FOPID-Based Vacuum Control System Using a PWM-Regulated Buck Converter for neumatic Soft Actuation

Abstract

Soft neumatic actuators require accurate pressure regulation to achieve repeatable and stable deformation, particularly in vacuum-driven applications where the nonlinear behavior of the actuator and pneumatic system can affect the dynamic response. This work presents the development and experimental evaluation of a vacuum pressure control system for a soft neumatic actuator using a DC air pump driven through a Buck converter. The converter was controlled by a 20 kHz pulse-width modulation (PWM) signal, allowing the pump voltage and, consequently, the vacuum level applied to the actuator to be regulated. A pressure sensor was integrated into the system to provide feedback for closed-loop control. Two control strategies, a conventional proportional–integral–derivative (PID) controller and a fractional-order PID (FOPID) controller, were experimentally implemented and compared under different operating conditions. The results showed that the FOPID controller provided improved pressure tracking and reduced deviations from the reference signal compared with the conventional PID controller. The average tracking error was reduced from 15.70% with the PID controller to 1.78% with the FOPID controller. These results demonstrate that the proposed Buckconverter- based actuation system, combined with fractional-order control, provides an effective approach for improving vacuum regulation in soft pneumatic actuators and offers a suitable platform for future soft robotic applications requiring accurate and stable pressure control.