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摘要
Traditional pressure servo valves used in hydraulic aircraft antiskid braking system are sensitive to contamination and require a high maintenance cost. This paper proposes an on/off-valve-based antiskid braking system with simple structure and high resistance to contamination for aircraft applications. It can improve the system reliability and reduce maintenance cost. An aircraft longitudinal motion model and a hydraulic antiskid braking system model with on/off valves are formulated. Based on these models, a switched controller with delay compensation is developed for an aircraft antiskid braking system using on/off valves. It features a switching surface derived through backstepping to govern the switching action of the valves and a pressure predictor to compensate the delay caused by response time of valves and brake lines. In addition, an approximation brake line model and a tire friction force observer are included in the controller to estimate the brake pressure and friction force, respectively. The system stability is analyzed with Lyapunov theory and Filippov framework. At last, hardware-in-loop tests are conducted on a research prototype of the hydraulic brake system and a computer-based simulator embedded with aircraft motion models. Experimental results show that the proposed on/off-valve-based aircraft antiskid braking system presents a smooth braking performance, and it is robust to uncertain road conditions.
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