Energy Optimal Control of Servo-Pneumatic Cylinders Through Nonlinear Static Feedback Linearization

Abstract

Although pneumatic actuators are widely used in industry, they have two major weaknesses—nonlinearities associated with compressibility of air and low energy efficiency. The former limits its applicability whenever accurate positioning is required, and the latter has a negative impact on users through increased energy costs. This paper addresses these issues with the aim of developing a widely applicable servo control strategy, which combines improved tracking accuracy and energy efficiency. A detailed actuator system model is linearized through nonlinear input–output feedback linearization, and the energy optimal velocity profile is derived. Simulation and experimental studies indicate that energy efficiency improvements of 3–7% are possible, while tracking accuracy can be ensured. The method is suitable for real-time implementation and is cost effective; it requires the implementation of an improved velocity profile, while hardware components do not need to be altered.