Experimental study on a bending type soft pneumatic actuator for minimizing the ballooning using chamber-reinforcement

Soft robotics is an emerging area of research due to its safe interaction with humans; it also has exciting applications, such as wearable soft medical devices for rehabilitation, prosthetics, etc. Soft robots require soft actuators for performing desired movements, including bending, expansion, contraction, and twisting. This work focuses on bending-type multi-chambered extra-soft actuators actuated by pneumatic pressure. The corrugated design of a multi-chambered soft pneumatic actuator (SPA) is analyzed experimentally to observe the radial, longitudinal, and lateral expansions of different chambers, i.e., ballooning of the chambers under the application of air pressure. From the experimental study, it is observed that the ballooning mainly occurs at the free end of the actuator in a cantilever-type boundary condition, which could not be demonstrated by the computational solution using the finite element analysis (FEA). Moreover, it is observed that the effect of ballooning also disturbs the constant curvature profile of SPA. Therefore, a chamber-reinforcement solution is provided for minimizing the ballooning and ensuring the uniform bending of a SPA.