Design of Three-Dimensional Missile Guidance Law via Sliding Mode with Saturation Constraint

Abstract

IntroductionThe missile guidance is a well-known nonlinear control engineering area of research. Since the basic principles were extensively covered The variable structure control law has been applied to many guidance Recently, Chen et al.[10] derived a new nonlinear fuzzy H ∞ guidance law with a saturation of actuators against maneuvering targets. They first approximated the nonlinear missile target pursuit dynamics with the Takagi -Sugeno linear fuzzy models. Then, based on this, they constructed a H ∞ control to handle the approximation error and external disturbances. However, it is a known fact that the approximation error between the fuzzy model and the true one is difficult to obtain exactly [11].In this paper, sliding mode guidance law based on the threedimensional (3-D) nonlinear engagement kinematics is proposed. The purpose of the proposed control design is to attenuate the influence of the target's maneuvers on the performance of the guidance law. That is to say that the proposed guidance is not only robust with respect to target maneuvering, but is also guaranteed state boundedness (Lyapunov stability). Statement of the ProblemFor a 3-D interception, relative motion between the missile and target is described by the spherical coordinates system (r , θ, Φ) with the origin fixed on the location of the missile.The 3-D missile -target engagement is shown in Figure 1, where a missile is attempting to intercept a moving target.The missile and target are assumed to be point masses in order to AbstractThe three-dimensional missile guidance law with saturating actuator is proposed for the pursuit of an unpredictably maneuvering target. The proposed guidance law achieves a satisfactorily robust performance without having to solve a complicated nonlinear Hamilton-Jacobi Partial Differential Inequality (HJPDI). In the proposed guidance scheme, the nonlinear part of the relative motion equations between the missile and target is first cancelled. Then, a tunable sliding mode law is designed to eliminate the effect of external disturbance. The proposed guidance law can achieve reduced interception time than others, yet it is considerably simpler. An example is proposed to confirm it.