A Knowledge-based Energy-saving Approach to PWM Control of a Novel Integrated Pneumatic Valve

Abstract

As manufacturers, the automotive industry, and many other sectors face an increasingly competitive global business environment; they seek opportunities to reduce production costs by reducing energy consumption. Energy costs have become one of the fastest-rising expenses of doing business, and the industrial sector is rushing to implement new energy conservation initiatives. Pressurized air, as an important source of energy, has been widely used by various industries, providing simple solutions for automated lines. In this project, an Accumulator-Based Equalization (ABE) strategy was combined with a knowledge-based PWM (Pulse Width Modulation) protocol, and then incorporated into an integrated solenoid valve to increase the energy efficiency of pneumatic systems through the optimization of ow consumption. Modeling and simulation of the proposed system was carried out to assess the proposed ideas and reduce the cost of system developments. An experimental setup was constructed to assess the performance of the proposed strategy when implemented on configured pneumatic control valves. Equalization was performed at home positions of a typical linear actuator, where the chambers of the pneumatic actuators were momentarily connected to each other. Furthermore, during the extension and retraction, a knowledge-based PWM signal was applied to the valves to maintain the actuator dynamics in an acceptable posture. To obtain the knowledge-based PWM signal, an expert-fuzzy controller was designed to control the speed of the actuator. This knowledge-based protocol was based on fuzzy structures, which were implemented on the configured pneumatic valves in an open-loop fashion to decrease the amount of ow consumption without compromising the dynamic performance of the pneumatic actuators. The identified duty cycles profiles from the expert fuzzy controller were implemented on an open-loop system. It was observed that, while an open-loop system is used, the pressurized air can be saved about 20% under 50 N load and almost 10% under 150 N load. "Smoothness index" was defined as a measure of the piston motion smoothness when applying the proposed strategies. In addition to smoothness of the motion in the closed-loop control methods, the energy-saving results were compared to the results of the open-loop system and the performance under different conditions was evaluated.