Study on non-linearity control of a piezoelectric nanoactuator

In order to improve the positioning accuracy and decrease the waveform distortion of a piezoelectric nanoactuator used in a laser scanning measurement system, two methods are introduced. Firstly, a method based on nonlinear compensation to the input voltage is presented and a corresponding table stored in the RAM of a microcomputer is made to realize perfect linearization between the output displacement and input voltage. Secondly, a composite control strategy, in which iterative learning control is combined with PID control, is proposed. Its basic principle is using the error signal between actual output and desired output to modify the control signal repeatedly until the errors meet the accuracy demand. Simulation and experiment results indicate that the positioning accuracy and distortion of the displacement waveform has been improved through the above methods.