VEHICLE GUIDANCE SYSTEM

• US 3,768,586 A
• Filed: 11/23/1971
• Issued: 10/30/1973
• Est. Priority Date: 11/23/1971
• Status: Expired due to Term

• Current Assignee: Yale Materials Handling Corporation Route 523 and 31 Flemington New Jersey 08822
• Original Assignee: John W. Mcdonell, Robert F. Thompson
• Inventors: Thompson, Robert F., McDonell, John W.
• Primary Examiner(s): Betts, Kenneth H.
• Application Number:
  US05/201,520
• Time in Patent Office: 707 Days
• Field of Search: 180/98,79.1,79 318/587,608,588 246/187B
• US Class Current: 180/168
• CPC Class Codes: G05D 1/0265 using buried wires
• CPC Class Codes: G05D 1/0272 comprising means for registering the travel distance, e.g. revolutions of wheels measuring distance traversed on the ground by vehicles, e.g. using odometers G01C22/00

Abstract

A vehicle guidance system includes first and second currentcarrying conductors defining a portion of the vehicle guide path and in which current flows. The current in one conductor is equal in magnitude to 90* and out of phase with the current in the other conductor. The conductors, when located in a parallel substantially overlapping relationship, establish a magnetic field having an effective phase different from the phase of the current in either conductor. The conductors are separated at at least one point of divergence to define separate vehicle guidepaths. A sensor unit on the vehicle sense the magnetic field of the conductors and controls the steering of the vehicle. The circuit which responds to the sensing unit is selectively controlled so that an output signal from only one or the other of the conductors controls the vehicle steering. In addition, the sensor unit which is on the vehicle senses data located along the guidepath in the form of lobes or nodes defined by the conductors. Furthermore, the sensor functions to sense phase modulation in the guidepath conductors as controlled from a central processor, and additional circuit means senses a change in phase modulation in the current flowing through the conductors and provides an output in response thereto so that data can be transmitted to the vehicle by phase modulation of the current transmitted through the guidepath conductors.

Claims

1. Apparatus for controlling a vehicle comprising first and second parallel current-carrying conductors defining a first portion of a vehicle guide path, means for establishing current in the conductors with the current in said first conductor being out of phase with the current in the second conductor, said conductors establishing a resultant magnetic field having an effective phase different from that of the current in either conductor, said conductors separating at at least one point of divergence to define separate first and second vehicle guide paths along said first and second conductors, each of said separated conductors establishing a magnetic field therearound having a phase different from that of the other conductor and different from said effective phase, sensor means at the vehicle for sensing the magnetic field of the guide path including coil means for sensing said effective phase when the vehicle is on said first portion of the vehicle guide path, phase-responsive circuit means for receiving control signals from said sensor unit and providing an output signal depending upon the relative phase of thE input signals thereto from said sensor means, steering means responsive to said output signal to effect steering of the vehicle along the guide path, and means for selectively controlling the phase of one of said control signals received by said circuit means to provide an output signal from said circuit means to make said steering means responsive principally to one or the other of said conductors at said point of divergence so that said sensor unit and said vehicle track one selected conductor of said separate guide paths.

2. Apparatus for controlling a vehicle comprising first and second parallel current-carrying conductors defining a first portion of a vehicle guide path;

means for establishing current in the conductors with the current in said first conductor being essentially 90* out of phase with the current in the second conductor;

said conductors establishing a resultant magnetic field having an effective phase essentially 45* lagging the phase of one conductor and 45* leading the phase of the other conductor;

said conductors separating at at least one point of divergence to define separate vehicle guide paths;

each of said separated conductors establishing a magnetic field therearound having a phase different from that of the other conductor and different from said effective phase;

sensor means at the vehicle for sensing the magnetic field of the guide path including coil means for sensing said effective phase when the vehicle is on said first portion of the vehicle guide path;

phase-responsive circuit means for receiving control signals from said sensor unit and providing an output signal depending upon the relative phase of the input signals thereto from said sensor means;

steering means responsive to said output signal to effect steering of the vehicle along the guide path;

means for selectively controlling said circuit means to provide an output signal responsive principally to one or the other of said conductors at said point of divergence so that said sensor unit and said vehicle track one selected conductor carrying a current of a selected phase from said point of divergence;

said phase-responsive circuit means also including phase comparison means having both a reference phase signal and a sense phase signal derived from said sensor unit whose relative phases are compared to determine said output signal; and

said means for selectively controlling also including means for selectively altering the phase of said reference phase signal to effect comparison in said phase comparison means of the altered reference phase signal and said sense phase signal.

3. Apparatus as defined in claim 2 wherein said means for selectively altering the phase of said reference signal comprises switch means having plural contacts and a 45* phase shift retard circuit in series with one contact and a 45* phase shift advance circuit in series with another contact, said switch means having means for connecting either one or the other of said 45* phase shift circuits to receive signals from said sensor unit and directing that signal with a phase shift to said phase comparison means.

4. Apparatus as defined in claim 3 wherein said sensor unit comprises a sense coil located so that its axis is disposed vertically of the guide path and a reference coil located so that its axis is disposed horizontally with respect to the guide path and perpendicular to the guide path.

5. Apparatus as defined in claim 3 wherein code means are located along the guide path for providing code signals to the vehicle, said code means comprising lobes formed by said guide path conductors, and said sensor means comprising means responsive to said lobes.

6. Apparatus for controlling a vehicle comprising first and second parallel current-carrying conductors defining a first portion of a vehicle guide path, means for establishing current in the conductors with the current in said first conductor being out of phase with the current in the secoNd conductor, said conductors establishing a resultant magnetic field having an effective phase different from that of the current in either conductor, said conductors separating at at least one point of divergence to define separate vehicle guide paths, each of said separated conductors establishing a magnetic field therearound having a phase different from that of the other conductor and different from said effective phase, sensor means at the vehicle for sensing the magnetic field of the guide path including coil means for sensing said effective phase when the vehicle is on said first portion of the vehicle guide path, phase-responsive circuit means for receiving control signals from said sensor unit and providing an output signal depending upon the relative phase of the input signal thereto from said sensor means, steering means responsive to said output signal to effect steering of the vehicle along the guide path, means for selectively controlling said circuit means to provide an output signal responsive principally to one or the other of said conductors at said point of divergence so that said sensor unit and said vehicle track one selected conductor carrying a current of a selected phase from said point of divergence, means for changing the phase of the current in said conductors and means responsive to the phase change to provide information for vehicle control.

7. Apparatus for controlling a vehicle comprising first and second electrical current-carrying conductors defining a first portion of a vehicle guide path, means for establishing AC currents in the conductors with the current in said first conductor being out of phase with respect to the phase of the current in the second conductor, said conductors establishing a magnetic field having an effective phase different from that of either conductor, said conductors being separated into lobes to provide code patterns along said guide path with each lobe corresponding to a binary digit depending upon the arrangement of the conductors in the node, said conductors at each node establishing a magnetic field having a phase characteristic dependent upon the conductor arrangement in the node, a sensor unit at the vehicle for sensing the magnetic field of the guide path and the magnetic field of the nodes including sensor coil means for sensing said effective phase during movement of the vehicle along said first portion of the vehicle guide path and the phase of the magnetic fields of said nodes, first phase-responsive circuit means for receiving control signals from said sensor unit and providing an output signal depending upon the phase of the input signal thereto from said sensor means, steering means responsive to said output signal to effect steering of the vehicle along the guide path, and second phase responsive circuit means for receiving control signals from said sensor unit and being responsive to the magnetic field of a node and providing an output signal depending upon the second phase characteristic of the magnetic field of the node.

8. Apparatus as defined in claim 7 further including means for establishing current flows in said conductors which are 90* out of phase.

9. Apparatus as defined in claim 8 wherein said lobes establish a magnetic field having a different phase characteristic depending upon the arrangement of the conductors in said lobe, said phase responsive circuit means comprising a phase demodulator circuit which provides an output positive signal on one lobe conductor arrangement and an output negative signal on another output lobe conductor arrangement.

10. Apparatus as defined in claim 9 wherein a 90* phase shifter circuit is interconnected between said phase demodulator circuit and said sensor unit so as to control the phase of one signal to said phase demodulator circuit.

11. Apparatus as defined in claim 10 wherein said sensor unit includes a reference coil located horizontally and perpendicular to the guide path to provide a signal to 90* phase sHifter circuit and a sensor coil located vertically to provide a signal to said phase demodulator circuit.

12. Apparatus for controlling a vehicle comprising current-carrying conductor means defining a vehicle guide path, means for establishing current in the conductor means, a central processor for controlling the phase of the current in the conductor means including means for changing the phase of the current in the conductor means, said conductor means establishing a magnetic field having a phase which changes with changes in the phase of the current in the conductor, a sensor unit on the vehicle for sensing the magnetic field of the guide path including sensor coil means for sensing the phase of the magnetic field, circuit means for receiving control signals from said sensor unit and providing an output signal depending upon the phase of the input signal thereto from said sensor means, steering means responsive to said output signal to effect steering of the vehicle along the guide path, and additional circuit means for sensing a change in phase of the magnetic field of said conductor means and providing an output in response thereto whereby data can be transmitted to said vehicle by changing the phase of the current transmitted through said guide path conductor means.

13. Apparatus as defined in claim 12 wherein said conductor means comprises a pair of conductor carrying currents which are 90* out of phase with respect to each other, said conductors establishing a resultant magnetic field having an effective phase different from that of the current in either conductor, said conductors separating at at least one point of divergence to define separate vehicle guide paths, each of said separated conductors establishing a magnetic field therearound having a phase different from that of the other conductor and different from said effective phase, said sensor unit including means for sensing the magnetic field of the guide path including coil means for sensing said effective phase when the vehicle is on a portion of the vehicle guide path when the conductors are together, phase-responsive circuit means for receiving control signals from said sensor unit and providing an output signal depending upon the relative phase of the input signals thereto from said sensor means, and means for selectively controlling said circuit means to provide an output signal responsive principally to one or the other of said conductors at said point of divergence so that said sensor unit and said vehicle track one selected conductor carrying a current of a selected phase from said point of divergence.

14. Apparatus for controlling a vehicle comprising a current-carrying conductor means defining a vehicle guide path, a vehicle movable along the guide path, code means located along the guide path for providing code signals to the vehicle, control means responsive to said code signals for controlling a vehicle operation, steering motor means operable to effect steering of the vehicle along the guide path, and sensor means on the vehicle used in common for sensing said code means and deviations of the vehicle from said guide path, said sensing means comprising at least one sensing coil responsive to vehicle deviation from the guide path and to said code means, circuit means interconnecting said sensing coil with said control means and said steering servomotor means to effect control thereof, said circuit means including phase responsive circuit means and said sensor means including a first coil providing a phase signal and a second coil providing a phase signal and means for selectively modifying the phase of one of said coil signals relative to the other prior to communication of said one signal to said phase responsive circuit means.

15. Apparatus for controlling a vehicle comprising two guide conductors defining a two-conductor portion of a first vehicle guide path and two separate single-conductor guide paths diverging from said two-conductor portion of said first guidE path, said two guide conductors carrying alternating currents of differing electrical phases producing magnetic fields which interact along said two conductor guide path;

position-sensing circuit means producing an output signal in accordance with the lateral position of the vehicle with respect to said guide conductors and having a preferential phase characteristic to preferentially sense lateral position of the vehicle with respect to the first guide conductor carrying current having a first electrical phase in preference to the second guide conductor having a second electrical phase;

steering control means responsive to said output signal to correctively steer said vehicle in a direction to position it laterally in juxtaposition with at least one selectively preferred guide conductor; and

phase characteristic controlling means for controlling said preferential phase characteristic of said position-sensing circuit means to prefer selectively one or the other of said first electrical phase or said second electrical phase;

whereby said vehicle may be selectively guided along a path defined by one of said single conductor guide paths when said first guide path diverges to form said separate single-conductor portions of said vehicle guide path.