Enhanced robust control based on ESO for high-pressure electro-pneumatic servo valve with strong anti-disturbance performance

Uncertain dynamics and strong time-varying disturbances are always present in high-pressure electro-pneumatic servo valves (HESV) directly driven by voice coil motors, significantly deteriorating tracking accuracy. To address this problem, a new enhanced robust control method (ERC-ESO) was proposed. The proposed enhanced robust controller (ERC) solves the problem of insufficient compensation capability of the robust integral of sign of error nonlinear control method for strong disturbances and fast-changing nonlinearities and further improves the anti-disturbance capability. To further reduce the compensation burden of the robust controller and avoid the negative effects caused by high-gain controller parameters, an extended state observer (ESO) with known model information was designed to compensate for the partial lumped disturbance. The proposed ERC further compensates for the remaining nonlinearities and disturbances. The asymptotic tracking performance of the HESV with dynamic uncertainty and unknown time-varying disturbances is ensured by the Lyapunov theory, and the increased robustness of the ERC-ESO compared to the RISE-ESO (robust, integral of the sgn of the error) is demonstrated theoretically. Using the HESV experimental platform, comparative experiments were conducted for different reference signals and different types of external disturbances to verify that the method has improved tracking performance and strong anti-disturbance capability.