System and method for causing an autonomous vehicle to track a path

• US 5,657,226 A
• Filed: 05/01/1995
• Issued: 08/12/1997
• Est. Priority Date: 02/05/1990
• Status: Expired due to Term

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Whittaker, William L., Shin, Dong Hun, Kemner, Carl A., Devier, Lonnie J., Singh, Sanjiv J.
• Primary Examiner(s): PARK, COLLIN
• Application Number:
  US08/431,596
• Time in Patent Office: 834 Days
• Field of Search: 364/424.02, 180/167, 180/168, 180/169
• US Class Current: 701/23
• 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 causing an autonomous vehicle to track a desired path uses reference postures to define the desired path. Actual vehicle postures are determined using sensors aboard the autonomous vehicle. An expected vehicle posture at the end of a next time interval is determined on the actual vehicle posture. A desired vehicle posture at the end of the next time interval is determined based on the reference postures. A steering angle for the next time interval for the autonomous vehicle is determined based on the difference between the reference posture and the desired vehicle posture at the end of the next time interval.

Claims

1. A method for causing an autonomous vehicle to track a desired path comprising the steps of:

(1) determining reference postures at regular unit distances along the desired path, wherein said reference postures are packets of information about a particular location on the path including longitude, latitude, heading, curvature, maximum velocity, and distance to the next posture;

(2) determining an actual vehicle posture;

(3) determining an expected vehicle posture at a future time corresponding to a current planning time interval based on the actual vehicle posture;

(4) determining a desired posture at the end of a next planning time interval based on the reference postures;

(5) determining a steering angle from the expected vehicle posture and the desired posture;

(6) commanding the vehicle to steer the determined steering angle; and

(7) repeating steps 2 through 6.

2. A system for causing an autonomous vehicle to track a desired path comprising:

(1) means for determining reference postures at regular unit distances along the desired path, wherein said reference postures are packets of information about a particular location on the path including longitude, latitude, heading, curvature, maximum velocity, and distance to the next posture;

(2) means for determining an actual vehicle posture;

(3) means for determining an expected vehicle posture at a future time corresponding to a current planning time interval based on the actual vehicle posture;

(4) means for determining a desired posture at the end of a next planning time interval based on the reference postures;

(5) means for determining a steering angle from the expected vehicle posture and the desired posture; and

(6) means for commanding the vehicle to steer the determined steering angle.

3. A method for causing an autonomous vehicle to track a desired path, comprising the steps of:

determining a plurality of reference postures along the desired path, said reference postures spaced apart at distances along the desired path, wherein a posture includes a position, a heading, and a curvature;

determining a sensed posture of the vehicle, said sensed posture based on measurements from sensors aboard the vehicle;

determining an expected posture at the end of a first time interval, said expected posture based on said sensed posture;

determining a desired posture at the end of a next time interval, said desired posture based on said plurality of reference postures;

determining a steering angle based on a difference between said expected posture and said desired posture; and

commanding the vehicle to steer said steering angle to track the desired path.

4. A system for causing an autonomous vehicle to track a desired path, the system comprising:

means for determining a plurality of reference postures along the desired path, said reference postures spaced apart at distances along the desired path, wherein a posture includes a position, a heading, and a curvature;

means for determining a sensed posture of the vehicle, said sensed posture based on measurements from sensors aboard the vehicle;

means for determining an expected posture at the end of a current planning time interval, said expected posture based on said sensed posture;

means for determining a desired posture at the end of a next planning time interval, said desired posture based on said plurality of reference postures;

means for determining a steering angle based on a difference between said expected posture and said desired posture; and

means for commanding the vehicle to steer said steering angle to thereby track the desired path.