A Fuzzy Logic Control Synthesis for an Airplane Antilock-braking System

In this paper, an airplane fuzzy logic control synthesis for an antilock-braking system (ABS) is proposed. The slip ratios of rear wheels are inferred, having from measurements (or from integration, in the case of model simulation) angular velocities of front wheels. The observing of these slip ratios, resulting from control variables applied in system, serves as basis of a phenomenological scenario – a road label inferring diagram – conceived to on line decide, via a fuzzy logic reasoning, upon the most suitable new control variables to apply at the current sample step. Control variables are synthesized in last component of a standard Mamdani type fuzzy logic control triplet: fuzzyfier, rules base and defuzzyfier. A rules base, clustered according to three road conditions – dry, wet and ice – is defined. The obtained fuzzy control variable is tuned taking into account the strong changes in the airplane speed during the landing brake process. The simulation results, performed on the mathematical model of a military jet braking, show that proposed ABS algorithm ensures the avoiding of wheel’s blockage, even in the worst road conditions, with adding measurement noise. Moreover, as a free model strategy, the obtained fuzzy control is advantageous from viewpoint of reducing design complexity and, also, antisaturating, antichattering and robustness properties of the controlled system.