A Systematic Design Procedure to Minimize a Performance Index for Robot Force Sensors

Abstract

This paper presents a systematic procedure for the structural design of a robot force sensor. The structural design is important since the force sensor detects forces and moments through the measurement of strains at specific points of the sensor body. The process of the measurement of force and moment is firstly analyzed from the viewpoint of structural behavior and then a performance index of the force sensor is introduced. It is demonstrated that the minimization of this index (the condition number of the strain compliance matrix) yields an optimal design in the sense that the static measurement error is minimized. It is proposed that the finite element be used for the evaluation of this index in the design process to search for the sensor dimensions that yield the minimum index. This way of proceeding eliminates the need of building intermediate prototypes. A systematic procedure for force sensor calibration is also presented. As an example, a force sensor of the Maltese cross bar type is constructed, and analyzed numerically and experimentally. The agreement between both sets of results corroborates the proposed design sequence.