【作者】 谢祥华；

【导师】 姜长生；

【作者基本信息】 南京航空航天大学 ， 导航、制导与控制， 2007， 硕士

【摘要】 从20世纪80年代美国军方提出了现代小卫星的概念以来,微小卫星发展迅速,成为目前航天器发展的一个重要方向。作为现代微小卫星的关键部分,现代微小卫星的姿态控制系统需具有结构简单、质量轻、可靠性高和低成本等特点。本文以某具体卫星的姿态控制系统的方案论证为背景,对微小卫星的姿态确定技术、主动磁控技术和姿控算法的硬件实现问题进行了研究。主要研究工作如下:较全面、系统的总结了欧拉角和四元数两种卫星姿态描述方法,建立了完整的卫星姿态运动模型,并分析了卫星受到的各种环境力矩的数学模型。姿态确定方面:对微小卫星的姿态敏感器的工作原理和测量方程进行了研究;基于确定性方法,讨论了TRIAD和QUEST两种双矢量定姿的具体算法,给出了一种利用地磁矢量和红外地平仪联合定姿的粗定姿算法;基于状态估计法,利用扩展卡尔曼滤波,设计了基于“红外地平仪+太阳敏感器+磁强计”的联合滤波定姿算法和基于磁强计的俯仰通道与滚动/偏航通道解耦的卡尔曼滤波定姿算法。通过仿真算例对各定姿算法的定姿精度和适用范围进行了验证。主动磁控方面:介绍了执行机构磁力矩器的工作原理和磁控力矩的特点,讨论了磁矩生成和分配的两种方式;设计了卫星在初始速率阻尼阶段的磁控算法;针对偏置动量卫星的运动特性,对其俯仰通道和滚动/偏航通道分别设计了相应的磁控算法;由于偏置动量轮有可能会停转,工程中常将重力梯度杆作为一种备份执行机构,针对重力梯度稳定卫星,设计了基于欧拉角反馈和基于四元数反馈两种形式的PD磁控算法。仿真算例表明所设计的磁控算法是有效的。最后对微小卫星姿控算法的FPGA实现进行了初步研究。以Altera公司的Stratix II系列的EP2S60F1024C4芯片作为目标器件,利用VHDL语言实现了偏置动量小卫星的双通道解耦的磁强计滤波定姿算法和相应的磁控算法,并利用Maltab/Simulink和Modelsim,构建了基于“Link for modelsim”的微小卫星姿态控制仿真系统,对实现的姿控算法进行了功能级仿真。结果表明,本文设计的姿控算法的FPGA实现在功能级是正确的。更多还原

【Abstract】 Since the concept of micro-satellite was proposed in the 80’s 20 centuries, its techniques have made great progress in recent years, the development of which is a significant trend in the aerospace area. As a key section of micro-satellite, the micro-satellite attitude control system should have the feature of simple configuration, light weight, high reliability and low cost. In this paper, taking a specific micro-satellite’attitude control system as an example, the method of micro-satellite attitude determination、magnetic attitude control and their hardware realization are studied. The main work done is as follows:At first, the attitude representation of Euler Angle and Quaternion are analyzed and generalized. Then the attitude kinematics and dynamic models are developed. The models of environmental torques are also discussed.About attitude determination: the attitude sensor’s measure theories are studied and their measure equations are established. Then, the deterministic method, including TRIAD and QUEST algorithm which determine the attitude from double vector observations and a simple attitude determination method using infrared earth sensor and magnetic vector, are presented. Based on state estimation, an extended kalman filter algorithm by fusing the data from sun sensor, magnetic sensor and infrared earth sensor is built. In order to reduce the calculation, a decoupled kalman filter algorithm using magnetic measurement only is designed. All of these attitude determination algorithms are demonstrated by simulation.About active magnetic attitude control: the work theory of magnetorquers and the characteristic of magnetic torque are analyzed at first. Then, the velocity damping magnetic control of satellite during the initial entering orbit is discussed. Based on the kinematics characteristic of biased momentum satellites, the magnetic control law for both of the pitch channel and roll/yaw channel are designed. Because the flywheel may stop running, the magnetic control algorithm for gravity gradient micro-satellite is studied too, The PD feedback control law based on Euler Angle and Quaternion are provided separately. All of these control algorithms are demonstrated by simulation, too.At last, the hardware realization of the attitude determination and control algorithm is simply discussed. Take the EP2S60F1024C4 chip, a mainstream product of Altera Co., as the goal FPGA device, the decoupled kalman filter algorithm and control algorithm for biased momentum micro-satellite is realized in VHDL. Based on the toolbox“Link for modelsim”, a micro-satellite Attitude Control Simulation System is built using Matlab and Modelsim. The simulation result shows that the hardware realization of the attitude control system in this paper is valid.更多还原