Nonlinear analysis and optimal design of a novel piezoelectric-driven compliant microgripper

In a piezoelectric-driven microgripper, obtaining parallel grasping and enlarging grasping stroke are important. This paper presents the nonlinear analysis and optimal design of a novel orthogonal displacement amplification mechanism (DAM)-based piezoelectric-driven microgripper without using traditional bridge-type mechanism or multi-stages DAM, which realizes parallel grasping and displacement amplification simultaneously in compact configuration and benefits further miniaturization. The structural design of proposed microgripper is given, in which a novel orthogonal DAM is used as the intermediate mechanism. The geometrical nonlinearity analysis of novel orthogonal DAM is conducted, including the finite difference-based analysis, the variance-based global sensitivity analysis and the correlation analysis. Based on the nonlinear analysis results, a static constraint restricting the large deflection geometrical nonlinearity degree is established. An optimal design framework of the proposed microgripper is further formulated, which maximizes the grasping movements with considering the property of piezoelectric stack actuator, the nonlinear geometric constraints, the established static constraints as well as the dynamic constraint. A design example verifies the optimal design framework, which can reduce the negative effect of large deflection nonlinearity on the orthogonal movement transformation without requiring specific experience. Experimental tests are used to verify the parallel grasping and the displacement amplification of microgripper.