Machine Positioning System Having Angular Rate Correction

• US 20140122016A1
• Filed: 10/31/2012
• Published: 05/01/2014
• Est. Priority Date: 10/31/2012
• Status: Abandoned Application

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: FRIEND, Paul Russell
• Application Number:
  US13/665,737
• Publication Number:
  US 20140122016A1
• Time in Patent Office: Days
• US Class Current: 702/145
• CPC Class Codes: E02F 3/842 using electromagnetic, optical or photoelectric beams, e.g. laser beams
• CPC Class Codes: E02F 9/205 Remotely operated machines, e.g. unmanned vehicles E02F3/8866 takes precedence
• CPC Class Codes: E02F 9/264 Sensors and their calibration for indicating the position of the work tool
• CPC Class Codes: G01C 21/183 Compensation of inertial measurements, e.g. for temperature effects

Abstract

A system and method for estimating orientation of a machine is disclosed. The method may include receiving, from a first sensor, a first angular rate of the machine measured in a body reference frame of the machine, and determining an estimated bias for a second sensor of the machine and an uncertainty measure for the estimated bias. The method may further include determining a scale factor based on the uncertainty measure and converting the first angular rate of the machine in the body reference frame to a first angular rate of the machine in a gravity reference frame by utilizing a rotation matrix including the scale factor. The method may further include estimating the orientation of the machine based on the first angular rate of the machine in the gravity reference frame.

Claims

1. A method of estimating an orientation of a machine, comprising:

receiving, from a first sensor, a first angular rate of the machine measured in a body reference frame of the machine;

determining an estimated bias for a second sensor of the machine and an uncertainty measure for the estimated bias;

determining a scale factor based on the uncertainty measure;

converting the first angular rate of the machine in the body reference frame to a first angular rate of the machine in a gravity reference frame by utilizing a rotation matrix including the scale factor; and

estimating the orientation of the machine based on the first angular rate of the machine in the gravity reference frame.

2. The method of claim 1, wherein the first angular rate is one of a pitch rate, a roll rate, and a yaw rate of the machine.

3. The method of claim 1, wherein the second sensor is one of a pitch rate sensor and a yaw rate sensor.

4. The method of claim 1, wherein the rotation matrix further includes a previously estimated orientation of the machine.

5. The method of claim 1, wherein determining the estimated bias for the second sensor of the machine and the uncertainty measure for the estimated bias includes using a Kalman filter.

6. The method of claim 1, wherein determining the scale factor based on the uncertainty measure includes dividing a predetermined goal bias uncertainty value by the uncertainty measure and setting a result of the division as the scale factor.

7. The method of claim 1, wherein determining the scale factor based on the uncertainty measure includes:

comparing the uncertainty measure with a threshold bias uncertainty value;

setting the scale factor equal to a predetermined first value if the uncertainty measure is greater than the threshold bias uncertainty value; and

setting the scale factor equal to a predetermined second value if the uncertainty measure is less than or equal to the threshold bias uncertainty value.

8. A system for estimating an orientation of a machine, comprising:

a first sensor configured to provide a first angular rate of the machine;

a second sensor configured to provide a second angular rate of the machine; and

a controller in communication with the first sensor and the second sensor, the controller configured to;

determine an estimated bias for the second sensor and an uncertainty measure for the estimated bias;

determine a scale factor based on the uncertainty measure;

convert the first angular rate of the machine in a body reference frame to a first angular rate of the machine in a gravity reference frame by utilizing a rotation matrix including the scale factor; and

estimate the orientation of the machine based on the first angular rate of the machine in the gravity reference frame.

9. The system of claim 8, wherein the first angular rate is one of a pitch rate, a roll rate, and a yaw rate of the machine.

10. The system of claim 8, wherein the second sensor is one of a pitch rate sensor and a yaw rate sensor.

11. The system of claim 8, wherein the rotation matrix further includes a previously estimated orientation of the machine.

12. The system of claim 8, wherein the controller is configured to determine the estimated bias for the second sensor of the machine and the uncertainty measure for the estimated bias by using a Kalman filter.

13. The system of claim 8, wherein the controller is configured to determine the scale factor based on the uncertainty measure by dividing a predetermined goal bias uncertainty value by the uncertainty measure and setting a result of the division as the scale factor.

14. The system of claim 8, wherein the controller is configured to determine the scale factor by:

comparing the uncertainty measure with a threshold bias uncertainty value;

setting the scale factor equal to a predetermined first value if the uncertainty measure is greater than the threshold bias uncertainty value; and

setting the scale factor equal to a predetermined second value if the uncertainty measure is less than or equal to the threshold bias uncertainty value.

15. A non-transitory computer-readable storage medium storing instructions for enabling a processor to execute a method of estimating an orientation of a machine, the method comprising:

receiving, from a first sensor, a first angular rate of the machine measured in a body reference frame of the machine;

determining an estimated bias for a second sensor of the machine and an uncertainty measure for the estimated bias;

determining a scale factor based on the uncertainty measure;

converting the first angular rate of the machine in the body reference frame to a first angular rate of the machine in a gravity reference frame by utilizing a rotation matrix including the scale factor; and

estimating the orientation of the machine based on the first angular rate of the machine in the gravity reference frame.

16. The non-transitory computer-readable storage medium of claim 15, wherein the first angular rate is one of a pitch rate, a roll rate, and a yaw rate of the machine.

17. The non-transitory computer-readable storage medium of claim 15, wherein the rotation matrix further includes a previously estimated orientation of the machine.

18. The non-transitory computer-readable storage medium of claim 15, wherein determining the estimated bias for the second sensor of the machine and the uncertainty measure for the estimated bias includes using a Kalman filter.

19. The non-transitory computer-readable storage medium of claim 15, wherein determining the scale factor based on the uncertainty measure includes dividing a predetermined goal bias uncertainty value by the uncertainty measure and setting a result of the division as the scale factor.

20. The non-transitory computer-readable storage medium of claim 15, wherein determining the scale factor based on the uncertainty measure includes:

comparing the uncertainty measure with a threshold bias uncertainty value;

setting the scale factor equal to a predetermined first value if the uncertainty measure is greater than the threshold bias uncertainty value; and

setting the scale factor equal to a predetermined second value if the uncertainty measure is less than or equal to the threshold bias uncertainty value.