Dynamic mobility of redundant robots using end-effector commands

The authors analyze the dynamic mobility of a kinematically redundant robot driven by forces/torques imposed on the end-effector, an interesting example of underactuated system. Under suitable assumptions, the system can be put via feedback in two special forms, namely the second-order triangular and Caplygin forms. Nonlinear controllability tools are used to derive conditions under which the robot can be steered between two given configurations using end-effector commands. With a PPR robot as a case study, a steering algorithm is proposed that achieves reconfiguration in finite time.