Mass Control of Pneumatic Soft Continuum Actuators with Commodity Components

Soft pneumatic hands offer the advantage of intrinsic mechanical compliance. We argue that to fully leverage the compliance available in soft pneumatic actuators, they should be controlled using air mass rather than position or force, as is customary in most research in soft robotics. We propose an air-mass controller that can servo to a preset position and also allows for the exploitation of fast, mechanical compliance without additional control burden. The proposed mass control scheme is based on discrete commodity valves and pressure sensors, filling a gap in available mass control systems for small-scale soft continuum actuators. The proposed mass controller exhibits low drift for mass trajectories lasting tens of seconds, without requiring a precise model of the actuator. Continuous mass control enables applications for soft robotics, in which leveraging compliance during actuation is of central importance.