A Virtual Force Based Path Following Approach for Unmanned Aerial Vehicles

A virtual force based path following approach is presented for unmanned aerial vehicles (UAVs). Three virtual forces, including a virtual centripetal force, a virtual spring force and a virtual drag force, are designed to calculate the desired heading rate. The virtual centripetal force compensates the influence of the reference curvature. The virtual spring force ensures the vehicle converge to the reference path. Meanwhile, the virtual drag force prevents oscillation in the convergence process. The proposed approach can be used to accurately follow straight-line, circle, as well as curve with time-varying curvature. The approach is equivalent to a proportional-derivative controller when following a straight-line, equivalent to a feedback linearization method when following circular or curved paths. The stability and convergence are analyzed. The influence of the input constraint on the following performance is considered. When using virtual forces to control UAVs, the physical meanings of the parameters are definite, which makes them easy to tune in application. Simulation results demonstrate the effectiveness of the proposed approach, and its performance is better than the NLGL (nonlinear guidance logic) approach.