Speed and Torque Control of Pneumatic Motors Using Controlled Pulsating Flow

Abstract

Pneumatic motors have several advantages over electric motors and have many robotics and automation applications. However, the performance control of pneumatic motors is not satisfactory mainly due to air compressibility and the high cost of conventional control methods using proportional control valves. This paper presents an unprecedented application of pneumatic motor control using a pulsating compressed air technique. The study also included validated simulations using the Automation Studio program to control the pneumatic motor’s speed and torque. The results showed a clear and noticeable improvement in controlling the pneumatic motor outputs and demonstrated that the improvements are frequency functions of the compressed air source pulses and pressure. In addition, the results showed remarkable success in controlling the pneumatic motor outputs depending on the frequency of the compressed air-source pulses and pressure. Pulsating air frequencies of 1.5, 3, and 4.5 Hz were considered as inlet source pressure changed from 1.72, 3.45, and 5.17 bar. Furthermore, empirical correlations have been developed for advanced use in automatic control circuits at an error of 6.3–9.5% in predicting the motor speed and torque outputs.