Collaborative workspace design of supernumerary robotic limbs base on multi-objective optimization

Supernumerary robotic limbs(SRLs) as a new type of wearable robot that assists the operator with additional robotic limbs. However, how to determine the optimal limb length parameters according to the task requirements and constraints is a key problem in the design of SRLs. In this paper, a design framework for SRLs was proposed based on the kinematic performance and human-robot factor indices. It can select the optimal parameters of SRLs including the base position, configuration and length via a multi-object optimization model. First, the task specification and the SRLs specification are obtained by analyzing the given task and the motion configuration. Then the kinematic synthesis of SRLs with the universal configuration is established via the screw theory, and a comprehensive evaluation index for the motion performance is proposed by considering the manipulability and the human-robot factor. Taking the evaluation indices as the objective function, the corresponding constraints and the optimization model are established to optimize the configuration of SRLs with both flexibility and safety. Then the prototype of SRLs was designed according to the optimal result, and the performance indices of the optimized SRLs were improved by 1.637% and 13.602%, respectively. Finally, a human–machine collaboration experiment was conducted to verify that the optimized SRLs have improved collaboration efficiency and safety.