A novel second-order feedforward approach for tracking control of a class of motion systems with flexible modes

Jerk derivative feedforward control is proposed and used in recent literatures. However, such feedforward control scheme is restricted to the minimum-phase system which has constrained static gains in the flexible modes. This paper presents a novel form of feedforward controller for a wider class of flexible motion systems, even to be non-minimum phase, as long as the summation of DC gains of flexible modes is positive. The newly proposed feedforward scheme gives superior performance over existing feedforward schemes. Especially, the tracking error can be almost eliminated, when the plant´s lowest frequency anti-resonance is outside the main frequency band of the reference trajectory. In other cases, this novel controller still gives adequate tracking performance, while other feedforward controllers are malfunctioned.