Kinematic control of redundant robots with guaranteed joint limit avoidance

• A novel kinematic control signal guaranteeing joint limit avoidance is proposed.
• In sensor driven tasks it generates feasible paths to the target.
• With planned task trajectories it can act as a null-space velocity.
• Smooth joint trajectories and accurate target reaching are achieved.
• Experimental results with a KUKA LWR4+ manipulator demonstrate its performance.

A novel approach for addressing the inverse differential kinematics of redundant manipulators in the presence of hard joint position constraints is presented. A prescribed performance signal for joint limit avoidance guarantees is proposed that can be utilized with both planned and on-line generated trajectories. In the first case, it is a null space velocity for the primary task velocity mapping while in the second case, it modifies the generated reference by acting on the whole velocity space producing a feasible path to the target. Experimental results utilizing a 7DOF KUKA LWR4+ arm demonstrate the performance of the proposed kinematic controller.