Nonsingular terminal sliding mode control for reusable launch vehicle with atmospheric disturbances

Author(s):  
Ming You ◽  
Qun Zong ◽  
Bailing Tian ◽  
Fanlin Zeng

The controller design for reusable launch vehicles is challenging due to enormous amounts of model parameter uncertainties and atmospheric disturbances. This paper first derives six-degree-of-freedom model of a reusable launch vehicle with atmospheric disturbances. Next, four kinds of atmospheric disturbances are introduced and wind models are established respectively. For attitude control of the reusable launch vehicle, a nonsingular terminal sliding mode controller is designed with stability guaranteed. Finally, simulation results show a satisfactory performance for the attitude tracking of the reusable launch vehicle with atmospheric disturbances.

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Ruimin Zhang ◽  
Qiaoyu Chen ◽  
Haigang Guo

This paper presents an adaptive nonsingular terminal sliding mode control approach for the attitude control of a hypersonic vehicle with parameter uncertainties and external disturbances based on Chebyshev neural networks (CNNs). First, a new nonsingular terminal sliding surface is proposed for a general uncertain nonlinear system. Then, a nonsingular sliding mode control is designed to achieve finite-time tracking control. Furthermore, to relax the requirement for the upper bound of the lumped uncertainty including parameter uncertainties and external disturbances, a CNN is used to estimate the lumped uncertainty. The network weights are updated by the adaptive law derived from the Lyapunov theorem. Meanwhile, a low-pass filter-based modification is added into the adaptive law to achieve fast and low-frequency adaptation when using high-gain learning rates. Finally, the proposed approach is applied to the attitude control of the hypersonic vehicle and simulation results illustrate its effectiveness.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Liang Zhang ◽  
Liang Jing ◽  
Liheng Ye ◽  
Xing Gao

Purpose This paper aims to investigate the problem of attitude control for a horizontal takeoff and horizontal landing reusable launch vehicle. Design/methodology/approach In this paper, a predefined-time attitude tracking controller is presented for a horizontal takeoff and horizontal landing reusable launch vehicle (HTHLRLV). Firstly, the attitude tracking error dynamics model of the HTHLRLV is developed. Subsequently, a novel sliding mode surface is designed with predefined-time stability. Furthermore, by using the proposed sliding mode surface, a predefined-time controller is derived. To compensate the external disturbances or model uncertainties, a fixed-time disturbance observer is developed, and its convergence time can be defined as a prior control parameter. Finally, the stability of the proposed sliding mode surface and the controller can be proved by the Lyapunov theory. Findings In contrast to other fixed-time methods, this controller only requires three control parameters, and the convergence time can be predefined instead of being estimated. The simulation results also demonstrate the effectiveness of the proposed controller. Originality/value A novel predefined-time attitude tracking controller is developed based on the predefined-time sliding mode surface (SMS) and fixed-time disturbance observer (FxTDO). The convergence time of the system can be selected as a prior control parameter for SMS and FxTDO.


2018 ◽  
Vol 25 (5) ◽  
pp. 1008-1018 ◽  
Author(s):  
Ruidong Yan ◽  
Zhong Wu

There exist complex disturbances in the attitude control system of flexible spacecrafts, such as space environmental disturbances, flexible vibrations, inertia uncertainties, payload motions, etc. To suppress the effects of these disturbances on the performance of attitude stabilization, a super-twisting disturbance observer (STDO)-based nonsingular terminal sliding mode controller (NTSMC) is proposed in this paper. First, STDO is designed for a second-order dynamical system constructed by applying the lumped disturbance and its integral as state variables, and applying the integral as virtual measurement. Since the virtual measurement is obtained by integrating the inverse attitude dynamics, STDO not only avoids the differential operation of angular velocity, but also fully utilizes the information of a nonlinear model. By combining STDO with NTSMC, a composite controller is designed to achieve high-accuracy spacecraft attitude stabilization. Since most of the disturbances are compensated for by a STDO-based feedforward compensator, only a small switching gain is required to deal with the residual disturbances and uncertainties. Thus, the chattering phenomenon of the controller can be alleviated to a great extent. Finally, numerical simulations for the comparison between STDO-based NTSMC and nonlinear disturbance observer-based NTSMC are carried out in the presence of complex disturbances to verify the effectiveness of the proposed approach.


Author(s):  
Shaobo Ni ◽  
Jiayuan Shan

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.


Author(s):  
Uzair Ansari ◽  
Abdulrahman H Bajodah

This paper presents the attitude control design of satellite launch vehicle based on the direct adaptive generalized dynamic inversion approach. The proposed adaptive generalized dynamic inversion approach encompasses the equivalent and the adaptive control elements. The equivalent (continuous) control part of adaptive generalized dynamic inversion is based on the conventional generalized dynamic inversion approach that comprises two noninterfering control actions, i.e. the particular part and the auxiliary part. In the particular part, dynamical constraint is prescribed in the form of time differential equation, which is evaluated along the vehicle attitude trajectories that encapsulates the control objectives and is inverted by utilizing Moore Penrose Generalized Inverse (MPGI). The singularity problem is solved by augmenting a dynamic scaling factor in the involved MPGI. In the auxiliary part, the null control vector is designed using the proportionality gain matrix, constructed by employing the Lyapunov function that guarantees global closed-loop asymptotic stability of the angular body rate dynamics. The adaptive (discontinuous) control part of adaptive generalized dynamic inversion is based on the sliding mode control with adaptive modulation gain, that provides robustness against tracking performance deterioration due to generalized scaling, system nonlinearities, and uncertainties, such that semi-global practically stable attitude tracking is guaranteed. External guidance loop based on the trajectory following method is designed, which reshapes the predefined pitch and yaw attitude profiles based on the respective normal and lateral positional errors, for acquiring the desired orbital parameters such as height, injection angle, orbital velocity, etc. To analyze the ascent flight trajectory, a detailed six-degrees-of-freedom simulator of a four-stage satellite launch vehicle is developed. The intensive numerical simulations are performed, which demonstrate the stability, robustness and the tracking capability of the proposed control and guidance methods in the presence of parametric uncertainties and external disturbances.


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