A finite-time 3D guidance law based on fixed-time convergence disturbance observer

Highlights

• The paper presents the generalized approach for first-order three-dimensional terminal guidance law design based on the line-of-sight (LOS) velocity based relative motion. A simple Lyapunov function is employed to illustrate the design idea.

• A high power observer is introduced to improve the dynamical performance of the robust exact differentiator, such that a fixed time convergence disturbance observer is obtained by a effective switching logic.

• The fixed-time convergence disturbance observer based composite three-dimensional guidance law are proposed. Technique for improving the composite guidance law is presented such that the target maneuver estimation admits lower overshoot, fast convergence and so on.

Abstract

In order to achieve accurate interception of high-speed maneuvering targets, this paper presents a relative Line-of-Sight (LOS) velocity based finite-time three-dimensional guidance law design framework, and discusses the application of fixed-time convergence disturbance observer in this framework. Firstly, a simple Lyapunov function is provided to show that the coupled terms in the relative kinematics can be ignored in the proposed guidance law design framework. Secondly, the realizations of several classical guidance laws are analyzed with the proposed framework, including TPN guidance law, finite-time Input-to-State Stability (ISS) guidance law, and sliding mode guidance law. Thirdly, fixed-time convergence disturbance observers are introduced to design the composite finite-time 3D guidance law, and Lyapunov method is employed to show the stability of the guidance system. Numerical simulations with different scenarios show that the proposed generalized guidance law performs high interception accuracy.