Macro/micro feed drive system has a long stroke with ultra precision. The combined system including a macro stage and a micro stage is designed. A ball screw based on servo motor is used as the macro stage and a piezoelectric actuator is used as the micro stage. Dual-servo control strategy is implemented. The macro stage tracks input signal

actual displacement is measured by linear encoder as inner servo loop. The tracking error of macro stage is the input signal of micro stage to compensate as outer servo loop. The method realizes continual tracking control of macro/micro feeding system. Simulation was implemented finally. In the case of command input of a 1mm amplitude and 0.4Hz sinusoidal frequency

the tracking error is reduced from ±1.6μm for only macro stage to ±6nm for macro/micro feed drive system.