Tracking with UAV using tangent-plus-Lyapunov vector field guidance

A dynamic path-planning algorithm is proposed for routing UAVs in order to track ground targets. Based on a combination of tangent vector field guidance (TVFG) and Lyapunov vector field guidance (LVFG), a theoretically optimal path is derived with UAV operational constraints given a target position and the current UAV dynamic state. In this paper, we first illustrate that path planning for a UAV tracking a ground target can be formulated as an optimal control problem consisting of a system dynamic, a set of boundary conditions, control constraints and a cost criterion. We then discuss the TVFG and LVFG, and demonstrate that the TVFG outperforms the LVFG as long as a tangent line is available between the UAV´s turning limit circle and an objective circle, which is a desired orbit pattern over a target. Particle filters are employed in a practical situation where a target is moving on a road network. Obstacle avoidance strategies are also addressed. With the help of computer simulations, we show that the T+LVFG algorithm provides effective and robust tracking performance in various scenarios, including a target moving according to waypoints or a random kinematics model in an environment that may include obstacles and/or wind.