Modeling and Control of a Magnetostrictive Tool Servo System

Abstract

A magnetostrictive actuator offers a long mechanical strain output in a broad bandwidth at a cost of a highly nonlinear magnetic hysteresis. Full utilization of this actuator in precision manufacturing requires a feedback loop as well as an advanced control scheme. A robust control scheme using sliding mode control with a variable switching gain was tailored to the nonlinear transducer. Nominal feedforward current controller that drives the magnetostriction was based on the inverse anhysteresis model. An additional switching gain based on the Lyapunov stability condition is implemented to restrain uncertainties. Compared to a traditional closed-loop control design, the proposed algorithm experimentally showed a greatly enhanced performance.