Robust position control of a pneumatic actuator

This paper proposes a position control strategy for a pneumatic actuation system, which demonstrates high accuracy while it is subjected to a varying external force. We use a novel approach for the mathematical modeling of the pneumatic actuator: based on energy methods, we combine the kinetic and potential energy to derive the Lagrangian of the actuator and then the Euler-Lagrange equation of motion. The nonlinear backstepping method is applied to derive the control law, and the derivative of the potential energy is used as the controlled parameter. Results from the experiment show that tracking a sine wave of 0.1[m] magnitude produces a maximum error of ±0.008[m], while the actuator is subjected to an external force with a magnitude of 570[N] to 1150[N].