Generalized impedance control of a redundant manipulator for handling tasks with position uncertainty while avoiding obstacles

Positioning uncertainty becomes a major problem for position-control-based robots when operating in contact with the environment. Inaccuracy in positioning parts or inadequate information about part placement has traditionally been addressed through accurate fixturing, calibration and robot programming. Impedance control provides a mechanism for using the reaction forces and torques at the end effector to compensate for positioning uncertainty. Redundant manipulators have greater manipulability than non-redundant manipulators thus facilitating the implementation of more complex tasks, and making it possible to also avoid collisions by taking advantage of the redundancies. Handling positioning uncertainty while simultaneously avoiding collisions are solved by using the generalized impedance control (GIC) algorithm developed in this study. This was successfully demonstrated on the 7 degree-of-freedom (DOF) redundant Robotics Research Corporation (RRC) K1207i manipulator.