Explicit Model Predictive Based Fault Tolerant Control for Turboshaft Engine System

Abstract

In order to tackle the faults of turboshaft engine-rotor systems and the real time implementation difficulty of traditional model predictive control methods, an explicit model predictive (EMPC) fault-tolerant control algorithm is designed based on an active fault-tolerant control scheme that implicitly detects the faults and adjusts the control law online. The proposed real time control algorithm can achieve good control command tracking performance and, at the same time, guarantee limit protection of turboshaft engine-rotor system. Firstly, to start with the algorithm, a dynamic system model library and a fault monitoring mechanism are established, in which the dynamic system model library contains sets of piecewise affine models (PWA) of normal engine mode and modes with faults. Secondly, the EMPC fault-tolerant controller is derived and designed for each sub-model in the modes of dynamic model library. Through the transformation and derivation of the traditional model predictive controller of turboshaft engine-rotor system, the explicit solution of its fault-tolerant controller is obtained. With the explicit solution which is in the form of state feedback control for each partition, controller gains can be designed off-line. Finally, the online engine control process is completed by searching the corresponding controller gain based on engine state, which improves the real-time performance of the control system. The effectiveness of the method for engine systems with modeled or un-modeled compressor faults and the robustness of the algorithm are verified by simulations.