Time-to-go rational function biased PN guidance law for precise impact angle

A new biased proportional navigation guidance law considering the missile's dynamic lag is proposed to control the impact angle. The homing guidance loop having the first-order dynamic lag is modeled as the confluent hyper-geometric differential equation and its analytic solution is derived. In consequence, the guidance law reduces to finding an appropriate biased acceleration command which satisfies the given terminal constraints. A systematic way to determine the time-varying biased terms is devised based on the closed-form homing trajectory. In comparison with the existing homing guidance laws, the proposed method could improve the impact angle control performance.