Inverse control algorithm to compensate the hysteresis and creep effect of piezoceramics

The high-precision positioning with scanners in scanning probe microscopes applications, particularly in atomic force microscopy (AFM), was studied. The piezoelectric ceramics actuators are usually used in this kind of scanner, which obviously exhibits the hysteresis and creep between the input voltages and the output displacements during the uncompensated open-loop operation. The hysteresis and creep reduce the positioning precision and produce a distortion in scanning images. A novel hysteresis and creep model was proposed, and the method that can on-line identify parameters was also provided. Furthermore, the model-based inverse control algorithm was used to compensate the hysteresis and creep effect of piezoceramics during AFM scanning. In the analysis, the Preisach hysteresis model and logarithmic creep model were used to characterize the nonlinear behavior of the piezoceramics actuator. This method is easy-to-use because it does not need set parameters in control procedure. Moreover, it has high resolution as it is an open-loop control scheme. Closed-loop operation can offer better hysteresis and creep compensation, but it can reduce image resolution for small scans/sample features due to limited dynamic range of sensors at higher bandwidth. Simulation results of tracking triangular wave trajectories show tracking error is on the magnitude of the sensor noise level, which demonstrate the validity of the method.