Method of controlling a hydraulic actuator drive, controller and actuator drive controller

A method of controlling a hydraulic actuator drive (1) with an actuator and a position of the actuator is set by at least one electrohydraulic proportional valve having at least one electrical input and at least one hydraulic output, which method comprises the following steps of:

• detecting the position of the actuator and an actual position value is generated therefrom;
• specifying a target position value in dependence on a default for a desired position of the actuator;
• controlling a difference between the target position value and the actual position value via the at least one electrohydraulic proportional valve so that the actuator assumes a position that corresponds to the target position value;
• and
• varying the target position value even when the default for the desired position of the actuator is not changed.

A controller for controlling at least one electrohydraulic proportional valve for controlling a hydraulic actuator drive having an actuator, the controller comprising:

• inputs and outputs for at least one actual position value and a target position value of a position of the actuator;
• said controller configured to:
• detect the position of the actuator and the actual position value is generated therefrom;
• specify the target position value in dependence on a default for a desired position of the actuator;
• control a difference between the target position value and the actual position value by the at least one electrohydraulic proportional valve so that the actuator assumes a position that corresponds to the target position value;
• and
• vary the target position value even when the default for the desired position of the actuator is not changed.

An actuator drive controller for controlling a hydraulic actuator drive having an actuator, the actuator drive controller comprising:

• a shared hydraulic pressure selection device;
• at least two redundantly disposed electrohydraulic proportional valves for generating a hydraulic input pressure for the hydraulic actuator drive, each of said electrohydraulic proportional valves having at least one electrical input and at least one hydraulic output, hydraulic outputs of said at least two electrohydraulic proportional valves are interconnected via said shared hydraulic pressure selection device for actuating the hydraulic actuator drive with a shared input pressure;
• a target position value input for each of said electrxohydraulic proportional valves and each said target position value input connected to said electrical input of a respective one of said electrohydraulic proportional valves;
• at least one position sensing device for sensing a position of said actuator of the hydraulic actuator drive, said position sensing device generating an actual position value;
• and
• each of said electrohydraulic proportional valves having a position controller configured with a target position value from said target position value input and the actual position value from said position sensing device, for controlling a difference between the target position value and the actual position value;
• at least one electronic switching device with which at least one said target position value from said target position value input, and/or the actual position value from said position sensing device, may optionally be replaced by a default value.