ICSV26

Inertial actuators can be used with velocity feedback controllers to reduce structural vibration, however, their finite stroke length can affect the behaviour and stability of the control system. Stroke saturation not only limits the amount of force available from the actuator but also causes the proof mass to suddenly decelerate, causing impulse-like excitations that are trans-mitted to the structure and may result in damage. The shocks produced by these impacts are in phase with the velocity of the structure, leading to a reduction of the overall damping of the system, which eventually destabilises the system. This paper examines the implementation of a nonlinear feedback controller to avoid collisions of the proof mass with the actuator's end-stops, thus preventing this instability. A nonlinear feedback control strategy is then presented, which actively increases the internal damping of the actuator only when the proof mass ap-proaches the end-stops. The nonlinear control strategy is investigated both theoretically and experimentally for the control of a cantilever beam, and a comparison in terms of stability is made when both control loops or only the velocity feedback loop are present. Finally, a virtu-al sensing approach based on an extended Kalman filter algorithm is discussed for the real-time estimation of the proof mass states that are used to calculate the feedback signal of the nonlinear control law. It is shown that larger velocity feedback gains can be used without the system becoming unstable when the nonlinear feedback loop is adopted.