ACTUATOR DRIVING METHOD

A method for driving an actuator for displacing a mechanism connected thereto to a target displacement and holding it there against static load, wherein the internal friction force is utilized for holding the displacement, thereby reducing the actuator load and energy consumption. Command value of the actuator is once directed above the target displacement with respect to the direction of gravity so as to cause the internal friction force to act in the direction opposite to the static load. For that purpose, the command value is varied by adding a bias or by changing a gain to be multiplied thereto.