System and method for enabling an autonomous vehicle to track a desired path

• US 5,684,696 A
• Filed: 05/01/1995
• Issued: 11/04/1997
• Est. Priority Date: 02/05/1990
• Status: Expired due to Fees

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Koehrsen, Craig L., Whittaker, William L., Shin, Dong Hun, Kemner, Carl A., Devier, Lonnie J., Peterson, Joel L., Schmidt, Larry E., Kleimenhagen, Karl W., Singh, Sanjiv J., Bradbury, Walter J., Rao, Prithvi N.
• Primary Examiner(s): PARK, COLLIN
• Application Number:
  US08/432,563
• Time in Patent Office: 918 Days
• Field of Search: 364/424.02, 364/424.027, 364/424.029, 364/424.031, 364/444.1, 364/444.2, 364/449.1, 180/167, 180/168, 180/169, 318/580, 318/587
• US Class Current: 701/25
• CPC Class Codes: B60K 31/0008 including means for detecting potential obstacles in vehicle path
• CPC Class Codes: B60K 31/04 and means for comparing one electrical quantity, e.g. voltage, pulse, waveform, flux, or the like, with another quantity of a like kind, which comparison means is involved in the development of an electrical signal which is fed into the controlling means
• CPC Class Codes: B62D 1/28 non-mechanical , e.g. following a line or other known markers
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/86 Combinations of lidar systems with systems other than lidar, radar or sonar, e.g. with direction finders
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G01S 19/11 wherein the cooperating elements are pseudolites or satellite radio beacon positioning system signal repeaters
• CPC Class Codes: G01S 19/27 creating, predicting or correcting ephemeris or almanac data within the receiver
• CPC Class Codes: G01S 19/41 Differential correction, e.g. DGPS [differential GPS]
• CPC Class Codes: G01S 19/46 the supplementary measurement being of a radio-wave signal type
• CPC Class Codes: G01S 19/47 the supplementary measurement being an inertial measurement, e.g. tightly coupled inertial
• CPC Class Codes: G01S 19/52 Determining velocity
• CPC Class Codes: G01S 5/009 Transmission of differential positioning data to mobile
• CPC Class Codes: G01S 7/4811 common to transmitter and receiver
• CPC Class Codes: G05D 1/0011 associated with a remote control arrangement
• CPC Class Codes: G05D 1/024 in combination with a laser lasers per se H01S
• CPC Class Codes: G05D 1/0242 using non-visible light signals, e.g. IR or UV signals
• CPC Class Codes: G05D 1/0268 using internal positioning means
• CPC Class Codes: G05D 1/027 comprising intertial navigation means, e.g. azimuth detector inertial navigation G01C21/16; inertial navigation combined with non-inertial navigation instruments G01C21/165
• 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
• CPC Class Codes: G05D 1/0278 : using satellite positioning signals, e.g. GPS
• CPC Class Codes: G05D 1/0297 : by controlling means in a control room
• CPC Class Codes: G08G 1/202 : Dispatching vehicles on the basis of a location, e.g. taxi dispatching

Abstract

A system and method for enabling an autonomous vehicle to track a desired path plans a continuous path to return to the desired path when the vehicle deviates from the desired path. The continuous path is determined based on the vehicle'"'"'s position, the desired path, and a lookahead distance. The lookahead distance is the distance on the desired path within which the continuous path and the desired path converge. The lookahead distance may vary as a function of vehicle speed. In one embodiment of the present invention, the continuous path is determined as a quintic polynomial.

Claims

1. A system for use with an autonomous vehicle for enabling the vehicle to track a desired vehicle path, the system comprising:

means for providing the desired vehicle path to the vehicle;

means for executing a vehicle command that causes the vehicle to attempt to follow the desired vehicle path;

means for determining an actual vehicle position;

means for determining an error between said actual vehicle position and the desired vehicle path; and

means for reducing said error between said actual vehicle position and the desired vehicle path including

means for planning a continuous path from said actual vehicle position to the desired vehicle path based on said error so that said continuous path converges to the desired vehicle path at a lookahead distance, wherein said continuous path is a quintic polynomial based on said actual vehicle position, the desired vehicle path, and said lookahead distance, and

means for compensating for vehicle response characteristics of the vehicle using feedback compensation to cause the vehicle to follow said continuous path.

2. The system of claim 1, wherein said means for executing a vehicle command comprises:

means for executing a speed control command; and

means for executing a steering control command.

3. The system of claim 1, wherein said means for reducing said error between said actual vehicle position and the desired vehicle path further includes:

means for compensating for latency in said vehicle response characteristics using feedforward compensation to cause the vehicle to follow said continuous path.

4. The system of claim 3, wherein said means for executing a vehicle command comprises:

means for executing a speed control command; and

means for executing a steering control command.

5. The system of claim 4, wherein said means for compensating for latency comprises:

means for feeding forward an early steering command.

6. The system of claim 5, wherein said means for feeding forward an early steering command includes:

means for using a preselected number of time constants associated with said latency in said vehicle response characteristics to advance said early steering command.

7. The system of claim 1, wherein said means for planning a continuous path comprises:

means for varying said lookahead distance based on a vehicle speed.

8. A method for use in an autonomous vehicle that enables the vehicle to track a desired vehicle path, the method comprising the steps of:

providing the desired vehicle path to the vehicle;

executing a vehicle command that causes the vehicle to attempt to follow the desired vehicle path;

determining an actual vehicle position;

determining an error between said actual vehicle position and the desired vehicle path; and

reducing said error between said actual vehicle position and the desired vehicle path including the steps of

planning a continuous path from said actual vehicle position to the desired vehicle path based on said error so that said continuous path converges to the desired vehicle path at a lookahead distance, wherein said continuous path is a quintic polynomial based on said actual vehicle position, the desired vehicle path, and said lookahead distance, and

compensating for vehicle response characteristics of the vehicle using feedback compensation to cause the vehicle to follow said continuous path.

9. The method of claim 8, wherein said step of executing a vehicle command comprises the steps of:

executing a speed control command; and

executing a steering control command.

10. The method of claim 8, wherein said step of reducing said error between said actual vehicle position and the desired vehicle path further includes the step of:

compensating for latency in said vehicle response characteristics using feedforward compensation to cause the vehicle to follow said continuous path.

11. The method of claim 10, wherein said step of executing a vehicle command comprises the steps of:

executing a speed control command; and

executing a steering control command.

12. The method of claim 11, wherein said step of compensating for latency comprises the step of:

feeding forward an early steering command.

13. The method of claim 12, wherein said step of feeding forward an early steering command includes the step of:

using a preselected number of time constants associated with said latency in said vehicle response characteristics to advance said early steering command.

14. The method of claim 8, wherein said step of planning a continuous path comprises the step of:

means for varying said lookahead distance based on a vehicle speed.

15. A system for use with an autonomous vehicle for enabling the vehicle to track a desired vehicle path, the system comprising:

means for providing the desired vehicle path to the vehicle;

means for executing a vehicle command that causes the vehicle to attempt to follow the desired vehicle path;

means for determining an actual vehicle position;

means for determining an error between said actual vehicle position and the desired vehicle path; and

means for reducing said error between said actual vehicle position and the desired vehicle path including

means for planning a continuous path from said actual vehicle position to the desired vehicle path based on said error so that said continuous path converges to the desired vehicle path at a lookahead distance, wherein said continuous path is based on said actual vehicle position, the desired vehicle path, and said lookahead distance, and

means for varying said lookahead distance based on a vehicle speed.

16. The system of claim 15, wherein said means for reducing error further comprises:

means for compensating for vehicle response characteristics of the vehicle using feedback compensation to cause the vehicle to follow said continuous path.

17. The system of claim 15, wherein said means for planning comprises:

means for planning a continuous path from said actual vehicle position to the desired vehicle path based on said error so that said continuous path converges to the desired vehicle path at a lookahead distance, wherein said continuous path is a quintic polynomial based on said actual vehicle position, the desired vehicle path, and said lookahead distance.

18. The system of claim 15, wherein said means for reducing said error between said actual vehicle position and the desired vehicle path further includes:

means for compensating for latency in said vehicle response characteristics using feedforward compensation to cause the vehicle to follow said continuous path.

19. The system of claim 18, wherein said means for executing a vehicle command comprises:

means for executing a speed control command; and

means for executing a steering control command.

20. The system of claim 19, wherein said means for compensating for latency comprises:

means for feeding forward an early steering command.

21. The system of claim 20, wherein said means for feeding forward an early steering command includes:

means for using a preselected number of time constants associated with said latency in said vehicle response characteristics to advance said early steering command.