In order to design a high telescopic actuator with high power to volume ratio

simple structure and flexible contact

a pneumatic soft actuator with expansion capsule structure was proposed. A method of variable cross-section cylinder was adopted for dynamic modeling and analysis

and a position servo controller for soft actuators was designed to achieve tracking control of the desired trajectory for this type of actuator. Firstly

a mathematical model of the dynamic characteristics of the actuator driving elastomer was established

based on the requirements of flexible contact and the elastomer being the contact target. Secondly

an experiment platform for the load characteristics of soft actuators was set up

and the accuracy of the model was verified by comparing the experimental results with the simulation data. Furthermore

the influence of spring stiffness and the pressure of the constant pressure source on the driving characteristics of soft actuators was analyzed. Subsequently

a position servo control system for the soft actuator was designed by combining the dynamic model and a bounded sliding mode control strategy

and the stability of the closed-loop control system was proven using Lyapunov function theory. Finally

trajectory tracking experiments were conducted to demonstrate the feasibility and effectiveness of the position servo control system under varying load conditions. The research findings can provide theoretical guidance for the application of inflatable soft actuators.