Design and implementation of multiaxial force sensing gripper fingers

This paper focuses on the integration of elementary force sensors into the fingers of parallel grippers. The theory of the approach of integrating three sensor elements into a gripper finger is described and the results of the practical evaluations are given. Strain gauges are used as elementary sensor elements. Two different design approaches are evaluated. The first one uses H-shaped cut-outs to weaken the structure at designated areas. The measurement accuracy of this system is compared with a second approach without cut-outs, which is easier to manufacture. Finite element analysis is used in both approaches to simulate the behaviour and to determine the best locations for strain gauge application. The performances of both design concepts are experimentally evaluated. It can be seen that the results of the finite-element analysis are correct and that a satisfactory decoupling of the basic sensors can be achieved using a physical or mathematical approach. Both prototypes are able to measure the gripping force with sufficient accuracy.