Drift compensation control method for a machine

• US 20080087163A1
• Filed: 10/17/2006
• Published: 04/17/2008
• Est. Priority Date: 10/17/2006
• Status: Active Grant

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Brickner, Chad T., Skwarnicki, Dominik, Lange, Philip F.
• Granted Patent: US 7,845,169 B2
• Time in Patent Office: Days
• US Class Current: 91/369.2
• CPC Class Codes: E02F 3/432 for keeping the bucket in a predetermined position or attitude
• CPC Class Codes: F15B 21/087 Control strategy, e.g. with block diagram
• CPC Class Codes: F15B 2211/20546 variable capacity
• CPC Class Codes: F15B 2211/327 electrically or electronically
• CPC Class Codes: F15B 2211/6336 representing a state of the output member, e.g. position, speed or acceleration
• CPC Class Codes: F15B 2211/6346 representing a state of input means, e.g. joystick position
• CPC Class Codes: F15B 2211/6656 Closed loop control, i.e. control using feedback
• CPC Class Codes: F15B 2211/7053 Double-acting output members
• CPC Class Codes: F15B 2211/7656 with continuous position control

Abstract

A method of controlling a machine having a hydraulically actuated linkage includes lowering a load suspended by the leakage at least in part by leaking hydraulic fluid from a portion of a hydraulic actuation system, and generating a drift compensation control signal responsive to leaking hydraulic fluid. A machine includes an electronic controller in control communication with a valve, the electronic controller being configured to compensate for leakage induced drift of at least one hydraulic actuator of a machine hydraulic system by selectively commanding adjusting of the valve if drift criteria for the hydraulic system are satisfied.

Claims

1. A method of controlling a machine having a linkage coupled with a hydraulic actuation system comprising the steps of:

suspending a load with the linkage;

lowering the load, including leaking hydraulic fluid from at least a portion of the hydraulic actuation system;

sensing an operating parameter value during lowering the load; and

generating a drift compensation control signal responsive to leaking hydraulic fluid.

2. The method of claim 1 wherein the sensing step comprises sensing an operating parameter value indicative of load position, and wherein the generating step comprises generating a drift compensation control signal responsive to a sensed operating parameter value indicative of a leakage induced drift condition of the hydraulic actuation system.

3. The method of claim 2 further comprising a step of raising the load at least in part via a step of commanding adjusting an electronically controlled fluid supply valve associated with at least one actuator of the hydraulic actuation system via the drift compensation control signal.

4. The method of claim 3 wherein the step of sensing an operating parameter value comprises sensing actuator position with a position sensor coupled with the at least one actuator.

5. The method of claim 4 wherein the lowering step comprises lowering the load via lowering the linkage from a target linkage position, and wherein the raising step comprises a step of returning the linkage toward the target linkage position via adjusting of the fluid supply valve.

6. The method of claim 5 further comprising a step of determining the existence of a leakage induced actuator drift condition at least in part by comparing the sensed actuator position with a target actuator position corresponding to the target linkage position.

7. The method of claim 6 wherein the sensing step comprises sensing a first actuator position and the generating step comprises generating a first drift compensation control signal, the method further comprising the steps of:

sensing a second actuator position, subsequent to generating the first drift compensation control signal;

comparing the second actuator position with the target actuator position; and

generating a second drift compensation control signal responsive to the comparison of the second actuator position with the target actuator position.

8. The method of claim 6 wherein the step of generating a drift compensation control signal comprises outputting a fluid flow rate control signal to adjust a fluid flow rate at the fluid supply valve responsive to the comparison of the sensed actuator position with the target actuator position.

9. The method of claim 2 wherein the linkage includes a plurality of linkage actuators, the method further comprising a step of generating a plurality of drift compensation control signals associated one with each of the plurality of linkage actuators, responsive to a leakage induced drift condition of each respective actuator.

10. The method of claim 2 wherein the linkage includes a plurality of linkage actuators, the method further comprising a step of controlling a position of a first linkage actuator via a drift compensation control signal generated responsive to a leakage induced drift condition of the first linkage actuator, and controlling a position of at least a second linkage actuator separately from controlling the position of the first linkage actuator.

11. The method of claim 2 further comprising the steps of:

receiving with an electronic controller a request to activate a drift compensation routine;

receiving with the electronic controller a request from an input device to adjust at least one actuator of the hydraulic system; and

deactivating the drift compensation routine responsive to the request to adjust the at least one hydraulic cylinder, if the request satisfies drift compensation deactivation criteria.

12. A method of compensating for actuator drift in a hydraulic system comprising the steps of:

changing a position of at least one hydraulic actuator of the hydraulic system at least in part by leaking hydraulic fluid from the at least one hydraulic actuator responsive to a load thereon;

sensing an operating parameter value during changing the position of the at least one hydraulic actuator; and

generating a drift compensation control signal responsive to leaking hydraulic fluid.

13. The method of claim 12 further comprising the steps of commanding a target position for the at least one hydraulic actuator prior to the changing step, and returning the at least one hydraulic actuator toward the target position at least in part via the drift compensation control signal.

14. The method of claim 13 wherein the step of sensing an operating parameter value comprises sensing an operating parameter value that corresponds with a leakage induced drift condition of the at least one hydraulic actuator.

15. The method of claim 14 wherein the at least one hydraulic actuator comprises a linear hydraulic actuator, and wherein the step of sensing an operating parameter value comprises sensing a position of the linear hydraulic actuator with a position sensor coupled therewith.

16. The method of claim 15 wherein the drift compensation control signal comprises a flow rate control signal, the method further comprising a step of increasing fluid flow to the at least one actuator at least in part by outputting the flow rate control signal to an electronically controlled fluid supply valve associated with the at least one actuator, based on a difference between the target position and the sensed position.

17. A machine comprising:

a hydraulic system having a valve and at least one hydraulic actuator; and

an electronic controller in control communication with said valve, and configured to compensate for leakage induced drift of said at least one hydraulic actuator by selectively commanding adjusting of said valve if actuator drift criteria are satisfied.

18. The machine of claim 17 further comprising a position sensor configured to sense a position of said at least one hydraulic actuator and output corresponding position signals to said electronic controller, wherein said electronic controller is configured to compensate for said leakage induced drift via a closed loop drift compensation control algorithm having an input term corresponding to position signal inputs from said sensor.

19. The machine of claim 18 wherein said electronic controller is further configured to determine satisfaction of actuator drift criteria at least in part by comparing a sensed position of said at least one hydraulic actuator with a target position.

20. The machine of claim 19 further comprising:

a plural component linkage coupled with said hydraulic system;

a plurality of linkage actuators; and

an implement coupled with said linkage and configured to suspend a load;

wherein said valve comprises a primary fluid supply valve for at least one of said plurality of linkage actuators.