Control strategy for hydraulic actuator with a pair of independent metering valves
Systems and methods for controlling valve assemblies associated with an actuator in an electro-hydraulic system are disclosed. In one method, a controller monitors hydraulic fluid flow for an actuator to identify one valve assembly connected to the actuator as a meter-in valve and another valve assembly connected to the actuator as a meter-out valve. In one aspect, the valve assembly most recently identified as the meter-in valve is controlled to maintain a pressure setpoint and the valve assembly most recently identified as the meter-out valve is controlled to maintain a hydraulic fluid flow rate. The method can also include determining whether the actuator is in a passive state or an overrunning state and controlling the valve most recently identified as the meter-in valve to maintain a first pressure setpoint when the actuator is in a passive state and to maintain a second pressure setpoint when the actuator is in an overrunning state.
1. A method for controlling valve assemblies associated with an actuator in an electro-hydraulic system, the method comprising the steps of:
(a) providing first and second valve assemblies, each valve assembly having at least one of a pressure sensor and a position sensor in communication with an electronic system controller, the valve assemblies being in fluid communication with the hydraulic actuator;
(b) monitoring hydraulic fluid flow to identify either of the first and second valve assemblies as a meter-in valve in which hydraulic fluid flow from the valve assembly to the actuator and the other of the first and second valve assemblies as a meter-out valve in which hydraulic fluid flows from the actuator to the valve assembly;
(c) controlling the valve most recently identified as the meter-in valve to maintain a pressure setpoint value; and
(d) controlling the valve most recently identified as the meter-out valve to maintain a hydraulic fluid flow rate value.
2. The method for controlling valve assemblies of claim 1 , further including the step of:
(a) determining whether the actuator is in a passive state or an overrunning state and controlling the valve most recently identified as the meter-in valve to maintain a first pressure setpoint value when the actuator is in a passive state and to maintain a second pressure setpoint value when the actuator is in an overrunning state.
3. The method of controlling valve assemblies of claim 1 , wherein the step of controlling the valve most recently identified as the meter-in valve to maintain a pressure setpoint value is controlled with reference to hydraulic pressure at a location between the meter-out valve and the actuator.
4. The method of controlling valve assemblies of claim 1 , wherein the valve assemblies include a first valve assembly in fluid communication with a head side of the actuator and a second valve assembly in fluid communication with a rod side of the actuator.
5. The method of controlling valve assemblies of claim 1 , wherein the hydraulic actuator is a hydraulic motor.
6. The method of controlling valve assemblies of claim 4 , wherein the actuator is a linear actuator associated with a lifting function of a work machine.
7. The method of controlling valve assemblies of claim 1 , wherein each of the first and second valve assemblies is a spool and sleeve type valve.
8. The method of controlling valve assemblies of claim 1 , wherein the steps of controlling the first and second valve assemblies are performed by an electronic controller.
9. A non-transitory computer-readable storage medium comprising instructions that, when executed by a control unit of an electronic computing system, causes the control unit to execute a method for controlling valve assemblies associated with an actuator in an electro-hydraulic system, the method comprising the steps of:
(a) providing first and second valve assemblies, each valve assembly having at least one of a pressure sensor and a position sensor in communication with an electronic system controller, the valve assemblies being in fluid communication with the hydraulic actuator;
(b) monitoring hydraulic fluid flow to identify either of the first and second valve assemblies as a meter-in valve in which hydraulic fluid flow from the valve assembly to the actuator and the other of the first and second valve assemblies as a meter-out valve in which hydraulic fluid flows from the actuator to the valve assembly;
(c) controlling the valve most recently identified as the meter-in valve to maintain a pressure setpoint value; and
(d) controlling the valve most recently identified as the meter-out valve to maintain a hydraulic fluid flow rate value.
10. The non-transitory computer-readable storage medium of claim 9 , further including the step of:
(a) determining whether the actuator is in a passive state or an overrunning state and controlling the valve most recently identified as the meter-in valve to maintain a first pressure setpoint value when the actuator is in a passive state and to maintain a second pressure setpoint value when the actuator is in an overrunning state.
11. The non-transitory computer-readable storage medium of claim 9 , wherein the step of controlling the valve most recently identified as the meter-in valve to maintain a pressure setpoint value is controlled with reference to hydraulic pressure at a location between the meter-out valve and the actuator.
12. The non-transitory computer-readable storage medium of claim 9 , wherein the valve assemblies include a first valve assembly in fluid communication with a head side of the actuator and a second valve assembly in fluid communication with a rod side of the actuator.
13. The non-transitory computer-readable storage medium of claim 9 , wherein the hydraulic actuator is a hydraulic motor.
14. The non-transitory computer-readable storage medium of claim 13 , wherein the actuator is a linear actuator associated with a lifting function of a work machine.
15. The non-transitory computer-readable storage medium of claim 9 , wherein each of the first and second valve assemblies is a spool and sleeve type valve.
16. The non-transitory computer-readable storage medium of claim 9 , wherein the steps of controlling the first and second valve assemblies are performed by an electronic controller.