Research On Algorithms Of Flush Airdata Sensing System

This paper mainly studies the flush airdata sensing system and its algorithms. It deduces the airdata parameters from the surface pressure distribution of the aircraft. Because it is the function of airdata parameters, the airdata parameters can be resolved from it.The pressure model of flush airdata sensing system is nonlinear equations of the angle of attack, angle of sideslip, dynamic pressure and static pressure of the free stream. The angle of attack and angle of sideslip can be calculated by an algorithm called"the Triples". After they have been worked out, the dynamic pressure and static pressure can be solved traditionally using iteration which contains two variables.However, improved algorithms for the flush airdata sensing system are presented in this paper.1. The formula for mach number has been optimized with least-squres solution, thus the precision of a polynomial of power of 5 is better than that of 9.2. After the solving of angle of attack and angle of sideslip, the theory of general inverse of matrix is used to simplify the nonlinear equations and to calculate the total pressure and the modified dynamic pressure ratio. These two parameters together with the angle of attack and angle of sideslip contain enough information to work out the dynamic pressure and static pressure. This makes the following algorithms work properly without allowing for the initial pressure vector. Thus, this improvement provides a new way to solve the pressure model.3. An improved iteration is presented based on the simplification by general inverse of matrix. The improved iteration contains only one iterate variable. Thus, it can be analyzed easily of its convergence and it can work faster than the original iteration.4. BP network is used in the solution as a result of its high nonlinear mapping ability, high speed and robustness. It is used to calculate dynamic pressure and static pressure instead of the iteration. It is used to calibrate the position error of the pressure model.5. The algorithm for the flush airdata system based on BP network and the...