Reduction of residual vibration in displacement-amplified micro-electromagnetic actuators with non-linear dynamics using input shaping

Micro-electromagnetic actuators have been used in many fields and industries for systems such as microftuidic systems, positioning stages, and robotic manipulators. Small-scale electromagnetic actuators are able to provide rapid motion with high positioning accuracy. The actuator presented in this paper utilizes a displacement amplification mechanism to increase the maximum stroke length that can be achieved. The dynamics of this actuator are nonlinear due to the dependence of the applied force on gap distance between the coils and the amplification mechanism. This nonlinearity causes the performance of PID control to vary with respect to the displacement of the actuator. The control method proposed in this paper to limit the overshoot resulting from nonlinearity uses a combination of PID control and robust input shapers. Using robust input shapers to account for parameter variation across the workspace, the combined controller eliminates the overshoot while maintaining short settling times. Simulations are presented to demonstrate the performance of the proposed method.