Design and optimization of a robotic gripper for the FEM assembly process of vehicles

The FEM (Front End Module) assembly process consists of lifting, positioning, and bolt tightening procedures in the automotive assembly line. This process requires operations for handling heavy objects precisely and repetitively. Powered wearable robots, which are regarded as human-robot cooperation systems, are expected to solve the difficulties and improve the productivity by combining the power of robots and human intelligence. Grippers are required for performing processes by a wearable robot, but conventional grippers or overhead type loaders cannot be used for this application in terms of their weight, size, and gripping force. Thus, we focused on the design of a special gripper for a wearable robot. A six-bar linkage incorporating a toggle mechanism is employed to reduce the overall weight of the gripper while maximizing the gripping force. For gripping a FEM over a wide operating range, it is necessary to follow the desired coupler path. To satisfy the requirements of both coupler path and drive torque, a multi-objective optimization approach is introduced. As a result, an optimum design is selected from the Pareto front, which satisfies the requirements of path tracking and torque capacity.