Optimization parameter for microgripper based on triple-stair compliant mechanism using GTs-TOPSIS

In manipulating the assembly of micro-components, the symmetrical microgripper mechanism often causes destruction, damaging those components during manipulation, due to the phenomenon of non-uniform clamping force output from the clamp. From this disadvantage, a new asymmetric microgripper structure is proposed with stable output clamping force. The asymmetric microgripper structure will have a smaller output displacement than that of the symmetric structure. Therefore, to increase the output displacement gain, a flexible hinge with a triple-stair half-bridge-style mechanism (TSBM) is adopted to design the amplifier of the asymmetrical microgripper. The finite element method is applied to analyze the displacement and stress. The optimization process is performed based on the geometric parametric properties of the structure. Using the technology for order preference by similarity to ideal solution (TOPSIS) based on the Grey relationship analysis (GRA), we obtained the maximum displacement output and minimum stress. Results show that the maximum output displacement is 5,818 mm, and stress after analysis is 2,432 MPa. The test is conducted to verify the optimal results and the effectiveness of the optimization method. Finally, experimental experiments were performed, with a 4.8% difference from the FEA results. The results from the experimental test verify that the microgripper’s maximum displacement amplification ratio is approximately 58.2 times.