bed. As used herein, various "control zones" may include a heating control zone, cooling control zone, misting control zone, irrigating control zone, shade control zone, heat retention control zone, horizontal flow control zone, and carbon dioxide atmosphere control zone. Each control zone has associate~ with it a controllable device for affecting the environment within the zone. A heating control zone comprises a bed area, including at least one sensing zone, that ~7~58 - has a controllable heating element associated therewith. A cooling control zone comprises a bed area, including at least one sensing zone, that has a controllable cooling system associated therewith. This may simply be a cross ventilation pathway controlled by one or more vents. ~ misting control zone 5 comprises a bed area, usually one sensing æone, having controllable water spray over the bed. An irrigating control zone comprises a bed area, usually one sensing zone, having a controllable bed watering system. A shade control zone comprises a bed area, including at least one sensing zone having a controllable sunscreen or shade assoeiated therewith. The shade control zone 10 might become a heat retention zone at night as radiative cooling can be controlled by the presence or not of the screen or shade over the bed. A
horizontal flow control zone is a bed area, including at least one sensing zone, that has a controllable horizontal circulation fan associated therewith to prevent stratification when no ventilation is being used. A carbon dioxide 15 atmosphere control zone comprises a bed area, generally the entire enclosed greenhouse, having means for generating carbon dioxide. It should be noted that the various control zones need not be contiguous but very often are overlapping. (For example, a large greenhouse may have two cooling zones but many heating zones.) Controllable devices associated with the control 20 zones are devices which may be activated, for example, by application of an AC current such as a solenoid control valve or an AC motor controlled by a motor controller which controller provides the function of starting, stopping, and reversing a motor.
As stated above, the microcomputer must be programmed with 25 algorithms or tasks to enable it to make intelligent decisions. An algorithm or task, at spaced intervals, inputs the digitalized temperatures (two for each bed) and averages the temperatures for each bed or sense zone. The average temperature is then compared to a set point, for example a maximum temperature, a minimum temperature or the dew point. Depending upon the 30 relationship of the average temperature sense and the set point, the computer will output control signals to adjust the controllable devices such as heating or ventilating equipment to adjust the temperature relative to the set point temperature.
Additionally, an algorithm may maintain the temperature and perhaps 35 mist, irrigation, or carbon dioxide atmosphere as a function of the availablelight to provide a desired growth rate and/or to make efficient use of energy.
., 7~S8 On a cloudy day, heat and carbon dioxide would not be wasted. A
second control criteria could be imposed with such an algorithm;
namely, to control the growth rate to be the maximum possible or to control the growth rate -to be that which is estimated to bring the crop to the desired size at a desired date. The latter criteria, of course, require a clock to log time from planting and may require a controllable shade. An algorithm or task according to one em-bodiment of this invention maintains the temperature by advance adjustments of controllable elements based upon changes in the remote sensors as well as upon the data from overhead sensors.
According to another specific embodiment, an algorithm or task initiates mist or irrigation as a function of light, temperature, humidity and age of the crop.
Thus, in accordance with a broad aspect of the invention, there is provided a system for controlling environ-mental conditions in greenhouses having a plurality of crop beds within one greenhouse enclosure arranged into a plurality of sense zones and a plurality of control zones comprising:
a. a plurality of sensors stationed over crop beds within each sense zone comprising an aspirated enclosure and means therein for generating analog electrical signals indicative of wet bulb and dry bulb temperatures and also means for generating an analog electrica] signal indicative of incident light over the bed;
b. a microcomputer located within the greenhouse comprising:
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- 5a -i. a central processing unit with associated scratch memory and program memory sections;
ii. an anolog to digital input section :Eor receiving the analog electrical signals from the sensors;
iii. an output section for converting computer logic signals to electrical signals at power levels to operate electro-mechanical apparatus; and iv. serial digital pathway means or connecting the central processing unit, input section and output section;
c. said program memory programmed with:
i. a task for inputting digital data from the in-put section indicative of wet bulb and dry bulb temperatures and for calculating the moisture content of the atmosphere over each bed and for inputting digital data from the input section indicative of light intensity;
ii. a task for selecting temperature and moisture command levels based upon the intensity of incident light and comparing the input temperature and moisture content with said selected command levels for each sense zone; and iii. a task which in response to said comparison generates commands to the output section capable of initiating therethrough electromechanical action asso~iated with each control zone to move the temperature and moisture content for each sense zone toward the selected command levels.
7~58 - 5b -The Drawings Further features and other objects and advantages of this invention will become clear from the following detailed description made with reference to the drawings in which Figure 1 ls a schematic illustrating a greenhouse, sensing zones and control zones according to this invention;
Figure 2 is a function aiagram of an input card for use with a microcomputer used in the practice of this invention;
Figure 3 is a function diagram of an output card for 10use with a microcomputer according to this invention;
Figure 4 is a function diagram of a microcomputer use-ful for the practice of this invention;
Figure 5 illustrates the serially transmitted data format useful with this invention;
Figure 6 is a flow chart for a main program useful according to this invention;
Figure 7 is a flow chart of a SENSE procedure called by the main program;
Figure 8 is a flow chart of an ALAR~S procedure called 20by the main program;
Figure 9 is a flow chart of a HEAT CONSERVATION proce-dure called by the main program;
Figure 10 is a flow chart of a HEAT STAGE UP procedure called by the main program;
~7~51~
Figure 11 is a flow chart of a HEAT STAGE DOWN procedure called by the main program;
Figure 12 is a flow diagram of a COOL STAGE UP procedure called by the main program;
Figure 13 is a flow diagram of a COOL STAGE DOWN procedure called by the main program;
Eigures 14A, 14B and 14C are flow diagrams of a VENT LIMITS
procedure called by the main program;
Figure 15 is a flow diagram of a VENT DeRH (decondensate by venting) procedure called by the main program;
Figure 16 is a flow diagram of a VARIABLE SHADE procedure called by the main program;
Figure 17 is a flow diagram of a P~OTOTT~F.RMAT. BLANKET
procedure;
Figure 18 is a flow diagram of a HEAT DeRH (decondensate by heating) procedure;
Figure 19 is a flow diagram of a LIGHT ACCUMULATOR procedure;
Figures 20A, 20B, and 20C are flow diagrams of a HEAT SET POINT
DRIVER based upon average light and accumulated light;
Figure 21 is a flow diagram for a PIPE TEMPERATURE ANTICI-PATOR procedure; and Figures 22A, 22B, and 22C are flow diagrams of a procedure that generates a factor for the PIPE TEMPERATURE ANTICIPATOR procedure based upon variation between zone temperature (as measured) and set point temperature (desired).
Detailed Description The equipment for the plant operated control system according to this invention can be considered in three groups based upon their functions.
First there are the sensors. These collect greenhouse data such as temperature, humidity, light, and such external conditions as temperature, light, humidity, wind speed and direction. A second group comprises the microcomputer with associated input and output boards. A third group comprises the valves and motors necessary to carry out the actions that bring about a change in the greenhouse environment.
i8 The grower must determine the number of "control zones" he intends to include in his greenhouse. A zone is defined as one part of the total greenhouse of which individual, independent control can be maintained. The type and location of e2cisting equipment within a greenhouse determine the 5 establishment of control zones. Sensing zones and control zones have already been described. Heating and cooling zones need not be related so it is not necessary that they each have the same division. ~or example, as a practical matter, an acre of greenhouse may have sixteen heatingr zones but only two cooling zones.
The crops in the adjacent sense zones within the same control zone theoretically might require a controlled condition to be different. However, due to the nature of crop requirements and the usual greenhouse control configurations, this is seldom the case. With some planning of crop placement, the problem can be avoided. For example, most sense zones are 15 coincident with a control zone for heating (for example, hot pipes); misting or irrigating. These are conditions that may vary from crop to crop. On the other hand, ventilation zones usually span a number of sense zones. The ventilation requirement is generally about the same for all crops.
Referring now to Figure 1, the system hardware according to this 20 invention is shown schematically. The large rectangle represents the greenhouse enclosure 10. Located within the greenhouse is a microcomputer 12 having associated A/D input sections and AC output (triac control) sections. Two IO stations 14 and 15 are spaced from the microcomputer.
The IO stations have associated A/D input sections and AC output sections 25 identical with those directly associated with the microcomputer and, as will be explained, they are functionally equivalent to those directly associated with the microcomputer. All A/D input sections and AC output sections are connected to the microcomputer by one common asynchronous serial address-data-control pathway referred to in here as the data pathway (DP~V). It is 30 possible that IO stations will be unnecessary in a small greenhouse. In fact,for the number of sense zones illustrated in Figure 1, the A/D input systems and AC output sections directly housed within the microcomputer would be sufficient. The use of IO stations depends upon the number of sense zones being monitored and the spacing thereof. It is desirable to reduce the length 35 of the sense input wires carrying analog signals and thus the additional IO
stations may be required.
~Z~7~5~3 The greenhouse of ~igure 1 is divided into eight sensing zones, each having two sense stations a, b, over the bed. Sense stations are aspirated enclosures for housing at least a dry bulb temperature sensor and often both dry b~b and wet bulb temperature sensors and for generating an analog 5 signal indicative of these temperatures. A light sens;ng station for generating an analog signal indicative of light intensity over the bed is often associated with the temperature sensing station. A second temperature sensing station is always associated with each sense zone. The two temperatures are averaged by the microcomputer to obtain a temperature representative of 10 the sense zone temperature.
Referring again to Figure 1, the greenhouse is further divided into a number of control zones. For example, four zones labelled A, B, C, and D
have individually controlled heating means. The heating means rmay comprise a number of possible devices, for example, on-off steam heating below the 15 beds, proportional hot-water heating below the beds, infrared heaters above the beds or gas fired unit heaters above the beds.
To illustrate that the control zones may overlap, two ventilation control zones are illustrated; one extending to heating control zones A and B and the other to heating control zones C and D. Ventilation may be by 20 opening vents on each side of the greenhouse or by turning on fans that draw air across the ventilation zone. The intake vents may or may not have evaporation coolers associated therewith depending upon the application.
Shade zones comprising canvas shades that are drawn horizontally over the beds just below the rafters may be arranged in zones. In the example of 25 Figure 1, there are two shade zones comprising control zones A and B and control zones C and D. The shades are useful for two purposes: In the daytime, the drawn shades reduce sunlight and temperature of the beds. At night the shades help to maintain temperature over the beds by reducing radiation cooling. Located above the shade is a light sensor 16 enabling the 30 detection of the availability of sunlight when the shade is drawn.
To this point, all of the elements of the system being described are positioned within the greenhouse enclosure. Two groups of optional elements may be positioned external to the greenhouse. An external temperature sensor, wind speed sensor, and wind direction sensor may be provided for 35 anticipatory control as will be explained herein. Also a host computer for downloading new control algorithms or tasks to the microcomputer may be positioned external to the greenhouse.
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g Plant operated control systems must gain an adequate amount of information from each zone to be able to make the proper decisions for the correct levels of control. Each zone contains at least two temperature sensors, one light sensor, and one humidity sensor. The overbed sensors are S housed in aspirated fan boxes. A light sensor must, of course, be mounted on top of the aspirated fan box. The temperature sensors comprise solid-state dry bulb temperature monitoring devices having a range -10C to 100C. The humidity sensor is a solid-state wet bulb temperature monitoring device. When used in conjunction with the dry bulb described above this provides a very precise humidity measurement. The light energy sensor measures light intensity in foot candles. Two types of sensors are used. The first provides very precise measurement of light in the range of 0 to 800 foot candles for use with artiîicial day length control. The second is a general daylight sensor that provides less resolution in a much wider photosynthetic range of 0 to 4,000 foot candles; that is, the range at which actual plant growth occurs. Typically the temperature sensors comprise a heat sensitive diode, say, LM335 with associated calibration potentiometers. They are commercially available calibrated for a 2.73 volt output in ice water and a 10 millivolt per degree Kelvin output.
To provide more efficient control, conditions outside of the green-house are also monitored. This enables the plant oriented control system to anticipate the greenhouse needs prior to any internal changes and also aids in conserving energy. A ten-mile per hour wind speed increase increases the heating load approximately fifteen percent.
The microcomputer comprises a microprocessor, RAI~ memory, ROM
memory, a 16-place l;eypad input and an 8-digit display, for example. The computer is enclosed within an air-tight cabinet; preferably protected from both direct sunlight and other temperature extremes. C~mputers are available at rated operating temperatures between 0 and 70C (32 and 158F). Operational greenhouses have an internal temperature well within this range.
The sense sections of the microcomputer, whether in the same cabinet or in an IO cabinet spaced thereflom, collects analog clata from the above mentioned sensory elements and converts it to a digital signal with an analog to digital signal converter.
:~2~ 58 Figure 2 illustrates an input card that coordinates sixteen individual sensory inputs for transmission to the computer. It is possible to connect a number of these sections to the computer permitting access to a large number of individual sensory inputs. There are shown two 8-channel analog 5 input sections comprising multiplexers 20, 21 for selecting one of eight input signals, analo~ to digital converters 22, 23 and asynchronous receiver-transmitter remote controllers (ARTtRC) 24, 25 for transmitting the serialized digital signal to the microcomputer. The input section also includes a 4-channel on-off input useful for reading limit switches which 10 comprises an asynchronous receiver-transmitter remote controller 26. This unit is also used to select the analog section and the channel within the analog section for application to the A/D converters through the multi-plexers. These input sections may be associated in the cabinet with the microcomputer or on a remotely located cabinet.
The microcomputer also comprises an AC output section which outputs control signals to controlled devices as directed by the computer. A
number of these output sections may be connected to the computer permitting control of a large number of devices. These output sections may be associated in the cabinet with the microcomputer or in a remotely located 20 IO cabinet. In a typical application, the output section provides a direct method of control of any electrical device present in the greenhouse through use of 24 volt relays.
Referring to Figure 3, there is shown a function diagram of an output section which includes an asynchronous receiver-transmitter remote con-25 troller 30 for receiving serialized digital commands from the microprocessorand for outputting a signal on one of eight channels for controlling an optically coupled triac 31 which in turn control higher duty triacs 32.
The communication between the microcomputer and the input and output sections is by master and slave configuration of two ARllRC units.
30 The master ART/RC 40 (see Figure 4) is associated with the microprocessor.
The slave ART/RC units (24, 25, 26, 30) are associated with the input and output sections. ART/RC devices are available, for example, from the National Mi~ll 54250. The simplest communication route between the master A~T/RC and its slave is by means of a twisted pair of wires or a coaxial 35 cable. The single line IO circuit of all ART/RC devices is an open drain driver ouput. Because the line is floating, the master ART/RC has the IO
~Z(~7~S~
communication line pulled up via one K ohm resistor. The pull up provides excellent data transmission over a distance of about 2,000 feet using standard coa2sial cable. Care should be talcen to reduce capacitance and resistance of this line and maintain good ground continuity between the master and slave 5 units.
Pulse width modulation techniques are used by the ART/RC to transmit the digitalized data. ~ practical pulse frequency is approximately ~50 K hertz. In practice, the frequency between each ART/RC can vary as much as 50,~ before performance is affected. This wide tolerance provides 10 excellent noise immunity, especially in heavy industrial environments.
Figure 5 illustrates the serially transmitted data format used by the ART/RC devices. Data in this format put upon the eommon pathway is read or written by or from the ART/RC device connected to the pathway having the 7-bit address first placed upon the line.
Referring more specifically to Figure 4, a microcomputer useful according to this invention diagram is shown in function format. The microprocessor unit 41 is central operative element and may have a resident basic interpreter, for example, the INS 8073. The computer has associated RAM memory 42 and EPROM memory 43 and in some embodiments of this 20 invention a real time clock 44. All elements are connected by address bus 45 and data bus ~6 and control lines not illustrated.
Hardware particularly suitable for use in the pract;ce of this invention comprises the computer system described in the "Vanderbilt Series K-8073 Tiny Basic Microcomputer HardwareiSoftware Users Manual" copy-25 righted in 1981 by Transwave Corporation of Vanderbilt, Pennsylvania and apublication entitled "Vanderbilt 8000 Series Computer Products" copyrighted in 1982 by Transwave Corporation. The latter publication describes a twenty-channel analog to digital input card and an eight channel triac 300 watt controller card. Certain features of this system make it particularly 30 suitable for greenhollse control. All or part of the control system can be placed within the greenhouse and analog transmission of data can be minimized.
Referring now to Figure 6, a ~low chart for the main program is set forth. The program passes sequentially from an initialization routine through 35 a data gathering procedure and through a temperature adjusting procedure that are repeated for each control zone and thence through a plurality of procedures that are not necessarily zone specific.
~2V~7~5~3 After the initialization (programming of ports and clearing of memory areas, etc.) which only takes place upon start-up or reset, the program moves to the main line loop.
l~eferring to Figure 7, the first procedure in the main line loop is labelled SENSE and comprises scanning the data available at the A/D
converters and storing valid reads. The data is then assembled by zone and scaled to provide appropriate units. The new reads are averaged into the existing reads or data.
Referring to Figure 8, the next procedure is labelled ~T ARM~ and is a procedure in which temperature data is compared with high Rnd low alarm temperatures and under the conditions that a sensing station is above the high set point or below the low alarm temperatures, the sensing station is noted and an alarm device is activated. The alarm temperature for the high temperatures is affixed differential DT1 above the high temperature set point. To avoid setting off an alarm for a condition that cannot be corrected (e,g. overheating on an extremely hot day the alarm is not activated if the temperature outside exceeds the alarm temperature).
~eferring to Figure 9, the next procedure labelled HEAT CON-SERVATION is an optional energy conservation routine used late in the afternoon duri~g the cool part of the year and which procedure increases the cooling set point to allow heat to build-up in the greenhouse during the late afternoon. This increase in the set points takes place only the first time through the procedure after a preselected time before sunset when heat build-up is to be allowed.
Referring to Fi~ures 10 and 11, the program next moves to heating and cooling procedures. The heating procedures HEAT STAGE UP and HEAT
STAGE DO~N ar~ implemented when the temperature external to the greenhouse falls below the desired temperatures and the cooling procedures are implemented when the temperatures external to the greenhouse exceed the desired temperature. The HEAT STAGE UP procedure is entered if the temperature in a heating zone is less than the heat set point. The procedure compares the most recent temperature reading with the last temperature reading to determine if the zone is rapidly cooling. If so, the output for increasing the stages delivering heat to the bed is incremented (by incrementing the stages is meant, for example, if two steam pipes are already turned on a third steam pipe is turned on). If rapid cooling is not 1~7~S~3 taking place, a timer is set for a fixed time period after which a comparison of the most recent temperature reading with a prior temperature reading is made to determine whether the heating stages already turned on are bringing the temperature back to the set point. If not, output for increasing the 5 stages heating the bed is implemented. The function of this routin~ is to avoid overshooting the set point and overmanipulating the devices that bring stages on and off.
The procedure for HEAT STAGE DOWN is entered if the zone heat is less than the zone heat set point. A procedure almost identical to that 10 for HEAT STAGE UP is used. In other words, if a temperature is not rapidly rising, stages are not cut out until after a delay to give prior stage changes a chance to take effect.
Referring to Figures 12 and 13, the COOL STAGE UP procedure is entered if a cooling zone temperatur~ is greater than the cooling set point.
15 The COOL STAGE DOWN procedure is entered if the temperature is less than the cool set point. All zones are checked for processing by the heating and cooling procedures before the main line program moves the series of routines that are not necessarily zone specific.
Referring to Figures 14A, 14B, and 1~C, the VENT LIMITS procedure
Background Automatic control of temperature in a greenhouse by regulating heating and ventilation is old in the art. In fact, other factors affecting the growth and health of the crops being grown in the greenhouse have been 10 automatically controlled. However, in the past control has been directed to maintaining the overall greenhouse environment based upon a small number of sensors and traditional control devices such as single thermostats.
Microprocessor control of greenhouse environment has been mllch discussed in various papers. However, attempts to use computers to control the 15 greenhouse environment, to applicants' knowledge, have not been totally suecessful. One problem has been the inherently noisy (electronically speaking) environment of the greenhouse causing distortion of small mag-nitude signals. Another has been the necessity to keep the computers outside of the greenhouse itself. Thus prior greenhouse control systems have not 20 been plant or crop oriented control systems. They have not addressed the problems of controlling growth and plant health conditions directly at the growing bed or plant level. Unfortunately, the control of the overall greenhouse conditions, while providing adequate plant growth and health conditions at one bed, may not provide the proper conditions at another bed.
25 This may be due to the nonuniformity of a condition, say temperature, throughout the greenhouse or the fact that different beds are planted with different crops or even that difeerent beds planted with the same crop are at different stages in the growing cycle. Prior greenhouse control systems have not provided adequate individualized control of bed areas based upon 30 feedback of temperature, light, and humidity conditions directly over the beds.
7~8 Summary of the Invention It is an object of this invention to provide a computerized plant oriented control system for control of the greenhouse environment including, for example, temperature, light, moisture, and/or carbon dioxide concentra-tion.
It is a further object to provide a computerized plant oriented control system for minimizing the amount of electrical or fuel energy required by the greenhouse and to maintain the temperature over the crop beds relative to a control point, say, maximum temperature, minimum temperature, and/or lD dew point.
It is a still further object to provide a computerized plant oriented control system which anticipates changes in the conditions over the crop beds by sensing remote conditions such as light above shades, external tempera-tures, wind velocity and direction.
It is yet another object of this invention to provide a plant oriented control system for programming growth rates by maintaining one or more conditions such as temperature, mist, irrigation, and carbon dioxide con-centration in the atmosphere over the beds as a function of the available light and/or a controlled amount of light incident the crop bed.
It is an object of one embodiment of this invention to provide a computerized plant oriented control system that as a function of light, temperature, and humidity over the beds and the age of the crops provides the amount of mist or irrigation necessary to insure healthful propagation and growth of the crop.
It is a feature according to this invention that a greenhouse has a plurality of sensing zones and a plurality of control zones which are not contiguous and wherein each sensing zone is provided individualized environ-mental control based upon its particular needs. According to an especially sophisticated embodiment of this invention where control conditions are changed from time to time, the control algorithms in the microcomputer witl7in the greenhouse may be changed by downloading from a host computer located external to the greenhouse and, for example, serving more than one greenhouse.
It is a still further advantage according to this invention to provide a plant oriented crop ~ontrol system that is extremely versatile in its accommodation to the type of heating and cooling and other environmental '7Q~i~
control systems already in place in a majority of existing greenhouses notwithstanding the diversity of the existing systems.
The plant oriented control system makes proper decisions based upon the needs of the plants or crops and will give the grower a more energy efficient method of control over the greenhouse environment. The system includes components that collect data such as temperature, light, humidity, wind speed and direction. A central microcomputer unit uses the data obtained to make decisions and act upon them. The microcomputer is programmed with one or more algorithms to mal~e the decisions. The algorithms may be modified depending upon the nature of the crop and the greenhouse system being controlled. The plant oriented control system provides a fully automated greenhouse environment with the ability to monitor and control all applicable conditions.
In it broadest expression, the computerized plant oriented control system comprises structure defining a plurality of sensing zones, structure defining a plurality of control zones and a microcomputer within the greenhouse programrned with algorithms or tasks for maintaining at least one environmental condition in the control zones to promote the health and growth of the crop or crops. For those embodiments which relate to anticipatory control condition, sensors remote from the bed such as external temperature, wind speed and wind direction sensors are required. For those embodiments involving programmed plant growth wherein conditions above the erop bed are controlled as a function of the crop age, the microcomputer must include a real time clock.
As the terms are used herein, a "sense zone" or "sensing zone" is a bed area, preferably not in excess of about 3,000 square feet all planted with the same crop at about the same time having at least two spaced temperature sensors positioned directly over and near ~within about three feet) of the bed, a light sensor directly over and near the bed and an aspirated humidity sensor directly over and near the bed. As used herein, various "control zones" may include a heating control zone, cooling control zone, misting control zone, irrigating control zone, shade control zone, heat retention control zone, horizontal flow control zone, and carbon dioxide atmosphere control zone. Each control zone has associate~ with it a controllable device for affecting the environment within the zone. A heating control zone comprises a bed area, including at least one sensing zone, that ~7~58 - has a controllable heating element associated therewith. A cooling control zone comprises a bed area, including at least one sensing zone, that has a controllable cooling system associated therewith. This may simply be a cross ventilation pathway controlled by one or more vents. ~ misting control zone 5 comprises a bed area, usually one sensing æone, having controllable water spray over the bed. An irrigating control zone comprises a bed area, usually one sensing zone, having a controllable bed watering system. A shade control zone comprises a bed area, including at least one sensing zone having a controllable sunscreen or shade assoeiated therewith. The shade control zone 10 might become a heat retention zone at night as radiative cooling can be controlled by the presence or not of the screen or shade over the bed. A
horizontal flow control zone is a bed area, including at least one sensing zone, that has a controllable horizontal circulation fan associated therewith to prevent stratification when no ventilation is being used. A carbon dioxide 15 atmosphere control zone comprises a bed area, generally the entire enclosed greenhouse, having means for generating carbon dioxide. It should be noted that the various control zones need not be contiguous but very often are overlapping. (For example, a large greenhouse may have two cooling zones but many heating zones.) Controllable devices associated with the control 20 zones are devices which may be activated, for example, by application of an AC current such as a solenoid control valve or an AC motor controlled by a motor controller which controller provides the function of starting, stopping, and reversing a motor.
As stated above, the microcomputer must be programmed with 25 algorithms or tasks to enable it to make intelligent decisions. An algorithm or task, at spaced intervals, inputs the digitalized temperatures (two for each bed) and averages the temperatures for each bed or sense zone. The average temperature is then compared to a set point, for example a maximum temperature, a minimum temperature or the dew point. Depending upon the 30 relationship of the average temperature sense and the set point, the computer will output control signals to adjust the controllable devices such as heating or ventilating equipment to adjust the temperature relative to the set point temperature.
Additionally, an algorithm may maintain the temperature and perhaps 35 mist, irrigation, or carbon dioxide atmosphere as a function of the availablelight to provide a desired growth rate and/or to make efficient use of energy.
., 7~S8 On a cloudy day, heat and carbon dioxide would not be wasted. A
second control criteria could be imposed with such an algorithm;
namely, to control the growth rate to be the maximum possible or to control the growth rate -to be that which is estimated to bring the crop to the desired size at a desired date. The latter criteria, of course, require a clock to log time from planting and may require a controllable shade. An algorithm or task according to one em-bodiment of this invention maintains the temperature by advance adjustments of controllable elements based upon changes in the remote sensors as well as upon the data from overhead sensors.
According to another specific embodiment, an algorithm or task initiates mist or irrigation as a function of light, temperature, humidity and age of the crop.
Thus, in accordance with a broad aspect of the invention, there is provided a system for controlling environ-mental conditions in greenhouses having a plurality of crop beds within one greenhouse enclosure arranged into a plurality of sense zones and a plurality of control zones comprising:
a. a plurality of sensors stationed over crop beds within each sense zone comprising an aspirated enclosure and means therein for generating analog electrical signals indicative of wet bulb and dry bulb temperatures and also means for generating an analog electrica] signal indicative of incident light over the bed;
b. a microcomputer located within the greenhouse comprising:
~Z~7~
- 5a -i. a central processing unit with associated scratch memory and program memory sections;
ii. an anolog to digital input section :Eor receiving the analog electrical signals from the sensors;
iii. an output section for converting computer logic signals to electrical signals at power levels to operate electro-mechanical apparatus; and iv. serial digital pathway means or connecting the central processing unit, input section and output section;
c. said program memory programmed with:
i. a task for inputting digital data from the in-put section indicative of wet bulb and dry bulb temperatures and for calculating the moisture content of the atmosphere over each bed and for inputting digital data from the input section indicative of light intensity;
ii. a task for selecting temperature and moisture command levels based upon the intensity of incident light and comparing the input temperature and moisture content with said selected command levels for each sense zone; and iii. a task which in response to said comparison generates commands to the output section capable of initiating therethrough electromechanical action asso~iated with each control zone to move the temperature and moisture content for each sense zone toward the selected command levels.
7~58 - 5b -The Drawings Further features and other objects and advantages of this invention will become clear from the following detailed description made with reference to the drawings in which Figure 1 ls a schematic illustrating a greenhouse, sensing zones and control zones according to this invention;
Figure 2 is a function aiagram of an input card for use with a microcomputer used in the practice of this invention;
Figure 3 is a function diagram of an output card for 10use with a microcomputer according to this invention;
Figure 4 is a function diagram of a microcomputer use-ful for the practice of this invention;
Figure 5 illustrates the serially transmitted data format useful with this invention;
Figure 6 is a flow chart for a main program useful according to this invention;
Figure 7 is a flow chart of a SENSE procedure called by the main program;
Figure 8 is a flow chart of an ALAR~S procedure called 20by the main program;
Figure 9 is a flow chart of a HEAT CONSERVATION proce-dure called by the main program;
Figure 10 is a flow chart of a HEAT STAGE UP procedure called by the main program;
~7~51~
Figure 11 is a flow chart of a HEAT STAGE DOWN procedure called by the main program;
Figure 12 is a flow diagram of a COOL STAGE UP procedure called by the main program;
Figure 13 is a flow diagram of a COOL STAGE DOWN procedure called by the main program;
Eigures 14A, 14B and 14C are flow diagrams of a VENT LIMITS
procedure called by the main program;
Figure 15 is a flow diagram of a VENT DeRH (decondensate by venting) procedure called by the main program;
Figure 16 is a flow diagram of a VARIABLE SHADE procedure called by the main program;
Figure 17 is a flow diagram of a P~OTOTT~F.RMAT. BLANKET
procedure;
Figure 18 is a flow diagram of a HEAT DeRH (decondensate by heating) procedure;
Figure 19 is a flow diagram of a LIGHT ACCUMULATOR procedure;
Figures 20A, 20B, and 20C are flow diagrams of a HEAT SET POINT
DRIVER based upon average light and accumulated light;
Figure 21 is a flow diagram for a PIPE TEMPERATURE ANTICI-PATOR procedure; and Figures 22A, 22B, and 22C are flow diagrams of a procedure that generates a factor for the PIPE TEMPERATURE ANTICIPATOR procedure based upon variation between zone temperature (as measured) and set point temperature (desired).
Detailed Description The equipment for the plant operated control system according to this invention can be considered in three groups based upon their functions.
First there are the sensors. These collect greenhouse data such as temperature, humidity, light, and such external conditions as temperature, light, humidity, wind speed and direction. A second group comprises the microcomputer with associated input and output boards. A third group comprises the valves and motors necessary to carry out the actions that bring about a change in the greenhouse environment.
i8 The grower must determine the number of "control zones" he intends to include in his greenhouse. A zone is defined as one part of the total greenhouse of which individual, independent control can be maintained. The type and location of e2cisting equipment within a greenhouse determine the 5 establishment of control zones. Sensing zones and control zones have already been described. Heating and cooling zones need not be related so it is not necessary that they each have the same division. ~or example, as a practical matter, an acre of greenhouse may have sixteen heatingr zones but only two cooling zones.
The crops in the adjacent sense zones within the same control zone theoretically might require a controlled condition to be different. However, due to the nature of crop requirements and the usual greenhouse control configurations, this is seldom the case. With some planning of crop placement, the problem can be avoided. For example, most sense zones are 15 coincident with a control zone for heating (for example, hot pipes); misting or irrigating. These are conditions that may vary from crop to crop. On the other hand, ventilation zones usually span a number of sense zones. The ventilation requirement is generally about the same for all crops.
Referring now to Figure 1, the system hardware according to this 20 invention is shown schematically. The large rectangle represents the greenhouse enclosure 10. Located within the greenhouse is a microcomputer 12 having associated A/D input sections and AC output (triac control) sections. Two IO stations 14 and 15 are spaced from the microcomputer.
The IO stations have associated A/D input sections and AC output sections 25 identical with those directly associated with the microcomputer and, as will be explained, they are functionally equivalent to those directly associated with the microcomputer. All A/D input sections and AC output sections are connected to the microcomputer by one common asynchronous serial address-data-control pathway referred to in here as the data pathway (DP~V). It is 30 possible that IO stations will be unnecessary in a small greenhouse. In fact,for the number of sense zones illustrated in Figure 1, the A/D input systems and AC output sections directly housed within the microcomputer would be sufficient. The use of IO stations depends upon the number of sense zones being monitored and the spacing thereof. It is desirable to reduce the length 35 of the sense input wires carrying analog signals and thus the additional IO
stations may be required.
~Z~7~5~3 The greenhouse of ~igure 1 is divided into eight sensing zones, each having two sense stations a, b, over the bed. Sense stations are aspirated enclosures for housing at least a dry bulb temperature sensor and often both dry b~b and wet bulb temperature sensors and for generating an analog 5 signal indicative of these temperatures. A light sens;ng station for generating an analog signal indicative of light intensity over the bed is often associated with the temperature sensing station. A second temperature sensing station is always associated with each sense zone. The two temperatures are averaged by the microcomputer to obtain a temperature representative of 10 the sense zone temperature.
Referring again to Figure 1, the greenhouse is further divided into a number of control zones. For example, four zones labelled A, B, C, and D
have individually controlled heating means. The heating means rmay comprise a number of possible devices, for example, on-off steam heating below the 15 beds, proportional hot-water heating below the beds, infrared heaters above the beds or gas fired unit heaters above the beds.
To illustrate that the control zones may overlap, two ventilation control zones are illustrated; one extending to heating control zones A and B and the other to heating control zones C and D. Ventilation may be by 20 opening vents on each side of the greenhouse or by turning on fans that draw air across the ventilation zone. The intake vents may or may not have evaporation coolers associated therewith depending upon the application.
Shade zones comprising canvas shades that are drawn horizontally over the beds just below the rafters may be arranged in zones. In the example of 25 Figure 1, there are two shade zones comprising control zones A and B and control zones C and D. The shades are useful for two purposes: In the daytime, the drawn shades reduce sunlight and temperature of the beds. At night the shades help to maintain temperature over the beds by reducing radiation cooling. Located above the shade is a light sensor 16 enabling the 30 detection of the availability of sunlight when the shade is drawn.
To this point, all of the elements of the system being described are positioned within the greenhouse enclosure. Two groups of optional elements may be positioned external to the greenhouse. An external temperature sensor, wind speed sensor, and wind direction sensor may be provided for 35 anticipatory control as will be explained herein. Also a host computer for downloading new control algorithms or tasks to the microcomputer may be positioned external to the greenhouse.
~Z~7~
g Plant operated control systems must gain an adequate amount of information from each zone to be able to make the proper decisions for the correct levels of control. Each zone contains at least two temperature sensors, one light sensor, and one humidity sensor. The overbed sensors are S housed in aspirated fan boxes. A light sensor must, of course, be mounted on top of the aspirated fan box. The temperature sensors comprise solid-state dry bulb temperature monitoring devices having a range -10C to 100C. The humidity sensor is a solid-state wet bulb temperature monitoring device. When used in conjunction with the dry bulb described above this provides a very precise humidity measurement. The light energy sensor measures light intensity in foot candles. Two types of sensors are used. The first provides very precise measurement of light in the range of 0 to 800 foot candles for use with artiîicial day length control. The second is a general daylight sensor that provides less resolution in a much wider photosynthetic range of 0 to 4,000 foot candles; that is, the range at which actual plant growth occurs. Typically the temperature sensors comprise a heat sensitive diode, say, LM335 with associated calibration potentiometers. They are commercially available calibrated for a 2.73 volt output in ice water and a 10 millivolt per degree Kelvin output.
To provide more efficient control, conditions outside of the green-house are also monitored. This enables the plant oriented control system to anticipate the greenhouse needs prior to any internal changes and also aids in conserving energy. A ten-mile per hour wind speed increase increases the heating load approximately fifteen percent.
The microcomputer comprises a microprocessor, RAI~ memory, ROM
memory, a 16-place l;eypad input and an 8-digit display, for example. The computer is enclosed within an air-tight cabinet; preferably protected from both direct sunlight and other temperature extremes. C~mputers are available at rated operating temperatures between 0 and 70C (32 and 158F). Operational greenhouses have an internal temperature well within this range.
The sense sections of the microcomputer, whether in the same cabinet or in an IO cabinet spaced thereflom, collects analog clata from the above mentioned sensory elements and converts it to a digital signal with an analog to digital signal converter.
:~2~ 58 Figure 2 illustrates an input card that coordinates sixteen individual sensory inputs for transmission to the computer. It is possible to connect a number of these sections to the computer permitting access to a large number of individual sensory inputs. There are shown two 8-channel analog 5 input sections comprising multiplexers 20, 21 for selecting one of eight input signals, analo~ to digital converters 22, 23 and asynchronous receiver-transmitter remote controllers (ARTtRC) 24, 25 for transmitting the serialized digital signal to the microcomputer. The input section also includes a 4-channel on-off input useful for reading limit switches which 10 comprises an asynchronous receiver-transmitter remote controller 26. This unit is also used to select the analog section and the channel within the analog section for application to the A/D converters through the multi-plexers. These input sections may be associated in the cabinet with the microcomputer or on a remotely located cabinet.
The microcomputer also comprises an AC output section which outputs control signals to controlled devices as directed by the computer. A
number of these output sections may be connected to the computer permitting control of a large number of devices. These output sections may be associated in the cabinet with the microcomputer or in a remotely located 20 IO cabinet. In a typical application, the output section provides a direct method of control of any electrical device present in the greenhouse through use of 24 volt relays.
Referring to Figure 3, there is shown a function diagram of an output section which includes an asynchronous receiver-transmitter remote con-25 troller 30 for receiving serialized digital commands from the microprocessorand for outputting a signal on one of eight channels for controlling an optically coupled triac 31 which in turn control higher duty triacs 32.
The communication between the microcomputer and the input and output sections is by master and slave configuration of two ARllRC units.
30 The master ART/RC 40 (see Figure 4) is associated with the microprocessor.
The slave ART/RC units (24, 25, 26, 30) are associated with the input and output sections. ART/RC devices are available, for example, from the National Mi~ll 54250. The simplest communication route between the master A~T/RC and its slave is by means of a twisted pair of wires or a coaxial 35 cable. The single line IO circuit of all ART/RC devices is an open drain driver ouput. Because the line is floating, the master ART/RC has the IO
~Z(~7~S~
communication line pulled up via one K ohm resistor. The pull up provides excellent data transmission over a distance of about 2,000 feet using standard coa2sial cable. Care should be talcen to reduce capacitance and resistance of this line and maintain good ground continuity between the master and slave 5 units.
Pulse width modulation techniques are used by the ART/RC to transmit the digitalized data. ~ practical pulse frequency is approximately ~50 K hertz. In practice, the frequency between each ART/RC can vary as much as 50,~ before performance is affected. This wide tolerance provides 10 excellent noise immunity, especially in heavy industrial environments.
Figure 5 illustrates the serially transmitted data format used by the ART/RC devices. Data in this format put upon the eommon pathway is read or written by or from the ART/RC device connected to the pathway having the 7-bit address first placed upon the line.
Referring more specifically to Figure 4, a microcomputer useful according to this invention diagram is shown in function format. The microprocessor unit 41 is central operative element and may have a resident basic interpreter, for example, the INS 8073. The computer has associated RAM memory 42 and EPROM memory 43 and in some embodiments of this 20 invention a real time clock 44. All elements are connected by address bus 45 and data bus ~6 and control lines not illustrated.
Hardware particularly suitable for use in the pract;ce of this invention comprises the computer system described in the "Vanderbilt Series K-8073 Tiny Basic Microcomputer HardwareiSoftware Users Manual" copy-25 righted in 1981 by Transwave Corporation of Vanderbilt, Pennsylvania and apublication entitled "Vanderbilt 8000 Series Computer Products" copyrighted in 1982 by Transwave Corporation. The latter publication describes a twenty-channel analog to digital input card and an eight channel triac 300 watt controller card. Certain features of this system make it particularly 30 suitable for greenhollse control. All or part of the control system can be placed within the greenhouse and analog transmission of data can be minimized.
Referring now to Figure 6, a ~low chart for the main program is set forth. The program passes sequentially from an initialization routine through 35 a data gathering procedure and through a temperature adjusting procedure that are repeated for each control zone and thence through a plurality of procedures that are not necessarily zone specific.
~2V~7~5~3 After the initialization (programming of ports and clearing of memory areas, etc.) which only takes place upon start-up or reset, the program moves to the main line loop.
l~eferring to Figure 7, the first procedure in the main line loop is labelled SENSE and comprises scanning the data available at the A/D
converters and storing valid reads. The data is then assembled by zone and scaled to provide appropriate units. The new reads are averaged into the existing reads or data.
Referring to Figure 8, the next procedure is labelled ~T ARM~ and is a procedure in which temperature data is compared with high Rnd low alarm temperatures and under the conditions that a sensing station is above the high set point or below the low alarm temperatures, the sensing station is noted and an alarm device is activated. The alarm temperature for the high temperatures is affixed differential DT1 above the high temperature set point. To avoid setting off an alarm for a condition that cannot be corrected (e,g. overheating on an extremely hot day the alarm is not activated if the temperature outside exceeds the alarm temperature).
~eferring to Figure 9, the next procedure labelled HEAT CON-SERVATION is an optional energy conservation routine used late in the afternoon duri~g the cool part of the year and which procedure increases the cooling set point to allow heat to build-up in the greenhouse during the late afternoon. This increase in the set points takes place only the first time through the procedure after a preselected time before sunset when heat build-up is to be allowed.
Referring to Fi~ures 10 and 11, the program next moves to heating and cooling procedures. The heating procedures HEAT STAGE UP and HEAT
STAGE DO~N ar~ implemented when the temperature external to the greenhouse falls below the desired temperatures and the cooling procedures are implemented when the temperatures external to the greenhouse exceed the desired temperature. The HEAT STAGE UP procedure is entered if the temperature in a heating zone is less than the heat set point. The procedure compares the most recent temperature reading with the last temperature reading to determine if the zone is rapidly cooling. If so, the output for increasing the stages delivering heat to the bed is incremented (by incrementing the stages is meant, for example, if two steam pipes are already turned on a third steam pipe is turned on). If rapid cooling is not 1~7~S~3 taking place, a timer is set for a fixed time period after which a comparison of the most recent temperature reading with a prior temperature reading is made to determine whether the heating stages already turned on are bringing the temperature back to the set point. If not, output for increasing the 5 stages heating the bed is implemented. The function of this routin~ is to avoid overshooting the set point and overmanipulating the devices that bring stages on and off.
The procedure for HEAT STAGE DOWN is entered if the zone heat is less than the zone heat set point. A procedure almost identical to that 10 for HEAT STAGE UP is used. In other words, if a temperature is not rapidly rising, stages are not cut out until after a delay to give prior stage changes a chance to take effect.
Referring to Figures 12 and 13, the COOL STAGE UP procedure is entered if a cooling zone temperatur~ is greater than the cooling set point.
15 The COOL STAGE DOWN procedure is entered if the temperature is less than the cool set point. All zones are checked for processing by the heating and cooling procedures before the main line program moves the series of routines that are not necessarily zone specific.
Referring to Figures 14A, 14B, and 1~C, the VENT LIMITS procedure
2~ positions roof vents based upon external wind speed. Roof vents when opened are very susceptible to wind damage. The procedure sets restrictions within which the COOL STAGE UP and DOWN procedures can work. It sets maximum cooling stage (vent openings) for given wind conditions.
Referring to Figure 15, the VENT DeRH (decondensate relative 25 humidity) procedure is a disease control routine that is crop specific. The overall objective is to avoid free water or cycling through the dew point.
The procedure is entered if the relative humidity is greater than the set point relative humidity and the outside temperature does not preclude opening the vents. A routine delay before venting action is taken to allow for 30 stabilization and self-correction. If after the the delay, the sensed relative humidity is greater than the set point relative humidity, vents are opened.
Referring to Figure 16, the VARIABLE S~IADE routine tests for available light greater than the maximum light set point. If so, a check is made to determine if the last movement of the shade or curtain was in the 35 opening (uncovering) direction. If so and if after a delay the condition persists, the curtain stage is incremented. On the other hand, if the ~7~S~
available light is less than the minimum light set point, a check is made to determine if last movement of the stage was to close the curtain (cover the crop). If so and if after a delay the condition persists, the curtain stage is decremented.
The PHOTOTHERMAL BLANI~ET procedure illustrated in Figure 17 tests to determine if the outside temperature is less than the rnaximum thermal blanket temperature and if the outside light is less than the maximum thermal blanket light. If so, the curtain is closed. If the curtain is already closed, the procedure obtains the month and day and determines the opening times for the curtain (after sunrise). The curtain must be opened in stages to allow slow intermixing of cooling air over the blanket with warmer air below the blanket or else await sufficient sunlight heating over the air above the blanket.
The HEAT DeRH (heat decondensate relative humidity) procedure is illustrated in Figure 18. The procedure is completely executed if the heat set point and original set points are equal and the measured relative humidity greater than the maximum relative humidity. If the heat set point is not already ten degrees above the outside temperature, the heat set point will be set to be ten degrees above the outside temperature causing rapid decondensation on the windows of the greenhouse resulting in drying of the atmosphere in the greenhouse.
The DEVICE/MODULATING DEVICE ACTUATOR is a procedure that adds stages and deietes stages from devices that are supposed to be a stage maximum or stage minimum to assure, for example, that valves are fully opened or fully closed. Hence no feedback is required from these control devices to the computing system. The adding of stages, for example, to fully closed devices is not detrimental to the devices since they have their own limit switches.
The LIGHT ACCUMULA'r~)R procedure integrates light intensity over time. Referring to Figure 19, a particular LIGHT ACCUMULATOR
procedure is described. The procedure first checks to determine if a new accumulator period should be started and if so, the variable LaCcm is set to zero. If not, the procedure checks to determine if a collection interval has passed. If so, the variable LaVg is set to zero. Otherwise, the variable LaVg is reassigned by adding the existing light level (lite) to the existing LaVg ' ;
7~5~
multiplied by a weight factor Lrd (number of average reads). The total is scaled by Lrd plus 1. The amount of light incident the zone is accumulated in the variables LaCcm (high order bit) and MLaCcm (low order bit~ scaled so that the maximum value of LaCcm is no more than 255. The values of LaVg 5and LaCcm are used in the ~IEAT SET POINT DRIVER procedure.
The SET POINT DRIVER is a procedure for changing set points to provide for controlled growth conditions. This is the procedure that accepts an algorithm, for example, which maintains the temperature and perhaps mist, irrigation or carbon dioxide atmosphere as a function of available light 10to provide a desired growth rate and/or to malce efficient use of energy. It is also the procedure which accepts an algorithm which may control the growth rate to be the maximum possiMe. A procedure for setting command levels to obtain maximum growth rate might be as follows: first the available light is sensed. Next, the carbon dioxide level is adjusted upward 15toward a maximum which is based upon the available light. ~inally the best temperature is calculated from the actual light and the carbon dioxide levels.
A HEAT SET POINT DRIVER that adjusts the heat set points in response to the LaVg (average iight) and the LaCcm (accumulated light) is described in Figures 20A, 20B, and 20C. The output of the calc~ation in the 20portions of the procedure shown in Figures 20A and 20B is a rate that the existing set point is to changed. Once that rate is established, an interval is also established after which the existing set point is incremented or decremented by one degree at a time (see entry point C on Figure 20C).
Thus, the calculation based upon LaVg and LaCcm made, for example every 25thirty minutes, and in the following thirty minutes the set point is increasedor decreased one degree at a time at spaced intervals (ten minute intervals if the rate of change is six degrees per minute).
In this procedure, temperature set point Tsp is set between a minimum temperature Tmn (say 58F) and a maximum temperature TmX (say 3068F) preselected for the specific crop. If the average light LaVg is below a minimum light Lmn (say zero foot candles) required for significant growth, the minimum temperature is selected. If the light is above LmX (say 4000 foot candles) i.e. the light intensity at which growth is to be pushed, the temperature is set for TmX- Between light intensities of LmX and Lmn the 35temperature is adjusted proportionally between TmX and Tmn.
7~8 The value Tsp is calculated by yet another algorithm based upon LaCcm. If that value (R) is less than the value of Tsp already calculated the value of R is adopted as Tsp.
The difference B between Tsp and the established set point is determined and the maximum difference is constrained by maximum increase RmX and minimum decrease FmX differences. The differences are then converted to a minutes per degree (MPD) change in the set point over the following interval of Sjnt minutes.
The PIPE TEhlPERATURE anticipator procedure is a procedure that predicts the pipe temperatures required to maintain a given temperature at the zone based upon outside temperatures. The procedure of ~igures 22A, 22B, and 22C establishes a value for R which is a correction factor used in the main PIPE TEMPERATURE ANTICIPATOR procedure shown in Figure 21.
The correction factor is based upon a comparison of the last zone temperature and the set point temperature.
The main PIPE TEMPERATURE ANTICIPATOR procedure is based upon the difference between outside temperature and the set point temperature and the capability of the heating system to respond to that difference. The maximum differential temperature that the heating system can overcome depends, of course, on the particular greenhouse and the particular heating system. The pipe temperature PmX is the max;mum pipe temperature at maximum heat output. The pipe temperature Pmn when no output is being required of the heating system may be taken as the ambient temperature. The target temperature Ptar for the pipes is assigned between PmX and Pmn taking into consideration the solar heating. (See the factor lite times Rad. Rad is a factor for each zone that scales the raw light energy sensor readings.) Having thus described the invention in the detail and with the particularity required by the Patent Laws, what is desired protected by I.etters Patent is set forth in the following claims.
Referring to Figure 15, the VENT DeRH (decondensate relative 25 humidity) procedure is a disease control routine that is crop specific. The overall objective is to avoid free water or cycling through the dew point.
The procedure is entered if the relative humidity is greater than the set point relative humidity and the outside temperature does not preclude opening the vents. A routine delay before venting action is taken to allow for 30 stabilization and self-correction. If after the the delay, the sensed relative humidity is greater than the set point relative humidity, vents are opened.
Referring to Figure 16, the VARIABLE S~IADE routine tests for available light greater than the maximum light set point. If so, a check is made to determine if the last movement of the shade or curtain was in the 35 opening (uncovering) direction. If so and if after a delay the condition persists, the curtain stage is incremented. On the other hand, if the ~7~S~
available light is less than the minimum light set point, a check is made to determine if last movement of the stage was to close the curtain (cover the crop). If so and if after a delay the condition persists, the curtain stage is decremented.
The PHOTOTHERMAL BLANI~ET procedure illustrated in Figure 17 tests to determine if the outside temperature is less than the rnaximum thermal blanket temperature and if the outside light is less than the maximum thermal blanket light. If so, the curtain is closed. If the curtain is already closed, the procedure obtains the month and day and determines the opening times for the curtain (after sunrise). The curtain must be opened in stages to allow slow intermixing of cooling air over the blanket with warmer air below the blanket or else await sufficient sunlight heating over the air above the blanket.
The HEAT DeRH (heat decondensate relative humidity) procedure is illustrated in Figure 18. The procedure is completely executed if the heat set point and original set points are equal and the measured relative humidity greater than the maximum relative humidity. If the heat set point is not already ten degrees above the outside temperature, the heat set point will be set to be ten degrees above the outside temperature causing rapid decondensation on the windows of the greenhouse resulting in drying of the atmosphere in the greenhouse.
The DEVICE/MODULATING DEVICE ACTUATOR is a procedure that adds stages and deietes stages from devices that are supposed to be a stage maximum or stage minimum to assure, for example, that valves are fully opened or fully closed. Hence no feedback is required from these control devices to the computing system. The adding of stages, for example, to fully closed devices is not detrimental to the devices since they have their own limit switches.
The LIGHT ACCUMULA'r~)R procedure integrates light intensity over time. Referring to Figure 19, a particular LIGHT ACCUMULATOR
procedure is described. The procedure first checks to determine if a new accumulator period should be started and if so, the variable LaCcm is set to zero. If not, the procedure checks to determine if a collection interval has passed. If so, the variable LaVg is set to zero. Otherwise, the variable LaVg is reassigned by adding the existing light level (lite) to the existing LaVg ' ;
7~5~
multiplied by a weight factor Lrd (number of average reads). The total is scaled by Lrd plus 1. The amount of light incident the zone is accumulated in the variables LaCcm (high order bit) and MLaCcm (low order bit~ scaled so that the maximum value of LaCcm is no more than 255. The values of LaVg 5and LaCcm are used in the ~IEAT SET POINT DRIVER procedure.
The SET POINT DRIVER is a procedure for changing set points to provide for controlled growth conditions. This is the procedure that accepts an algorithm, for example, which maintains the temperature and perhaps mist, irrigation or carbon dioxide atmosphere as a function of available light 10to provide a desired growth rate and/or to malce efficient use of energy. It is also the procedure which accepts an algorithm which may control the growth rate to be the maximum possiMe. A procedure for setting command levels to obtain maximum growth rate might be as follows: first the available light is sensed. Next, the carbon dioxide level is adjusted upward 15toward a maximum which is based upon the available light. ~inally the best temperature is calculated from the actual light and the carbon dioxide levels.
A HEAT SET POINT DRIVER that adjusts the heat set points in response to the LaVg (average iight) and the LaCcm (accumulated light) is described in Figures 20A, 20B, and 20C. The output of the calc~ation in the 20portions of the procedure shown in Figures 20A and 20B is a rate that the existing set point is to changed. Once that rate is established, an interval is also established after which the existing set point is incremented or decremented by one degree at a time (see entry point C on Figure 20C).
Thus, the calculation based upon LaVg and LaCcm made, for example every 25thirty minutes, and in the following thirty minutes the set point is increasedor decreased one degree at a time at spaced intervals (ten minute intervals if the rate of change is six degrees per minute).
In this procedure, temperature set point Tsp is set between a minimum temperature Tmn (say 58F) and a maximum temperature TmX (say 3068F) preselected for the specific crop. If the average light LaVg is below a minimum light Lmn (say zero foot candles) required for significant growth, the minimum temperature is selected. If the light is above LmX (say 4000 foot candles) i.e. the light intensity at which growth is to be pushed, the temperature is set for TmX- Between light intensities of LmX and Lmn the 35temperature is adjusted proportionally between TmX and Tmn.
7~8 The value Tsp is calculated by yet another algorithm based upon LaCcm. If that value (R) is less than the value of Tsp already calculated the value of R is adopted as Tsp.
The difference B between Tsp and the established set point is determined and the maximum difference is constrained by maximum increase RmX and minimum decrease FmX differences. The differences are then converted to a minutes per degree (MPD) change in the set point over the following interval of Sjnt minutes.
The PIPE TEhlPERATURE anticipator procedure is a procedure that predicts the pipe temperatures required to maintain a given temperature at the zone based upon outside temperatures. The procedure of ~igures 22A, 22B, and 22C establishes a value for R which is a correction factor used in the main PIPE TEMPERATURE ANTICIPATOR procedure shown in Figure 21.
The correction factor is based upon a comparison of the last zone temperature and the set point temperature.
The main PIPE TEMPERATURE ANTICIPATOR procedure is based upon the difference between outside temperature and the set point temperature and the capability of the heating system to respond to that difference. The maximum differential temperature that the heating system can overcome depends, of course, on the particular greenhouse and the particular heating system. The pipe temperature PmX is the max;mum pipe temperature at maximum heat output. The pipe temperature Pmn when no output is being required of the heating system may be taken as the ambient temperature. The target temperature Ptar for the pipes is assigned between PmX and Pmn taking into consideration the solar heating. (See the factor lite times Rad. Rad is a factor for each zone that scales the raw light energy sensor readings.) Having thus described the invention in the detail and with the particularity required by the Patent Laws, what is desired protected by I.etters Patent is set forth in the following claims.
Claims (10)
1. A system for controlling environmental conditions in greenhouses having a plurality of crop beds within one greenhouse enclosure arranged into a plurality of sense zones and a plurality of control zones comprising:
a. a plurality of sensors stationed over crop beds within each sense zone comprising an aspirated enclosure and means therein for generating analog electrical signals indicative of wet bulb and dry bulb temperatures and also means for generating an analog electrical signal indicative of incident light over the bed;
b. a microcomputer located within the greenhouse comprising:
i. a central processing unit with associated scratch memory and program memory sections;
ii. an analog to digital input section for receiving the analog electrical signals from the sensors;
iii. an output section for converting computer logic signals to electrical signals at power levels to operate electro-mechanical apparatus; and iv. serial digital pathway means for connecting the central processing unit, input section and output section;
c. said program memory programmed with:
i. a task for inputting digital data from the input section indicative of wet bulb and dry bulb temperatures and for calculating the moisture content of the atmosphere over each bed and for inputting digital data from the input section indicative of light intensity;
ii. a task for selecting temperature and moisture command levels based upon the intensity of incident light and comparing the input temperature and moisture content with said selected command levels for each sense zone; and iii. a task which in response to said comparison generates commands to the output section capable of initiating therethrough electromechanical action associated with each control zone to move the temperature and moisture content for each sense zone toward the selected command levels.
a. a plurality of sensors stationed over crop beds within each sense zone comprising an aspirated enclosure and means therein for generating analog electrical signals indicative of wet bulb and dry bulb temperatures and also means for generating an analog electrical signal indicative of incident light over the bed;
b. a microcomputer located within the greenhouse comprising:
i. a central processing unit with associated scratch memory and program memory sections;
ii. an analog to digital input section for receiving the analog electrical signals from the sensors;
iii. an output section for converting computer logic signals to electrical signals at power levels to operate electro-mechanical apparatus; and iv. serial digital pathway means for connecting the central processing unit, input section and output section;
c. said program memory programmed with:
i. a task for inputting digital data from the input section indicative of wet bulb and dry bulb temperatures and for calculating the moisture content of the atmosphere over each bed and for inputting digital data from the input section indicative of light intensity;
ii. a task for selecting temperature and moisture command levels based upon the intensity of incident light and comparing the input temperature and moisture content with said selected command levels for each sense zone; and iii. a task which in response to said comparison generates commands to the output section capable of initiating therethrough electromechanical action associated with each control zone to move the temperature and moisture content for each sense zone toward the selected command levels.
2. A system for controlling environmental conditions in greenhouses have a plurality of crop beds within one greenhouse enclosure arranged into a plurality of sense zones and a plurality of control zones comprising:
a. a plurality of sensors stationed over crop beds within each sense zone comprising an aspirated enclosure and means therein for generating analog electrical signals indicative of wet bulb and dry bulb temperatures and also means for generating an analog electrical signal indicative of incident light over the beds;
b. a microcomputer located within the greenhouse comprising:
i. a central processing unit with associated scratch memory and program memory sections;
ii. an analog to digital input section for receiving the analog electrical signals from the sensors;
iii. an output section for converting the computer logic signals to electrical signals at power levels to operate electro-mechanical apparatus; and iv. serial digital pathway means for connecting the central processing unit, input section and output section;
c. said program memory programmed with:
i. a task for inputting digital data for the input section indicative of wet bulb and dry bulb temperatures and for calculating the moisture content of the atmosphere over each bed and for inputting digital data from the input section indicative of light intensity;
ii. a task for comparing the intensity of the incident light with a preselected command level and for selecting temperature and moisture command levels based upon the intensity of incident light and comparing the input temper-ature and moisture data with said selected command levels for each sense zone; and iii. a task which in response to the comparison of the intensity of the incident light with the preselected command level generates commands to the output section capable of initiating therethrough electromechanical action to adjust intensity of the light over the bed toward the preselected command and which in response to the comparison of the input temperature and moisture content with the said selected command levels generates commands to the output section capable of initiating therethrough electromechan-ical action associated with each control zone to move the temperature and moisture content for each sense zone toward the selected command levels.
a. a plurality of sensors stationed over crop beds within each sense zone comprising an aspirated enclosure and means therein for generating analog electrical signals indicative of wet bulb and dry bulb temperatures and also means for generating an analog electrical signal indicative of incident light over the beds;
b. a microcomputer located within the greenhouse comprising:
i. a central processing unit with associated scratch memory and program memory sections;
ii. an analog to digital input section for receiving the analog electrical signals from the sensors;
iii. an output section for converting the computer logic signals to electrical signals at power levels to operate electro-mechanical apparatus; and iv. serial digital pathway means for connecting the central processing unit, input section and output section;
c. said program memory programmed with:
i. a task for inputting digital data for the input section indicative of wet bulb and dry bulb temperatures and for calculating the moisture content of the atmosphere over each bed and for inputting digital data from the input section indicative of light intensity;
ii. a task for comparing the intensity of the incident light with a preselected command level and for selecting temperature and moisture command levels based upon the intensity of incident light and comparing the input temper-ature and moisture data with said selected command levels for each sense zone; and iii. a task which in response to the comparison of the intensity of the incident light with the preselected command level generates commands to the output section capable of initiating therethrough electromechanical action to adjust intensity of the light over the bed toward the preselected command and which in response to the comparison of the input temperature and moisture content with the said selected command levels generates commands to the output section capable of initiating therethrough electromechan-ical action associated with each control zone to move the temperature and moisture content for each sense zone toward the selected command levels.
3. A system for controlling environmental conditions in greenhouses having a plurality of crop beds within one greenhouse enclosure arranged into a plurality of sense zones and a plurality of control zones comprising:
a. a plurality of sensors stationed over crop beds within each sense zone comprising an aspirated enclosure and means therein for generating analog electrical signals indicative of wet bulb and dry bulb temperatures and also means for generating an analog electrical signal indicative of incident light over the bed;
b. a microcomputer located within the greenhouse comprising:
i. a central processing unit with associated scratch memory program memory sections and a real time clock;
ii. an analog to digital input section for receiving the analog electrical signals from the sensors;
iii. an output section for converting the computer logic signals to electrical signals at power levels to operate electro-mechanical apparatus; and iv. serial digital pathway means for connecting the central processing unit, input section and output section;
c. said program memory programmed with:
i. a task for reading the real time clock and setting and updating the duration of time a crop has been growing;
ii. a task for inputting digital data from the input section indicative of wet bulb and dry bulb temperatures and for calculating the moisture content of the atmosphere over each bed and for inputting digital data from the input section indicative of light intensity;
iii. a task for selecting temperature and moisture levels based upon the intensity of the incident light and the time the crop has been growing and comparing the input tempera-ture and moisture data with said selected levels for each sense zone; and iv. a task which in response to said comparison generates commands to the output section capable of initiating therethrough electromechanical action associated with each control zone to move the temperature and moisture content for each sense zone toward the selected levels.
a. a plurality of sensors stationed over crop beds within each sense zone comprising an aspirated enclosure and means therein for generating analog electrical signals indicative of wet bulb and dry bulb temperatures and also means for generating an analog electrical signal indicative of incident light over the bed;
b. a microcomputer located within the greenhouse comprising:
i. a central processing unit with associated scratch memory program memory sections and a real time clock;
ii. an analog to digital input section for receiving the analog electrical signals from the sensors;
iii. an output section for converting the computer logic signals to electrical signals at power levels to operate electro-mechanical apparatus; and iv. serial digital pathway means for connecting the central processing unit, input section and output section;
c. said program memory programmed with:
i. a task for reading the real time clock and setting and updating the duration of time a crop has been growing;
ii. a task for inputting digital data from the input section indicative of wet bulb and dry bulb temperatures and for calculating the moisture content of the atmosphere over each bed and for inputting digital data from the input section indicative of light intensity;
iii. a task for selecting temperature and moisture levels based upon the intensity of the incident light and the time the crop has been growing and comparing the input tempera-ture and moisture data with said selected levels for each sense zone; and iv. a task which in response to said comparison generates commands to the output section capable of initiating therethrough electromechanical action associated with each control zone to move the temperature and moisture content for each sense zone toward the selected levels.
4. A system for controlling environmental conditions in greenhouses having a plurality of crop beds within one greenhouse enclosure arranged into a plurality of sense zones and a plurality of control zones comprising:
a. a plurality of sensors stationed over crop beds within each sense zone comprising an aspirated enclosure and means therein for generating analog electrical signals indicative of wet bulb and dry bulb temperatures and means for generating an analog electrical signal indicative of incident light over the beds and also means for generating an analog electrical signal indicative of available sunlight;
b. a microcomputer located within the greenhouse comprising:
i. a central processing unit with associated scratch memory and program memory sections;
ii. an analog to digital input section for receiving the analog electrical signals from the sensors;
iii. an output section for converting the computer logic signals to electrical signals at power levels to operate electro-mechanical apparatus; and iv. serial digital pathway means for connecting the central processing unit, input section and output section;
c. said program memory programmed with:
i. a task for inputting digital data for the input section indicative of wet bulb and dry bulb temperatures and for calculating the moisture content of the atmosphere over each bed and for inputting digital data from the input section indicative of light intensity over the bed and available sunlight;
ii. a task for comparing the intensity of the incident light with a preselected command level and for selecting temperature and moisture command levels based upon the intensity of incident light over the bed and comparing the input temperature and moisture data with said selected command levels for each sense zone;
iii. a task which in response to the comparison of the intensity of the incident light with the preselec-ted command level generates commands to the output section capable of initiating therethrough elec-tromechanical action for each control zone to adjust intensity of the light over the bed toward the command level and which in response to the compari-son of the input temperature and moisture content with the said selected command levels generates commands to the output section capable of initiat-ing therethrough electromechanical action for each control zone to move the temperature and moisture content toward the selected command levels for each sense zone, and iv. a task which in response to the available sunlight generates commands to the output section capable of initiating therethrough electromechanical action for each control zone to position a shading device over the bed to reduce radiation heat losses under conditions where the bed must be heated to maintain the selected level.
a. a plurality of sensors stationed over crop beds within each sense zone comprising an aspirated enclosure and means therein for generating analog electrical signals indicative of wet bulb and dry bulb temperatures and means for generating an analog electrical signal indicative of incident light over the beds and also means for generating an analog electrical signal indicative of available sunlight;
b. a microcomputer located within the greenhouse comprising:
i. a central processing unit with associated scratch memory and program memory sections;
ii. an analog to digital input section for receiving the analog electrical signals from the sensors;
iii. an output section for converting the computer logic signals to electrical signals at power levels to operate electro-mechanical apparatus; and iv. serial digital pathway means for connecting the central processing unit, input section and output section;
c. said program memory programmed with:
i. a task for inputting digital data for the input section indicative of wet bulb and dry bulb temperatures and for calculating the moisture content of the atmosphere over each bed and for inputting digital data from the input section indicative of light intensity over the bed and available sunlight;
ii. a task for comparing the intensity of the incident light with a preselected command level and for selecting temperature and moisture command levels based upon the intensity of incident light over the bed and comparing the input temperature and moisture data with said selected command levels for each sense zone;
iii. a task which in response to the comparison of the intensity of the incident light with the preselec-ted command level generates commands to the output section capable of initiating therethrough elec-tromechanical action for each control zone to adjust intensity of the light over the bed toward the command level and which in response to the compari-son of the input temperature and moisture content with the said selected command levels generates commands to the output section capable of initiat-ing therethrough electromechanical action for each control zone to move the temperature and moisture content toward the selected command levels for each sense zone, and iv. a task which in response to the available sunlight generates commands to the output section capable of initiating therethrough electromechanical action for each control zone to position a shading device over the bed to reduce radiation heat losses under conditions where the bed must be heated to maintain the selected level.
5. The systems according to Claim 1, 2 or 3 wherein the tasks for selecting command levels do so to maximize crop growth.
6. The systems according to Claim 1, 2 or 3 wherein the tasks for selecting command levels do so to maximize crop growth and minimize heating power input other than sunlight.
7. The systems according to Claims 1, 2 or 3 further comprising at least one sensor external the greenhouse for genera-ting an analog signal indicative of an external condition affecting heat loss from the greenhouse and said program memory programmed with a task which in response to external conditions generates a command to the output section capable of initiating electromechan-ical action in all control zones therethrough to move the temper-ature in all sense zones in anticipation of a change in heat loss.
8. The systems according to Claim 4, wherein the tasks for selecting command levels do so to maximize crop growth,
9, The systems according to Claim 4, wherein the tasks for selecting command levels do so to maximize crop growth and mini-mize heating power input other than sunlight.
10, The systems according to Claim 4, further comprising at least one sensor external the greenhouse for generating an ana-log signal indicative of an external condition affecting heat loss from the greenhouse and said program memory programmed with a task which in response to external conditions generates a command to the output section capable of initiating electromechanical action in all control zones therethrough to move the temperature in all sense zones in anticipation of a change in heat loss.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US472,889 | 1983-03-08 | ||
| US06/472,889 US4430828A (en) | 1983-03-08 | 1983-03-08 | Plant oriented control system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1207058A true CA1207058A (en) | 1986-07-02 |
Family
ID=23877317
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000440920A Expired CA1207058A (en) | 1983-03-08 | 1983-11-10 | Plant oriented control system |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US4430828A (en) |
| CA (1) | CA1207058A (en) |
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| Publication number | Publication date |
|---|---|
| US4430828A (en) | 1984-02-14 |
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