复合风场影响下RLV着陆段固定时间控制

Fixed Time Control of RLV landing Section Under the Influence of Complex Wind Field

本文针对垂直起降的可重复使用运载器(RLV)返回着陆段面临多类型复合风场干扰影响导致的姿态跟踪控制收敛时间上界与初始状态强耦合及跟踪性能严重下降等问题,提出一种基于双幂次固定时间稳定理论的快速高精度控制方法。首先,对可重复使用运载器返回着陆段所受的自然风场进行分类建模,并分析风场对着陆段姿态控制的影响;其次,基于反步法框架,设计高低幂次加权多项式形式的趋近律,以保证系统状态误差在固定时间内收敛,且收敛时间和上界与初始状态无关;同时,为降低风场扰动对着陆段控制系统性能的影响,保证着陆段控制性能的稳定性及着陆安全性,引入固定时间扩张状态观测器对风场扰动进行估计和补偿;最后基于Lyapunov理论,证明了所设计的控制律可使RLV返回着陆段姿态控制误差在固定时间内收敛;多组数值仿真验证了所提方法的有效性。

A fast and high-precision control method based on the double-power fixed-time stabilization theory is presented to address the problems of the vertical takeoff and landing reusable launch vehicle(RLV)under the influence of multi-type complex wind field disturbance during the return-landing section,e.g.,strong coupling between the convergence time upper bound of attitude tracking control and the initial state and the serious degradation of the tracking performance.First,the natural wind fields subject to the RLV return-landing section is classified and modeled,and the influence of the wind fields on the attitude control of the return-landing section is analyzed.Second,based on the back-stepping framework,a convergence law in the form of high and low power-weighted polynomials is designed to ensure that the system state error converges within a fixed time and the convergence time and the upper bound are independent of the initial state.Meanwhile,in order to reduce the influence of wind field disturbance on the performance of the control system of the RLV return-landing section and ensure the stability of the control performance of the landing section and landing safety,a fixed-time extended state observer is introduced to estimate and compensate for the wind field perturbation.Finally,based on the Lyapunov theory,it is proved that the control law can make the attitude control error of the RLV return-landing section converge within a fixed time.Moreover,the effectiveness of the proposed control scheme is verified by various numerical simulations.