Optimization and Control of Cable Tensions for Hyper-redundant Snake-arm Robots

Based on the feedback linearization of joints motion and the tension optimization of cables, a hyper-redundant snake-arm robot control strategy is presented to solve the problems caused by the joint motion coupling and the cable drive redundancy. First, a hierarchical control system architecture of snake-arm robot is developed. Subsequently, the computed torque control method is utilized to decouple the motion in the joint space, and the tension distribution satisfying the constraint condition is obtained in the cable space by quadratic programming. Since it is hard and also expensive to feedback joint motion and cable tension by sensors, the cable tensions are obtained by the system dynamics equation and the position and speed of joints motion is calculated approximately from the driving electric motors’ position. Finally, the control performance under three typical conditions is studied by numerical simulation. The results demonstrate that the presented method can effectively limit the cable tensions within the range of the minimum preload tension and the maximum allowable tension.