Design, control, and experimental study of a piezoelectric bimorph-based microgripper

In the field of micro-nanomanipulation, piezoelectric microgrippers have attracted significant attention due to their high precision, fast response, and lack of electromagnetic interference. This paper presents a compact, fast-response piezoelectric microgripper based on a parallel piezoelectric bimorph structure, which achieves large tip displacement through bending deformation. To address the impact of the inherent nonlinear hysteresis characteristics of piezoelectric materials on gripping accuracy, an improved Prandtl-Ishlinskii (PI) hysteresis model is proposed. This model introduces an uneven threshold division to effectively reduce computational complexity and incorporates a unilateral dead-zone operator and an optimized operator weight to enhance fitting accuracy. The improved PI inverse model is derived to achieve feedforward compensation, and a feedforward-feedback compound control strategy is proposed in conjunction with a Proportional-Integral-Derivative controller. Simulation comparison and analysis are performed, and experimental validation through dSPACE real-time control platform testing demonstrates the gripping performance of the designed microgripper, highlighting its potential for micro-object manipulation.