Adaptive nonsingular sliding mode based guidance law with terminal angular constraint

Abstract

In this paper, a new adaptive nonsingular terminal sliding mode control theory based impact angle guidance law for intercepting maneuvering targets was documented. In the design procedure, a new adaptive law for target acceleration bound estimation was presented, which allowed the proposed guidance law to be used without the requirement of the information on the target maneuvering profiles. With the aid of Lyapunov stability criteria, the finite-time convergent characteristics of the line-of-sight angle and its derivative were proven in theory. Numerical simulations were also performed under various conditions to demonstrate the effectiveness of the proposed guidance law.

Smooth Adaptive Finite Time Guidance Law with Impact Angle Constraints

“…Consider two-dimensional engagement geometry as shown in Figure 1, where the missile (marked as ) and the target (marked as ) are regarded as point mass; the engagement dynamics equations can be described by [29,32] = cos ( − ) − cos ( − ) ,…”

“…However, the expressions of the above guidance laws contain negative exponential term of the system state, which leads to the singularity problem when error being controlled becomes very small; it is almost a disaster for the attitude control system to track. To this end, the nonsingular terminal sliding mode control scheme (NTSMC) and nonsingular fast terminal sliding mode control scheme (NFTSMC) were proposed in [26][27][28] and had been successfully used to design IAGLs [29][30][31][32][33][34]. Within the above articles, the target acceleration is considered as the unknown model disturbance.…”

“…(1) Some guidance laws are noncontinuous due to the usage of the signum function [1,18,24,25,29,[31][32][33], which would pose great challenges to the system stability and deduce the control quality of the system.…”

“…(2) To determine the switching gain of the signum function, the information of the target maneuvering is required [1,18,21,22,24,26,28,29,32,33], such as the target acceleration bound, which is an unreality condition for noncooperative target. Another idea is to ignore the target acceleration [22], which is only suitable for the scenario that the maneuverability of the target (such as tanks or large ships) is far weaker than the missile.…”

“…(3) To obtain the target information, different adaptive methods [29,32] for estimating the target acceleration bound are integrated with IAGLs. However, these guidance laws still contain discontinuous term about the estimated value, which also brings the problem of nonsmoothness and chattering.…”