Nonlinear robust control of pump controlled single-rod actuator with observing and compensating modeling...

High-precision control technology for the pump controlled single-rod actuator (PCSA) system is in high demand in industrial applications. In the PCSA system, there are both matched and mismatched uncertainties. However, it is still a challenging task for existing observer-based controllers to simultaneously observe and compensate for the uncertainty of mismatched and matched. To solve this issue, in this article, a modeling-uncertainty-observer based nonlinear robust control strategy was designed. The working mechanism of the proposed method is to observe the uncertainties from measurable state variables and then, based on the uncertainties observation, take feedforward control to compensate for the uncertainties. The developed observer can simultaneously observe and compensate for the uncertainties of mismatched and matched. Meanwhile, to improve transient response, the robust control technology was employed to deal with the compensation error. Comparative experiments show that the proposed method can effectively estimate and compensate for the model uncertainty, achieving the prescribed control accuracy. Compared with the robust controller and PID controller, the proposed method reduces the maximum control error by more than 20 % and 61 %, respectively.