Adaptive Obstacle Avoidance of UAV Leader/Followers with Nonlinear Logarithm Quaternion Control

This paper addresses a significant challenge within the realm of fixed wing Unmanned Aerial Vehicles (UAVs), namely obstacle avoidance of the Leader-Follower system. The proposed approach involves formulating the Leader-Follower problem, consisting of one leader and three followers, with control strategies utilizing the logarithm exponential Quaternion method. Subsequently, the designed control law employing quaternions is applied to both the leader and the follower UAVs. Moreover, a notable contribution of this research lies in the incorporation of adaptive obstacle avoidance. The idea based on potential field as obstacle avoidance algorithm, with adaptive techniques for determining obstacle avoidance parameters. These parameters are dynamically adjusted based on the distance between the UAV and the obstacle through a non-linear adaptation function. The comprehensive implementation of these methods is rigorously evaluated by employing a predefined reference path for the leader and conducting numerous scenario-based tests. Random directions of followers were used in case of stuck in local minimum to avoid it; this was applied in case when potential filed force is less than small value. Experiments to test some scenarios of obstacle avoidance were conducted. The final results conclusively demonstrate the stability of the control law even in the presence of obstacles. The effectiveness of the adaptive obstacle avoidance approach is clearly evident from the trajectories of the UAV followers.