Robust anti-disturbance control of a high-pressure electro-pneumatic servo valve directly driven by voice coil motor

Abstract

System uncertainty, external disturbances and complex nonlinearities are the main obstacles for high precision control of HESVs. Due to good anti-disturbance capability and low model dependence, linear active disturbance rejection control (LADRC) is popular in engineering practice. However, when LADRC is applied to HESVs, LADRC has limited anti-disturbance capability for high-pressure gas flow force, slow response speed and small response bandwidth, and quickly causes step oscillations. In this paper, the reasons for the remarkable phenomenon of step oscillations and the limited anti-disturbance capability of LADRC are theoretically analyzed and then proved by simulations and experiments. Subsequently, a new robust anti-disturbance control method (RI-ESO) is proposed for the HESV to solve the problem of step oscillations and further improve the dynamic response and anti-disturbance capability. The RI-ESO combines an extended state observer (ESO) and a robust controller. The partial total disturbance is estimated by ESO and then compensated online. The robust integrated controller (RI) can further compensate the remaining nonlinearities and external disturbances to achieve better control performance. The introduction of ESO can reduce the parameter limitations of the robust controller. Various simulations and experiments demonstrate that the RI-ESO can greatly improve the control performance and anti-disturbance capability of HESVs, and effectively avoid step oscillations.