HYSTERESIS, CREEP, AND VIBRATION COMPENSATION FOR PIEZOACTUATORS: FEEDBACK AND FEEDFORWARD CONTROL

摘要

We present an integrated two-step approach, which combines feedback and feedforward control, to compensate for the effects of hysteresis, creep, and vibration in piezoactuators. In this approach, the control of hysteresis and creep is decoupled from the control of vibrational dynamics. First, high-gain feedback control is used to minimize positioning error caused by hysteresis and creep. Second, an inversion-based feedforward approach, which can achieve exact tracking for general output trajectories, is used to compensate for error due to vibration at high scan rates. The feedforward approach is applicable to minimum (collocated sensor and actuator) and nonminimum phase (noncollocated sensor and actuator) positioning systems. The decoupling of hysteresis and creep control from vibration control simplifies the inversion-based approach, and the use of feedback provides robustness. We show significant improvement in positioning precision and scanning rate, and illustrate our results with an experimental piezoactuator scanner that is used in Atomic Force Microscope (AFM) applications.