Force control loop affected by bounded uncertainties and unbounded inputs for pneumatic actuator systems

The purpose of this paper is to develop an accurate closed-loop acting force technique for a pneumatic actuator as an essential stage in the implementation of positioning control strategy. Since an analytical nonlinear structure, which linearly depends on parameter uncertainties, generically characterizes pneumatic plants, a feedback linearization design is proposed to cancel most of the resulting nonlinearities. Then, we proposed a linear state-feedback control and an additive nonlinear action to robustly bound the force error dynamics, devices which are required to handle the further parametric uncertainties and exogenous unbounded disturbances that will arise on the deduced structure. The design of the linear control gains is performed within robust closed-loop pole clustering using a linear matrix inequality approach. Finally, various experimental results illustrate the validity of the approach.