Antidisturbance Slip Ratio Algorithm of Aircraft Braking System Based on On/Off Valves

A safe and high-efficiency braking process is the primary consideration for the aircraft braking system. The traditional servo valve is prone to blockage, which can cause serious safety accidents. Based on the analysis of the operation principle of the braking system, a safer aircraft braking system based on an on/off valve is proposed, which uses a normally open valve as the downstream valve. The braking system based on on/off valves has problems such as fluctuating pressure, harsh working conditions, and strong nonlinearity of the system. An algorithm with a strong antidisturbance ability and high braking efficiency is proposed to solve the above three problems. The algorithm typically consists of two main components: outer and inner loops. The outer loop uses the active disturbance rejection control, and the inner loop adopts the segmented nonlinear predictive pressure regulation algorithm with compensation. The outer loop can compensate for the internal uncertainty and external disturbance of the system. The inner loop can compensate for the flow rate during the closing process of the on/off valve to ensure the pressure regulation effect and the life of the on/off valve. The experimental results show that the proposed algorithm has a strong antidisturbance ability and high regulation precision. The braking distance of the algorithm can be reduced by 5.48–15.15% under three different working conditions, which significantly improves the braking efficiency of the aircraft.