Mixed Slip-Deceleration PID Control of Aircraft Wheel Braking System

Abstract

Aircraft antiskid braking system is designed to prevent the main wheels from locking and additionally seeking the optimal braking performance. Wheel deceleration is the traditional controlled target used in antiskid system, since it can be easily measured by angular velocity transducer. However the optimal target value is hard to find due to the changing of road-surface and aircraft velocity. An alternative controlled target is the wheel longitudinal slip which is more robustly controllable under all conditions. But the wheel slip cannot be measured directly, that will definitely result in control error from the poor estimated aircraft speed. In this work a PID control scheme based on mixed slip-deceleration input variable is proposed for aircraft antiskid braking system. This control algorithm is able to stabilize the wheel slip around any equilibrium point. Moreover, it inherits all the appealing characteristics of slip control, while overcoming its sensitivity to slip measurement errors.