Control of Multiple McKibben Pneumatic Actuators Using Small Solenoid Valves and Dynamic Quantizer

Abstract

McKibben pneumatic actuators (MPAs) are soft actuators that exert tension by inflating a rubber tube with compressed air. Although electropneumatic regulators can control air pressure, their cost and size limit their applications. This study employs a dynamic quantizer to control an MPA using a small solenoid valve that can only open or close, as opposed to an electropneumatic regulator. A dynamic quantizer is a type of quantizer that converts continuous signals into discrete signals. Our previous study confirmed that the tension or length control of MPA can be achieved using a dynamic quantizer. As MPA exerts force only in the direction of contraction, multiple MPAs must be combined when using them as robot actuators. This study demonstrates that control using a dynamic quantizer is feasible, even when multiple MPAs are employed. We focused on a pendulum driven by two MPAs to achieve angle-tracking control using a dynamic-quantizer-based control method. The results of numerical simulations and experimental tests confirm that the angle of the pendulum can be controlled using MPAs with a dynamic quantizer.