Composite anti-disturbance control strategy for high-pressure pneumatic position servo system

The high-pressure pneumatic position servo system (HPPSS) employs a high-pressure electro-pneumatic servo valve (HESV) as the inner loop and a high-pressure double-acting cylinder as the outer actuator. Under high pressure, gas-flow forces and friction degrade response and accuracy. We propose a composite anti-disturbance strategy: for the valve, a decoupled fast non-singular terminal sliding-mode controller (NTSMC) augmented by an extended state observer (ESO) and a super-twisting law achieves finite-time convergence and strong rejection of flow-induced disturbances; for the cylinder, a robust integral controller with disturbance compensation mitigates nonlinear friction, while a cascaded extended state observer (CESO) enhances disturbance estimation. The design integrates nonlinear robust control with active disturbance estimation to match the system's complex nonlinearities. Experiments demonstrate faster transients, improved tracking, and higher steady-state precision compared with conventional schemes.