Smooth second-order nonsingular terminal sliding mode control for reusable launch vehicles

• Published in: International journal of intelligent computing and cybernetics Vol. 7; no. 1; pp. 95 - 110
• Main Authors: Ni, Shaobo, Shan, Jiayuan
• Format: Journal Article
• Language: English
• Published: Bingley Emerald Group Publishing Limited 01.01.2014
• Subjects: Accuracy; Computer simulation; Control systems; Controllers; Convergence; Design; Disturbances; Electrical & electronic engineering; Engineering; Mathematical analysis; Mathematical models; Reusable launch vehicles; Robust control; Sliding mode; Terminals; Tracking errors; Vehicles; Flight control; Nonlinear control; Reusable launch vehicles; Sliding mode control; Finite-time convergence
• ISSN: 1756-378X; 1756-3798
• DOI: 10.1108/IJICC-12-2013-0050

Purpose – The purpose of this paper is to present a sliding mode attitude controller for reusable launch vehicle (RLV) which is nonlinear, coupling, and includes uncertain parameters and external disturbances. Design/methodology/approach – A smooth second-order nonsingular terminal sliding mode (NTSM) controller is proposed for RLV in reentry phase. First, a NTSM manifold is proposed for finite-time convergence. Then a smooth second sliding mode controller is designed to establish the sliding mode. An observer is utilized to estimate the lumped disturbance and the estimation result is used for feedforward compensation in the controller. Findings – It is mathematically proved that the proposed sliding mode technique makes the attitude tracking errors converge to zero in finite time and the convergence time is estimated. Simulations are made for RLV through the assumption that aerodynamic parameters and atmospheric density are perturbed. Simulation results demonstrate that the proposed control strategy is effective, leading to promising performance and robustness. Originality/value – By the proposed controller, the second-order sliding mode is established. The attitude tracking error converges to zero in a finite time. Meanwhile, the chattering is alleviated and a smooth control input is obtained.