Soft Actuator Model for a Soft Robot With Variable Stiffness by Coupling Pneumatic Structure and Jamming Mechanism

Current research into soft robots not only needs to improve their compliance, but also requires consideration of the real-time controllability of rigidity and flexibility. By combining the advantages of Pneu-Net structure and the driven jamming mechanism, we developed a soft actuator model for a soft robot with real-time variable stiffness. Firstly, the model of the soft actuator coupled with pneumatic structure and jamming mechanism was built. Secondly, we analyzed the pneumatically-driven structure by using the finite element method and researched the influences of pressure in cavities as well as shape and size of cavities on the performance of bending motion. On this basis, the pneumatically-driven structure was optimized. Finally, a prototype of the soft robot arm with variable stiffness was designed to carry out the experiment for verifying the variable stiffness of the soft actuator. Theoretical analysis and experimental results demonstrate that the soft robot can withstand a variable stiffness of between 0.025–0.138N/mm. In addition, the maximum elongation of the designed coupling mechanism can reach 25mm.