VEHICLE GUIDANCE SYSTEM

• US 3,757,887 A
• Filed: 07/09/1971
• Issued: 09/11/1973
• Est. Priority Date: 07/09/1971
• Status: Expired due to Term

• Current Assignee: Gerard L. Lafond, Wilcy I. Moore
• Original Assignee: Gerard L. Lafond, Wilcy I. Moore
• Inventors: Moore, Wilcy I., Lafond, Gerard L.
• Primary Examiner(s): Betts, Kenneth H.
• Assistant Examiner(s): Silverstrim, John P.
• Application Number:
  US05/161,078
• Time in Patent Office: 795 Days
• Field of Search: 180/98,79.1,79 318/580,587
• US Class Current: 180/168
• CPC Class Codes: G05D 1/0265 using buried wires

Abstract

A system for guiding a vehicle on a surface along a predetermined path defined by at least one wire coupled to an oscillator for generating an electromagnetic field. A field sensor carried by the vehicle including pick-up coils having mutually orthogonal axes lying in a plane substantially parallel to the plane of the track senses the horizontal components of the field. Signals induced in the pick-up coils are then utilized by a deviation computer in the vehicle to determine the angle and distance of deviation from the track. A steering control which responds to the deviation adjusts the steering mechanism of the vehicle to minimize the deviation.

Claims

1. In a system for guiding a vehicle having a steering means along a predetermined path on a surface, wherein an angle theta a represents the angle between the predetermined path and the path steered by said steering means, an angle theta p represents the angle between the predetermined path and a longitudinal axis of the vehicle, and an angle phi represents the angle between the steered path and the longitudinal axis of the vehicle, said system comprising:

a track means for generating a field along said predetermined path, said track means being fixed with respect to said surface;

a pick-up means carried by said vehicle for sensing said field;

a deviation computer means carried by said vehicle for solving a steering equation phi theta a + theta p comprising means for determining the angles theta a and theta p in response to said sensed field and means for determining the difference between the angle phi and the sum of the angles theta a and theta p; and

a steering control means carried by said vehicle for controlling said steering means in response to said difference in a manner tending to reduce said difference.

2. The system of claim 1 wherein said means for determining the angle theta a comprises:

a means for determining (K1D)1/2 in response to said sensed field where D is the distance between said steering means and said predetermined path and K1 is a constant;

a means for determining ( K2D ) in response to said sensed field where K2 is a constant; and

a means for determining the difference between ( K1D )1/2 and (K2D), said difference approximating theta a.

3. The system of claim 2 wherein, K1 8 phi m/Vm and K2 -1/Vm where phi m is the maximum turning rate of the steering means and Vm is the maximum velocity of the vehicle.

4. The system of claim 3 whwerein said means for determining the angle theta p determines the sin theta p as an approximation of the angle theta p.

5. The system of claim 1 wherein said sensing means comprises a pair of pick-up coils hAving mutually orthogonal axes lying in a plane parallel to said surface, one of said pick-up coils having an axis parallel to the longitudinal axis of said vehicle.

6. The system of claim 5 wherein said track means comprises at least one wire extending along said predetermined path and at least one oscillator means coupled to said at least one wire.

7. The system of claim 6 wherein said track means comprises a single wire and a single oscillator and said sensing means further comprises another pick-up coil having an axis perpendicular to the longitudinal axis of the vehicle and a means for determining the field gradient Delta Ds/d between said other pick-up coil and the longitudinal axis of the vehicle, where d is the separation distance between said other pick-up coil and said one of said pair of said coils having an axis parallel to the longitudinal axis of the vehicle and Ds is the distance separating said one of said pair of coils and said single wire so as to indicate the distance of the vehicle from said single wire.

8. The system of claim 7 wherein said deviation computer means includes:

a means for normalizing the value of Ds by dividing a signal representing a function of Ds by said field gradient Delta Ds/d.

9. The system of claim 8 wherein said deviation computer means includes means for generating an '"'"''"'"''"'"''"'"'in area'"'"''"'"''"'"''"'"' signal from said field gradient.

10. A vehicle guidance system comprising:

at least one reference signal generating means;

at least one track wire defining a predetermined path of travel for said vehicle over a surface, said reference signal generating means being coupled to said track wire to generate an electromagnetic field along said predetermined path;

a pair of pick-up coils mounted on said vehicle, said coils having mutually orthogonal axes lying in a plane substantially parallel to said surface for sensing said electromagnetic field;

deviation determining means coupled to both said coils and responsive to the electromagnetic field sensed thereby for determining the angular deviation of said vehicle from said predetermined path and the lateral displacement from said predetermined path independent of the instantaneous steering angle of said vehicle with respect to said predetermined path; and

steering means responsive to the output of said deviation determining means.

11. The vehicle guidance system of claim 10 including feedback means coupled between said steering means and said deviation determining means.

12. The vehicle guidance system of claim 11 wherein said deviation determining means comprises a means for determining the angle theta a representing the angle between the predetermined path and the steered path of the steering means, a means for determining the angle theta p representing the angle between the predetermined path and the longitudinal axis of said vehicle, and a means for determining the angle phi representing the angle between the steered path of said steering means and longitudinal axis of the vehicle, said steering control means controlling said steering means in a manner tending to maintain equality between the angle phi and the sum of the angle theta a and theta p.

13. The taxi guidance system of claim 12 wherein said system includes a pair of track wires defining said predetermined path of travel, said reference signal generating means coupled to said pair of track wires, one of said pair of track wires carrying a signal representing the sum of two sinusoidal functions of different frequencies provided by said signal generating means and the other of said track wires carrying a signal representing the difference of said two sinusoidal functions as provided by said signal generating means.

14. The taxi guidance system of claim 12 comprising a single track wire carrying a signal representing a sinusoidal function of a single frequency generated by said generating meAns.

15. The taxi guidance system of claim 12 wherein said deviation determining means includes a means of determining the angle theta p without a constant level field.