Effect of hysteresis on the control of AFM Micro Robot by using both piezoelectric layer and base actuation

Abstract

in this paper, the effect of hysteresis on the control of atomic force microscope (AFM) multilayer micro cantilever (MC) have been studied. Governing equations are derived by using the modified couple stress theory (MCS). Hysteresis phenomenon causes amplitude difference and phase delay between simulation and experimental analysis. In this regard, PI model is utilized to investigate hysteresis effect on MC since it focuses on the physical aspect of hysteresis. Moreover, it is more suitable for real-time applications. In order to find unknown PI coefficients, genetic algorithm has been used. The results show 0.05 nm amplitude difference and 0.7ms phase delay. In addition, amplitude control of MC is examined in non-contact mode. The non-classic dynamic modeling of MC plays a great role in improving AFM control which differentiates it with previous studies. Two control methods of PID and nonlinear sliding mode control (SMC) are applied to the system. In near-surface mode, nonlinear forces act on MC which counts for a more complex dynamics. Two methods of base and piezo excitation have been inquired in each state. Overall, SMC reveals more accurate results in near-surface mode. In this mode, SMC control effort is less than PID control.