CA1232655A - Location identification arrangement for vehicle guidance systems - Google Patents
Location identification arrangement for vehicle guidance systemsInfo
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- CA1232655A CA1232655A CA000478149A CA478149A CA1232655A CA 1232655 A CA1232655 A CA 1232655A CA 000478149 A CA000478149 A CA 000478149A CA 478149 A CA478149 A CA 478149A CA 1232655 A CA1232655 A CA 1232655A
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- 230000037361 pathway Effects 0.000 claims abstract description 7
- 238000004804 winding Methods 0.000 claims description 20
- 238000001514 detection method Methods 0.000 claims description 6
- 230000008859 change Effects 0.000 claims description 3
- 230000004044 response Effects 0.000 claims description 2
- 230000011664 signaling Effects 0.000 claims 2
- 239000003990 capacitor Substances 0.000 description 31
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- 230000015654 memory Effects 0.000 description 8
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Classifications
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D1/00—Control of position, course, altitude or attitude of land, water, air or space vehicles, e.g. using automatic pilots
- G05D1/02—Control of position or course in two dimensions
- G05D1/021—Control of position or course in two dimensions specially adapted to land vehicles
- G05D1/0259—Control of position or course in two dimensions specially adapted to land vehicles using magnetic or electromagnetic means
- G05D1/0261—Control of position or course in two dimensions specially adapted to land vehicles using magnetic or electromagnetic means using magnetic plots
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D1/00—Control of position, course, altitude or attitude of land, water, air or space vehicles, e.g. using automatic pilots
- G05D1/02—Control of position or course in two dimensions
- G05D1/021—Control of position or course in two dimensions specially adapted to land vehicles
- G05D1/0259—Control of position or course in two dimensions specially adapted to land vehicles using magnetic or electromagnetic means
- G05D1/0265—Control of position or course in two dimensions specially adapted to land vehicles using magnetic or electromagnetic means using buried wires
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- General Physics & Mathematics (AREA)
- Aviation & Aerospace Engineering (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Electromagnetism (AREA)
- Automation & Control Theory (AREA)
- Train Traffic Observation, Control, And Security (AREA)
- Near-Field Transmission Systems (AREA)
- Control Of Position, Course, Altitude, Or Attitude Of Moving Bodies (AREA)
- Platform Screen Doors And Railroad Systems (AREA)
- Traffic Control Systems (AREA)
Abstract
ABSTRACT
A vehicle guidance system in which vehicles are guided along a traffic layout, includes a location identification arrangement for identifying locations along the layout and for enabling each vehicle to derive information for directing the vehicle in its movement along the traffic layout. The arrangement includes an interrogator for each vehicle including a coil which is excited by a high frequency signal, and a responder for each location including an identification signal generator for generating a signal encoded to represent an identification code for the location, a second coil located relative to the pathway for the vehicle to enable signal coupling to occur between the two coils as the vehicle moves adjacent to the responder in its travel along the traffic layout, and a modulating circuit responsive to the encoded signal to alternatively de-tune and tune the responder coil in correspondence with the information code, the interaction between the two coils resulting in modulation of the frequency signal with the information code which is detectable by a signal detector of the interrogator.
A vehicle guidance system in which vehicles are guided along a traffic layout, includes a location identification arrangement for identifying locations along the layout and for enabling each vehicle to derive information for directing the vehicle in its movement along the traffic layout. The arrangement includes an interrogator for each vehicle including a coil which is excited by a high frequency signal, and a responder for each location including an identification signal generator for generating a signal encoded to represent an identification code for the location, a second coil located relative to the pathway for the vehicle to enable signal coupling to occur between the two coils as the vehicle moves adjacent to the responder in its travel along the traffic layout, and a modulating circuit responsive to the encoded signal to alternatively de-tune and tune the responder coil in correspondence with the information code, the interaction between the two coils resulting in modulation of the frequency signal with the information code which is detectable by a signal detector of the interrogator.
Description
~3~2~5S
LOCATION IDENTIFICATION ARRANGEMENT
FOR VEHICLE GUIDANCE SYSTEMS
_ The present invention is directed to guidance systems in which at least one mobile vehicle is guided along a traffic path to arrive at a predetermined location along a traffic layout, and more particularly to an arrangement for enabling a vehicle to derive information for directing its movement along the traffic path.
Various systems have been proposed in the prior art for guiding a driverless mobile unit along a traffic path. An example of such system is disclosed in U.S. Patent 4,284,160 which was issued in the names of Robert L. DeLiban and David Lieby, and which is assigned to the assignee of this application. In such system, the traffic path is defined by guidance conductors energized to radiate an electro-magnetic field, and a guide path sensing circuit on the vehicle detects the radiated energy and controls the vehicle steering means to follow such path.
Station selection means provided on each vehicle instructs the vehicle to proceed to any one of a plurality of stations located at different points along the path.
A location-identification code device at each station provides an identification code signal which is detectable.
An identification code sensing circuit on the vehicle, senses the code signal as the vehicle approaches a station, and halts the vehicle when the vehicle arrives at the station selected~
The system includes a main traffic path and a plwrality of secondary paths which branch away from the main path at different points designated as decision points. Whenever the vehicle arrives at a decision point in the system, one o~ at least two alternate paths is selected as a preferred path to a selected station. Each decision point includes an associated location-identification code device which provicles a unique codefor the decision point. The code sensing circuit on the vehicle detects such code as the vehicle approaches the decision point, and vehicle control circuits enable the vehicle to follow the one of the paths which is predetermined as the preferred path from the decision point to the selected station.
In the embodiment disclosed, the code devices comprise variably polarized magnets embedded in the floor at each of the identified locations. Each code device comprises two, three or four magnets polarized for either north or south polarity~ the magnets being positioned in one, two or more rows and in pre-selected positions of each row to define the unique coding for each location.
More specifically, each row has four magnet positions which may locate a magnet having either a north or a south polarity thus defining eight line numbers.
Different types of coding are provided for idertifying stations, diverging points, converging points, etc. A code identifying a given location may comprise a first magnet having a north pole located in position one of row one, and a further magnet having a north pole located in position one of row two.
In general, each code device provides a unique coding which enables the vehicle carried controL circuits to identify the location and effect vehicle actions; such as converging and diverging operations, transfer to a bypass path, etc.
~3~5'~
The sensors which sense the floor code provided by the magnetic devices comprise four pairs of reed switches which are mounted in side-by-side relationship and spaced apart as to be influenced by only one of the magnets in a given row~ Each reed switch includes normally closed contacts which are operable under the influence of the magnets as the vehicle passes thereover to open associated contacts, providing a set of coded signals over eight sensor output lines indicating the coding of the magnetic code devices.
The location-identification arrangement described above provides information for vehicle guidance in a relatively simple manner through the use of sets oP magnets embedded in the floor at selected locations along the guidance path. However, space restrictions limit the number of magnets which can be used and thus the number of unique codes available. Also, once the set of magnets has been installed in the floor, it is impractical to reprogram the code devices to modify the code. This lirnits the effectiveness of the system particularly in terms of expansion of the system to add stations or secondary paths.
SUMMARY OF THE INVENTION
The present invention provides an arrangement for a vehicle guidance system for enabling a vehicle to derive information for directing the vehicle in its movement along a traffic layout~
In accordance with the invention, the arrangement comprises interrogator means carried by the vehicle, responder rneans for each location including code means providing a signal encoded to represent information for the associated location, couplin~ means to enable signal coupling to occur between the interogator rneans and the responder means as the vehicle rnoves adjacent to the responder means in its travel along khe kraffic layout, the responder means including coupling modulator means responsive to the encoded signal for varying the signal coupling between the interrogator means and the responder means in correspondence with the information providcd by the cocle means 9 the interrogator means including detection means ~or detecting the variation in signal coupling to recover the information represented by the encoded signal.
In ac~cordance with one aspect of the invention~
the coupling means comprises a first coil carried by the vehicle and a second coil associated with the responder means and located relative to the pathway of the vehicle to enable signal coupling to occur between the first and second coil as the vehicle moves adjacent to the responder ; means, the coupling modulator rrleans controlling the second coil to vary the signal coupling in correspondence with the information provided by the code means. The first coil is energized by a frequency signal so that the variation in signal coupling results in modulation of the frequency signal from which the coded information is detected by the detecting rneans for use by the vehicle control circuitsO
The responder means are disposed at various locations along the traffic layout, including the locations of each station and at decision points and the information provided includes a unique identifying code for each location. The codes are sensed by the vehicle carried interrogator means as the vehicle passes adJacent to the responcler means, enabling the control circuit on the vehicle to deterrnine the location of the vehicle along the traffic t'~
layout, provided information for guiding the vehicle in selecting the shortest route to its designated station, and halt the vehicle when it reached its designated station.
In accordance with a feature of the invention, the iclentification code arrangement includes a passive code responder means for each location to be identified. Each responder means derives both a time base and DC power from the signal generated by the interrogator means carried by the vehicle. ~hen a vehicle passes adjacent to the responder means, the identification signal generating means is enabled to generate a pulse code signal which drives a switching circuit which alternately detunes and tunes the coil of the responder means. The interaction on the primary coil on the vehicle due to transformer action results in a modulation envelope on the primary coil voltage. The modulation represents the code of the resporder means and its signal is detected, separated from the carrier signal and processed to provide the identification code at the output of the vehicle sensing circuits.
In accordance with a further feature of the invention, the signal generating means of the responder means is programmable by way of manually settable switches.
This enables the responder means to be reprogrammed at will. In addition, as indicated, the responder means is a passive device, deriving its power from the interrogating signal generated by the vehicle carried control circuits.
Thus, no power is required to maintain the floor mounted responder means energized.
~3~
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a simplified layout diagram illustrating a traffic layout for a guidance system including the ].ocation identiEication arrangement of the present invention;
FIG. 2 is a block diagram of the location identification circuits of the present invention;
FIG. 3 is a plan view of a mobile vehicle for use in the guidance system;
FIGS. 4 and 4A are a partial schematic circuit and block diagram of the vehicle interrogator of the location identification circuits shown in FIG. 2; and FIG. 5 is a partial schematic circuit and block diagram of the responder circuit of the location identification circuits;
DESCRIPTION OF PREFERRED EMBODIMENTS
_ The location-identification arrangement of the present invention is described with reference to an application in a vehicle guidance system in which one or more driverless vehicles are guided along a traffic layout.
The traffic layout of the vehicle guidance system, shown in simplified fashion in FIG. 1, is generally formed by a pair of guide wires 15 and 16 laid down in a pattern to define main and secondary paths of the systems for guiding driverless mobile vehicles 35, 35', etc. along the traffic layout. The main traffic path is defined by guide wire 15, indicated by the solid line, which extends in a continuous loop and which is energized by a signal at a first frequency fl provided by an oscillator 25 oE a central contro:l unit 2~. The other guide wire 16 defines three ~2321~i55 secondary traffic paths, depicted in dashed lines designated by reference numerals 16A-16C. The secondary paths intersect with the main path at points 17-22, and are interconnected with one another by lines 16', indicated by dot-dashed line, to form a further continuous guidance loop which is energized by a signal at a second frequency f2 provided by an oscillator 24 of the central control unit
LOCATION IDENTIFICATION ARRANGEMENT
FOR VEHICLE GUIDANCE SYSTEMS
_ The present invention is directed to guidance systems in which at least one mobile vehicle is guided along a traffic path to arrive at a predetermined location along a traffic layout, and more particularly to an arrangement for enabling a vehicle to derive information for directing its movement along the traffic path.
Various systems have been proposed in the prior art for guiding a driverless mobile unit along a traffic path. An example of such system is disclosed in U.S. Patent 4,284,160 which was issued in the names of Robert L. DeLiban and David Lieby, and which is assigned to the assignee of this application. In such system, the traffic path is defined by guidance conductors energized to radiate an electro-magnetic field, and a guide path sensing circuit on the vehicle detects the radiated energy and controls the vehicle steering means to follow such path.
Station selection means provided on each vehicle instructs the vehicle to proceed to any one of a plurality of stations located at different points along the path.
A location-identification code device at each station provides an identification code signal which is detectable.
An identification code sensing circuit on the vehicle, senses the code signal as the vehicle approaches a station, and halts the vehicle when the vehicle arrives at the station selected~
The system includes a main traffic path and a plwrality of secondary paths which branch away from the main path at different points designated as decision points. Whenever the vehicle arrives at a decision point in the system, one o~ at least two alternate paths is selected as a preferred path to a selected station. Each decision point includes an associated location-identification code device which provicles a unique codefor the decision point. The code sensing circuit on the vehicle detects such code as the vehicle approaches the decision point, and vehicle control circuits enable the vehicle to follow the one of the paths which is predetermined as the preferred path from the decision point to the selected station.
In the embodiment disclosed, the code devices comprise variably polarized magnets embedded in the floor at each of the identified locations. Each code device comprises two, three or four magnets polarized for either north or south polarity~ the magnets being positioned in one, two or more rows and in pre-selected positions of each row to define the unique coding for each location.
More specifically, each row has four magnet positions which may locate a magnet having either a north or a south polarity thus defining eight line numbers.
Different types of coding are provided for idertifying stations, diverging points, converging points, etc. A code identifying a given location may comprise a first magnet having a north pole located in position one of row one, and a further magnet having a north pole located in position one of row two.
In general, each code device provides a unique coding which enables the vehicle carried controL circuits to identify the location and effect vehicle actions; such as converging and diverging operations, transfer to a bypass path, etc.
~3~5'~
The sensors which sense the floor code provided by the magnetic devices comprise four pairs of reed switches which are mounted in side-by-side relationship and spaced apart as to be influenced by only one of the magnets in a given row~ Each reed switch includes normally closed contacts which are operable under the influence of the magnets as the vehicle passes thereover to open associated contacts, providing a set of coded signals over eight sensor output lines indicating the coding of the magnetic code devices.
The location-identification arrangement described above provides information for vehicle guidance in a relatively simple manner through the use of sets oP magnets embedded in the floor at selected locations along the guidance path. However, space restrictions limit the number of magnets which can be used and thus the number of unique codes available. Also, once the set of magnets has been installed in the floor, it is impractical to reprogram the code devices to modify the code. This lirnits the effectiveness of the system particularly in terms of expansion of the system to add stations or secondary paths.
SUMMARY OF THE INVENTION
The present invention provides an arrangement for a vehicle guidance system for enabling a vehicle to derive information for directing the vehicle in its movement along a traffic layout~
In accordance with the invention, the arrangement comprises interrogator means carried by the vehicle, responder rneans for each location including code means providing a signal encoded to represent information for the associated location, couplin~ means to enable signal coupling to occur between the interogator rneans and the responder means as the vehicle rnoves adjacent to the responder means in its travel along khe kraffic layout, the responder means including coupling modulator means responsive to the encoded signal for varying the signal coupling between the interrogator means and the responder means in correspondence with the information providcd by the cocle means 9 the interrogator means including detection means ~or detecting the variation in signal coupling to recover the information represented by the encoded signal.
In ac~cordance with one aspect of the invention~
the coupling means comprises a first coil carried by the vehicle and a second coil associated with the responder means and located relative to the pathway of the vehicle to enable signal coupling to occur between the first and second coil as the vehicle moves adjacent to the responder ; means, the coupling modulator rrleans controlling the second coil to vary the signal coupling in correspondence with the information provided by the code means. The first coil is energized by a frequency signal so that the variation in signal coupling results in modulation of the frequency signal from which the coded information is detected by the detecting rneans for use by the vehicle control circuitsO
The responder means are disposed at various locations along the traffic layout, including the locations of each station and at decision points and the information provided includes a unique identifying code for each location. The codes are sensed by the vehicle carried interrogator means as the vehicle passes adJacent to the responcler means, enabling the control circuit on the vehicle to deterrnine the location of the vehicle along the traffic t'~
layout, provided information for guiding the vehicle in selecting the shortest route to its designated station, and halt the vehicle when it reached its designated station.
In accordance with a feature of the invention, the iclentification code arrangement includes a passive code responder means for each location to be identified. Each responder means derives both a time base and DC power from the signal generated by the interrogator means carried by the vehicle. ~hen a vehicle passes adjacent to the responder means, the identification signal generating means is enabled to generate a pulse code signal which drives a switching circuit which alternately detunes and tunes the coil of the responder means. The interaction on the primary coil on the vehicle due to transformer action results in a modulation envelope on the primary coil voltage. The modulation represents the code of the resporder means and its signal is detected, separated from the carrier signal and processed to provide the identification code at the output of the vehicle sensing circuits.
In accordance with a further feature of the invention, the signal generating means of the responder means is programmable by way of manually settable switches.
This enables the responder means to be reprogrammed at will. In addition, as indicated, the responder means is a passive device, deriving its power from the interrogating signal generated by the vehicle carried control circuits.
Thus, no power is required to maintain the floor mounted responder means energized.
~3~
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a simplified layout diagram illustrating a traffic layout for a guidance system including the ].ocation identiEication arrangement of the present invention;
FIG. 2 is a block diagram of the location identification circuits of the present invention;
FIG. 3 is a plan view of a mobile vehicle for use in the guidance system;
FIGS. 4 and 4A are a partial schematic circuit and block diagram of the vehicle interrogator of the location identification circuits shown in FIG. 2; and FIG. 5 is a partial schematic circuit and block diagram of the responder circuit of the location identification circuits;
DESCRIPTION OF PREFERRED EMBODIMENTS
_ The location-identification arrangement of the present invention is described with reference to an application in a vehicle guidance system in which one or more driverless vehicles are guided along a traffic layout.
The traffic layout of the vehicle guidance system, shown in simplified fashion in FIG. 1, is generally formed by a pair of guide wires 15 and 16 laid down in a pattern to define main and secondary paths of the systems for guiding driverless mobile vehicles 35, 35', etc. along the traffic layout. The main traffic path is defined by guide wire 15, indicated by the solid line, which extends in a continuous loop and which is energized by a signal at a first frequency fl provided by an oscillator 25 oE a central contro:l unit 2~. The other guide wire 16 defines three ~2321~i55 secondary traffic paths, depicted in dashed lines designated by reference numerals 16A-16C. The secondary paths intersect with the main path at points 17-22, and are interconnected with one another by lines 16', indicated by dot-dashed line, to form a further continuous guidance loop which is energized by a signal at a second frequency f2 provided by an oscillator 24 of the central control unit
2 8. The central control unit 28 also synchronizes the operation of the control circuits of all of the vehicles by way of a synchronizing signal generated by generator 29.
Referring to FIG. 3, there is shown a plan view of a vehicle 35 shown following a course defined by signals radiated from guide wire 15. Such vehicle may include a front drive and steering wheel 36, left and right rear wheels 37 and 38 respectively, and a coupler 39 attached to the rear of the vehicle. The vehicle 35 further includes a guide path detector 32 which responds to the signals at frequeney fl conducted over the guide wire 15 to provide control outputs to a steering control unit 33 which controls the front wheel 36 to maintain the vehicle traveling along the guide path defined by conductor 15. The steering control unit also receives signals from the control circuit 30 for the vehicle 35 which responds to location-identification data provided by a code sensor orinterrogator 31 and code devices or responders located in the floor along the guide path, indicative of the location of the vehicle along the traffic layout. The manner in which the identification code data is generated is described herein below.
.1"~
, ,;
~3~655 I'he present system provides converging, diverging and radio blocking functions. In laying out the system, "decision points" are defined, and then "stopping points".
Responders are provided at these points. To regulate traffic flow, these decision points and stopping points are used to deEine blocking ~ones, and if necessary, additional responders are added for blocking only.
Referring again to FIG. 1, a number of typical stations or locations are referenced by numerals 1-10 on the layout. After a mobile vehicle is directed to proceed to a preselected station, the control circuit 30 selects the shortest route in proceeding to the station. The points at which the secondary paths diverges from the main path, are dominated "decision points". When a vehicle approaches any oE these points in its travel to a preselected station, the control circuit carried by the vehicle determines whether to maintain the vehicle on the main path, or to depart and travel over the secondary path in traversing the preferred route, or shortest distance, to the station.
Converging points 21 and 22 indicate where the secondary path converges with the main path. The control circuit 30 includes a programmer having associated select switches which are manually set at the station from which the vehicle starts, to "instruct" the vehicle to proceed toward and stop at a predetermined station, and to take the shortest route to the designated station.
~ ~26~i5 The location-identification arrangement of this invention enables the control circuit 30 to determine the location of the vehicle along the traffic layout.
Responders are provided at various points along the traffic layout~ including the locations of the stations 1-10 and at the points 17-22 where the secondary paths 16A-16C
interconnect with the main path 15. Each responder has been given the same reference numeral as its location, but with an added "prime" notation. Thus, the responder for station 1 is indicated as 1', for point 17 is indicated as 17', etc. In general, each of the responders provides a unique coding which is detected or read by an interrogator 31 (FIG. 3) on the vehicl?, as the vehicle moves along the traffic layout.
The interrogator detects the code provided by the responder as the vehicle passes adjacent to the responders and provides location identification data to the vehicle control circuit 30 for enabling the control circuit to determine when the vehicle reaches decision points and generate appropriate commands to direct the vehicle in its movement, and to respond to the coding of the station which is the designated destination for the vehicle to halt the vehicle at such station.
Each responder provides a unique coding which identifies the location of the device, and in some cases information for use by the vehicle control circuit 30 in directing the vehicle in its movement, such information including identification of converging and diverging points, availability of bypass paths, and instructions to change frequency to enter a bypass path or to reenter the main path.
~3~5 :~
Referring to FIG. 2, the lnterrogator 31 includes a drive stage 42 including a time base generator 43, a frequency divider 44 and power drive circuit 45 which drives an antenna or coil 40. The coil 40 is mounted on the forward portion of the vehicle, as shown in FIG. 3 and is located approximately one inch above the floor. The interrogator 31 further includes a detection stage 46 including a modulation envelope detector 47, a carrier reject filter 48 and a pulse detector 49~
Each responder, such as responder 17' shown in FI~. 2, includes a coil 50 connected to the output of a modulator 51 which is driven by a pulse code generator 52 having associated code select switches 53. The responder 17' further includes a frequency divider circuit 54 and a power supply circuit 54.
The drive circuit 45 of the interrogator 31 generates an RF signal at a frequency established by the time bage generator 43 and applies the signal to the coil 40. In the instant embodiment, the coil 40 is energized with a 70 kHz signal. As the vehicle moves along the traffic layout and approaches the location of a responder, such as responder 17', signal coupling occurs between the coils 40 and 50. The RF signal is coupled to the responder coil and is detected by the power supply circuit 54 which derives DC power from such signal for the modulator 51, the pulse code generator 52 of the responder. In addition, the code generator 52 derives a time base for the responder circuits from the RF signal coupled to coil 50.
The code generator 52 generates a signal which is encoded in binary fashion in accordance with the code indicateed by code select circuit 53, the code representing the floor location of responder 17'. In the exemplary embodiment, the identif'ication code data is transmitted to the interrogator in two six-bit segments, each preceded by a two bit header and followed by a parity bit for synchronization and security purposes. The responders may be embedded in the floor, and the code select circuit 53 may be accessible to permit reprogramming of the responder.
The responder code select circuit 53 may also be remotely adjustable, by way of wires (not shown) which could extend from the responder. The responder coil is positioned to enable signal coupling to occur between the responder and interrogator coils as the vehicle moves adjacent to the responder.
The serially encoded signal is applied to the modulator circuit 51 which varies interaction between the two windings~ for example by detuning or tuning the coil 50 in accordance with the coding of the signal. In the exempla~y embodiment 9 the modulator circuit 51 detunes the coil 50 for each logic 1 resulting in unloading on the primary winding 40, relative to that provided for each logic 0, i.e. the normal loading condition when the coil 50 is tuned. The interaction due to transformer action on the primary coil 40, associated with the interrogator 31, with the secondary winding 50 results in a modulation envelope on the primary coil voltage, representing the code of the responder floor package, that is, modulation of the 70 kHz signal provided by the interrogator with identification data. The modulation is detected by the modulating envelope detector 47 and separated from the carrier signal by carrier reject filter 48 and passed to pulse detector circuit 49 which provides the identification code in binary form at .~3296~D
the output~ The binary encoded signal is processed by suitable parity and security checking circuits and passed to the input of the vehicle control circuit 30, providing two six-bit code words representative of the coding of the floor responder 17'.
DETAILED DESC~IPTION
INTERROGATOR CIRCUIT
Referring to FIGS. 4 and 4A, The interrogator time base generator 43 is of conventional design and includes a crystal oscillator formed by crystal 61, resistors 62 and 63, capacitors 64 and 65 and an inverter 66 connected to provide a signal at a 3.58 mHz rate.
This signal is divided down to provide a clock signal at a 70 kHz rate by the frequency divider 43 which provides a divide by 51 function. The frequency divider ~3 includes a pair of decade counters 67 and 67a, NAND gates 68-70 and inverter 71 connected to respond to outputs of the decade counters 67 and 67a and generate a reset signal for the decade counters each time a count of fifty-one is reached. The outputs of decade counter 67a are combined by NAND gate 72 and inverters 73 and 74 to provide a signal at a 70 kHz rate. This clock signal at a 70 kHz rate i5 applied to the drive circuit 42 to drive the coil 40. This signal may also be used to derive timing signals for other circuits of the vehicle control circuit 30, a twelve stage counter 75 enabling the 70 kHz clock signal to be counted down to a rate less than the 70 kHz rate, if desired. The ~3~6~
output clock signal is extended to the vehicle control circuit 30 through an interface including inverters 76, 76a, level translator 76a and line driver circuit 77.
The power drive circuit 45 includes a Darlington power transistor stage 81. The transistor stage 81 is driven at the 70 kHz rate by the clock signal which is supplied to the base of the transistor circuit through variable resistor 82 which together with a resistor 83, connected between the base of transistor 81 and ground, define a voltage divider providing variable level adjustment for the input signal to the transiskor stage. The emitter of the transistor 81 is connected to ground through resistor 84 and the colleckor is connected to the coil 40. A
feedback circuit including a resistor 85 and a capacitor 86 are connected between the collector and base of the transistor 81.
The system is short-range so that the location of the floor mounted responder is identified within a few inches of travel of the vehicle. Accordinglyt the power level of the drive signal supplied to the primary coil ~0 is sufficient to insure detection of ea~h floor responder as the vehicle passes adjacent thereto.
The coil or antenna 40 comprises multiple turns of number 20 wire having a center tap 91 which is connected to the output of the power amplifier 45. The coil is wound on a suitable cylindrical body approximately three inches wide with winding 92 being wound on top of winding 93.
Capacitors 94 and 95 are provided to tune the coils in series. As indicated, the coil is mounted beneath the ~3~65~
vehicle near one end. The coil is connected to the input of the sensing circuit by a shielded cable. The ends of the coil windings are connected to a terminal block 96 to which is connected the conductors of a three wire shielded cable. The center tap 91 is connected to the output of the power drive circuit 42. One end of winding 93 is connected to a voltage source of +A, and one end of winding 92 is connected to the input of the modulation envelope detector circuit 47.
The detector circuit 47 includes a pair of diodes 101 and 102 connected as a peak rectifier circuit which receives the antenna signal coupled to the detector circuit 47 through a capacitor 103, separating the low frequency modulating signal from the 70 kHz carrier. A capacitor 104 and resistor 105 are connected across the outputs of the envelope detector circuit 47 to establish a time constant for maximum removal of the 70 kHz carrier without loss of'the D.C. level corresponding to the responder code.
In the exemplary embodiment, the coil 40 is mounted near the front of the vehicle and thus detects the responders as the front end of the vehicle moves past them.
A rear antenna 40' and associated power amplifier drive circuit 42' are provided to enable detection of the floor mounted responders just before the back end of the vehicle passes over the responders. lt is pointed out that in addition to front (and/or rear) location, the coil 40 may be disposed laterally to detect responders located at the side of the pathway.
~ 3~76~
Selection of either the front antenna or the rear (side) antenna is accomplished by an analog switch 111 which is operable to connect the output ei,ther detector circuit 47 associated with the front antenna or detector circuit 47' associated with the rear (side) antenna to the input of the carrier reject filter 48. Enabling of the analog switch device 111 is controlled by an enabling signal provided over input 112 from the vehicle control circuit 30 and conductor 112'. This signal also enables AND gate lO9 or AND gate lO9l to gate the 70 kHz drive signal to the power drive circuit 45. A low level signal at input 112 enables gate lO9 and switch device 113 to connect the output of detector circuit 47 to the input of the carrier reject filter 48. In addition, the input signal inverted by inverter 115 disables switch 114 to disconnect detector 47' from the çarrier reject filter 48. When the input at terminal 112 is high, switch 113 is disabled and switch 114 is ~enabled so that the signal detected by the rear antenna 40' is supplied to the carrier reject filter 48.
An indicator circuit on the vehicle7 comprised of a pair of light emitting diodes 116 and 117 and associated drive circuits 118 and 119, indicates the status o~ the analog switch 111 and thus which antenna 40 or 40' is activated.
The carrier reject filter 48 comprises a low pass filter stage formed by inductor 121 and capacitor 122 which serves as a parallel trap for the 70 kHz carrier.
~3~
Capacitors 126 and 127 form a smoothing stage to eliminate ripple. Resistor 125 isolates capacitor 125 from capacitor 127.
The output of the carrier reject filter 48 is extended to the pulse detector circuit ll9 which performs limiting and slicing, reconstructing the binary coded data word at the output thereof. The pulse detector circuit 49 includes a differentiating circuit formed by an operational amplifier 130 having its inverting input coupled through capacitor 131 to the output of the filter circuit 48 and its non-inverting input connected to a reference circuit, including resistors 132 and 133, which provides a bias reference at the non-inverting input of the amplifier 130. A feedback network formed by resistor 13l1 and capacitor 135 is connected from the output of the amplifier 130 to its inverting input. The output of amplifier 130 is also connected through a resistor 137 to the inverting input of a further operational amplifier 140 and through a resistor 138 to the non-inverting input of the amplifier 140 configured for operation as a slicer circuit. Amplifier 1~0 has a time constant network formed by resistor 137 and capacitor 137a connected to one input to follow the average D.C. level to the amplifier 1400 Resistor 139 provides positive feedback to the other input to provide a hysteresis effect to prevent the amplifier 140 from responding to minor variations in the input signal.
The serial pulse train provided at the output of amplifier 140 is extended through a buffer circuit 142 to an interface circuit including a line driver circuit 1 ~
~23;2~S~
143 which extends the digital pulse output of the pulse detector circuit 49 to parity and security checking circuit (not shown) before the six bit data portion is stored in the memory circuit of the control circuit 30.
The sensor input circuit includes two eight-bit memories. This arran~ement may be adapted for interfacing with the identification code arrangement of the present invention by storing one six-bit word in the first row memory and the other six-bit word in the second row memory.
Other interfacing arrangements are also possible as is apparent to one skilled in the art.
RESPONDER CIRCUIT
Referring now to FIG. 5, the responder antenna or coil 50 comprises forty turns of number 20 wire wound on a cylindrical core (not shown) with terminals 154 and 155. A tap 151 defines a thirty turn section between the tap 151 and terminal 155. A capacitor 156 and an inductor 157 are connected in series between terminals 154 and 155, the inductor being variable to enable fine tunin~ of the responder an-tenna circuit. The junction of capacitor 156 and indicator 157 is connected to ground. A capacitor 158 and a diode 159 are connected in a series undirectional charging path from ground to terminal 151. Terminal 154 is coupled through a capacitor 160 to the input of the power supply circuit 54 which, in effect, is connected across the coil 50.
The power supply circuit 54 includes diodes 161 and 162 which provide peak rectification of the 70 kH7 signal coupled to the winding 50 from the vehicle mounted ., ~326~
transponder. A diode 1~2, which is a Zener diode connected between the ground terminal and the junction of capacitor 160 and diode 161, provides a limiting operation. A
capacitor 1639 connected between the cathode of ~iode 161 at conductor 165 and ground, provides smoothing of the raw DC signal provided on conductor 165. This DC signal is supplied to a voltage switahing circuit formed by transistors 166 and 167.
The unregulated DC is applied to the base of transistor 166 through resistors 168 and 169 which are connected in series between conductor 165 and ground~ A
capacitor 170 connected parallel with resistor 169 provides filtering for the input signal. The transistor 166 has its emitter connected to ground and its collector is connected through resistor 171 to the base of transistor 167 which has its emitter connected to conductor 165 and its collector connected through positive feedback resistor 172 to the base of transistor 166. Transistors 166 and 167 are complimentary transistors connected for operation as a low level Schmitt trigger circuit, extending the DC
signal on conductor 165 to conductor VDD at the collector of transistor 167 for energizing the pulse code generator and the modulating circuit of the responder. The positive feedback through resistor 172 provides hysteresis turn off for the switch, preventing disconnection of power from line VDD for minor level shifts in the input signal due to noise, but allowing "snap-action" disconnection of power to line VDD when the input power drops below a given level.
1~
~ r~
~L~3~ 33 The code generator circuit 52 comprises a timing and control circuit 173 and a parallel-to-serial shift register 174. The timing and control circuit 173 divides down the RF signal to generate a time base for the code generator circuit 52 as well as signals for controlling the readout of the identification code provided by the code select circuit 53.
The code select circuit 53 comprises three switches 53A, 53B and 53C, a switch 178, and an interface circuit 179. The switches 53A-53C provide outputs on twelve output lines 53~1 to 53~12 to inputs of the interface circuit 179 which provides outputs on six output lines 179-1 to 179-6 to inputs of the shaft register 174. The switches 53A-53C are manually settable to provide the desired unique identification and information code for the position at which the responder is located along the guidance path.
As indicated above, the idencification code format is a six-bit data word preceded by a start bit and an identification bit, and follo~ed by a parity bit. The shift 20 register 174 provides six stages, one corresponding to each of the output lines 179-1 to 179-6, and three additional stages for storing the start bit, the identification bit and the parity bit. The start bit is a "mark" or logic 1 bit. The identification bit is a logic 1 bit for the first of the two data segments transmitted, and a logic 0 bit for the second segment. The parity bit is a logic 1 bit or a logic 0 bit determined by the setting of switch 178. After transmission of two data segments, the sequence
Referring to FIG. 3, there is shown a plan view of a vehicle 35 shown following a course defined by signals radiated from guide wire 15. Such vehicle may include a front drive and steering wheel 36, left and right rear wheels 37 and 38 respectively, and a coupler 39 attached to the rear of the vehicle. The vehicle 35 further includes a guide path detector 32 which responds to the signals at frequeney fl conducted over the guide wire 15 to provide control outputs to a steering control unit 33 which controls the front wheel 36 to maintain the vehicle traveling along the guide path defined by conductor 15. The steering control unit also receives signals from the control circuit 30 for the vehicle 35 which responds to location-identification data provided by a code sensor orinterrogator 31 and code devices or responders located in the floor along the guide path, indicative of the location of the vehicle along the traffic layout. The manner in which the identification code data is generated is described herein below.
.1"~
, ,;
~3~655 I'he present system provides converging, diverging and radio blocking functions. In laying out the system, "decision points" are defined, and then "stopping points".
Responders are provided at these points. To regulate traffic flow, these decision points and stopping points are used to deEine blocking ~ones, and if necessary, additional responders are added for blocking only.
Referring again to FIG. 1, a number of typical stations or locations are referenced by numerals 1-10 on the layout. After a mobile vehicle is directed to proceed to a preselected station, the control circuit 30 selects the shortest route in proceeding to the station. The points at which the secondary paths diverges from the main path, are dominated "decision points". When a vehicle approaches any oE these points in its travel to a preselected station, the control circuit carried by the vehicle determines whether to maintain the vehicle on the main path, or to depart and travel over the secondary path in traversing the preferred route, or shortest distance, to the station.
Converging points 21 and 22 indicate where the secondary path converges with the main path. The control circuit 30 includes a programmer having associated select switches which are manually set at the station from which the vehicle starts, to "instruct" the vehicle to proceed toward and stop at a predetermined station, and to take the shortest route to the designated station.
~ ~26~i5 The location-identification arrangement of this invention enables the control circuit 30 to determine the location of the vehicle along the traffic layout.
Responders are provided at various points along the traffic layout~ including the locations of the stations 1-10 and at the points 17-22 where the secondary paths 16A-16C
interconnect with the main path 15. Each responder has been given the same reference numeral as its location, but with an added "prime" notation. Thus, the responder for station 1 is indicated as 1', for point 17 is indicated as 17', etc. In general, each of the responders provides a unique coding which is detected or read by an interrogator 31 (FIG. 3) on the vehicl?, as the vehicle moves along the traffic layout.
The interrogator detects the code provided by the responder as the vehicle passes adjacent to the responders and provides location identification data to the vehicle control circuit 30 for enabling the control circuit to determine when the vehicle reaches decision points and generate appropriate commands to direct the vehicle in its movement, and to respond to the coding of the station which is the designated destination for the vehicle to halt the vehicle at such station.
Each responder provides a unique coding which identifies the location of the device, and in some cases information for use by the vehicle control circuit 30 in directing the vehicle in its movement, such information including identification of converging and diverging points, availability of bypass paths, and instructions to change frequency to enter a bypass path or to reenter the main path.
~3~5 :~
Referring to FIG. 2, the lnterrogator 31 includes a drive stage 42 including a time base generator 43, a frequency divider 44 and power drive circuit 45 which drives an antenna or coil 40. The coil 40 is mounted on the forward portion of the vehicle, as shown in FIG. 3 and is located approximately one inch above the floor. The interrogator 31 further includes a detection stage 46 including a modulation envelope detector 47, a carrier reject filter 48 and a pulse detector 49~
Each responder, such as responder 17' shown in FI~. 2, includes a coil 50 connected to the output of a modulator 51 which is driven by a pulse code generator 52 having associated code select switches 53. The responder 17' further includes a frequency divider circuit 54 and a power supply circuit 54.
The drive circuit 45 of the interrogator 31 generates an RF signal at a frequency established by the time bage generator 43 and applies the signal to the coil 40. In the instant embodiment, the coil 40 is energized with a 70 kHz signal. As the vehicle moves along the traffic layout and approaches the location of a responder, such as responder 17', signal coupling occurs between the coils 40 and 50. The RF signal is coupled to the responder coil and is detected by the power supply circuit 54 which derives DC power from such signal for the modulator 51, the pulse code generator 52 of the responder. In addition, the code generator 52 derives a time base for the responder circuits from the RF signal coupled to coil 50.
The code generator 52 generates a signal which is encoded in binary fashion in accordance with the code indicateed by code select circuit 53, the code representing the floor location of responder 17'. In the exemplary embodiment, the identif'ication code data is transmitted to the interrogator in two six-bit segments, each preceded by a two bit header and followed by a parity bit for synchronization and security purposes. The responders may be embedded in the floor, and the code select circuit 53 may be accessible to permit reprogramming of the responder.
The responder code select circuit 53 may also be remotely adjustable, by way of wires (not shown) which could extend from the responder. The responder coil is positioned to enable signal coupling to occur between the responder and interrogator coils as the vehicle moves adjacent to the responder.
The serially encoded signal is applied to the modulator circuit 51 which varies interaction between the two windings~ for example by detuning or tuning the coil 50 in accordance with the coding of the signal. In the exempla~y embodiment 9 the modulator circuit 51 detunes the coil 50 for each logic 1 resulting in unloading on the primary winding 40, relative to that provided for each logic 0, i.e. the normal loading condition when the coil 50 is tuned. The interaction due to transformer action on the primary coil 40, associated with the interrogator 31, with the secondary winding 50 results in a modulation envelope on the primary coil voltage, representing the code of the responder floor package, that is, modulation of the 70 kHz signal provided by the interrogator with identification data. The modulation is detected by the modulating envelope detector 47 and separated from the carrier signal by carrier reject filter 48 and passed to pulse detector circuit 49 which provides the identification code in binary form at .~3296~D
the output~ The binary encoded signal is processed by suitable parity and security checking circuits and passed to the input of the vehicle control circuit 30, providing two six-bit code words representative of the coding of the floor responder 17'.
DETAILED DESC~IPTION
INTERROGATOR CIRCUIT
Referring to FIGS. 4 and 4A, The interrogator time base generator 43 is of conventional design and includes a crystal oscillator formed by crystal 61, resistors 62 and 63, capacitors 64 and 65 and an inverter 66 connected to provide a signal at a 3.58 mHz rate.
This signal is divided down to provide a clock signal at a 70 kHz rate by the frequency divider 43 which provides a divide by 51 function. The frequency divider ~3 includes a pair of decade counters 67 and 67a, NAND gates 68-70 and inverter 71 connected to respond to outputs of the decade counters 67 and 67a and generate a reset signal for the decade counters each time a count of fifty-one is reached. The outputs of decade counter 67a are combined by NAND gate 72 and inverters 73 and 74 to provide a signal at a 70 kHz rate. This clock signal at a 70 kHz rate i5 applied to the drive circuit 42 to drive the coil 40. This signal may also be used to derive timing signals for other circuits of the vehicle control circuit 30, a twelve stage counter 75 enabling the 70 kHz clock signal to be counted down to a rate less than the 70 kHz rate, if desired. The ~3~6~
output clock signal is extended to the vehicle control circuit 30 through an interface including inverters 76, 76a, level translator 76a and line driver circuit 77.
The power drive circuit 45 includes a Darlington power transistor stage 81. The transistor stage 81 is driven at the 70 kHz rate by the clock signal which is supplied to the base of the transistor circuit through variable resistor 82 which together with a resistor 83, connected between the base of transistor 81 and ground, define a voltage divider providing variable level adjustment for the input signal to the transiskor stage. The emitter of the transistor 81 is connected to ground through resistor 84 and the colleckor is connected to the coil 40. A
feedback circuit including a resistor 85 and a capacitor 86 are connected between the collector and base of the transistor 81.
The system is short-range so that the location of the floor mounted responder is identified within a few inches of travel of the vehicle. Accordinglyt the power level of the drive signal supplied to the primary coil ~0 is sufficient to insure detection of ea~h floor responder as the vehicle passes adjacent thereto.
The coil or antenna 40 comprises multiple turns of number 20 wire having a center tap 91 which is connected to the output of the power amplifier 45. The coil is wound on a suitable cylindrical body approximately three inches wide with winding 92 being wound on top of winding 93.
Capacitors 94 and 95 are provided to tune the coils in series. As indicated, the coil is mounted beneath the ~3~65~
vehicle near one end. The coil is connected to the input of the sensing circuit by a shielded cable. The ends of the coil windings are connected to a terminal block 96 to which is connected the conductors of a three wire shielded cable. The center tap 91 is connected to the output of the power drive circuit 42. One end of winding 93 is connected to a voltage source of +A, and one end of winding 92 is connected to the input of the modulation envelope detector circuit 47.
The detector circuit 47 includes a pair of diodes 101 and 102 connected as a peak rectifier circuit which receives the antenna signal coupled to the detector circuit 47 through a capacitor 103, separating the low frequency modulating signal from the 70 kHz carrier. A capacitor 104 and resistor 105 are connected across the outputs of the envelope detector circuit 47 to establish a time constant for maximum removal of the 70 kHz carrier without loss of'the D.C. level corresponding to the responder code.
In the exemplary embodiment, the coil 40 is mounted near the front of the vehicle and thus detects the responders as the front end of the vehicle moves past them.
A rear antenna 40' and associated power amplifier drive circuit 42' are provided to enable detection of the floor mounted responders just before the back end of the vehicle passes over the responders. lt is pointed out that in addition to front (and/or rear) location, the coil 40 may be disposed laterally to detect responders located at the side of the pathway.
~ 3~76~
Selection of either the front antenna or the rear (side) antenna is accomplished by an analog switch 111 which is operable to connect the output ei,ther detector circuit 47 associated with the front antenna or detector circuit 47' associated with the rear (side) antenna to the input of the carrier reject filter 48. Enabling of the analog switch device 111 is controlled by an enabling signal provided over input 112 from the vehicle control circuit 30 and conductor 112'. This signal also enables AND gate lO9 or AND gate lO9l to gate the 70 kHz drive signal to the power drive circuit 45. A low level signal at input 112 enables gate lO9 and switch device 113 to connect the output of detector circuit 47 to the input of the carrier reject filter 48. In addition, the input signal inverted by inverter 115 disables switch 114 to disconnect detector 47' from the çarrier reject filter 48. When the input at terminal 112 is high, switch 113 is disabled and switch 114 is ~enabled so that the signal detected by the rear antenna 40' is supplied to the carrier reject filter 48.
An indicator circuit on the vehicle7 comprised of a pair of light emitting diodes 116 and 117 and associated drive circuits 118 and 119, indicates the status o~ the analog switch 111 and thus which antenna 40 or 40' is activated.
The carrier reject filter 48 comprises a low pass filter stage formed by inductor 121 and capacitor 122 which serves as a parallel trap for the 70 kHz carrier.
~3~
Capacitors 126 and 127 form a smoothing stage to eliminate ripple. Resistor 125 isolates capacitor 125 from capacitor 127.
The output of the carrier reject filter 48 is extended to the pulse detector circuit ll9 which performs limiting and slicing, reconstructing the binary coded data word at the output thereof. The pulse detector circuit 49 includes a differentiating circuit formed by an operational amplifier 130 having its inverting input coupled through capacitor 131 to the output of the filter circuit 48 and its non-inverting input connected to a reference circuit, including resistors 132 and 133, which provides a bias reference at the non-inverting input of the amplifier 130. A feedback network formed by resistor 13l1 and capacitor 135 is connected from the output of the amplifier 130 to its inverting input. The output of amplifier 130 is also connected through a resistor 137 to the inverting input of a further operational amplifier 140 and through a resistor 138 to the non-inverting input of the amplifier 140 configured for operation as a slicer circuit. Amplifier 1~0 has a time constant network formed by resistor 137 and capacitor 137a connected to one input to follow the average D.C. level to the amplifier 1400 Resistor 139 provides positive feedback to the other input to provide a hysteresis effect to prevent the amplifier 140 from responding to minor variations in the input signal.
The serial pulse train provided at the output of amplifier 140 is extended through a buffer circuit 142 to an interface circuit including a line driver circuit 1 ~
~23;2~S~
143 which extends the digital pulse output of the pulse detector circuit 49 to parity and security checking circuit (not shown) before the six bit data portion is stored in the memory circuit of the control circuit 30.
The sensor input circuit includes two eight-bit memories. This arran~ement may be adapted for interfacing with the identification code arrangement of the present invention by storing one six-bit word in the first row memory and the other six-bit word in the second row memory.
Other interfacing arrangements are also possible as is apparent to one skilled in the art.
RESPONDER CIRCUIT
Referring now to FIG. 5, the responder antenna or coil 50 comprises forty turns of number 20 wire wound on a cylindrical core (not shown) with terminals 154 and 155. A tap 151 defines a thirty turn section between the tap 151 and terminal 155. A capacitor 156 and an inductor 157 are connected in series between terminals 154 and 155, the inductor being variable to enable fine tunin~ of the responder an-tenna circuit. The junction of capacitor 156 and indicator 157 is connected to ground. A capacitor 158 and a diode 159 are connected in a series undirectional charging path from ground to terminal 151. Terminal 154 is coupled through a capacitor 160 to the input of the power supply circuit 54 which, in effect, is connected across the coil 50.
The power supply circuit 54 includes diodes 161 and 162 which provide peak rectification of the 70 kH7 signal coupled to the winding 50 from the vehicle mounted ., ~326~
transponder. A diode 1~2, which is a Zener diode connected between the ground terminal and the junction of capacitor 160 and diode 161, provides a limiting operation. A
capacitor 1639 connected between the cathode of ~iode 161 at conductor 165 and ground, provides smoothing of the raw DC signal provided on conductor 165. This DC signal is supplied to a voltage switahing circuit formed by transistors 166 and 167.
The unregulated DC is applied to the base of transistor 166 through resistors 168 and 169 which are connected in series between conductor 165 and ground~ A
capacitor 170 connected parallel with resistor 169 provides filtering for the input signal. The transistor 166 has its emitter connected to ground and its collector is connected through resistor 171 to the base of transistor 167 which has its emitter connected to conductor 165 and its collector connected through positive feedback resistor 172 to the base of transistor 166. Transistors 166 and 167 are complimentary transistors connected for operation as a low level Schmitt trigger circuit, extending the DC
signal on conductor 165 to conductor VDD at the collector of transistor 167 for energizing the pulse code generator and the modulating circuit of the responder. The positive feedback through resistor 172 provides hysteresis turn off for the switch, preventing disconnection of power from line VDD for minor level shifts in the input signal due to noise, but allowing "snap-action" disconnection of power to line VDD when the input power drops below a given level.
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~L~3~ 33 The code generator circuit 52 comprises a timing and control circuit 173 and a parallel-to-serial shift register 174. The timing and control circuit 173 divides down the RF signal to generate a time base for the code generator circuit 52 as well as signals for controlling the readout of the identification code provided by the code select circuit 53.
The code select circuit 53 comprises three switches 53A, 53B and 53C, a switch 178, and an interface circuit 179. The switches 53A-53C provide outputs on twelve output lines 53~1 to 53~12 to inputs of the interface circuit 179 which provides outputs on six output lines 179-1 to 179-6 to inputs of the shaft register 174. The switches 53A-53C are manually settable to provide the desired unique identification and information code for the position at which the responder is located along the guidance path.
As indicated above, the idencification code format is a six-bit data word preceded by a start bit and an identification bit, and follo~ed by a parity bit. The shift 20 register 174 provides six stages, one corresponding to each of the output lines 179-1 to 179-6, and three additional stages for storing the start bit, the identification bit and the parity bit. The start bit is a "mark" or logic 1 bit. The identification bit is a logic 1 bit for the first of the two data segments transmitted, and a logic 0 bit for the second segment. The parity bit is a logic 1 bit or a logic 0 bit determined by the setting of switch 178. After transmission of two data segments, the sequence
3~
is repeated, with the identification bit being charged to a logic 1 for the first segment of the subsequent transmission.
Ths interface circuit 179 multiplexes the twelve switch lines 53-1 to 53-12, six at a time, t~ the parallel inputs of the shifit register 174 under the control of timing signals provided by the timing and control circuit 173 on - line 173a. The timing and control circuit 173 provides a jam signal on line 173b signal to load the shift register 174 with the six data bits provided on lines 179 1 to 179-6 along with the start bit, the identification bit and the parity bit via lines 179-7 to 179-9 to which are applied a voltage level corresponding to the desired logic level.
The timing and control circuit 173 also provides clock pulses on line 173c to effect serial readout of the shift register 174. The timing and control circuit 173 controls the interface circuit 179 to select the set of data outputs as weli as the state of the identification bit for each data segment transmission.
In summary, the code generator circuit 52 responds to the RF signal coupled thereto to generate two data words, each including a six data bits preceded by a start bit and an identification bit, and followed by a parity bit. The data word for each data segment transmission is provided as a serial pulse train at the output of the code generator circuit 52. Each serial pulse train is coupled through resistor 179 to the base of transistor 180 which comprises the modulating circuit 51.
~3~
Transistor 180 has its emitter-collector circuit connected across the diode 159. Thus the output circuit of transistor 180 is connected to shunt the diode 159 when the transistor 180 is conducting, permitting capacitor 158 to discharge, detuning the coil 50 by the added capacitance in the coil circuit.
Transistor 180 is turned on in response to each "mark" or logic 1 level bit of the serial pulse train provided by the pulse code generating circuit 52. The transistor la0 is cut off with each "space" or logic 0 level signal of the pulse train. Consequently, for each logic 1 level bit of the pulse train, capacitor 158 is connected with the thirty turn portion 153 of the secondary winding 50. This detunes winding 50 unloading the primary winding 40 with a resulting brief increase in the amplitude of the carrier signal appearing across the primary winding ~0.
The duration of the amplitude increase corresponds to the duration of the data pulse driving transistor 180.
OPERATION OF T~E IDENTIFICATION CODE SENSING ARRANGEMENT
The manner in which the detected code is used in deriving commands for the vehicle is known in the art of vehicle guidance systems, and so the following operational description is limited to a description of the detection of the identification codes.
Referring to FIGS. 1 and 2, for purposes of illustration of the operation of the interrogator and the responders it assumed that vehicle 35 is moving along the path defined by guide wire 15 between station 9 and station 1 and is approaching diverging point 17 which is identified by code device 17'. The front antenna coil 40 is assumed to be activated at this time, and the drive circuit 43 is continuously generating a 70 kHz signal energizing the front antenna coil 40 at the 70 kHz rate~
Referring now to FIG. 5, as the vehicle draws adjacent to code device 17l, the energizi.ng signal generated by the front antenna coil 40 is coupled to the coil 50 of the responder circuit 17'. The RF signal, coupled to the power supply circuit 54 through capacitor 160, is peak lO rectified by diode 1610 The resultant DC signal charges capacitor 163 maintains a DC level on conductor 165 as long as the RF signal is being supplied to the coil 50.
Capacitor 163 stores sufficient energy to maintain DC power to the circuit during times that the transistor 180 of the detuning switch 51 is enabled. The raw DC signal on line 165 is smoothed by capacitor 163 and supplied via transistor 167 to the code generating circuit 52 of the responder.
The RF signal coupled to coil 50 is coupled by capacitor 175 and is divided down by the timing and control 20 circuit 173 providing a first timing signal to enable interface circuit 179 to gate the four bits provided by s~itch 53A and the first two bits provided by switch 53B
through interface circuit 179 via lines 179-1 to 179-6 to the inputs of the parallel load shift register 174. The outputs on lines 179-7 to 179-9, including the start bit, the identification bit and the parity bit are also extended to further inputs of the parallel load shift register 174.
A further timing signal generated by timing and control circuit 173 is extended to the parallel load shift ~3~5~
register 174 as a load command to parallel load the data on lines 179-1 to 179-9, into the shift register 174.
The timing and control circuit 173 generates clock pulses at a selectable rate to the shift register 174 to effect ser;al readout of the data stored therein.
After all the bits of the first transmission segment have been gated out of the shift register 174, the timing and control circuit 173 resets the interface circuit 179 changing the status of the identification bit via line 179-8 and extending the last two bits of switch 53B and the four bits of switch 53C via lines 179-1 to 179-6 to the inputs of the shift register 174 along with the start bit, the modified identification bit and the parity bit, in preparation for readout of the second segment of data in a manner described for readout of the first segment of data.
Referring to FIGo 59 the serial data read out of the shift register 174 during the first transmission segment is extended to the base of transistor 180 of the modulator circuit 51. Each logic 1 bit of the output pulse train causes 20 transistor 180 to conduct, connecting capacitor 158 in circuit across the 30 turn section 153 of the winding 50 detuning the winding. The transistor 180 is maintained nonconducting by each logic 0 level of the data train.
Referring now to FIGS~ 4 and 4A, the interaction between coil 50 and the coil 40 due to transformer action as the switching transistor 180 responds to the logic 1 bits of the output pulse code during each segment transmission results in modulation of the primary coil voltage in a manner representing the code of the floor package. The modulated signal appearing across the antenna 40 is coupled to the detector 47.
~L~3;~6~;
The peak rectifier diodes 101 and 102 receive the antenna signal coupled to the detector circuit 47 through capacitor 103, and separate the low frequency modulating signal from the 70 k~lz carrierO Capacitor 104 and resistor 105 establish a time constant for maximum removal of the 70 kHæ carrier without loss of the DC level corresponding to the responder code.
The resultant signal is extended through analog switch 113 to the carrier reject filter 48 formed by inductor 121 and capacitors 122 and 123 which traps the 70 k~lz carrier. Capacitors 126 and 127 form a smoothing stage to eliminate ripple.
The output of the carrier reject filter 48 is extended to the pulse detector circuit 49 which performs limiting and slicing, reconstructing the binary coded data word at the output thereof.
The serial pulse train provided at the output of amplifier 140 is extended through the buffer circuit 142 and line driver circuit 143 which interfaces the pulse detector circuit 49 with parity and security checking circuit (not shown) prior to storing the verified data in a memory.
The sensor input circuit includes two eight-bit memories. This arrangement may be adapted for interfacing with the identification code arrangement of the present invention by storing one six-bit word in the Eirst row memory and the other six-bit word in the second row memory.
Other interfacing arrangements are also possible as is apparent to one skilled in the art.
The sequence of data readout will be provided as long as the vehicle is in the proximity of the responder ~` ~L23~S~i device 17' and sufficient coupling in provided between the primary winding 40 carrried by the vehicle and the coil 50 of the responder unit located in the floor.
. 24a
is repeated, with the identification bit being charged to a logic 1 for the first segment of the subsequent transmission.
Ths interface circuit 179 multiplexes the twelve switch lines 53-1 to 53-12, six at a time, t~ the parallel inputs of the shifit register 174 under the control of timing signals provided by the timing and control circuit 173 on - line 173a. The timing and control circuit 173 provides a jam signal on line 173b signal to load the shift register 174 with the six data bits provided on lines 179 1 to 179-6 along with the start bit, the identification bit and the parity bit via lines 179-7 to 179-9 to which are applied a voltage level corresponding to the desired logic level.
The timing and control circuit 173 also provides clock pulses on line 173c to effect serial readout of the shift register 174. The timing and control circuit 173 controls the interface circuit 179 to select the set of data outputs as weli as the state of the identification bit for each data segment transmission.
In summary, the code generator circuit 52 responds to the RF signal coupled thereto to generate two data words, each including a six data bits preceded by a start bit and an identification bit, and followed by a parity bit. The data word for each data segment transmission is provided as a serial pulse train at the output of the code generator circuit 52. Each serial pulse train is coupled through resistor 179 to the base of transistor 180 which comprises the modulating circuit 51.
~3~
Transistor 180 has its emitter-collector circuit connected across the diode 159. Thus the output circuit of transistor 180 is connected to shunt the diode 159 when the transistor 180 is conducting, permitting capacitor 158 to discharge, detuning the coil 50 by the added capacitance in the coil circuit.
Transistor 180 is turned on in response to each "mark" or logic 1 level bit of the serial pulse train provided by the pulse code generating circuit 52. The transistor la0 is cut off with each "space" or logic 0 level signal of the pulse train. Consequently, for each logic 1 level bit of the pulse train, capacitor 158 is connected with the thirty turn portion 153 of the secondary winding 50. This detunes winding 50 unloading the primary winding 40 with a resulting brief increase in the amplitude of the carrier signal appearing across the primary winding ~0.
The duration of the amplitude increase corresponds to the duration of the data pulse driving transistor 180.
OPERATION OF T~E IDENTIFICATION CODE SENSING ARRANGEMENT
The manner in which the detected code is used in deriving commands for the vehicle is known in the art of vehicle guidance systems, and so the following operational description is limited to a description of the detection of the identification codes.
Referring to FIGS. 1 and 2, for purposes of illustration of the operation of the interrogator and the responders it assumed that vehicle 35 is moving along the path defined by guide wire 15 between station 9 and station 1 and is approaching diverging point 17 which is identified by code device 17'. The front antenna coil 40 is assumed to be activated at this time, and the drive circuit 43 is continuously generating a 70 kHz signal energizing the front antenna coil 40 at the 70 kHz rate~
Referring now to FIG. 5, as the vehicle draws adjacent to code device 17l, the energizi.ng signal generated by the front antenna coil 40 is coupled to the coil 50 of the responder circuit 17'. The RF signal, coupled to the power supply circuit 54 through capacitor 160, is peak lO rectified by diode 1610 The resultant DC signal charges capacitor 163 maintains a DC level on conductor 165 as long as the RF signal is being supplied to the coil 50.
Capacitor 163 stores sufficient energy to maintain DC power to the circuit during times that the transistor 180 of the detuning switch 51 is enabled. The raw DC signal on line 165 is smoothed by capacitor 163 and supplied via transistor 167 to the code generating circuit 52 of the responder.
The RF signal coupled to coil 50 is coupled by capacitor 175 and is divided down by the timing and control 20 circuit 173 providing a first timing signal to enable interface circuit 179 to gate the four bits provided by s~itch 53A and the first two bits provided by switch 53B
through interface circuit 179 via lines 179-1 to 179-6 to the inputs of the parallel load shift register 174. The outputs on lines 179-7 to 179-9, including the start bit, the identification bit and the parity bit are also extended to further inputs of the parallel load shift register 174.
A further timing signal generated by timing and control circuit 173 is extended to the parallel load shift ~3~5~
register 174 as a load command to parallel load the data on lines 179-1 to 179-9, into the shift register 174.
The timing and control circuit 173 generates clock pulses at a selectable rate to the shift register 174 to effect ser;al readout of the data stored therein.
After all the bits of the first transmission segment have been gated out of the shift register 174, the timing and control circuit 173 resets the interface circuit 179 changing the status of the identification bit via line 179-8 and extending the last two bits of switch 53B and the four bits of switch 53C via lines 179-1 to 179-6 to the inputs of the shift register 174 along with the start bit, the modified identification bit and the parity bit, in preparation for readout of the second segment of data in a manner described for readout of the first segment of data.
Referring to FIGo 59 the serial data read out of the shift register 174 during the first transmission segment is extended to the base of transistor 180 of the modulator circuit 51. Each logic 1 bit of the output pulse train causes 20 transistor 180 to conduct, connecting capacitor 158 in circuit across the 30 turn section 153 of the winding 50 detuning the winding. The transistor 180 is maintained nonconducting by each logic 0 level of the data train.
Referring now to FIGS~ 4 and 4A, the interaction between coil 50 and the coil 40 due to transformer action as the switching transistor 180 responds to the logic 1 bits of the output pulse code during each segment transmission results in modulation of the primary coil voltage in a manner representing the code of the floor package. The modulated signal appearing across the antenna 40 is coupled to the detector 47.
~L~3;~6~;
The peak rectifier diodes 101 and 102 receive the antenna signal coupled to the detector circuit 47 through capacitor 103, and separate the low frequency modulating signal from the 70 k~lz carrierO Capacitor 104 and resistor 105 establish a time constant for maximum removal of the 70 kHæ carrier without loss of the DC level corresponding to the responder code.
The resultant signal is extended through analog switch 113 to the carrier reject filter 48 formed by inductor 121 and capacitors 122 and 123 which traps the 70 k~lz carrier. Capacitors 126 and 127 form a smoothing stage to eliminate ripple.
The output of the carrier reject filter 48 is extended to the pulse detector circuit 49 which performs limiting and slicing, reconstructing the binary coded data word at the output thereof.
The serial pulse train provided at the output of amplifier 140 is extended through the buffer circuit 142 and line driver circuit 143 which interfaces the pulse detector circuit 49 with parity and security checking circuit (not shown) prior to storing the verified data in a memory.
The sensor input circuit includes two eight-bit memories. This arrangement may be adapted for interfacing with the identification code arrangement of the present invention by storing one six-bit word in the Eirst row memory and the other six-bit word in the second row memory.
Other interfacing arrangements are also possible as is apparent to one skilled in the art.
The sequence of data readout will be provided as long as the vehicle is in the proximity of the responder ~` ~L23~S~i device 17' and sufficient coupling in provided between the primary winding 40 carrried by the vehicle and the coil 50 of the responder unit located in the floor.
. 24a
Claims (23)
1. In a guidance system for guiding at least one vehicle along a traffic layout, an arrangement for enabling each vehicle to derive information for directing the vehicle in its movement along the traffic layout, said arrangement comprising: interrogator means carried by the vehicle, responder means for each location including code means providing a signal encoded to represent information for the associated location, coupling means to enable signal coupling to occur between said interrogator means and said responder means as the vehicle moves adjacent to said responder means in its travel along the traffic layout, said responder means including coupling modulator means responsive to said encoded signal for varying the signal coupling between said interrogator means and said responder means in correspondence with the information provided by said code means, said interrogator means including detection means for detecting the variation in signal coupling to recover the information represented by the encoded signal.
2. A guidance system according to claim 1, wherein said coupling means comprises a first coil carried by said vehicle and a second coil associated with said responder means and located relative to the pathway of the vehicle to enable signal coupling to occur between said first and second coil as the vehicle moves adjacent to said responder means.
3. A guidance system according to claim 2, wherein said interrogator means comprises drive means for applying a frequency signal to said first coil, said coupling modulator means controlling said second coil to vary the signal coupling between said coils causing modulation of said frequency signal with the information provided by said code means.
4. A guidance system according to claim 3, wherein said responder means presents a load on said first coil when signal coupling is provided between said coils, said coupling modulator means varying the loading on said first coil, and thus modulation of the frequency signal, in correspondence with the information provided by said code means.
5. A guidance system according to claim 3, wherein said coupling modulator means responds to said encoded signal to alternately tune and detune said second coil in correspondence with the information provided by said code means, the interaction between said coils as said second coil is tuned and detuned, resulting in modulation of the frequency signal with the information provided by said code means.
6. In a guidance system for guiding at least one vehicle along a traffic layout, a location identification arrangement for identifying locations along the traffic layout and for enabling each vehicle to derive information for directing the vehicle in its movement along the traffic layout, said location identification arrangement comprising: interrogator means carried by the vehicle and including a first coil, drive circuit means and signal detecting means; responder means for each location including identification signal generating means, modulating means, and a second coil; said second coil being located relative to the pathway for the vehicle to enable signal coupling to occur between said first and second coils as the vehicle moves adjacent to said responder means in its travel along the traffic path, said drive circuit means generating a frequency signal and coupling the frequency signal to said first coil, said identification signal generating means generating a signal encoded to represent an identification code for the associated location, said modulating means being responsive to the encoded signal for modulating the frequency signal coupled to said first coil with the information code, and said detecting means being coupled to said first coil for detecting the modulated signal to recover the identification code from the modulated frequency signal.
7. A guidance system according to claim 6, wherein said responder means presents a load on said first coil when signal coupling is provided between said first and second coils, said modulating means responding to the encoded signal to vary the loading on said first coil thereby modulating the frequency signal in correspondence with the identification code.
8. A guidance system according to claim 6, wherein said responder means further comprises means for detecting said frequency signal and deriving therefrom a DC signal for energizing said identification signal generating means and said modulating means.
9. A guidance system according to claim 6, wherein said identification signal generating means includes timing means for deriving a time base from said frequency signal for controlling said identification signal generating means in the generation of said encoded signal.
10. A guidance system according to claim 6, wherein said identification signal generating means includes code select means for providing data representing the information code for said identification signal generating means, said code select means being controllable to change the identification code.
11. A guidance system according to claim 10, wherein the identification code includes first data identifying the location and second data indicative of the configuration of the traffic layout in the proximity of the identified location.
12. In a guidance system for guiding at least one vehicle along a traffic layout, a location identification arrangement for identifying locations along the traffic layout and for enabling each vehicle to derive information for directing the vehicle in its movement along the traffic layout, said location identification arrangement comprising: interrogator means carried by the vehicle and including a first coil, drive circuit means, and signal detecting means; responder means for each location including identification signal generating means, modulating means, and a second coil; said second coil being located relative to the pathway for the vehicle to enable signal coupling to occur between said first and second coils as the vehicle moves adjacent to said responder means in its travel along the traffic path, said drive circuit means generating a frequency signal and coupling the frequency signal to said first coil, said identification signal generating means generating a signal encoded to represent an identification code for the associated block, and said modulating means being connected to said second coil and responsive to the encoded signal to vary the loading on said first coil in correspondence with the information code, the interaction between said first and second coils as the loading on said first coil is varied resulting in modulation of the frequency signal with the information code, and said signal detecting means being coupled to said first coil for detecting the modulated signal to recover the identification code from the modulated frequency signal.
13. A guidance system according to claim 12, wherein said identification signal generating means includes code means providing a set of signals representing the identification code, and code signal generating means responsive to said set of signals for generating a train of pulses binary encoded to represent the identification code, said modulating means alternatively tuning and detuning said first coil in correspondence with the information code provided by said code signal generating means.
14. A guidance system according to claim 13, wherein said code means is controllable to change the identification code data.
15. A guidance system according to claim 14, wherein the code means comprises switch means manually settable to provide said set of output signals.
16. A guidance system according to claim 12, wherein said modulating means comprises a detuning device connected in circuit with said second coil and responsive to said encoded signal to alternatively tune and detune said second coil in correspondence with the identification code.
17. A guidance system according to claim 16, wherein said second coil comprises a multi-turn winding having first and second ends and at least one tap defining first and second winding portions, said detuning device being connected in circuit with one of said winding portions and operable to reduce temporarily the number of turns of said one winding portion.
18. A guidance system according to claim 12, wherein said responder means includes timing circuit means for generating timing signals for controlling said identification signal generating means in the generation of said encoded signal.
19. A guidance system according to claim 18, wherein said responder means further includes power circuit means connected to said second coil for detecting said frequency signal and deriving therefrom a DC signal for energizing said identification signal generating means, said timing circuit means and said modulating means.
20. A guidance system according to claim 18, wherein said identification signal generating means includes code select means which provides a set of binary coded output signals representing the identification data and means responsive to timing signals generated by said timing circuit means to generate said encoded signal.
21. In a guidance system for guiding at least one vehicle along a traffic layout, a location identification arrangement for identifying locations along the traffic layout and for enabling each vehicle to derive information from the location identification for directing the vehicle in its movement along the traffic layout, said location identification arrangement comprising:
interrogator means carried by each vehicle, and including a first coil, drive circuit means for generating a frequency signal, and means for coupling the frequency signal to said first coil; responder means for each location including identification signal generating means for generating a serially encoded signal representing an identification code for the associated location, and a second coil located relative to the pathway for the vehicle to enable signal coupling to occur between said first and second coils as the vehicle moves adjacent to said responder means in its travel along the traffic path; said responder means including time base generating means coupled to said second coil and responsive to said frequency signal for generating a plurality of timing signals for controlling said identification signal generating means in the generation of said serially encoded signal, and means connected to said second coil and responsive to said serially encoded signal to alternately de-tune and tune said second coil in correspondence with the identification code, the interaction between said first and second coils as said second coil is de-tuned and tuned resulting in modulation of the frequency signal with the identification code; said interrogator means further including detecting means coupled to said first coil for detecting the modulated signal to recover the identification code from the modulated frequency signal.
interrogator means carried by each vehicle, and including a first coil, drive circuit means for generating a frequency signal, and means for coupling the frequency signal to said first coil; responder means for each location including identification signal generating means for generating a serially encoded signal representing an identification code for the associated location, and a second coil located relative to the pathway for the vehicle to enable signal coupling to occur between said first and second coils as the vehicle moves adjacent to said responder means in its travel along the traffic path; said responder means including time base generating means coupled to said second coil and responsive to said frequency signal for generating a plurality of timing signals for controlling said identification signal generating means in the generation of said serially encoded signal, and means connected to said second coil and responsive to said serially encoded signal to alternately de-tune and tune said second coil in correspondence with the identification code, the interaction between said first and second coils as said second coil is de-tuned and tuned resulting in modulation of the frequency signal with the identification code; said interrogator means further including detecting means coupled to said first coil for detecting the modulated signal to recover the identification code from the modulated frequency signal.
22. A guidance system according to claim 21, wherein said identification signal generating means includes code select means which provides a set of binary coded output signals representing the identification code, parallel-to-serial converter means, and means responsive to a first one of said timing signals for gating said set of output signals into said parallel-to-serial converter means, said output signals being read out of said parallel-to-serial converter means in response to further ones of said timing signals, providing said serially encoded signal.
23. A guidance system according to claim 22, wherein said code select means comprises switch means manually settable to provide said set of binary coded output signals.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US60421584A | 1984-04-26 | 1984-04-26 | |
| US604,215 | 1984-04-26 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1232655A true CA1232655A (en) | 1988-02-09 |
Family
ID=24418671
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000478149A Expired CA1232655A (en) | 1984-04-26 | 1985-04-02 | Location identification arrangement for vehicle guidance systems |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0159680A3 (en) |
| JP (1) | JPS60235299A (en) |
| AU (1) | AU4146685A (en) |
| CA (1) | CA1232655A (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3521577A1 (en) * | 1985-06-15 | 1986-12-18 | Krauss-Maffei AG, 8000 München | VIEW-INDEPENDENT GUIDE SYSTEM FOR AIRPLANES AND COMMERCIAL VEHICLES TO BE MOVED IN THE AIRPORT GROUND AREA |
| JPS6374762A (en) * | 1986-09-16 | 1988-04-05 | 神鋼電機株式会社 | Position transducer for unmanned cart |
| FR2644599A1 (en) * | 1989-03-14 | 1990-09-21 | Renault Automation | ROBOTIC HANDLING SYSTEM |
| US5179329A (en) * | 1989-04-25 | 1993-01-12 | Shinko Electric Co., Ltd. | Travel control method, travel control device, and mobile robot for mobile robot systems |
| US5764014A (en) * | 1996-02-01 | 1998-06-09 | Mannesmann Dematic Rapistan Corp. | Automated guided vehicle having ground track sensor |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3147817A (en) * | 1961-01-09 | 1964-09-08 | Barrett Electronics Corp | Guidance systems |
| US3245493A (en) * | 1964-03-26 | 1966-04-12 | Barrett Electronics Corp | Automatic control system for vehicles |
| US3411603A (en) * | 1966-07-20 | 1968-11-19 | Webb Co Jervis B | Control for self-guided vehicle |
| US4284160A (en) * | 1979-03-19 | 1981-08-18 | Barrett Electronics Corporation | Vehicle guidance system employing radio blocking |
-
1985
- 1985-04-02 CA CA000478149A patent/CA1232655A/en not_active Expired
- 1985-04-20 EP EP85104795A patent/EP0159680A3/en not_active Withdrawn
- 1985-04-22 AU AU41466/85A patent/AU4146685A/en not_active Abandoned
- 1985-04-25 JP JP60089890A patent/JPS60235299A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| AU4146685A (en) | 1985-10-31 |
| EP0159680A3 (en) | 1987-10-07 |
| EP0159680A2 (en) | 1985-10-30 |
| JPS60235299A (en) | 1985-11-21 |
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