Design and experimental validation of a hierarchical control strategy for 7 DOF manipulators

This paper presents a novel hierarchical control strategy for rigid manipulators to track a desired trajectory in the robot's joint space. The hierarchical control strategy consists in controlling the last joint by assuming that the remaining joints follow their desired trajectories. The same strategy is applied by going backward to the (n-1)-th joint, i.e. we control the (n-1)-th joint while the remaining joints are assumed stable. This strategy is applied backward until the first joint. The global stability of the error dynamics is guaranteed. This algorithm is implemented in real time on a 7 DOF hyper redundant articulated nimble adaptable trunk (ANAT. Experimental results and the comparison with the computed torque approach show the effectiveness of the approach and good tracking performance in the joint space.