Virtual Sensor Research

The angle of attack and the sideslip angle are the two important measured quantities for the aircraft navigation/control aerodynamics analysis and structure analysis. For the different kinds of disturbance influence, now the sensors can't measure it accurately, In the High Angle of Attack, the error will add with the angle of attack increase. How to measure it accurately is an important problem. The question for discussion in this paper belongs to items of the pre-investigation of tenth five-year plan.Through the relation of signal, using calculation to get the needed signal, this is the definition of virtual sensor. This paper introduces two methods to get the virtual sensor signal of angle of attack and sideslip angle: Nonlinear Observer method and INS/GPS method. The main contribution in this paper includes:1. A batch of equations with atmosphere turbulence about aircraft movement and others mathematic models;2. The observer using the coupling of axial and lateral and having feedback of acceleration is investigated. This method can estimate the angle of attack and the sideslip angle synchronously. An optimization named Extrem is applied to optimize the feedback plus matrix. The simulated estimation indicated that this observer not only have high estimated precise in kinds of maneuvering fly, but also have good robustness to atmosphere turbulence or the change of flight stat. Last a project is gave for the engineering application.3. The project using INS/GPS system data to estimate the angle of attack and sideslip is brought forward first. This project using the INS/GPS system data, such as acceleration and velocity signal, and others signals of the aircraft, such as gyros and the mathematic models, to estimate virtual signal. This method not only have the high estimated precise in kinds of maneuvering fly and good robustness to atmosphere turbulence or the change of flight stat, but also have the good ability of Real-time. This paper also gives a project for the engineering application.4. Validating those two methods through simulation in all kinds of situations, especially high angle of attack of the 4th generation aircraft. Those prove those two method have good estimator in those situations. Last bring forward some problems need improve.We can draw the follow conclusions from simulation and theoretic analysis: Nonlinear Observer and INS/GPS system have those virtues: high estimated precision good-robustness and simple structure, convenience used to engineer, It can replace the measured value of sensors or be used to detect fault.