Methods to detect contact state by force sensing in an edge mating task

Methods to detect the contact state of an end-effector and the environment by force sensing, which is a useful technique for very small motions, are described. One method estimates the position of the contact point, while another method detects the transition of the contact state. These methods are implemented on an edge-mating task. The contact position is estimated with two sets of observed relative force and moment, and the forces to be applied for the estimation are determined based on the singular value decomposition technique. Transition detection is achieved by monitoring the relation between observed force and moment. Experiments demonstrate the effectiveness of this technique, which is robust against force noise caused by friction and the characteristics of the manipulator control