Payload system that compensates for rotational forces

• US 20090139119A1
• Filed: 11/30/2007
• Published: 06/04/2009
• Est. Priority Date: 11/30/2007
• Status: Active Grant

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Tozawa, Shoji, Berry, Jeffrey Kent, Brandt, Everett Gene, Price, Robert J., Janardhan, Vijayakumar, King, Kevin Dwight, Mintah, Brian
• Granted Patent: US 7,912,612 B2
• Time in Patent Office: Days
• US Class Current: 37/413
• CPC Class Codes: B25J 9/1638 compensation for arm bending/inertia, pay load weight/inertia
• CPC Class Codes: E02F 9/264 Sensors and their calibration for indicating the position of the work tool
• CPC Class Codes: G01G 19/021 having electrical weight-sensitive devices G01G19/04 - G01G19/07 take precedence
• CPC Class Codes: G05B 2219/45012 Excavator

Abstract

The present disclosure is directed to a payload calculation system for use with a work implement. The payload calculation system may have a state sensor configured to measure a state of the work implement. The payload calculation system may further have a processing device configured to calculate a mass of a payload moved by the work implement. The processing device may be configured to use the measured state to compensate the calculation of the mass for centrifugal, inertial, and frictional forces of the work implement caused by the work implement rotating about a vertical pivot.

Claims

1. A payload calculation system for use with a work implement, comprising:

a state sensor configured to measure a state of the work implement; and

a processing device configured to calculate a mass of a payload moved by the work implement, the processing device being configured to use the measured state to compensate the calculation of the mass for centrifugal, inertial, and frictional forces of the work implement caused by the work implement rotating about a vertical pivot.

2. The payload calculation system of claim 1, wherein the work implement further includes:

at least one linkage member having an actuator; and

a force sensor configured to measure a force at the actuator, wherein the processing device is in communication with the force sensor, and the processing device is configured to use the measured force in addition to the measured state to calculate the mass of the payload.

3. The payload calculation system of claim 2, wherein the measured state includes at least one of an angle, an angular velocity, or an angular acceleration of the at least one linkage member.

4. The payload calculation system of claim 3, wherein the processing device is configured to:

determine a joint torque using the measured force;

determine one or more moments created by the centrifugal and inertial forces of the work implement; and

compensate the calculation of the mass by subtracting the moments from the joint torque.

5. The payload calculation system of claim 4, wherein the processing device is configured to modify the value of the moments as a function of the angular velocity of the at least one linkage member.

6. The payload calculation system of claim 5, wherein the processing device is configured to modify the value of the moments as a function of a ratio of the angular velocity of the at least one linkage member and a threshold velocity.

7. The payload calculation system of claim 6, wherein the threshold velocity is a function of temperature.

8. The payload calculation system of claim 1, wherein the work implement is coupled to a platform, the platform is rotatably coupled to an undercarriage via the vertical pivot, and a power source is configured to rotate the platform relative to the undercarriage.

9. A method of calculating a mass of a payload, comprising:

actuating a work implement to move a payload;

measuring a state of the work implement;

calculating a mass of the payload moved by the work implement using the measured state; and

compensating the calculation of the mass for centrifugal, inertial, and frictional forces of the work implement caused by the work implement rotating about an axis that is substantially normal to a work surface.

10. The method of claim 9, wherein the work implement includes at least one linkage member.

11. The method of claim 10, further including determining a torque acting at a joint of the at least one linkage member, wherein calculating the mass includes using the torque in addition to the measured state.

12. The method of claim 11 wherein the measured state includes at least one of an angle, an angular velocity, or an angular acceleration of the at least one linkage member.

13. The method of claim 12, wherein compensating includes subtracting one or more moments from the torque, the moments being created by the centrifugal and inertial forces.

14. The method of claim 13, wherein compensating includes modifying the value of the moments depending on the angular velocity of the at least one linkage member.

15. The method of claim 13, wherein the calculated mass of the payload is used to determine the value of the moments.

16. The method of claim 15, wherein calculating and compensating are performed in an iterative fashion.

17. A machine, comprising:

an undercarriage;

a platform coupled to the undercarriage;

a work implement coupled to the platform;

a power source configured to rotate the platform relative to the undercarriage;

a state sensor configured to measure a state of the work implement; and

a processing device configured to calculate a mass of a payload moved by the work implement, the processing device being configured to use the measured state to compensate the calculation of the mass for centrifugal, inertial, and frictional forces of the work implement caused by the work implement rotating about a vertical pivot.

18. The machine claim 17, wherein the vertical pivot is configured to couple the platform to the undercarriage.

19. The machine of claim 18, wherein the work implement further includes:

at least one linkage member having an actuator; and

a force sensor configured to determine a force at the actuator, wherein the processing device is in communication with the force sensor, and the processing device is configured to use the measured force in addition to the measured state to calculate the mass of the payload.

20. The machine of claim 19, wherein the processing device is configured to:

determine a joint torque using the measured force;

determine one or more moments created by the centrifugal and inertial forces of the work implement;

modify the value of the moments depending on an angular velocity of the at least one linkage member; and

compensate the calculation of the mass by subtracting the modified moments from the joint torque.