Abstract
In this study, the three-dimensional optimal trajectory planning of an unmanned fixed-wing aerial vehicle was investigated for Terrain Following – Terrain Avoidance (TF-TA) purposes using the Direct Collocation method. For this purpose, firstly, the appropriate equations representing the translational movement of the aircraft were described. The three-dimensional optimal trajectory planning of the flying vehicle was formulated in the TF-TA manoeuvre as an optimal control problem. The terrain profile, as the main allowable height constraint was modelled using the Fractal Generation Method. The resulting optimal control problem was discretized by applying the Direct Collocation numerical technique and then, was transformed into a Nonlinear Programming Problem (NLP). The efficacy of the proposed method was demonstrated by extensive simulations, and it was particularly verified that the purposed approach can produce a solution satisfying almost all the performance and environmental constraints encountering in a low -altitude flight.
Highlights
Over the past three decades, Unmanned Aerial Vehicles (UAVs) have been well considered due to their numerous merits such as low manufacturing cost, advanced automatic control systems, withstanding the high accelerations, and high maneuverability
Terrain Following and Terrain Avoidance (TF-TA) are among the main challenges discussed in terms of low-altitude flight, especially, in the mountainous areas (Kassaei & Kosari, 2018)
Nowadays, many airports are located in the mountainous areas with adverse weather conditions; probability of the accidents occurring near these airports will be increased (Pourtakdoust et al, 2011)
Summary
Over the past three decades, Unmanned Aerial Vehicles (UAVs) have been well considered due to their numerous merits such as low manufacturing cost, advanced automatic control systems, withstanding the high accelerations, and high maneuverability. Since these robots are widely employed for low-altitude mission purposes, such as traffic control they are significantly considered nowadays. Terrain Following and Terrain Avoidance (TF-TA) are among the main challenges discussed in terms of low-altitude flight, especially, in the mountainous areas (Kassaei & Kosari, 2018). Some approaches should be considered for solving the problem based on the missions defined for a UAV (Kosari et al, 2017)
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