Identification and control of a pneumatic robot

Pneumatic actuators have a number of advantages over electric motors, including strength-to-weight ratio, tunable compliance at the mechanism level, robustness, as well as price. Their properties are in many ways similar to muscle properties, which further makes them a good choice for bio-inspired robotic designs. However they are considered harder to control, and often avoided. Here we report results on modeling and control of a 2-dof robot, as well as preliminary results on a state-of-the-art 38-dof humanoid. Contrary to popular belief, we found it surprisingly easy to work with these pneumatically-actuated robots and obtained high tracking performance. We were also able to achieve end-effector control of the highly redundant arm of the humanoid. This was done by building parametric models, fitting them to experimental data, designing model-based feedback controllers, and optimizing their performance.