Finite-Time Prescribed Performance Sliding Mode Guidance Law with Impact-Angle Constraint for Maneuvering Target

In the guidance algorithms with impact-angle constraint, most methods concern the steady-state performance of the system, but neglect the transient-state performance. In this article, a new sliding mode guidance law with finite-time (FT) prescribed performance is proposed for intercepting maneuvering targets at the desired impact angle. Both the steady-state and the transient-state performance of the convergence of the proposed guidance law is guaranteed. Different from the widely adopted FT control methods through Lyapunov theory, FT convergence is realized by a new and plain form of FT prescribed function (FTPF). Then, a finite-time convergence disturbance observer (FTDOB) is utilized to estimate the information of the maneuvering target. To enhance the response rate and overcome the singular problem of traditional sliding mode, nonsingular fast terminal sliding mode (NFTSM) is introduced in the proposed guidance law. Theoretical analysis shows that the proposed law can realize FT convergence. Numerical simulations demonstrate the effectiveness of the proposed guidance law.