Adaptive sliding mode control strategy for the aircraft antiskid braking system based on slip ratio

An adaptive sliding mode control (ASMC) algorithm was proposed to control the nonlinear system with parameter uncertainty. The complex characteristics of aircraft antiskid braking system (ABS) were analyzed. According to uncertainty about the system, a sliding mode control (SMC) algorithm was presented with bipolar sigmoid function reaching law. The sliding mode gain factor and boundary layer were discussed and its adaptive algorithm was designed in order to decrease the chattering. The convergence of the ASMC algorithm was analyzed with Lyapunov theory at last. The results from simulation indicate that ASMC strategy, compared with the traditional SMC strategy, makes the ABS obtain the maximum friction coefficient in a shorter time. Additionally it is shown that the system works under optimal slip ratio and shortens the braking time.