Vehicle position determining apparatus

• US 5,467,084 A
• Filed: 03/28/1994
• Issued: 11/14/1995
• Est. Priority Date: 03/28/1994
• Status: Expired due to Term

• Current Assignee: Jervis B Webb Company (Daifuku Company Limited)
• Original Assignee: Jervis B Webb Company (Daifuku Company Limited)
• Inventors: Drenth, Ronald R., Alofs, Cornell W.
• Primary Examiner(s): Swarthout, Brent
• Assistant Examiner(s): TONG, NINA C
• Application Number:
  US08/218,716
• Time in Patent Office: 596 Days
• Field of Search: 340/933, 340/941, 340/938, 340/988, 340/905, 180/167, 180/168, 180/169, 318/587, 364/424.02
• US Class Current: 340/933
• CPC Class Codes: G05D 1/0261 using magnetic plots
• 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

Apparatus for determining the position of a mobile vehicle relative to a fixed location marker device which comprises a coil energized to emit a magnetic field composed of lines of magnetic flux extending radially and arcuately from the ends of the coil'"'"'s longitudinal axis. A sensor unit mounted on the mobile vehicle comprises four identical sensing coils each responsive to the frequency of the magnetic field of the marker device and each having a major axis. These sensor coils are supported in two pairs with the major axes of the sensor coils of each pair disposed on either side of a common central plane and extending parallel thereto, this common central plane extending transversely to the longitudinal axis of the marker device coil. Each pair of sensor coils is arranged in an X pattern in which their major axes cross each other medially and perpendicularly to define a center for the coil pair. The two pairs of coils are mounted with their centers spaced apart a fixed distance on a base line which the major axes of the coils cross at a 45 degree angle. Position signals from the sensor coils are processed to produce X and Y coordinate values indicating the relative position of the sensor unit to the marker device. The marker device may be inductively excited from an antenna on the mobile vehicle.

Claims

1. An apparatus for determining the position of a mobile vehicle relative to a fixed location marker device wherein:

said location marker device includes a coil having a central longitudinal axis, exciter means for causing said coil to emit a magnetic field of a certain frequency and composed of lines of magnetic flux extending radially and arcuately outwardly from the ends of said longitudinal axis;

said apparatus including a sensor unit mounted on said mobile vehicle, said sensor unit comprising four identical sensor coils each responsive to the frequency of said magnetic field, and each having a major axis;

said sensor unit including means for supporting said sensor coils in two pairs with their major axes disposed in two parallel planes positioned on said mobile vehicle so as to extend transversely to said longitudinal axis of said marker device, the major axis of one sensor coil of each pair lying in one of said two planes and the major axis of the other sensor coil of each pair lying in the other of said two planes, the major axes of the sensor coils of each pair being arranged in an X pattern in which the major axis of one coil of each pair extends perpendicularly to the major axis of the other coil of each pair, and in which said major axes of each pair cross medially of the length thereof to define a center for each pair of said sensor coils, said centers of said pairs of sensor coils being spaced apart by a fixed reference distance along a base line, said base line being crossed by the major axis of each of said sensor coils at an angle of 45 degrees;

circuit means for obtaining a position signal from each of said sensor coils in response to the passage thereof through said magnetic field;

and means for computing from said position signals and from the angular relations between said sensor coils which include Y and X coordinate values indicative of the position of said sensor unit relative to said location marker device.

2. An apparatus according to claim 1 wherein said two parallel planes extend perpendicularly to said longitudinal axis of said marker device.

3. An apparatus according to claim 1 wherein said exciter means comprises a source of alternating current connected to said coil of said location marker device.

4. An apparatus according to claim 1 wherein said means for supporting said sensor coils comprises a panel having oppositely facing substantially parallel surfaces, one sensor coil of each of said two pairs being positioned on one of said parallel surfaces, and the other sensor coil of each of said two pairs being positioned on the other of said parallel surfaces.

5. An apparatus according to claim 4 wherein said panel is formed by a circuit board.

6. An apparatus according to claim 5 wherein said circuit means is composed at least in part of circuit elements on said circuit board.

7. An apparatus according to claim 5 wherein said centers of said pairs of sensor coils are located on said circuit board.

8. An apparatus according to claim 1 wherein said exciter means is carried by said mobile vehicle and includes antenna means for transmitting a frequency adapted to inductively excite said coil of said location marker device.

9. An apparatus according to claim 8 wherein said means for supporting said sensor coils comprises a panel having oppositely facing substantially parallel surfaces, one sensor coil of each of said two pairs being positioned on one of said parallel surfaces, and the other sensor coil of each of said two pairs being positioned on the other of said parallel surfaces.

10. An apparatus according to claim 9 wherein said antenna means is carried by said panel and is formed by an antenna loop surrounding said pairs of sensor coils.

11. An apparatus according to claim 10 wherein said panel is formed by a circuit board.

12. An apparatus according to claim 11 wherein said antenna is formed on said circuit board.

13. An apparatus according to claim 12 wherein said antenna surrounds said pairs of sensor coils.

14. An apparatus according to claim 13 wherein said circuit means includes filter and amplifier elements for enhancing the signal from each of said sensor coils, means for converting each of said enhanced signals from analog to digital form, and said means for computing includes a microprocessor supplied with said converted signals.

15. A sensor unit adapted to be mounted on a mobile vehicle for detecting the position of said vehicle relative to a fixed location marker, said sensor unit comprising two pairs of sensor coils, each of said sensor coils having a longitudinal axis, each of said pairs of sensor coils being arranged in an X pattern in which their longitudinal axes cross each other medially and perpendicularly to define a center for each of said pairs of sensor coils, means for mounting said pairs of sensor coils with their said centers spaced apart a fixed reference distance along a base line which said longitudinal axis of each of said sensor coils cross at an angle of 45 degrees;

and with said longitudinal axes of the sensor coils of each of said pairs positioned on opposite sides of and extending parallel to a common central plane;

circuit means connected to each of said sensor coils for obtaining a position signal therefrom; and

means for obtaining from said position signals and said fixed reference distance including Y and X coordinate values indicative of the position of said mobile vehicle.

16. A sensor unit according to claim 15 wherein said common central plane is formed by a circuit board.

17. A sensor unit according to claim 16 wherein said circuit means are provided at least in part on said circuit board.

18. A sensor unit according to claim 17 wherein said circuit board is provided with an antenna.

19. A sensor unit according to claim 18 wherein said antenna surrounds said pairs of sensor coils and is located substantially in said common plane.