New impact time and angle guidance strategy via virtual target approach

In this paper, a new guidance strategy is proposed for intercepting stationary and constant-velocity moving targets with desired impact time and angle via a virtual target approach, subject to nonlinear engagement kinematics and lateral-acceleration limits. The guidance procedure is divided into two stages by introducing a virtual target. Specifically, for the first stage, the nonsingular terminal sliding-mode guidance law is employed to intercept the virtual target with a specified impact angle in finite time. Furthermore, to achieve the desired impact angle on the real target, the proportional navigation guidance law is used in the second stage to keep the missile traveling with invariant flight-path angle. The impact time and angle on the real target are simultaneously controlled by selecting a proper guidance parameter whose optimal value is obtained via an optimization routine with a small number of iterations. This technique is user/designer-friendly in that it does not involve the time-to-go estimation procedure. In addition, less control energy is required in the overall guidance process. Numerical simulations with comparisons are conducted to validate the effectiveness and feasibility of the proposed guidance strategy in different engagement scenarios.