In this thesis, a force control scheme for tele-operation is presented to control the contact force using a 6-axis force sensor. Large force induced by collision or position error between a robot and object in tele-operation may cause severe stress to the robot and the object. To avoid this problem, a hybrid position/force control algorithm is adopted. For the applications of the hybrid control, a surface following and an edge following algorithms are presented and implemented. Hybrid position/force control scheme is used to control the force under position constraints and the position under force constraints. Position constraints are obtained by the surface or line normal vector estimated from the sensed force between the end effector and the object. In the surface following task, surface normal vector is obtained by the friction force estimated from the previous path-step and the sensed force. In the edge following task, line normal vector is obtained from only the sensed force. Additionally, a lead-through teaching method using he 6-axis force sensor is also experimented.
