Path Following and Obstacle Avoidance for Unmanned Aerial Vehicles Using a Virtual-Force-Based Guidance Law

This paper presents a virtual-force-based guidance law (VFGL) for path following and obstacle avoidance in unmanned aerial vehicles. First, a virtual spring force and a virtual drag force are designed for straight-line following; then, the dynamic of the cross-track-error is equivalent to a spring mass system, which is easy to tune to acquire stability and non-overshoot convergence. Secondly, an additional virtual centripetal force is designed to counteract the influence of the curvature of the planned path so that the guidance law can accurately track a curve with a time-varying curvature. Thirdly, an extra virtual repulsive force is designed directly according to the sensor inputs; the virtual repulsive force pushes the vehicle away to move around obstacles. The use of artificial physics means the guidance law is founded on solid physical theory and is computationally simple. The physical meanings of the parameters are definite, and the VFGL has a large parameter adaptation. These make the guidance law easy to tune in application. Both the numerical and hardware-in-the-loop simulation results demonstrated the effectiveness of the proposed guidance law for path following and obstacle avoidance in unmanned aerial vehicles.