Parameter Optimization of Micro-gripper System for Nonlinear Contradictory Objectives

Maximum output displacement and resolution are two contradictory performance indexes of micro positioning system. Usually, the two important indexes cannot be satisfied simultaneously by flexibility-targeting structure optimization method. A final optimal model was established considering both output displacement and resolution. And the corresponding solution was established for the special model with two nonlinear contradictory objectives. Firstly, the parameters with a greater effect on the whole performance of the system were found out and the optimization variables were obtained. Constrained condition was built up according to the design requirements and relationship among these variables. Secondly, by the usage of these optimization variables, two expressions for the maximum output displacement and the resolution were built up and defined as objective function and constrained function respectively. At last, a synthetic algorithm was adopted to solve this kind of optimization model by integrating three methods, that's the branch and bound method, interior point method and exterior point method. The optimization model was obtained by interior point method. The synthetic algorithm took any one of the possible solutions of this optimization model as the starting point. The branch and bound method were applied to narrow searching scope. Then the final optimized solution could be obtained based on the solution of exterior point method. The method was applied to a micro-griper system. Results showed that the constrained effect on the maximum output displacement was different when the resolution requirement changed within different scopes. During the process of parameter optimization for the micro-griper system, the global optimization was realized by taking into account of two contradictory objectives. © 2019, Editorial Department of Advanced Engineering Sciences. All right reserved.