For a manipulator to interact predictably with its environment, it is possible to program its visco-elastic properties by feedback control, so they assume simple forms such as strictly diagonal stiffness and damping matrices. The sensing and actuation system of IREQ's GRLA (General Large Robot Arm, a.k.a the ``Gorilla'' arm, Figure ) SARCOS manipulator lends itself to decentralized control strategies to achieve this goal. However these strategies cannot in general guarantee the achievement of simple forms for the visco-elastic properties, even when its human-like kinematic redundancy is put to contribution to select the most favorable arm postures. We are proposing a generalization of the basic decentralized control scheme which can achieve any desired form of the stiffness and damping matrices within the limits of the actuators operational capacities.
M. Doyon, V. Hayward
SARCOS GRLA Arm. It has a reach of 1.75 m from shoulder to wrist.