Miss Distance Error Research Articles

Analytic Solution for Nonlinear Impact-Angle Guidance Law with Time-Varying Thrust

This paper presents an impact-angle guidance law of unmanned aerial vehicles (UAVs) with time-varying thrust in a boosting phase. Most current research on impact-angle guidance law assumes that UAV speed is constant in terms of controlled thrust. However, the UAV speed and the acceleration in a boosting phase keep changing because of time-varying thrust. Environmental factors and manufacturing process error may prohibit accurately predicting vehicle-thrust profiles. We propose a nonlinear impact-angle guidance law by analytically solving second-order error dynamics with nonlinear time-varying coefficients. The proposed analytic solution enables one to update guidance gains according to initial and current states so that desired impact angle is met while the miss-distance error is reduced. We prove the finite-time error convergence of the proposed guidance law with the Lyapunov stability theory. Various simulation studies are performed to verify the proposed guidance law.

Evaluation of Conceptual Midcourse Guidance Laws for Long-Range Exoatmospheric Interceptors

This paper presents a comprehensive study on the performance analysis of 8 conceptual guidance laws for exoatmospheric interception of ballistic missiles. The problem is to find the effective thrust direction of interceptor for interception of short-to-super range ballistic missiles. The zero-effort miss and the generalized required velocity concept are utilized for interception of moving targets. By comparison of the 8 conceptual guidance laws, the thrust direction is suggested to be in the direction of generalized velocity-to-begained, or constant velocity-to-be-gained direction, rather than to be in the direction along zero-effort miss, or that of linear optimal solution for long-to-super range interception. Even for short coasting ranges, the generalized velocity-to-be-gained may be utilized because of reasonable computational burden for required velocity rather than the numerical computation for zero-effort miss or linear optimal solution with the same miss distance error. In addition, the fuel consumption of the suggested direction has less sensitivity due to estimation error in intercept time. The guidance law based on constant velocity-to-be-gained direction and the optimal solution are suitable for satellites launch vehicles and space missions.