Three-Dimensional Nonlinear LOS-Angle Shaping Guidance with Prescribed Initial Acceleration and Field-of-View Constraints

To address the constrained nonlinear guidance problem of simultaneously satisfying impact-angle, seeker field-of-view, and prescribed-initial-acceleration constraints during three-dimensional pre-terminal-to-terminal handover, a nonlinear line-of-sight-angle shaping guidance method is proposed. The LOS-angle profiles are parameterized by normalized relative range, with the pre-terminal acceleration imposed as an initial boundary condition of the terminal-guidance reference. Three-dimensional velocity geometry and lead-angle dynamics reveal a sequential solution for the initial LOS curvatures, yielding an explicit mapping from prescribed acceleration to curvature. Endpoint-vanishing shape functions regulate the intermediate field-of-view profile without changing the boundary conditions or acceleration-inheritance relationship. A dynamic-inversion law tracks the reconstructed reference lead angles. Theoretical analysis establishes exact acceleration inheritance, exponential tracking-error convergence, terminal impact-angle satisfaction, and field-of-view constraint satisfaction under a sufficient reference margin. Numerical simulations show that the proposed method nearly eliminates the acceleration mismatch at the switching instant compared with conventional polynomial shaping guidance. Closed-loop and Monte Carlo validations further demonstrate that this improvement remains pronounced in the presence of actuator dynamics and randomized handover conditions, while terminal accuracy and seeker visibility are consistently maintained.