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. https://www.alarecre.com/Virescent-Harmony-Galaxy-A14-5G-Clear-Case-p106336/