Compensation of leadscrew pitch error using GMA

Ultra-precision machining is a key technology developed with the process of manufacturing. At the point of micro driving, regulating the accuracy of machine tool with smart materials that can generate micro movement to an extent of nanometer level is often introduced to satisfy the required precision. Aiming at reducing the positioning error of a precision working table driven by an AC servo motor, the measurement of the dynamical characteristics of the system was carried on by a laser interferometer. The leadscrew pitch error, which takes the major portion in the measurement error, was separated by signal filtering. Based on this, a giant magnetostrictive actuator (GMA) as well as a flexure hinge micro-motion table was designed to verify the compensation result for the separated pitch error. The hysteresis nonlinearity of the GMA was controlled effectively by PID control techniques. Experimental results showed great improvements of the tracking accuracy, which proved the feasibility of the compensation method.