Threshold current control system for hydraulic valves
First Claim
1. A system for controlling the position of an implement coupled to a work vehicle, the implement being moveable by a hydraulic positioning assembly comprising an actuator and a valve assembly configured to control the flow of fluid to and from the actuator in response to control signals, the valve assembly requiring control signals substantially equal to a first threshold value before fluid begins to flow, the system comprising:
- a sensor configured to detect the position of the implement and to generate a signal representative thereof;
a control circuit coupled to the sensor and the valve assembly, the control circuit configured to generate the control signals applied to the valve assembly based upon the first threshold value in response to a change in a position command signal and, after detecting undesirable implement movement based at least upon the sensed position signal, to generate the control signals based upon a modified threshold value; and
a memory circuit coupled to the control circuit, the memory storing the modified threshold value and wherein the control circuit uses the modified threshold value as the first threshold value for subsequent valve actuation.
3 Assignments
0 Petitions
Accused Products
Abstract
A system or method for controlling the position of an implement coupled to a work vehicle. The implement is moveable by a hydraulic positioning assembly including an actuator and a valve assembly which control the flow of fluid to the actuator in response to control signals. The valve assembly includes raise and lower valves, each valve requiring a control signal equal to a threshold value before the valve opens and fluid begins to flow. The system includes a sensor to detect the position of the implement and a control circuit. In response to a change in a position command, the control circuit applies a control signal to the appropriate raise or lower valve based upon the respective threshold value. The control signal may include a component for moving the implement at a desired rate of movement. After undesirable implement movement is detected, the control circuit modifies the threshold value. The modification may occur when the control circuit detects that the implement is moving at an excessive rate due to the effects of valve hysteresis and implement weight. The control circuit may detect the undesirable movement by determining that the position error value is more negative than a predetermined value. The modified threshold value then replaces the threshold value for subsequent implement movement. The new threshold value prevents the undesirable movement in subsequent implement movement.
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Citations
30 Claims
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1. A system for controlling the position of an implement coupled to a work vehicle, the implement being moveable by a hydraulic positioning assembly comprising an actuator and a valve assembly configured to control the flow of fluid to and from the actuator in response to control signals, the valve assembly requiring control signals substantially equal to a first threshold value before fluid begins to flow, the system comprising:
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a sensor configured to detect the position of the implement and to generate a signal representative thereof; a control circuit coupled to the sensor and the valve assembly, the control circuit configured to generate the control signals applied to the valve assembly based upon the first threshold value in response to a change in a position command signal and, after detecting undesirable implement movement based at least upon the sensed position signal, to generate the control signals based upon a modified threshold value; and a memory circuit coupled to the control circuit, the memory storing the modified threshold value and wherein the control circuit uses the modified threshold value as the first threshold value for subsequent valve actuation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A method for controlling the position of an implement coupled to a work vehicle, the implement being moveable by a hydraulic positioning assembly comprising an actuator and a valve assembly configured to control the flow of fluid to and from the actuator in response to control signals, the valve assembly requiring control signals substantially equal to a first threshold value before fluid begins to flow, the method comprising the steps of:
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(a) generating the control signals applied to the valve assembly based upon the first threshold value in response to a change in a commanded position; (b) detecting undesirable implement movement; (c) upon detecting undesirable implement movement, modifying the threshold value used to generate the control signal until control is achieved; and (d) replacing the first threshold value with the modified threshold value for generating subsequent control signals. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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Specification