Fault Estimation Method for Second-Order Sliding Mode Observer Based on Superhelix Algorithm

The control system of the aero engine is subjected to severe working conditions, such as high temperature, high pressure, and strong vibration, leading to a decrease in reliability and multiple failures. This paper proposes a second-order sliding mode observer based on the superhelix algorithm to estimate the sensor constant deviation and asymptotic fault. Due to the special nonlinear switching term of the sliding mode observer, the robustness to the uncertainty is ensured and the influence of the observer uncertainty on the state estimation is minimized. The observer's stability in finite time is proved, and fault information contained in the equivalent output error injection term is used to achieve sensor fault estimation. Simulation results demonstrate that the proposed method accurately estimates the sensor constant deviation and asymptotic fault under interference-free conditions with fast response and no significant jitter. The proposed method has the potential to enhance the reliability of aero engine control systems in harsh environments.