WO1992004699A1

WO1992004699A1 - Vehicle approach warning device

Info

Publication number: WO1992004699A1
Application number: PCT/AU1991/000403
Authority: WO
Inventors: Bruce Henry Johnson
Original assignee: Teknis Systems (Australia) Pty. Ltd.
Priority date: 1990-08-31
Filing date: 1991-08-30
Publication date: 1992-03-19
Also published as: NZ239590A

Abstract

A vehicle approach warning device is disclosed comprising a master unit (11) located in the vicinity of personnel working adjacent a carriageway upon which vehicles travel and one or more remote units (10, 15) which are located ahead of the master unit with respect to oncoming traffic. The remote units (10, 15) change state when they detect with radar devices, the passing of oncoming vehicles and communicate their changed state to the master unit (11) which alerts personnel in its vicinity with audible and visual alarm devices.

Description

"VEHICLE APPROACH WARNING DEVICE"

This invention relates to a device to detect the approach of a vehicle and in particular an apparatus which alerts personnel working in the vicinity of a vehicle carriageway of the approach of a vehicle.

BACKGROUND OF THE INVENTION

Maintenance and work gangs who are required to work in close proximity to carriageways upon which motor vehicles and in some instances trains travel, are constantly in danger from the passage of those vehicles near where they are working. The task of forewarning the impending arrival of vehicles into their area, has in the past been relegated to the use of flagmen to control passing traffic and in the case of railway lines flagmen are used in combination with detonators placed on railway tracks which when activated by the passage of the train explode and audibly signal the flagmen and workers alike. It is not unusual to require at least two flagmen and two detonator personnel per work site to enable this method of operation to be supported.

Not only is this a costly and inefficient utilisation of human effort, the use of detonators also requires additional skilled personnel to transport and place them, and then replace them after use. These methods of operation are not only cumbersome but also very costly, and it has been found that unnecessary interruption to the flow of traffic can be created. In particular train timetables can be adversely affected by the overly cautious application of these methods of operation.

It has also been known for detonators to fail to explode when run over by a train, and in combination with the possibility that detonators are not replaced, the overall reliability of these very manually orientated methods presents a continuing problem to railway administrators. However, regardless of incidences of detonator failure, their use is widespread throughout the world and these old methods continue to be used.

It is therefore apparent that a cost effective and reliable early warning device is required, to enable workmen to be alerted to take the necessary action to clear the hazardous areas of the work site during the passage of vehicles past them. Additionally it is advantageous if the early warning device is also able to shut down equipment in use by the work gang at the same time the warning is given to personnel.

In its broadest form the invention comprises a vehicle approach early warning device for workers located on or adjacent to a vehicle carriageway comprising, at least one vehicle detector unit whereby a first vehicle detector unit is located remote from said workers and along said carriageway having a plurality of states of detection, said first vehicle detector comprising; a first one radar device so arranged as to detect a vehicle which is travelling along said carriageway towards said workers and to provide a signal representative of a first state of said first vehicle detector unit, a transmitter means for transmitting a transmission signal representative of said state towards the location of said workers, a master unit located adjacent said workers comprising a receiver means for receiving a transmission signal, approaching vehicle alerting means for signalling to said workers the approach of a vehicle, a state detection means to determine if the received transmission signal is representative of a first state of a vehicle detector unit, and if so, actuating said approaching vehicle alerting means. In a further aspect of the invention there is provided a second vehicle detector unit located remote from said workers and along said carriageway in an opposite direction away from said first vehicle detector unit having a plurality of states of detection, said second vehicle detector unit comprising; at least one radar device so arranged as to detect the approach of a vehicle which is travelling along said carriageway towards said workers and to provide a signal representative of a first state of said second vehicle detector unit.

In a yet further aspect of the invention the vehicle detector units further comprise timing means adapted to receive signals from said radar devices representative of said first and second states and to determine from the time of receipt of said first and second states the direction of travel of said vehicle travelling on said carriageway, whereby if said first state precedes said second state the detector unit transmits a transmission signal representative of a third state and if said second state precedes said first state the detector unit transmits a transmission signal representative of a fourth state.

It is also an aspect of the invention that there are indicators or optional voice communications between the remote units and the master unit such that setup procedures for these devices may be co-ordinated prior to the equipment being placed into operation.

Further there is supplied a local alarm transmission signal from the master unit to indicate to a mobile alarm unit within its range various states of operation of the early warning device independent of the actuation of warning indicator means associated with the master unit. An embodiment of the invention will now be described with reference to the following figures in order that it may be more clearly understood, wherein:

Fig 1 depicts an early warning system configuration as used along a railway line;

Fig 2 depicts a functional block diagram of a detector unit; and

Fig 3 depicts a functional block diagram of a master unit.

As depicted in Fig 1, the early warning unit comprises at least one remote detector unit 10 located a predetermined distance from the position on the rail line of the work gang, which in this embodiment is two kilometres. A functional block diagram of the remote detector unit is provided at Fig 2. The remote unit comprises in this embodiment two Doppler radar devices which are positioned on respective sides of the detector unit 10 and which are orientated to radiate and thereby detect reflected energy upwards and downwards along the track from the location of the detector unit. The detector unit may be placed within any safe distance of the track itself.

At the work gang site the early warning apparatus comprises a master unit 11. The master unit is located a safe distance from the railway line and contains a power supply, radio transceiver, associated antenna, alarm system, status display and control interface and audible/visible alarm devices . In particular the visual alarm comprises a bright light 12 located on top of the master unit enclosure and the audible alarms comprise horns 13 which provide sufficiently loud and penetrating signals when the alarm mode is triggered to alert workers in the vicinity of the master unit. A work gang supervisor or supervisors may be supplied with a mobile alarm unit 14 which can receive coded radio signals from the master unit to indicate operation of the alarm state or the occurrence of internal fault states occurring with either the master unit or its associated remote detector units .

As shown in this system configuration, an additional remote detector unit 15 is located approximately two kilometres on the opposite side of remote detector unit 10 along the rail line and performs exactly the same function as remote detector unit 10.

It will be apparent that where there is only one direction of traffic along the rail line or indeed in road vehicle applications, a single remote detector unit is all that is required to ensure the safety of a work gang located beyond the remote detector unit.

Referring to Fig 2, the remote detector unit comprises Doppler Radar Unit 16 and Doppler Radar Unit 17. Both radars are operational and orientated to transmit and receive radiation in opposite directions along the rail line, thus providing a first stage of vehicle movement detection along the track. A vehicle must be detected by one Doppler unit followed by the other and thereby will indicate its direction of travel and indicate that a vehicle has in fact traversed the location of the remote unit by the order in which the units detect the vehicle. As depicted in Fig 2, a frequency driver module for Doppler Radar Unit 16 is provided by circuit 18 and likewise circuit 19 supplies frequency driving signals for Doppler Radar Unit 17. Reflected signals received by either of the Doppler units are transformed into varying audio signals and their output is amplified via circuits 20 and 21 respectively. The amplified signal is then signal processed via circuits 22 and 23. In the case of Doppler Radar Unit 16, circuit 22 provides a check that the Doppler radar is functioning correctly and signals nil reception of the source frequency of 50 kHz driving the Doppler Radar Unit 16, thus, the output of circuit 22 comprises a Doppler check signal which is directed to the control microprocessor 26. Circuit 23 also receives the amplified output from circuit 20 and processes the signal to provide outputs representative of the characteristics of the received radiation of Doppler Radar Unit 16. Those characteristics may comprise a maximum amplitude signal received between reset commands from the microprocessor 26. These reset commands are provided via discharge control 'O' output from the microprocessor 26. The maximum output signal is available on a peak hold output of circuit 23. A dynamic representation of the change of frequency of the received radiation in Doppler Radar Unit 16 is provided by the output of a squaring amplifier at output denoted squared input 'O' , which is subsequently fed to microprocessor 26 to a similarly labelled input.

Circuit 24 functions in a similar manner to circuit 22 and is designed to receive and detect a fundamental driving frequency of Doppler Radar Unit 17 of 50 kHz. Its output is a Doppler check signal which is communicated to microprocessor 26 to a similarly labelled input.

Circuit 25 functions in a like manner to circuit 23 and provides two outputs, a peak hold '1', value of the maximum received signal level from Doppler Radar Unit 17 and a dynamic varying signal representative of the received signal at Doppler Radar Unit 17 which is squared and outputted via squared input '1' to the microprocessor 26. An output from the microprocessor to circuit 25 comprises discharge control ' 1 ' which is used to zero measurements between peak hold readings received from Doppler Radar Unit 17.

Circuit 27 depicts the power supply portion of the remote detector unit 10 of Fig 1. Rechargeable batteries 33 are the primary source of power for the unit, with an external charger input facility 37 provided for convenient recharging access from an external power source. Battery voltage level detector 30 is communicated to microprocessor 26 at an input labelled BAT so that appropriate alarm status can be indicated and communicated to the supervisor should the level decrease below a preset level. Various voltages +12V, +6.4V and +5V D.C. are supplied and provided to the remote detector unit for the operation of its circuits.

Microprocessor 26 as mentioned previously is provided with inputs from circuits 22, 23, 24 and 25 respectively. The microprocessor 26 also comprises a modem output 35 to a modem 36 and hence to a radio interface circuit 38. The radio transceiver communicates all relevant alarm status and check signals associated with the remote unit to the master unit located a distance along the rail line.

To ensure the remote unit is not tampered with or is displaced from its set position, a trembler device 39 and mounting tension switch 40 provides an input signal at 41 to the microprocessor 26 when the unit is disturbed. The microprocessor 26 monitors input 41 and provides an alarm signal to alert the supervisor to the fact that a disturbance has triggered the trembler device 39 or the mounting tension switch 40 in the remote unit. As a fail-safe the general warning alert can be operated at the master unit as well, so that until the cause of the disturbance is determined and the unit is reset, workers are warned of possible danger. Microprocessor 26 has a variety of operations and inputs as previously described, amongst those operations is analogue to digital conversion of the two peak hold levels which are supplied from Doppler Radar Unit 16 and Doppler Radar Unit 17 at inputs ADCO 42 and ADC1 43 respectively of the microprocessor 26. Analogue to digital conversion is also applied to the battery voltage level at input ADC3 44 of the microprocessor 26. Inputs 46 and 47 receive the squared signal output levels of Doppler Radar Units 16 and 17 respectively, while digital inputs 48 and 49 receive filter check signals relating to the 50 kHz signals of Doppler Radar Units 16 and 17 respectively.

Digital outputs 50 and 51 are used to control the reset of the peak measurement period of the peak hold signal processors associated with Doppler Radar Units 16 and 17 respectively.

EPROM 52 supports the software memory requirements of microprocessor 26 and contains a program which controls the operation of the data lines 46 through to 51 as previously described and, the use of the analogue to digital conversions that are made via inputs 42 to 44.

The two Doppler Radar Units 16 and 17 are continuously operating. When there are no moving trains in their immediate vicinity, the lack of reflected radar detector signals is processed by the detector receiver amplifiers, filtered and fed to the microprocessor. Alternatively when moving objects are in their vicinity, reflected radar signals are received and processed in a similar way. The microprocessor checks that the received signal has appropriate signal characteristics to determine if they match the characteristics of a moving vehicle or not. One of many possible characteristics measured as the vehicle approaches the remote detector unit is the resulting Doppler shifted signal which is detected by each radar. This signal is processed by the microprocessor by examining both the peak hold signal and the squared input signals from each of Doppler Radar Units 16 and 17. The microprocessor is then used to determine when a train detected status word is to be sent to the modem port buffer. This information along with the results of the monitoring functions previously mentioned are then sent as a single status word to the modem port buffer 53. The contents of the buffer 53 is periodically transmitted to the master unit a preset number of times, after which it is cleared.

The battery voltage of the remote detector unit which represents a further state of the vehicle detector unit is also sent to the master unit within the status word via the modem port buffer or may initiate the separate transmission of a status word representative of a low battery state of the vehicle detector.

As depicted in Fig 3 the master unit comprises a microprocessor 57, a radio transceiver 58 and associated antenna 59, an alarm circuit 60, a power supply 61, a status display 62 and an external data port 63.

Incoming radio signals 64 and 65 from the remote detector units 10 and 15 are received by the antenna 59 which is connected to the radio transceiver 58, which supplies a demodulated audio signal 66 on output connection 67 representative of the status word sent from one of the remote units. Modem 68 receives the demodulated audio signal input from the radio transceiver 58 and supplies to data port 69 a digital representation of the status word to microprocessor 57. The status word is decoded and displayed on the status display unit 62 and may represent various remote unit status signals indicative of train movement, fault detection and disturbance of the remote unit. Recognising that one of the remote units indicates movement from DOWN the rail line or track and the other of the remote units indicates movement from UP the rail line or track, the status display indicates in this embodiment 1) time and date when the master is in stand-by mode or the remote unit number when the system is reporting a certain status, 2) indicates that the master unit battery is low, 3) shows that the remote unit indicated by display 1) is in one of the following states: a) it is operating correctly but has not had a vehicle pass, b) it has detected a vehicle, c) it is faulty, d) it has been disturbed, or e) it has a low battery.

The microprocessor 57 communicates to the remote units by issuing a data word via data port 69. The data word is converted by the modem 68 into a audio level digitally encoded bit stream and fed via connection 67 into the radio transceiver 58. The microprocessor concomitantly operates the PTT of the transceiver 58 to effect transmission of the data word.

When the master unit's microprocessor 57 interprets the various data words received from the remote units and it is indicated to the master unit that a train or vehicle is moving towards the master unit from the position of the remote units, a trigger signal is provided on output 70 and alarm circuit 60 is activated. In this embodiment a relay 71 is used to supply power to external alarm device 72 which may include singly or in combination a siren, hooter and/or strobe lights. These alarm indications are operated until the master unit is reset. This is accomplished by a number of actions, one example being the depression of the cancel switch 73 which is located on an external portion of the housing of the master unit. In another example, the supervisor may remotely control the function of the cancel switch via their radio link to the master unit 11.

Power supply 61 provides the appropriate voltage and current to power the microprocessor 57 via input 74 and also supplies current via the power supply/battery packs output 75 to the alarm devices via the alarm circuit relay 71. An external 12 volt D.C. supply/charger may also provide charging current or alternatively primary power to the power distribution system via input 76. Battery interface circuit 77 provides a signal to the microprocessor via input 78 which may be used to indicate the state of the battery to the microprocessor monitoring functions. Power is continuously supplied to data storage device 79 from the power supply 61 from a separate regulator 80 which is unaffected by the on/ off switch 81.

The RAM data storage device 79 provides a data logging facility for storage of the various date, time and event types that are monitored by the master unit 11 on a first in- first out basis, and has sufficient storage space for the recordal of up to 64 events. Access to this memory area is restricted to authorised persons only having a compatible computer data recording device of known arrangement and configuration. This data is downloaded via the microprocessor 57 via data output 82 to data output interface circuit 83 and available via external data port 63.

EPROM 84 supports the software memory requirements of microprocessor 57 and contains a program which controls operation of the data word input line 69 and the use of the A-D conversion that is available via dc input 74. The microprocessor 57 is capable of signalling not only the occurrence of an alarm operation but may also indicate low battery, faulty circuits either within the master unit 11 or at the remote detector units 10 and 15 or other status levels of either the remote units or of the master unit itself.

To set up the equipment comprising the master and remote units, the following procedure is followed once a work gang has reached the operational site adjacent the rail line or traffic carriageway. The master unit is switched on with a key operated switch 81 which provides power to operate the master unit and causes the master unit to automatically enter stand-by mode. Workmen are then despatched in each direction up and down the line or carriageway a distance approximately two kilometres from the master unit, each taking with them one of the remote detection units 10 and 15 respectively. Upon reaching the desired remote unit location, the units are mounted on stable platforms and switched on, after which the units perform a self test and then test the radio and link path by attempting to communicate with the master unit using predetermined coded signals. A failed test will be indicated on each of the units status display, and appropriate corrective action can then be taken by the supervisor or workmen. Of course the procedure described could also be performed by a single workman by locating one unit at a time.

Additional features may be incorporated into the system which may comprise local mobile alarm beacons which are carried by each work gang member to receive alarm messages independent and concomitant with the operation of the external alarms of the main unit. The system may also incorporate radio transmitting and receiving equipment which is compatible with centralised train control systems and which may also be received by train drivers. Additional alarm circuit contacts may also be provided which will automatically shut down or turn off equipment being operated by the work gang.

Claims

The claims defining the invention are as follows: -

1. A vehicle approach early warning apparatus for workers who are located on or adjacent a vehicle carriageway comprising, at least one vehicle detector unit whereby a first vehicle detector unit is located remote from said workers and along said carriageway having a plurality of states of detection, said first vehicle detector comprising; a first one radar device so arranged as to detect a vehicle which is travelling along said carriageway towards said workers and to provide a signal representative of a first state of said first vehicle detector unit, a transmitter means for transmitting a transmission signal representative of said state towards the location of said workers, a master unit located adjacent said workers comprising a receiver means for receiving a transmission signal, approaching vehicle alerting means for signalling to said workers the approach of a vehicle, a state detection means to determine if the received transmission signal is representative of a first state of a vehicle detector unit, and if so, actuating said approaching vehicle alerting means.

2. A vehicle approach early warning apparatus according to claim 1 wherein a second vehicle detector unit is located remote from said workers and along said carriageway in an opposite direction away from said first vehicle detector unit having a plurality of states of detection, said second vehicle detector unit comprising; at least one radar device so arranged as to detect the approach of a vehicle which is travelling along said carriageway towards said workers and to provide a signal representative of a first state of said second vehicle detector unit.

3. A vehicle approach early warning apparatus according to claim 2 wherein said vehicle detector units comprise a second radar device so arranged as to detect a vehicle which is travelling along said carriageway towards said workers which has passed the location of the detector unit to provide a signal representative of a second state of a detector unit.

4. A vehicle approach early warning apparatus according to claim 3 wherein said vehicle detector units further comprise timing means adapted to receive signals from said radar devices representative of said first and second states and to determine from the time of receipt of said first and second states the direction of travel of said vehicle travelling on said carriageway, whereby if said first state precedes said second state the detector unit transmits a transmission signal representative of a third state and if said second state precedes said first state the detector unit transmits a transmission signal representative of a fourth state.

5. A vehicle approach early warning device according to claim 1 wherein said alerting means comprises an audible warning device.

6. A vehicle approach early warning device according to claim 1 wherein said alerting means comprises a visual warning device.

7. A vehicle approach early warning device according to - claim 1 wherein said alerting means comprises switch means which is operated to stop workers equipment attached thereto.

8. A vehicle approach early warning apparatus according to claim 1 wherein said master unit further comprises a master transmitter means for transmitting a signal representative of said states of a detection unit, and said apparatus further comprising a portable receiver means for receiving said master transmitter means transmitted signal of said states having indicating means to indicate selected ones of said states.

9. A vehicle approach early warning apparatus according to claim 1 wherein said vehicle detection units further comprise a movement sensor means adapted to sense movement of the detector means and to provide a signal to said detector transmitter means representative of a fifth state of said vehicle detector unit.

10. A vehicle approach early warning apparatus according to claim 1 wherein said transmitter means periodically transmits the current state of the vehicle detection units.

11. A vehicle approach early warning apparatus according to claim 1 wherein said transmission signal has the form of a digitally encoded word representative of the state of the vehicle detector unit.