Pneumatic cylinder speed and force control using controlled pulsating flow

Abstract

An application for accurate and low-cost force and velocity control of a pneumatic actuator, which can be used in any pneumatic circuit, is described in this paper. Control of a pneumatic cylinder is proposed via a pulsating flow technique. The technique uses on/off solenoid coils in the direction control valves in lieu of expensive servo controllers, such as proportional directional control valves. Pulsating air frequencies of 1.5, 3, and 4.5 Hz are applied by the designed circuit to investigate inlet constant pressures ranging from 1.72 to 5.17 × 105 Pa. The speed and force of a pneumatic cylinder rod are controlled using the generated pulsating flow and the results show success of idea of ​​controlling the speed and force of the pneumatic cylinder rod using the pulse flow technique. Empirical correlations suitable for later use in automatic control circuits are derived and are shown to exhibit an accuracy of up to ∼ 90–95.5% in predicting output force and velocity. It is also used to select the required frequency to obtain the speed and force required for the cylinder. To validate the pneumatic cylinder speed and force control using pulse flow technique, simulations are carried out using the Automation Studio program. The results show an improvement in control of the pneumatic cylinder mechanical performance and demonstrate that improvements are a function of the frequency of compressed air source pulses and pressure. An empirical correlation is also derived for predicting the cylinder rod speed and force at any source pressure and pulse frequency.

Keywords

• Pneumatic actuator control
• High speed directional control valve
• Pulsating flow
• Position control
• Speed control
• Force control