US Patent 7594487 Apparatus for and method of controlling motion mechanism

A variable valve mechanism, which rotates a control shaft by means of an actuator to continuously change a lift amount of an engine valve, is configured in a manner such that when a sensor output in response to a minimum valve lift position defined by a stopper capable of restricting the rotation of the control shaft, is detected, a manipulated variable for the actuator is restricted so as to restrict a pressing force by the stopper, and also an angular speed of the control shaft toward the minimum valve lift position, to thereby reduce an inertia force of the control shaft.