High-speed and high-precision motion control with an optimal hybrid feedforward controller

An optimal feedforward controller which makes a hybrid usage of the shift (q) and delta (δ) operators is proposed for high-speed and high-precision digital motion control systems. Uncancellable discrete-time zeros arising from sampling the continuous-time plant at high rates, which make the mathematical inverse unstable, are handled in a natural way. The controller is optimized to have good performance in both low and high frequency ranges, and it is able to handle uncancellable discrete-time zeros in the right half plane. The optimization problem is generalized to an H^∞ problem. Convex minimization is used to find the solution to the optimization problem. Simulation results and experiments carried out on an MC-510V Matsuura vertical machining center show superior performance of the proposed optimal hybrid feedforward controller.