Semi-physical Simulation Of Aircraft Brake Control Algorithm

As an indispensable subsystem of aircraft, the aircraft braking system plays an important role in take-off and landing process, which is the most critical part during the sailing of aircraft. To meet rising demand of civil aviation and national defense, the aircraft is developing toward bigger tonnage and higher speed. This brought unprecedented challenges to aircraft braking system. Considering that the brake control algorithm is the most important factor that affecting the performance of aircraft braking system, the optimization of the brake control algorithm is researched deeply in this paper.Since the inertial platform and digital simulation can hardly provide efficient or reliable test support for the early design of brake control algorithm, starting with the structure and working principle of aircraft braking system, based on the characteristics of semi-physical simulation technology, the mathematical model such as airframe movement, wheel movement, runway characteristics were bulid first in Matlab/Simulink. And then some brake components like brake control box, electro-hydraulic servo valve were integrated into the simulation loop, a reliable semi-physical simulation test platform for the design of aircraft braking control algorithm is implemented in this paper. To solve the real-time and interaction of the semi-physical simulaiton,the Windows real-time expansion tool(RTX) and graphic programming language(LabVIEW) were introduced.For design of a practical optimized brake control algorithm, this thesis does in-depth analysis on the most widely used "PD+PBM" brake control algorithm, and explores the underlying cause of its low speed sliding, severe tire wear. Then an optimized brake control algorithm based on fuzzy self-tuning deceleration rate of reference speed was proposed. In the last part, the braking performance of "PD+PBM" and fuzzy "PD+PBM" were analyzed through semi-physical simulation, and the simulation result shows that the fuzzy "PD+PBM" brake control algorithm will greatly enhance the braking performance.