Modified circular curve-based impact angle control guidance

To plan the path for unmanned aerial vehicles (UAVs) considering the impact angle and acceleration constraints, a novel geometric rule is proposed in this paper. Firstly, under the nonlinear engagement kinematics, the geometric rule is derived from the modified circular curve including two parameters, one for the convergence of the acceleration, the other for extending the flight envelope. Furthermore, the convergence of the nominal guidance law developed from the geometric rule is rigorously proved. Secondly, to eliminate the angle tracking error regardless of the initial error size, a fixed-time convergent controller is adopted to formulate the impact angle control guidance law. Moreover, the implementation of the proposed guidance law only requires angle information, which can be readily obtained by the on-board device. The proposed guidance law is also applicable for varying-speed UAVs and moving targets. The simulation results and the comparative studies demonstrate the validity and superiority of the proposed guidance law.