Virtual-Target-Based trajectory following using a light-of-sight angle constraint for long-range guided projectiles

Abstract

This paper proposes a novel trajectory-following algorithm by combining the concept of virtual target with terminal guidance for a class of long-range guided projectiles. A virtual target point (VTP) is selected from a reference trajectory, and a line-of-sight (LOS) angle constraint that takes the curvature of the reference trajectory into account is presented for the projectile to track the VTP. The trajectory-following problem is transformed into a LOS angle-constrained terminal guidance problem with respect to the VTP. It has been proven that the trajectory-following error is simply proportional to the tracking error of the desired LOS angle. With the use of the nonsingular fast terminal sliding mode control technique, the finite-time trajectory-following position error convergence of the proposed guidance method is presented. The effectiveness and advantage of the proposed method are verified by using extensive dispersion simulations with a realistic guided projectile model. Comparative simulations highlight significant improvement in trajectory-following errors by employing the proposed LOS angle constraint.