Guidance and Control Algorithm Design for Terrain-Following Flight of a Fixed-Wing UAV

This paper describes the terrain following flight algorithm for explosive ground search. The aircraft needs to fly at a low altitude for the terrain following flight, which requires a precise altitude following algorithm. However, errors can occur dynamically when changing altitude commands in fixed-wing aircraft. Therefore, this study presents the VTF(Virtual Target Following) and IVTF(Impedance Virtual Target Following) algorithms to increase the precision of terrain following flight. Additionally, simulations were conducted using inner control algorithms, namely PID(Proportional-Integral-Derivative) and LQTI(Linear Quadratic Tracker with Integrator) control algorithm. Two types of terrains were used in the simulations: terrain profile in the form of a sinusoidal wave and DTED(Digital Terrain Elevation Data). The results confirm that the IVTF algorithm proposed in this paper is effective for precise altitude control during terrain following flight.