Integral terminal sliding-mode-based singularity-free finite-time tracking control for entry vehicle with input saturation

This paper investigates the finite-time tracking control problem for entry vehicle under input saturation and uncertainty. First, a new integral terminal sliding mode surface is devised, which not only renders fast finite-time convergence, but also presents an explicit estimate of settling time. Subsequently, a singularity-free adaptive integral terminal sliding mode control approach is exploited with application of the designed integral terminal sliding mode surface, anti-windup compensator and adaptive technique, which ensures the superior control performance. By introducing linear and fractional power feedback functions into the adaptation mechanism and anti-windup compensator, the designed controller achieves finite-time convergence of tracking errors and estimation errors, while circumventing the overestimation of control gain. Moreover, the finite-time stability is proved by employing Lyapunov theory and bi-limit homogeneity technique. The results of a Monte Carlo simulation show that the final tracking precision within 3 km of the target is improved about 40% under the developed controller.