Aircraft Flight State Estimation With Flight Quality Assessment Study

In this paper, six improved kalman filters are studied and used in flight state estimation. These improved kalman filters are the incorporations of three covariance square root filters and two nonlinear filters. Concretely speaking, we get Extended Kalman Filter (EKF) and the Single Step Iterative Filter (SSIF) based on Choleskey decomposition (CD), U-D decomposition (UDD) or Singular value decomposition (SVD). The SVD-based SSIF is the novel filter among them. All of them have good numerical robustness and can handle correlated measurement noise. The simulation results show that they can finely satisfy the engineering requests.Three classes of equivalent system methods (ESM) which are used in finding high order flight control system's low order equivalent are studied. The first class methods are the classical frequency domain-based equivalent system methods (F-ESM) which recommended by MIL-F-8785C and MIL-STD-1797A. Five longitudinal low order equivalent systems and fourteen lateral ones are discussed in detail and some pieces of advice are given. Also conduct an investigation in the time domain-based equivalent system methods (T-ESM) .And for longitude short period movement, two least square (LS) identification methods of estimating its parameters are studied.The software about evaluating flying quality is introduced. It includes ESM and T-ESM and some flying quality evaluating laws such as the bandwidth law (BWL), the Neal-Smith law (NSL), the Chalk law (CL) and the C* law. This software is useful for the design of flight control systems.