Patent ID: 8434398

Claim:
A control method for controlling a hydraulic actuator to impart oscillatory excitation to a load, the actuator comprising at least one hydraulic chamber and a movable member capable of moving in said chamber between two extreme positions under the action of a liquid under pressure, wherein the method comprises the steps of: determining an operating point for said actuator, which operating point corresponds to a rest position of said movable member; applying a hydraulic command to bring said movable member into correspondence with said rest position; and applying a hydraulic command to cause said movable member to perform reciprocating movement about said rest position, said reciprocating movement being adapted to apply oscillatory excitation to said load; the rest position of said movable member being selected to be significantly off-center relative to said extreme positions; wherein said rest position is selected to be as close as possible to one of said extreme positions of the movable member.