Patent ID: 9546672
Date: 2017-01-17
CPC Classifications: F15B,G05B

Claim:
1. A method comprising: receiving, at a controller, a command for moving a piston of a hydraulic actuator at a given speed in a given direction, wherein the hydraulic actuator includes a first chamber and a second chamber, and wherein a valve assembly couples a source of pressurized hydraulic fluid to the first chamber and couples the second chamber to a return line; based on the command, the controller providing a signal to operate the valve assembly to provide the pressurized hydraulic fluid to the first chamber and allow hydraulic fluid in the second chamber to flow from the second chamber to the return line so as to cause motion of the piston at the given speed in the given direction; receiving position information indicative of the piston reaching a first position at a first threshold distance from an end-stop of the hydraulic actuator; in response, the controller modifying the signal to the valve assembly so as to reduce a speed of the piston; receiving position information indicative of the piston reaching a second position at a second threshold distance closer to the end-stop of the hydraulic actuator; and in response, the controller further modifying the signal to the valve assembly to cause the hydraulic fluid in the second chamber to apply a force on the piston in a direction away from the end-stop.