Super-Twisting Fast Sliding Mode Guidance for Rocket Powered Landing

This paper investigates the guidance problem for powered landing of reusable rockets based on sliding mode control method. To track a reference trajectory, a nonsingular fast terminal sliding mode (NFTSM) surface is designed. Though traditional NFTSM controller is characterized by finite time convergence and high robustness against uncertainties, it results in high-frequency oscillation in control action, which is undesirable in engineering application. To address this issue, a super-twisting sliding mode controller is combined with the NFTSM surface to provide smoother control signal. The finite-time convergence of the proposed guidance law is proven using Lyapunov theorem. Taking parameter perturbations, initial state errors and wind disturbances into account, a 1000-run Monte Carlo simulation is performed. Simulation results illustrate the high tracking precision, strong robustness as well as low chattering property of the proposed controller.