Integrated multiple actuator electro-hydraulic units
Integrated multiple actuator electro-hydraulic systems as well as their methods of use are described. Depending on the particular application, the integrated electro-hydraulic systems may exhibit different frequency responses and/or may be integrated into a single combined unit.
1. A method of controlling relative motion between a first structure and a second structure by applying a net force on the two structures, the method comprising:
driving a hydraulic pump with an electric motor operatively coupled to the hydraulic pump;
supplying pressurized hydraulic fluid to a volume in a first actuator, wherein the first actuator is interposed between the first and the second structures;
supplying pressurized hydraulic fluid to a volume in a second actuator, wherein the second actuator is interposed between the first and the second structures and arranged operatively in a parallel arrangement with the first actuator;
wherein a total Effective Force Area of the first actuator and the second actuator in at least one of a compression direction and an extension direction is a function of a frequency of pressure produced by the hydraulic pump.
2. The method of claim 1 , further comprising using a hydraulic low pass filter located in a flow path between a port of the hydraulic pump and at least one of a compression volume and an extension volume of the second actuator in order to reduce the Effective Force Area of the second actuator above a threshold frequency.
3. The method of claim 2 , wherein the threshold frequency is 3 Hz.
4. The method of claim 2 , wherein the threshold frequency is 0.1 Hz.
5. The method of claim 1 , wherein the hydraulic pump is a hydraulic motor-pump.
6. A method of controlling relative motion between a vehicle body and a wheel assembly by applying a net force on the vehicle body and the wheel assembly, the method comprising:
driving a hydraulic pump;
supplying pressurized hydraulic fluid to a hydraulic actuation apparatus that is interposed between the vehicle body and the wheel assembly, wherein the pressure of the hydraulic fluid acts on a Total Effective Force Area (TEFA) of the hydraulic actuation apparatus to produce a force, wherein the TEFA is a function of a frequency of the pressure of the hydraulic fluid supplied by the hydraulic pump;
applying the force to the vehicle body and the wheel assembly.
7. The method of claim 6 , wherein the hydraulic pump is operatively coupled to an electric motor to drive the hydraulic pump.
8. The method of claim 6 , wherein the actuation apparatus includes a first actuator and a second actuator.
9. The method of claim 8 , wherein the actuation apparatus includes a third actuator.
10. The method of claim 6 , wherein the hydraulic pump is back drivable and the hydraulic actuation apparatus has an inertance for frequencies of pressure produced by an external stimulus at frequencies above a threshold frequency that is lower than the inertance at frequencies below the threshold frequency.
11. The method of claim 6 , wherein the frequency of the pressure of the hydraulic fluid is controlled by controlling an electric motor.
12. The method of claim 6 , further comprising at least one electronically-controlled hydraulic valve, wherein the frequency of the pressure of the hydraulic fluid is controlled by the at least one electronically-controlled hydraulic valve.
13. The method of claim 6 , wherein the hydraulic pump is a hydraulic motor-pump.