A design methodology of wrist force sensor for a robot insufficient degree of freedom

The usage of robots in industry is expanding very fast. Different industrial applications require different size of robots and degree of freedom (dof) especially in the new trend of flexible manufacturing system when robots deal with multiple products manufacturing and varied complex tasks. There is significant difference in price of a robot of same type having different dof. The improvement in the degree of freedom allows the robot to expand its sphere of applications. Such an effort is laid in this paper where, the capability of a robot with an insufficient degree of freedom is improved by adding an additional arm and utilizing the robot for tactile sensing and surface exploration. A robotic wrist force sensor (wfs) is designed and developed for this purpose. In this paper the methodologies of wfs design by mathematical modeling, mechanical design and fabrication of the wfs are discussed. The wfs design is a modified Maltese cross sensor used on the 4 axis articulated Fanuc Robot LR-Mate 100i. An additional arm is created to overcome the limitation of the four dof of the Fanuc LR Mate Robot thus allowing more flexible usage of the robot wfs. A roller probe is also employed for probing and exploration of unknown surface.