Design and optimization of a novel rescue end-effector

This paper describes the design of a novel multi-functional rescue end-effector with tonging, shearing and grasping capabilities to meet the demands of urban catastrophe rescue applications. The tonging and shearing form and the grasping form of the end-effector are analysed. The two forms are determined using the transformations of their grasping mechanisms. Four objectives (to maximize shearing space, minimize mass, minimize the equivalent stress and minimize deformation) are proposed for selection of the optimal grasping mechanism structure. Additional objectives also involve the end-effector's structural strength and kinematic characteristics. A nested optimization structure that is composed of the non-dominated sorting genetic algorithm II (NSGA-II) and finite element analysis is proposed to perform multi-domain and multi-objective optimization of the end-effector. To improve the optimization efficiency, a traditional synthesis technique and a sensitivity analysis are applied to reduce the outer and inner numbers of the design variables. Simulation results indicate that the values of the four target objectives are superior to those before optimization and two referenced objectives, and the end-effector mass in particular, can evidently be reduced.