Pneumatic artificial muscles (PAMs) are widely used in pneumatic musculoskeletal robots due to their lightweight nature and high power output. On the other hand, their control typically relies on electro-pneumatic valves, electronic sensors, and peripheral circuits such as A/D converters. This increases the number of distributed electronic components and electrical interconnections, potentially leading to greater system mass as well as higher maintenance requirements, particularly in systems containing many PAMs. To overcome these challenges, inspired by the intrafusal-extrafusal muscle interactions in biological systems, this paper proposes a length control method for PAMs in which the pneumatic feedback loop is implemented mechanically, while the target length is commanded by a minimal electronic actuator. We first examined flow path conditions to suppress oscillations caused by pneumatic delays. Second, Experiments demonstrated a tracking error of ≤ 2.01% for input frequencies ≤ 0.20 Hz.
Sakamoto et al. (Tue,) studied this question.