Design and motion analysis of soft robotic arm with pneumatic-network structure

Soft robotic arms have been widely explored in recent years because of their excellent flexibility and infinite degrees of freedom which distinguishes them form traditional rigid robots. This paper focuses on the design, fabrication and kinematic analysis of a new modular soft robotic arm featuring multiple segments, each one with three degrees of freedom. In contrast to most research, this paper utilizes soft pneu-net structure instead of fiber-reinforced structure, thereby preventing large local strains due to membrane pressurized against a fiber reinforcement. We employed finite element method and orthogonal experiment were to ascertain the optimal structural parameters. Furthermore, we present the kinematic model of the soft arm by the parameterization of the Denavit-Hartenberg convention under the basis of constant curvature assumption. Finally, the experimental evaluation of the soft robotic arm including bending angle, elongation, deflection and flexibility test were carried out. The experimental data, particularly concerning the bending angle and spatial position of both single modular and two-modular soft arm agree well with the finite element method simulation. Additionally, we performed both grasping and obstacle-avoidance grasping tests for dual modular soft robotic. The results demonstrate that the soft robotic arm exhibits superior performance and highlights its potential for various applications.