A new cable-driven torsion and bending soft actuator inspired by parallel robot

The cooperation of torsion and bending can improve the flexibility in the motion process especially in complex and narrow space. There is few research about torsion in soft actuators until now, most of them focus on bending and elongation. Moreover, motion form is often single so that it is hard to imply complex tasks. In this paper, inspired by the structure features of parallel robot, we propose a new cable-driven soft actuator whose driven cable is arranged imitating the supporting rod of parallel robot. This actuator can implement clockwise and anti-clockwise torsion and two modes bending motion respectively. The maximum torsion angle can realize 45瀞and the maximum bending angle is 90瀞. First, we introduce the design principle and fabrication process. After that, we utilize conservation of energy method and force decomposition analysis to establish the kinematics of actuator, in addition, based on that, we conduct the parameters optimization. Finally, we design an experiment platform to conduct experiments and make the contrast with theory. This soft actuator can highly improve the flexibility in soft robotics, especially in wrist joint imitation.