Control of a fast parallel robot with a redundant chain and gearboxes: experimental results

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/s² and velocities up to 4 m/s. Experimental results show the feasibility of this high-speed robot concept