Six-axis force sensor evaluation and a new type of optimal frame truss design for robotic applications

The different means currently available for six-axis wrist force sensor evaluation are discussed, and a unified criteria is proposed that is based on the condition number, the overall static and dynamic stiffness of the sensor, and the strain gauge sensitivity. In this light a new frame/truss type of sensor body design is introduced. The uniqueness of the design lies in the elastic members that exhibit truss (axial deformation), as opposed to the commonly used beam (bending) behavior. Several improvements over previous designs result, including: increased force sensitivity with a consistently low condition number, increased rigidity, and improved design flexibility. In addition, a design methodology is presented that uses optimization theory in combination with finite element analysis, to yield the best possible frame/truss force sensor design for a given set of specified principal forces.