US20130158818A1

US20130158818A1 - Implement control system for a machine

Info

Publication number: US20130158818A1
Application number: US13/332,017
Authority: US
Inventors: Joshua Callaway
Original assignee: Caterpillar Inc
Current assignee: Caterpillar Inc
Priority date: 2011-12-20
Filing date: 2011-12-20
Publication date: 2013-06-20
Also published as: WO2013095918A1

Abstract

A system for automated movement of a ground engaging blade of a machine includes a sensor on the blade to indicate a measured roll rate of the ground engaging blade. A controller determines whether the operator roll rate command is within an expected range of the roll rate signal. Movement of the ground engaging blade is at least in part based upon the operator roll rate command.

Description

TECHNICAL FIELD

This disclosure relates generally to controlling an implement and, more particularly, to a system and method for controlling the cross slope of a ground engaging blade.

BACKGROUND

Machines such as a tractors, bulldozers and the like are often equipped with attached implements for performing various tasks. For example, a tractor may be equipped with a ground engaging blade for performing tasks such as scraping the ground and moving material in a controlled fashion. An operator may move the blade in various directions relative to the ground. This helps the tractor complete the task of properly leveling or contouring the ground on which the tractor is operating. This is a task often performed during the construction of roads, buildings, or other structures.
One difficulty when operating such a machine is maintaining a consistent position of the blade as the tractor moves over uneven terrain. Movement of the machine up and down and from side to side results in similar movements of the blade despite a desire to maintain the blade in a fixed orientation relative to a ground reference. As a result of such movement, the work surface created by the machine may be uneven and require additional work to create a desired work surface.
An operator of a machine may correct for uneven terrain by adjusting the motion of the blade as the machine moves to compensate for the machine's movement, resulting in a smoother surface. However, the quality of the resulting grade is dependent on the skill of the operator in anticipating the need to adjust the blade. The operator may, in addition or alternatively, slow the speed of the machine while adjusting the blade position in response to uneven terrain. Such operations tend to reduce efficiency and increase cost.
U.S. Pat. No. 7,121,355 to Lumpkins et. al (“Lumpkins”) discloses a control system for controlling the position of a machine blade for grading. The control system determines the difference between a target position of the blade and its actual position, and generates a control signal calculated to move the blade to the target position.
The foregoing background discussion is intended solely to aid the reader. It is not intended to limit the innovations described herein, nor to limit or expand the prior art discussed. Thus, the foregoing discussion should not be taken to indicate that any particular element of a prior system is unsuitable for use with the innovations described herein, nor is it intended to indicate that any element is essential in implementing the innovations described herein. The implementations and application of the innovations described herein are defined by the appended claims.

SUMMARY

In one aspect, a control system is provided for controlling automated movement of a ground engaging blade of a machine. The ground engaging blade is configured for rotational movement. The sensor is located on the ground engaging blade and is configured to provide a roll rate signal indicative of a measured roll rate of the ground engaging blade. The controller is configured to receive the roll rate signal, receive an operator roll rate command signal, generate a command signal based at least in part on the roll rate signal and the operator roll rate command signal, and transmit the command signal to a system to control movement of the ground engaging blade.
In another aspect, a controller implemented method of adjusting a ground engaging blade of a machine is provided. The ground engaging blade has a sensor configured to provide a roll rate signal indicative of a measured roll rate of the ground engaging blade. The method includes receiving the roll rate signal within a controller, receiving an operator roll rate command signal within the controller, generating a command signal within the controller based at least in part on the roll rate signal and the operator roll rate command signal, and transmitting the command signal from the controller to a system to control movement of the ground engaging blade.
In another aspect, a machine includes a ground engaging blade, a sensor on the ground engaging blade configured to provide a roll rate signal indicative of a measured roll rate of the ground engaging blade, and a controller. The controller is configured to receive the roll rate signal, receive an operator roll rate command signal, generate a command signal based at least in part on the roll rate signal and the operator roll rate command signal, and transmit the command signal to a system to control movement of the ground engaging blade.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a side view of a machine including a system in accordance with the disclosure;

FIG. 2 shows a front view of a machine similar to that of FIG. 1 with certain components removed and other components broken away for clarity; and

FIG. 3 shows a flowchart illustrating a cross slope control process in accordance with the disclosure.

DETAILED DESCRIPTION

FIG. 1 shows a diagrammatic illustration of a machine that may be used in accordance with an embodiment of the disclosure. A machine 10 includes a frame 12 and a prime mover such as an engine 13. A pair of drive wheels (one of which is illustrated as a drive wheel 14) are disposed on each side of machine 10 and operate to drive a pair of tracks (one of which is shown as a track 15) to propel machine 10. Although machine 10 is shown in a “track-type” configuration, other configurations, such as a wheeled configuration, may be used. In addition, the systems and methods of the disclosure may be used with any machine propulsion and drive train mechanisms applicable in the art. Further, the systems and methods disclosed herein may also be used on machines other than a tractor having a ground engaging blade, such as a loader or a motor grader.
Machine 10 includes an implement such as ground engaging blade 16 pivotally connected to frame 12 by a pair of opposed arm (one of which is illustrated as an arm 17) disposed on each side of machine 10. A lift hydraulic cylinder 21 is coupled to frame 12 and supports ground engaging blade 16 in the vertical direction, and allows ground engaging blade 16 to move up or down vertically from the point of view of FIG. 1. A pair of pitch hydraulic cylinders 22 on each side of machine 10 (FIG. 2) allow the pitch angle of blade tip 18 to change relative to an axis or centerline of the machine (“CL” in FIG. 1). Actuating the pitch hydraulic cylinders 22 in opposite directions may permit the ground engaging blade 16 to rotate or tilt relative to the machine 10. In other words, operating the pitch hydraulic cylinders 22 in this manner will permit the rotation of the ground engaging blade 16 generally about an attachment point of the ground engaging blade to the machine 10 so that opposite corners 19 of the bottom edge of the blade may be disposed at different heights relative to the ground. The machine of FIG. 2 depicts an alternate manner of affecting the rotation of ground engaging blade 16 by utilizing a tilt hydraulic cylinder 23. Each of the hydraulic cylinders may be electrically controlled and receive signals from a controller 30. Controller 30 generates a signal that may be translated into a direction and magnitude of movement of the appropriate hydraulic cylinders as will be understood by those skilled in the art.
Machine 10 includes cab 28 from which an operator may provide input to control machine 10. Cab 28 includes one or more controls with which the operator may issue commands. FIG. 1 shows a joystick 27 from which an operator may control one or more machine implements, such as ground engaging blade 16. Joystick 27 may be configured to automatically return to a “neutral” position if the operator is not moving joystick 27. The operator may move joystick 27 to either side to control the tilt or rotation of ground engaging blade 16 relative to machine 10. Joystick 27 may operate as part of a control system of machine 10 wherein the operator's movement of joystick 27 (including the magnitude of the movement of joystick 27) is translated into a signal and sent to a controller 30. Movement of joystick 27 generates a signal to controller 30 indicative of the magnitude and direction of the operator's movement of the joystick. As described in more detail below, the controller 30 may process the signal and potentially adjust the signal prior to issuing or generating a command signal to the tilt hydraulic cylinder 23 to adjust the cross slope or angular orientation of ground engaging blade 16.
Machine 10 may be equipped with a plurality of sensors that provide data indicative (directly or indirectly) of the performance or operating conditions of various aspects of the machine. A sensor 34 such as a roll rate sensor (e.g., a gyroscope) may be provided on the ground engaging blade 16 of machine 10. The sensor 34 may be used to provide a roll rate signal indicative of a measured roll rate of the ground engaging blade 16. The measured roll rate is the angular velocity or rate of change of the ground engaging blade 16 as it rotates about the axis of the machine. In other words, as the tilt hydraulic cylinder 23 causes ground engaging blade 16 to rotate about an attachment point, the measured roll rate will be indicative of the velocity or rate of change of the position of the blade.
As described in more detail below, controller 30 may utilize the measured roll rate from sensor 34 to determine that a change is occurring in the cross slope of ground engaging blade 16. Controller 30 may perform various functions such as filtering and scaling the roll rate signal so as to provide a signal indicative of the rate of change of the angular position or cross slope of the ground engaging blade 16. The measured roll rate may then be used to determine whether and how the cross slope angular position of the ground engaging blade 16 should be adjusted.
A control system may be provided to control the operation of the machine 10 including the cross slope control aspects of the system. The control system may include an electronic control module such as controller 30. The controller 30 may receive operator input command signals and control the operation of the hydraulic systems that operate the various hydraulic cylinders. The controller 30 may be mounted at any convenient location on machine 10. The control system may include one or more input devices such as joystick 27 to control the machine 10 and one or more sensors, including sensor 34, to provide data and other input signals representative of various operating parameters of the machine 10. A portion of the control system may operate as cross slope control system to control the cross slope of the ground engaging blade 16.
The controller 30 may be an electronic controller that operates in a logical fashion to perform operations, execute control algorithms, store and retrieve data and other desired operations. The controller 30 may include or access memory, secondary storage devices, processors, and any other components for running an application. The memory and secondary storage devices may be in the form of read-only memory (ROM) or random access memory (RAM) or integrated circuitry that is accessible by the controller. Various other circuits may be associated with the controller such as power supply circuitry, signal conditioning circuitry, driver circuitry, and other types of circuitry.
The controller 30 may be a single controller or may include more than one controller disposed to control various functions and/or features of the machine 10. The term “controller” is meant to be used in its broadest sense to include one or more controllers and/or microprocessors that may be associated with the machine 10 and that may cooperate in controlling various functions and operations of the machine. The functionality of the controller 30 may be implemented in hardware and/or software without regard to the functionality employed. The controller 30 may rely on one or more data maps relating to the operating conditions of the machine 10 that may be stored in the memory of controller. Each of these maps may include a collection of data in the form of tables, graphs, and/or equations. The controller 30 may use the data maps to maximize the efficiency of the machine 10.
Referring to FIG. 3, a flow chart of the operation of the cross slope control system is depicted. The cross slope control system may be started automatically upon the start up of machine 10 at stage 41. At decision stage 42, the controller 30 may determine whether certain predetermined threshold conditions have been met to activate the cross slope control system. One threshold condition may be that the machine transmission (not shown) is in a certain state (e.g., not in neutral). Another example of a threshold condition may be that the machine ground speed is above or below a threshold amount or that the engine speed is within a predetermined range. Still another threshold condition may be that one or more other control systems are not active in controlling the implement. This type of condition may be desirable if the machine is equipped with multiple different implement control systems that are mutually exclusive and therefore cannot operate together. Another threshold condition may be based upon the receipt of predetermined steering commands. For example, the controller may turn off the cross slope control system during certain turning operations. Other threshold conditions may be set as desired. It should be noted that the determination of whether the threshold conditions have been met may be based upon monitoring the operating characteristics of aspects of the machine 10 for a particular period. In addition, different time periods may apply to different threshold conditions.
If the system threshold conditions are not met at decision stage 42, the controller 30 will generate at stage 43 a command signal approximately equal to a roll rate command issued by the operator. In other words, the controller will not implement the functionality of the cross slope control system and a command signal approximately equal to the operator roll rate command will be transmitted at stage 44 to the control system to control the position of ground engaging blade 16. If the system threshold conditions have been met at stage 42, the controller receives the roll rate signal from the sensor 34 at stage 45. At stage 46, the controller 30 receives an operator roll rate command reflective of a desired movement of the ground engaging blade 16 based upon an input from joystick 27.
At decision stage 47, the controller determines whether the operator roll rate command is within an expected range. A command within an expected range might be one that is within a predetermined rate (e.g., 2 degrees per second) or within a predetermined percentage (e.g., 150%) of a target (e.g., the measured roll rate that is detected by the sensor 34). Other expected ranges, calculations and targets or references may be set as desired. In one example, as machine 10 moves along uneven terrain, sensor 34 will provide a signal indicative of a change in roll rate (e.g., a change in roll rate of +3 degrees per second). An operator may attempt to manually compensate for the change in roll rate by issuing a roll rate command in an opposite direction (e.g., −2 degrees per second). In such example, the controller 30 may be configured to read the difference between the operator roll rate command and the measured roll rate as if the operator roll rate command is within the expected range.
If the operator command is not within the expected range, the controller 30 may be configured to generate at stage 48 a command generally equal to the operator roll rate command. The command signal generated by the controller 30 is transmitted at stage 44 to the electro-hydraulic system to control the movement of the ground engaging blade 16. As an example, if the machine 10 undergoes a change in position such that sensor 34 provides a roll rate signal indicating a measured roll rate of +1.5 degrees per second and the operator issues an operator roll rate command of +5 degrees per second, the controller 30 may be configured to respond to such actions as if the operator intended to change the cross slope of the ground engaging blade 16 rather than merely attempting to compensate for the change of machine position. In such example, the controller 30 will generate a command signal at stage 48 approximately equal to the operator roll rate command, or +5 degrees.
If the operator roll rate command is within the expected range at decision stage 47, the controller generates at stage 51 a command signal based upon the roll rate signal received at stage 45 from sensor 34 and the operator roll rate command received at stage 46. The controller logic may be configured so that the cross slope control system attempts to maintain the current operating conditions (e.g., maintain the roll rate signal generally equal to a velocity of 0) and respond as if changes made by the operator were intended to compensate for the changes in the roll rate of the ground engaging blade 16. In other words, the controller 30 may generate a command signal to move the ground engaging blade 16 in a direction so as to compensate for movement reported by sensor 34. The controller 30 may utilize a roll rate command from the operator as part of the input when generating the command signal. Using the example above in which the sensor 34 indicated a measured roll rate of +3 degrees per second and the operator issued an operator roll rate command of −2 degrees per second, the controller 30 may generate at stage 51 a command of approximately −1 degree per second. Depending upon the measured roll rate and the operator roll rate command, the command signal generated by the controller 30 may move the ground engaging blade in a direction generally identical to a direction commanded by the operator roll rate command signal or in a direction generally opposite to the direction commanded by the operator roll rate command signal.
At stage 52, the controller 30 determines whether the ground engaging blade 16 is at or near its maximum travel position. In other words, the controller determines whether the command signals generated at stage 51 will cause the tilt hydraulic cylinder 23 to reach its maximum travel position and cause the ground engaging blade 16 to reach its maximum cross slope position. If the tilt hydraulic cylinder 23 has or will reach its maximum travel position based upon the signal generated at stage 51, the controller will modify at stage 54 the command signal to generate a modified command signal to limit the travel of the tilt hydraulic cylinder 23 and prevent movement of the ground engaging blade 16 past its predetermined maximum displacement. As such, the ground engaging blade 16 will be maintained within its operating parameters and not exceed its maximum travel position. This modified command signal is transmitted at stage 44 to control the tilt hydraulic cylinder 23.
If the ground engaging blade 16 is not at or near its maximum travel position at decision stage 52, the controller does not change the generated command signal at stage 53. The command signal is transmitted at stage 44 to control movement of the ground engaging blade 16.
It should be noted that even when the operator is not issuing a roll rate command, the controller will be receiving at stage 46 an operator roll rate command equal to 0. In most cases, this operator roll rate command will be within the expected range at decision stage 47 and the controller will generate at stage 51 a command signal based upon the measured roll rate and the operator roll rate command equal to 0. As such, the command signal may be generated based primarily on the measured roll rate received at stage 45.

INDUSTRIAL APPLICABILITY

The industrial applicability of the system described herein will be readily appreciated from the foregoing discussion. The foregoing discussion is applicable to machines 10 that utilize an implement such as a ground engaging blade 16 for which it is desirable to control its angular orientation or cross slope. In one aspect, a control system for automated movement of a ground engaging blade 16 of a machine 10 includes a sensor 34 and a controller 30. The ground engaging blade 16 is configured for rotational movement. The sensor 34 is on the ground engaging blade 16 and is configured to provide a roll rate signal indicative of a measured roll rate of the ground engaging blade. The controller 30 is configured to receive the roll rate signal, receive an operator roll rate command signal, generate a command signal based at least in part on the roll rate signal and the operator roll rate command signal, and transmit the command signal to control movement of the ground engaging blade 16.
In another aspect, a controller implemented method of adjusting a ground engaging blade 16 of a machine 10 is provided. The ground engaging blade 16 has a sensor 34 configured to provide a roll rate signal indicative of a measured roll rate of the ground engaging blade. The method includes receiving the roll rate signal within a controller 30, receiving an operator roll rate command signal within the controller 30, generating a command signal within the controller 30 based at least in part on the roll rate signal and the operator roll rate command signal, and transmitting the command signal from the controller 30 to control movement of the ground engaging blade 16.
In another aspect, a machine 10 includes a ground engaging blade 16, a sensor 34 on the ground engaging blade configured to provide a roll rate signal indicative of a measured roll rate of the ground engaging blade, and a controller 30. The controller 30 is configured to receive the roll rate signal, receive an operator roll rate command signal, generate a command signal based at least in part on the roll rate signal and the operator roll rate command signal, and transmit the command signal to control movement of the ground engaging blade 16.
It will be appreciated that the foregoing description provides examples of the disclosed system and technique. However, it is contemplated that other implementations of the disclosure may differ in detail from the foregoing examples. For example, the disclosed system may employ a roll rate sensor that is already disposed on the blade for use in other control functions. That is, other sensors may be employed to determine the roll rate of the ground engaging blade that may then be used to determine a command signal to control the ground engaging blade. All references to the disclosure or examples thereof are intended to reference the particular example being discussed at that point and are not intended to imply any limitation as to the scope of the disclosure more generally. All language of distinction and disparagement with respect to certain features is intended to indicate a lack of preference for those features, but not to exclude such from the scope of the disclosure entirely unless otherwise indicated.
Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context.
Accordingly, this disclosure includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the disclosure unless otherwise indicated herein or otherwise clearly contradicted by context.

Claims

What is claimed is:

1. A control system for automated movement of a ground engaging blade of a machine, the ground engaging blade being configured for rotational movement, comprising:

a sensor located on the ground engaging blade configured to provide a roll rate signal indicative of a measured roll rate of the ground engaging blade; and

a controller configured to:

receive the roll rate signal;

receive an operator roll rate command signal;

determine whether the operator roll rate command is within an expected range of the roll rate signal;

generate a command signal based at least in part on the operator roll rate command signal; and

transmit the command signal to control movement of the ground engaging blade.

2. The control system of claim 1, wherein the roll rate signal measures an angular velocity of the ground engaging blade about an attachment point of the ground engaging blade to the machine.

3. The control system of claim 1, wherein the controller generates a command signal generally equal to the operator roll rate command signal if predetermined threshold conditions are not met.

4. The control system of claim 1, wherein the controller generates the command signal to move the ground engaging blade in a direction generally identical to a direction commanded by the operator roll rate command signal.

5. The control system of claim 1, wherein the controller generates the command signal to move the ground engaging blade in a direction generally opposite to a direction commanded by the operator roll rate command signal if the operator roll rate command is within the expected range.

6. The control system of claim 1, wherein the command signal moves the ground engaging blade when an operator has not commanded a specific movement of the ground engaging blade.

7. The control system of claim 1, wherein the controller generates a command signal generally equal to the operator roll rate command signal if the operator roll rate command is outside the expected range.

8. The control system of claim 7, wherein the controller is further configured to attempt to maintain the roll rate signal generally equal to a velocity of 0 if the operator roll rate command is within the expected range.

9. The control system of claim 1, wherein the controller generates a command signal based upon the operator roll rate command and the roll rate signal and further attempts to maintain the roll rate signal generally equal to a velocity of 0 if the operator roll rate command is within the expected range.

10. The control system of claim 1, wherein the sensor is a gyroscope.

11. A controller implemented method of adjusting a ground engaging blade of a machine, the ground engaging blade having a sensor configured to provide a roll rate signal indicative of a measured roll rate of the ground engaging blade, comprising:

receiving the roll rate signal within a controller;

receiving an operator roll rate command signal within the controller;

determining whether the operator roll rate command is within an expected range of the roll rate signal;

generating a command signal within the controller based at least in part on the roll rate signal and the operator roll rate command signal; and

transmitting the command signal from the controller to control movement of the ground engaging blade.

12. The controller implemented method of claim 11, further including measuring an angular velocity of the ground engaging blade about an attachment point of the ground engaging blade to the machine.

13. The controller implemented method of claim 11, further including generating a command signal generally equal to the operator roll rate command signal if predetermined threshold conditions are not met.

14. The controller implemented method of claim 11, further including moving the ground engaging blade in a direction generally identical to a direction commanded by the operator roll rate command signal.

15. The controller implemented method of claim 11, further including moving the ground engaging blade in a direction generally opposite to a direction commanded by the operator roll rate command signal if the operator roll rate command is within the expected range.

16. The controller implemented method of claim 11, further including moving the ground engaging blade when an operator has not commanded a specific movement of the ground engaging blade.

17. The controller implemented method of claim 11, further including the controller generating a command signal generally equal to the operator roll rate command signal if the operator roll rate command is outside the expected range.

18. The controller implemented method of claim 17, further including attempting to maintain the roll rate signal generally equal to a velocity of 0 if the operator roll rate command is within the expected range.

19. The controller implemented method of claim 11, further including attempting to maintain the roll rate signal generally equal to a velocity of 0 if the operator roll rate command is within the expected range.

20. A machine comprising:

a ground engaging blade;

a controller configured to:

receive the roll rate signal;

receive an operator roll rate command signal;

generate a command signal based at least in part on the roll rate signal and the operator roll rate command signal; and

transmit the command signal to an electro-hydraulic system to control movement of the ground engaging blade.