Patent ID: 8513906

Claim:
An apparatus for controlling a mechanical system including an actuator configured to position a load, comprising: a vibration attenuation controller configured to produce a vibration attenuation control signal in response to an input signal for the mechanical system; a tracking controller configured to produce a tracking control signal in response to the input signal; and means for switching, in response to an output signal from the mechanical system, either the vibration attenuation control signal or the tracking control signal as a control signal for the mechanical system to reduce both vibration in the mechanical system and improve tracking the load, wherein the vibration attenuation control signal is u b (t), the tracking control signal is u r (t), and the control signal is u(t)=αu b (t)+(1−α)u r (t), where, α is a scalar that has a value of 0 or 1 determined by a switching function ƒ(t) as follows α = 0 ⁢ ⁢ f ⁡ ( t ) ≥ 0 = 1 ⁢ ⁢ f ⁡ ( t ) < 0.