Fixed-time disturbance observer-based nearly optimal control for reusable launch vehicle with input constraints

2021 ◽  
Author(s):  
Chaofan Zhang ◽  
Guoshan Zhang ◽  
Qi Dong
Keyword(s):  
Optimal Control ◽  
Disturbance Observer ◽  
Fixed Time ◽  
Launch Vehicle ◽  
Input Constraints ◽  
Reusable Launch Vehicle

Predefined-time control for a horizontal takeoff and horizontal landing reusable launch vehicle

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Liang Zhang ◽  
Liang Jing ◽  
Liheng Ye ◽  
Xing Gao
Keyword(s):  
Disturbance Observer ◽  
Control Parameter ◽  
Sliding Mode ◽  
Fixed Time ◽  
Launch Vehicle ◽  
Convergence Time ◽  
Content Type ◽  
Reusable Launch Vehicle ◽  
Attitude Tracking ◽  
Tracking Controller

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.

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