Guidance Law for Automatic Landing of Tilt-Rotor Aircraft

Abstract

This paper presents a three-dimensional guidance law applicable to automatic landing of tilt-rotor aircraft. The proposed guidance law generates horizontal position, velocity and altitude commands in the longitudinal channel and heading angle command in the lateral channel to track a predetermined trajectory for automatic landing. The longitudinal guidance commands are derived from the approximated horizontal and vertical dynamic equations of tilt-rotor aircraft regarding accelerations, thrust, nacelle angle and control inputs. These longitudinal guidance commands are appropriately distributed to each control input as the flight mode of tilt-rotor aircraft is changed. The concept of VOR(VHF Omnidirectional Range) guidance system, which is used in general landing guidance system for fixed wing aircraft, is applied to generate the required heading angle commands to eliminate the lateral deviation from the desired trajectory. The performance of the proposed guidance law is evaluated using the nonlinear simulation model of “Smart UAV (Unmanned Aerial Vehicle)” a tilt-rotor type vehicle being developed by KARI(Korea Aerospace Research Institute). Simulation results show that the proposed guidance law for automatic landing provides good tracking performance along the predetermined landing trajectory.