Heading Error Shaping Guidance Law for 3-D Impact Time Control

This study presents a guidance law for controlling the impact time of homing missiles in three dimensions when aiming at stationary objects. This guidance law requires less maximum lateral acceleration and keeps the time-to-go error at zero during the entire engagement. When the missile guidance commands exceed the saturation limit, the missile control system attempts maneuvers beyond its capabilities. This can cause oscillations, instability, wide deviations from the flight path, and undue stress on its structural components. One of the reasons for the high demand for maximum lateral acceleration is the necessity for an additional bias term for reducing the time-to-go error. The core idea of this work is to assume a suitable heading error profile, which results in the derivation of an accurate expression for the impact time. This approach eliminates the need for an additional bias factor because it results in zero time-to-go error. Control over impact time is attained through a control parameter defined by the desired impact time, with lateral accelerations being dependent on this control parameter. The guidance law is subsequently expanded to encompass engagements with nonmaneuvering moving targets. Numerical simulations are conducted to evaluate the methodology's effectiveness and to confirm its suitability for autopilot lag. Simulations of salvo attacks on stationary targets illustrate the method's effectiveness in achieving simultaneous target hits. The proposed guidance law demonstrates superiority through comparative evaluations with existing methods.