A 2 DOF parallel redundant manipulator (PA-R-MA) is introduced. The manipulator is redundantly actuated by three servomotors with high-reduction gears. It is equipped with structurally integrated torque sensors. An elastic model of the null-space dynamics is derived needed for feedback control of redundant torques. A cartesian rigid-body dynamic model of the motion DOF is shown to be decoupled from the elastic model. Experimental results show the validity of the models.

The control of a prototype 2 DOF parallel redundant manipulator (PA-R-MA) is outlined. The manipulator has a redundant chain and is actuated by 3 servomotors and high-reduction gears, giving it the potential of high accelerations and a uniform force transmission. Link torques are picked up by strain gauges, null-space torques are controlled to avoid backdriving of the gearboxes and to allow the use of torque optimization. A decoupled cartesian motion controller then allows operation with accelerations exceeding 100 m/s/sup 2/ and velocities up to 4 m/s. Experimental results show the feasibility of this high-speed robot concept.

A 2-DOF parallel manipulator with actuation redundancy is examined for high-speed and stiffness-controlled operation. Advantages of actuation redundancy are outlined. The kinematics and singularity-free workspace of the manipulator are presented together with a force transmission analysis. Finally, a novel control scheme that guarantees a lower bound of the end-effector stiffness (LBSC) is presented. Simulation results are compared with a traditional control scheme for high-speed applications using the minimal 2-norm of actuator torques.