ANALYTICAL REDUNDANCY IN THE AUTOMATIC CONTROL SYSTEM OF AN AIRCRAFT TURBOJET BYPASS ENGINE BASED ON OPTIMAL OBSERVERS

Abstract

An analytical redundancy in the automatic control system of a bypass turbojet engine (ACS turbofan engine) based on optimal observers is proposed. This article is based on previously obtained results in previous author's works and is a generalization and analysis of these results in order to develop a methodology for improving the fault tolerance of ACS turbofan engines. This method is based on the use of optimal observers: the Kalman filter and the Yazvinsky filter, consistent with the mathematical model of the ACS turbofan engine. The analysis of the mathematical model of the ACS was carried out using the least squares method in a moving window. The accuracy of identification of the mathematical model and the required delay time are ensured by optimizing the width of the moving window. Estimated with the help of optimal observers, the output vector of the ACS turbofan engine includes the following parameters: the rotor speed of the low-pressure compressor rotor nв, the rotor speed of the high-pressure compressor nk, the air pressure behind the highpressure compressor PK, the gas temperature behind the low-pressure turbine TT. When modeling the Kalman filter, a correlation analysis of the input signals was preliminarily carried out. The rationale for the advantage of the adaptive Yazvinsky filter compared to the Kalman filter is given. The results of mathematical modeling of the algorithmic method of reserving the measurement channel of the ACS turbofan engine based on the data of flight tests of a bypass engine of the PS-90A type as part of the main narrow-body aircraft TU-214 both in stationary and transient modes are presented. Statistical analysis of errors in estimation of the output vector of ACS turbofan engines based on the Kalman and Yazvinsky filter has been carried out. It is shown that the proposed analytical redundancy algorithm ensures the fulfillment of the requirements for the accuracy and stability of estimates of the output vector of ACS turbofan engines when using the Yazvinsky filter and can be recommended for use in advanced ACS turbofan engines. Based on the results proposed redundancy method, a direction for further research has been formed.