PRECISION POSITION CONTROL OF PIEZOELECTRIC ACTUATORS USING CHARGE FEEDBACK

This paper examines the current state of the art in position control of actuators constructed from piezoelectric materials. Piezoelectric actuators are typically activated by an applied voltage, but there exists significant hysteresis between the voltage applied to the actuator and the actuator output. An explanation for this hysteresis is presented using as a basis the laws governing the behavior of dielectric materials. This hysteresis explanation indicates that it is impossible to derive a linear relationship between an input voltage and actuator output. In light of this, a new control relationship is developed based on the piezoelectric material constitutive relationships that relates actuator displacement to an amount of applied charge. Experimental data from tests of both voltage control and charge control show that charge control is significantly more linear and less hysteretic than voltage control over the same actuator displacement range.