Position/force control, or robot manipulators without velocity/force measurements

A reduced version of this paper appeared in [24]. The authors consider the problem of designing a position/force controller for robot manipulators during constrained motion. The proposed controllers are based on exact knowledge of the system dynamics and do not require measurements of link velocity and end-effector force. The elimination of velocity measurements is accomplished by two different methods: (1) a model-based velocity observer, and (2) a high-pass filtering technique. Both of the controllers also include an open-loop force control strategy to achieve semi-global exponential end-effector position/velocity/force tracking. A simulation study for a two-link planar robot is included.