Stability analysis and improvement of ZP/LTR method of aeroengine

Zero placement/loop transfer recovery(ZP/LTR) method was analyzed theoretically to find and demonstrate the conditions of stability.However,these strict conditions have placed constraint on the application of ZP/LTR method.Kalman filter was thus introduced for the purpose of improvement of ZP/LTR method.With some special parameters selected,Kalman filter loop could approximate and replace original target feedback loop(TFL).While the performance of ZP/LTR method is maintained,the stability of final closed-loop system could be guaranteed along with the stability of Kalman filter loop.The stability conditions of improved ZP/LTR method was presented and demonstrated,showing that the stability conditions of improved ZP/LTR method were less strict,thus expanding the scope of applications for original ZP/LTR method.