System and method for controlling autonomous machine within lane boundaries during position uncertainty

• US 8,755,966 B2
• Filed: 04/03/2012
• Issued: 06/17/2014
• Est. Priority Date: 04/03/2012
• Status: Active Grant

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Halder, Bibhrajit, Bhatia, Ruchi
• Primary Examiner(s): Beaulieu, Yonel
• Application Number:
  US13/438,167
• Publication Number:
  US 20130261870A1
• Time in Patent Office: 805 Days
• Field of Search: 701 25- 27, 701/400, 701408-411, 701/50
• US Class Current: 701/25
• CPC Class Codes: G05D 1/0274 using mapping information stored in a memory device navigation using map-matching G01C21/30
• CPC Class Codes: G05D 1/0278 using satellite positioning signals, e.g. GPS

Abstract

An autonomous machine control system includes a positioning unit measuring position and orientation, and a navigation unit storing a route plan including an intended travel path along a lane. The lane has a width defined by a left-hand boundary and a right-hand boundary. The navigation unit receives an uncertainty value associated with the position or orientation, and creates a virtual two-dimensional footprint based on an actual machine footprint and the uncertainty value. The navigation unit also simulates movement of the virtual footprint along the intended travel path, calculates a left-hand margin value defined by the virtual footprint and the left-hand boundary, and calculates a right-hand margin value defined by the virtual footprint and the right-hand boundary. The margin values are compared to a predetermined value, and speed or travel direction of the machine is controlled if either of the margin values is below the predetermined value.

Claims

1. A control system for an autonomous ground based machine, comprising:

a positioning unit configured to measure a position and an orientation of the machine;

a navigation unit in communication with the positioning unit and storing a route plan including an intended travel path along a lane, wherein the lane has a width defined by a left-hand boundary and a right-hand boundary, the navigation unit configured to;

receive an uncertainty value associated with at least one of the position and the orientation;

create a virtual two-dimensional footprint based on an actual footprint of the machine and the uncertainty value, wherein the virtual two-dimensional footprint encompasses the actual footprint;

simulate movement of the virtual two-dimensional footprint along the intended travel path;

calculate a left-hand margin value defined by the virtual two-dimensional footprint and the left-hand boundary, and a right-hand margin value defined by the virtual two-dimensional footprint and the right-hand boundary;

compare the left-hand margin value and the right-hand margin value to a predetermined minimum lane margin value; and

control at least one of a speed and a travel direction of the machine if either of the left-hand margin value and the right-hand margin value is below the predetermined minimum lane margin value.

2. The control system of claim 1, wherein the navigation unit is further configured to identify a desired travel speed based on a smaller value of the left-hand margin value and the right-hand margin value, and increase or decrease the speed of the machine toward the desired travel speed.

3. The control system of claim 1, wherein the navigation unit is further configured to decrease the speed of the machine according to a minimal deceleration rate if either of the left-hand margin value and the right-hand margin value is below a first lane margin threshold value.

4. The control system of claim 3, wherein the navigation unit is further configured to decrease the speed of the machine according to an aggressive deceleration rate if either of the left-hand margin value and the right-hand margin value is below a second lane margin threshold value, wherein the second lane margin threshold value is less than the first lane margin threshold value, wherein the aggressive deceleration rate is greater than the minimal deceleration rate.

5. The control system of claim 4, wherein the navigation unit is further configured to stop the machine if either of the left-hand margin value and the right-hand margin value is below a third lane margin threshold value, wherein the third lane margin threshold value is less than the second lane margin threshold value.

6. The control system of claim 1, wherein the navigation unit is further configured to increase or decrease the speed of the machine to maintain a desired traveling distance between the machine and a non-stationary leading machine, wherein the desired traveling distance is based on the virtual two-dimensional footprint.

7. The control system of claim 1, wherein the navigation unit is further configured to increase or decrease the speed of the machine to maintain a desired queuing distance between the machine and a stationary leading machine, wherein the desired queuing distance is based on the virtual two-dimensional footprint.

8. The control system of claim 1, wherein the navigation unit is further configured to:

create a virtual reference footprint based on the actual footprint of the machine;

simulate movement of the virtual reference footprint relative to a spotting point; and

stop the machine if the uncertainty value is greater than a spotting tolerance of the spotting point.

9. A method of controlling an autonomous ground based machine, the machine including a positioning unit configured to measure a position and an orientation of the machine, and a navigation unit in communication with the positioning unit and storing a route plan including an intended travel path along a lane, wherein the lane has a width defined by a left-hand boundary and a right-hand boundary, the method comprising steps of:

receiving an uncertainty value associated with at least one of the position and the orientation;

creating a virtual two-dimensional footprint based on an actual footprint of the machine and the uncertainty value, wherein the virtual two-dimensional footprint encompasses the actual footprint;

simulating movement of the virtual two-dimensional footprint along the intended travel path;

calculating a left-hand margin value defined by the virtual two-dimensional footprint and the left-hand boundary, and a right-hand margin value defined by the virtual two-dimensional footprint and the right-hand boundary;

comparing the left-hand margin value and the right-hand margin value to a predetermined minimum lane margin value; and

controlling at least one of speed and travel direction of the machine if either of the left-hand margin value and the right-hand margin value is below the predetermined minimum lane margin value.

10. The method of claim 9, further including:

identifying a desired travel speed based on a smaller value of the left-hand margin value and the right-hand margin value; and

increasing or decreasing the speed of the machine toward the desired travel speed.

11. The method of claim 9, further including decreasing the speed of the machine according to a minimal deceleration rate if either of the left-hand margin value and the right-hand margin value is below a first lane margin threshold value.

12. The method of claim 11, further including decreasing the speed of the machine according to an aggressive deceleration rate if either of the left-hand margin value and the right-hand margin value is below a second lane margin threshold value, wherein the second lane margin threshold value is less than the first lane margin threshold value, wherein the aggressive deceleration rate is greater than the minimal deceleration rate.

13. The method of claim 12, further including stopping the machine if either of the left-hand margin value and the right-hand margin value is below a third lane margin threshold value, wherein the third lane margin threshold value is less than the second lane margin threshold value.

14. The method of claim 9, further including increasing or decreasing the speed of the machine to maintain a desired traveling distance between the machine and a non-stationary leading machine, wherein the desired traveling distance is based on the virtual two-dimensional footprint.

15. The method of claim 9, further including increasing or decreasing the speed of the machine to maintain a desired queuing distance between the machine and a stationary leading machine, wherein the desired queuing distance is based on the virtual two-dimensional footprint.

16. The method of claim 9, further including:

creating a virtual reference footprint based on the actual footprint of the machine;

simulating movement of the virtual reference footprint relative to a spotting point; and

stopping the machine if the uncertainty value is greater than a spotting tolerance of the spotting point.