Control of Soft Pneumatic Actuators with Approximated Dynamical Modeling

TL;DR

This paper presents a comprehensive modeling and control approach for soft pneumatic actuators using an approximated dynamical model, validated through experiments on prototypes and a soft gripper system.

Contribution

It introduces a novel full system modeling strategy combining beam theory and damping estimation, enabling effective LQR control of soft actuators.

Findings

High-speed, accurate control of soft actuators achieved

Robustness of the modeling method demonstrated across prototypes

Successful stable grasping of delicate objects with the system

Abstract

This paper introduces a full system modeling strategy for a syringe pump and soft pneumatic actuators(SPAs). The soft actuator is conceptualized as a beam structure, utilizing a second-order bending model. The equation of natural frequency is derived from Euler's bending theory, while the damping ratio is estimated by fitting step responses of soft pneumatic actuators. Evaluation of model uncertainty underscores the robustness of our modeling methodology. To validate our approach, we deploy it across four prototypes varying in dimensional parameters. Furthermore, a syringe pump is designed to drive the actuator, and a pressure model is proposed to construct a full system model. By employing this full system model, the Linear-Quadratic Regulator (LQR) controller is implemented to control the soft actuator, achieving high-speed responses and high accuracy in both step response and square wave function response tests. Both the modeling method and the LQR controller are thoroughly evaluated through experiments. Lastly, a gripper, consisting of two actuators with a feedback controller, demonstrates stable grasping of delicate objects with a significantly higher success rate.