Research on Driving Characteristics of Three-Chamber Pneumatic Bellows Soft Actuator for Wall-Climbing Robots

To overcome the limitations of existing pneumatic soft actuators, a three-chamber pneumatic bellows soft actuator was designed for soft wall-climbing robots. Based on the constant-curvature assumption and Euler–Bernoulli beam theory, a three-parameter decoupled mechanical model was established to describe axial elongation, bending direction, and bending angle. The model reveals the mechanism by which the bending direction is independently controlled by the pressure ratio among the three chambers. Finite element analysis was employed for structural parameter optimization, identifying the optimal configuration that achieves both high displacement-stress efficiency and excellent linearity: two-layer bellows, 20 mm length, and low-hardness YG-G15 material. Experimental analysis shows that under optimal configuration conditions, the actuator can achieve continuously controllable bending and elongation motion at 0.01–0.04 MPa. Compared to the predicted values from the theoretical model, the maximum relative error in the bending angle is 14%, and the maximum relative error in the elongation is 12.5%. The study validates the accuracy of the mechanical model and provides important design guidance for pneumatic drive systems in soft wall-climbing robots.