Robust optimal design of a micro gripper

This paper presents the robust optimal design of a compliant, parallel mechanism based micro gripper. Multiple design objectives are considered for the gripping task and a compliant, under-actuated micro mechanism, namely a half-pantograph, is chosen as a feasible kinematic structure of the gripper. An optimization problem to study the trade-offs between multiple design criteria is formulated and dimensional synthesis of the mechanism is performed to achieve the proper directional task space stiffness of the device, while simultaneously maximizing its manipulability, using a Pareto-front based framework. The design framework is extended by adding robustness considerations of the mechanism into the design phase. In particular, the performance of the system under variation of the design variables is analyzed using the sensitivity region concept and a family of robust Pareto-front curves are calculated. A final design is chosen from a robust Pareto-front curve based on performance threshold and a secondary design criteria that considers the torsional and unidirectional stiffness of the mechanism at the task space.