Research on the active steering control of an aircraft tractor

Methods of enhancing an aircraft traction system's track following ability and maneuvering stability through automatic tractor steering while the tractor is towing aircraft were discussed.A nonlinear 3 degree of freedom dynamic traction system model,including the steering system,was derived,taking into consideration the articulated angle between tractor and aircraft.Tractor steering angle controllers were designed based on the backstepping variable structure control method,taking into account the aircraft parameters and operating conditions.The boundary layer method was also adopted to modify the control.The simulation results show that the front steering angle controller enables the system to accurately follow the appointed track,and an additional rear steering angle can greatly improve the system stability when the relative angle is too large.The controller can restrict the effect of uncertain parameters,giving the system a robust performance.