航天器姿态控制采用的动量偏置系统

自从上世纪50年代末，空军的Agena卫星采用重力梯度稳定方法以来，动量偏置系统对于航天器的姿态控制与稳定一直占据突出的地位。从那时以来，此类系统已经历了许多发展和改进，而且对于当前的地球同步轨道通信卫星来说，仍是占据主导地位的稳定方法。本文跟踪了Space／Systems Loral公司建造的航天器上所采用的动量偏置系统的一个特别的发展过程，重点讨论三类滚动／偏航控制系统。第一类是在具有动量偏置的早期卫星上使用的WHECON系统，第二类是在80年代中至90年代初的卫星主要采用了Terasaki控制系统，第三类是高斯线性二次型最优(LQG)动量偏置控制系统，该类系统90年代初引入，并在当前飞行的许多卫星上所采用。     

偏置动量卫星姿态运动特点及其控制

本文对偏置动量卫星的运动特点进行了详细的分析，并针对其特点设计了双脉冲喷气和卫星稳定运动时段的磁进动和磁章动控制，对结果进行了分析和仿真。     

基于飞轮的偏置动量卫星周期干扰补偿方法

为了提高偏置动量卫星姿态控制精度,针对三轴稳定偏置动量卫星滚动/偏航回路周期干扰力矩补偿问题,提出了一种基于反作用飞轮的滚动/偏航回路周期干扰力矩补偿方案.采用频率分离法,分析了周期干扰力矩对卫星滚动/偏航回路姿态控制精度的影响.设计了周期干扰力矩的飞轮补偿方案,该干扰力矩补偿方案由安装在卫星滚动/偏航轴上的反作用飞轮实现.仿真结果表明,所设计的飞轮补偿方案提高了滚动/偏航轴的控制精度,从而验证了飞轮补偿方案的可行性和有效性.     

偏置动量卫星阻尼力矩作用下的姿态运动特性分析及控制方法

针对偏置动量卫星阻尼阶段的姿态运动特性进行分析,并基于时域分析方法提出弱偏置角动量的选取方法,改善阻尼过程中滚动-偏航角收敛的动态性能.以实际应用为背景,考虑一箭多星发射模式下,安装约束的限制导致星箭分离后偏置角动量方向严重偏离轨道面法线方向的情况,提出一种基于弱偏置角动量的姿态控制方法,在无需三轴姿态信息的情况下,可以避免由于偏置角动量的定轴性导致滚动-偏航角收敛时间很长的问题.仿真结果表明,所提出的方法能够有效减少姿态捕获时间,且易于实现,具有较高的工程实用价值.     

基于滑模控制的卫星姿态控制算法研究

针对卫星姿态控制系统存在外部扰动和执行器故障的情况下,提出一种基于非线性观测器技术和滑模控制理论的容错控制器设计方案。首先,建立含有外部扰动和执行器故障的刚体卫星姿态控制系统运动学方程和动力学方程。然后,通过非线性干扰观测器估计系统中的未知故障,进而利用故障信息基于滑模控制策略设计容错控制器。通过Lyapunov函数证明闭环姿态控制系统的稳定性。最后通过数值仿真验证该容错控制方案的鲁棒性和可行性。     

六旋翼飞行器姿态控制系统优化设计

六旋翼飞行器的控制系统具有欠驱动、强耦合、非线性等特点,针对控制系统中的姿态控制易受系统内部参数变化和外部未知条件干扰的问题,提出了一种基于指数收敛的干扰观测器的控制方法。为了提高系统的响应速度和鲁棒性,在干扰观测器的基础上和自适应滑模控制器相结合,并采用边界层法,降低控制系统的抖振。通过Lyapunov稳定性定理证明了飞行器控制系统是稳定且指数收敛的。仿真结果表明:和传统的干扰观测器相比,所设计控制器对六旋翼无人飞行器的姿态控制具有更快的响应速度,提高了干扰抑制能力和系统稳定性。     

基于动态控制分配的卫星姿态控制系统容错控制

针对卫星姿态控制系统执行机构故障情况下的姿态跟踪问题,研究了一种基于动态控制分配的容错控制方法。首先,考虑由卫星转动惯量不确定性与外界干扰组成复合干扰,设计了基于干扰观测器的反步姿态跟踪控制器,利用干扰观测器对复合干扰进行估计,并且采用李雅普诺夫方法分析了闭环系统的稳定性;其次,针对发生乘性执行机构故障的卫星姿态控制系统,设计了基于动态控制分配的容错控制方法,该方法无需对控制律进行调整,而是利用故障信息调整目标函数,通过动态控制分配方法实现容错控制。仿真结果表明,该方法能够在执行机构发生故障情况下有效完成姿态跟踪。     

基于高阶滑模观测器的自适应时变滑模再入姿态控制

针对再入飞行器鲁棒姿态控制问题, 提出一种基于高阶滑模观测器的自适应时变滑模控制器设计方法. 首先, 设计了一种时变滑模面, 并在此基础上推导了相应的时变滑模控制律, 其中滑模控制中切换增益通过一种自适应算法获得, 消除了控制器设计过程中对系统不确定性上界已知的要求; 然后, 利用高阶滑模观测器对控制器设计过程中用到的姿态角导数信息进行观测, 同时能够获得系统扰动估计值, 从而构造一种基于观测器的控制器形式; 最后, 通过仿真验证了所提出的控制算法在提高再入飞行器姿态控制精度以及系统鲁棒性方面的有效性.     

微纳卫星姿态控制系统的精细抗干扰容错控制方法

本文针对一类微纳卫星姿态控制系统飞轮突变故障提出了一种具有干扰抑制和补偿能力的精细故障诊断及容错控制方法.针对反作用飞轮的突变故障,本文不仅考虑了星体转动惯量变化导致的系统参数不确定性,而且考虑了姿态控制系统中飞轮振动带来的干扰影响,设计基于干扰观测器和故障诊断观测器的复合抗干扰容错控制器,并基于线性矩阵不等式对控制器进行求解,使复合系统稳定并满足一定的鲁棒H∞性能.仿真结果表明,基于微纳卫星姿态控制系统的精细故障诊断方法在有效诊断系统时变故障的同时,可有效抵消与抑制干扰.     

Two‐Layer Terminal Sliding Mode Attitude Control of Satellites Equipped with Reaction Wheels

This paper addresses the global stability and robust attitude tracking problem of a near polar orbit satellite subject to unknown disturbances and uncertainties. It is assumed that the satellite is fully actuated by a set of reaction wheels (RW) as control actuators because of their relative simplicity, versatility and high accuracy. The terminal sliding mode control (TSMC) approach is utilized in a two‐level architecture to achieve control objectives. In the lower layer a detumbling‐like controller is designed which guarantees the finite‐time detumbling and tracking of the desired angular velocities and based on this result a robust attitude tracking controller is designed in the upper layer to achieve 3‐axis attitude tracking in the presence of unknown disturbances and bounded uncertainties. Robust stability and tracking properties of designed controllers are proved using the Lyapunov theory. Finally, a set of numerical simulation results are provided to illustrate the effectiveness and performance of the proposed control method.     

Observer‐Based Multiple Faults Diagnosis Scheme for Satellite Attitude Control System

This paper proposes a multiple fault diagnosis (MFD) scheme based on an observer method for satellite attitude control systems (ACSs) subject to nonlinearity and external disturbances of the system. The essential idea is to develop a fault diagnosis scheme and design the corresponding observers for satellite ACSs. The nonlinearity, space external disturbances, sensor uncertainties, and multiple faults problem of the satellite ACS are all taken into account. The proposed MFD scheme is developed at two different levels. First, at the system level, two nonlinear observers based on analytical redundancy are designed for the MFD of the satellite ACS; this level roughly reveals the fault source. Then, at the component level, a bank of sliding mode observers activated by the results of the previous diagnosis is designed to precisely diagnose multiple faults of actuators in the satellite ACS; this level further precisely reveals the fault source. Both the nonlinear observers and the sliding mode observers are confirmed to be asymptotically stable via Lyapunov stability theory. Finally, numerical simulations of a satellite ACS are performed to illustrate the effectiveness of the proposed MFD scheme.     

高超声速飞行器姿态的变结构控制

针对高超声速飞行器运行环境中气动参数大范围变化可能导致失稳现象,构建高超声速飞行器姿态的滑模变结构控制器。通过多时间尺度理论将飞行器姿态控制系统分为内外双闭环子系统,分别为内外环设计滑模姿态控制律,保证控制系统对气动参数变化不敏感,能稳定准确地跟踪期望姿态角指令。仿真结果表明所提滑模变结构姿态控制算法性能良好,对气动参数变化有一定的鲁棒性。     

Attitude Control of Multiple Rigid Bodies with Uncertainties and Disturbances

Decentralized attitude synchronization and tracking control for multiple rigid bodies are investigated in this paper. In the presence of inertia uncertainties and environmental disturbances, we propose a class of decentralized adaptive sliding mode control laws. An adaptive control strategy is adopted to reject the uncertainties and disturbances. Using the Lyapunov approach and graph theory, it is shown that the control laws can guarantee a group of rigid bodies to track the desired time-varying attitude and angular velocity while maintaining attitude synchronization with other rigid bodies in the formation. Simulation examples are provided to illustrate the feasibility and advantage of the control algorithm.      

航天器姿态跟踪系统的自适应滑模控制

针对存在不确定惯量矩阵和外干扰的刚体航天器姿态跟踪系统,提出了一种自适应滑模控制方法。首先建立了姿态跟踪误差动力学方程,并对刚体航天器跟踪误差动力学定义了滑模,设计了自适应滑模控制律,该控制律的优点在于可以估计系统不确定块,消除了传统滑模控制中对不确定界的要求。Lyapunov分析表明了提出的自适应滑模控制器确保闭环系统取得渐近稳定性。仿真结果验证了提出的控制策略的有效性。     

Magnetic Attitude Control System for Low-Earth Orbit Satellites

A small spacecraft (SC) under consideration is intended forperforming a scientific mission on the low-Earth orbit for a long time(a year or more). A control system of the SC provides the constructionof regime of three-axis orientation of the SC in the orbital coordinatesystem and the stabilization of that regime, and must be autonomous,low-weight and low-cost. The magnetic control system that consists ofthe information subsystem based solely on three-axis magnetometermeasurings and the magnetic actuators satisfies in the best wayrequirements mentioned above. Such system can estimate both orbitalmotion parameters and attitude ones of the SC. But the absence of theadditional instruments and damping devices complicates the estimationsince the range of initial conditions uncertainly is wide and theproblem of estimating becomes essentially nonlinear. To get over thesedifficulties a recursive state estimation algorithm with enhancedconvergence is proposed. The magnetic control moment is synthesized bythe vector function Lyapunov method.     

基于新型动态积分滑模的运载火箭姿态控制

运载火箭在飞行过程中面临着参数变化范围大、外界干扰复杂的飞行环境,传统的控制方法已经很难满足姿态控制系统的要求.本文将传统的动态滑模和积分滑模综合起来,尝试一种新型的动态积分滑模控制策略律.仿真结果表明,在存在系统参数摄动和外部干扰的情况下,该法很好的消除了抖振,取得较理想的控制效果.     

小卫星编队飞行姿态协同控制及仿真

针对具体的对地定向三星编队成像高度计的姿态协同控制问题,基于四元素方法进行了姿态控制系统设计和数字仿真研究.首先定义了坐标系及姿态误差变量.接着设计了一种非线性姿态跟踪控制器,并运用Lyapunov稳定性理论证明了该控制律的全局稳定性.最后通过基于Matlab的数值仿真和基于STK的可视化,进一步验证了该控制律的稳定性和有效性.数值仿真结果表明利用这种方法可以保证编队中的从星时刻跟踪目标姿态.也就是能够实现合成孔径干涉测量的任务目标.     

Attitude control of spacecraft simulator without angular velocity measurement

In this paper the attitude control of a spacecraft simulator using Reaction Wheels (RW) as the actuators is investigated. The main goal of the current study is to bring the RWs to the rest at the end of the maneuver without angular velocity measurement. A modified feedback linearization controller is applied by considering the Euler angles of the simulator as the output and the RWs angular momentums as the internal state variables. The stability of the proposed controller and the internal dynamics is analyzed using Lyapunov theory. Two modified sliding mode observers are designed to estimate the angular velocities of the spacecraft attitude control subsystem simulator. The proposed observers do not use the control input and the detailed knowledge of the model and thus it can be implemented easily. The global stability of the system is proved. The proposed controller and observers are finally evaluated numerically and experimentally on an attitude spacecraft simulator.