HYSTERESIS AND VIBRATION COMPENSATION FOR PIEZOACTUATORS

Structural vibrations and hysteresis nonlinearities in piezoactuators have been fundamental limitations when using these actuators for high- speed precision-positioning applications. Positioning speed (bandwidth ) is limited by structural vibrations, typically, to about one tenth t he fundamental vibrational frequency of the piezoprobe. Further, preci sion in positioning is limited by hysteresis nonlinearities, which can result in significant errors for large-range positioning applications . This paper shows that significant improvements in precision and band width can be achieved by using an inversion-based approach to compensa te for hysteresis and vibrations in the piezodynamics. The approach de couples the inversion into 1) inversion of the hysteresis nonlinearity and 2) inversion of the structural dynamics, to find an input voltage profile that achieves precision tracking of a desired position trajec tory The approach is applied to a piezoactuator, and experimental resu lts show that an order of magnitude improvement in positioning speed i s achieved, while maintaining precision tracking of the desired positi on trajectory.