【作者】 郝东；

【导师】 陈小前；

【作者基本信息】 国防科学技术大学 ， 航空宇航科学与技术， 2011， 硕士

【摘要】 在卫星技术日益成熟和发展的今天,微小卫星以其低成本、短周期等特点受到许多研究机构和大学的关注。但是,由于微小卫星受到物理尺寸、重量、功耗、研制成本等因素的限制,使得微小卫星不能采用传统卫星的设计方法。为了更好的满足微小卫星发展过程中的需求,提高微小卫星的整体性能,本论文立足于工程应用,对磁控微小卫星的姿态确定与控制技术进行了研究,具有重要的工程参考价值。在微小卫星的姿态确定上,本论文采用三轴磁强计、模拟太阳敏、微机械陀螺作为姿态敏感器件,建立了卫星姿态运动学、动力学数学模型和姿态敏感器测量模型。考虑到微小卫星姿态确定中的非线性因素和星载计算机的计算速度、存储容量等约束,本论文采用常规的处理非线性问题的扩展Kalman滤波方法进行数据处理和姿态估计,将状态方程、测量方法进行线性化、离散化,推导了线性化模型误差,获得扩展Kalman滤波模型,并通过数字仿真给出了“磁强计+陀螺”、“太阳敏+陀螺”两种姿态敏感器组合下的仿真结果。在微小卫星速率阻尼阶段的控制上,本论文采用磁力矩器、冷喷气装置作为执行机构,分别对Minus-dot-B控制器和PID控制器进行了设计,并通过数字仿真给出了“磁力矩器”、“偏置动量轮+磁力矩器”、“微喷气装置+磁力矩器”三种执行机构组合下的仿真结果。仿真结果表明,在Minus-dot-B控制下,卫星速率阻尼的时间较短,但是阻尼精度不高,角速度波动比较大;在PID控制下,卫星速率阻尼时间较长,但是能量消耗少,阻尼精度较高,角速度波动很小。在微小卫星三轴稳定阶段的控制上,本论文仍采用磁力矩器、冷喷气装置作为执行机构。针对装有偏置动量轮的卫星,分析了卫星姿态自由运动的特点,分别对俯仰通道和滚动—偏航通道的姿态控制算法进行了研究和设计,给出了利用磁力矩器进行三轴稳定控制的仿真结果。针对无偏置动量轮的卫星,采用“微喷气装置+磁力矩器”作为组合执行机构,对这种执行机构组合下的控制器进行了设计,给出了仿真结果。仿真结果表明,本论文采用的三轴稳定控制方法满足微小卫星姿态控制的精度要求。最后,本论文对于姿态确定与控制系统中的重要姿态敏感器——三轴磁强计的测量误差修正方法进行了研究,分析了三轴磁强计测量误差的来源,建立了测量误差修正数学模型,并通过实验对本测量误差修正方法进行了实验验证。实验结果表明,本论文提出的三轴磁强计测量误差修正方法能有效对三轴磁强计的测量输出数据进行修正,提高了其测量精度,为高精度的微小卫星姿态确定与控制提供了良好的姿态敏感器条件。更多还原

【Abstract】 With the development of satellites, the satellite technology has become more advanced and more sophisticated today. For its low-cost, short-cycle and other features, the small satellite is subject to many research institutions and universities concerned. However, due to the restrictions of the physicial size, the mass, the power, the researching cost and other factors the general designing method which is used in traditional satellites can not be used in small satellites. In order to meet the demands of small satellites in the outgrowth and improve the overall performance, we do researches on the attitude determination and magnetic control technology for small satellites basing on the practical project application point of view. This paper has an important engineering reference value.In the small satellite attitude determination part, we use a three-axis magnetometer, a simulating sun sensor and a micromechanical gyroscope as the satellite attitude sensors. We set up the satellite attitude kinematics equation, the dynamics equation and the measuring models of the attitude sensors. Taking the nonlinear elements of the satellite attitude determination, the operating speed of the computer and the memory capacity, and so on into account, we apply the extended Kalman filter method to execute the data processing and the attitude estimation. The extended Kalman filter is ofen used to deal with nonlinear problems. We linearize the state equation and the measuring equation, then discrete them. We also obtain the linearized error model and do digital simulations by two kinds of attitude sensor combinations: a three-axis magnetometer and a gyroscope, a sun sensor and a gyroscope.In the small satellite velocity damping control part, we adopt magnetic torque rods and micro thrusters as actuators. We have designed the Minus-dot-B controller and the PID controller. We give the simulating results of different actuator combinations. The results show that the time for the velocity damping process is shorter under the control of Minus-dot-B, but the accuracy is not high. The angle velocity fluctuation of the satellite is relatively large. Under the control of PID, the time for the velocity damping process is longer and the energy depletion is smaller with a higher accuracy. The angle velocity fluctuation is very small.In the small satellite three-axis stabilized control part, we still use the magnetic torque rods and the micro thrusters as the actuators. For the small satellite with a biased momentum wheel, we analyze the free attitude movement features and respectively design the pitch path controller and the roll-yaw path controller. Then we give the smulating results of the three-axis stabilized control. For the satellite without the biased momentum wheel, we design the controller by the actuator combination of micro thrusters and magnetic torque rods. The results show that the three-axis stabilized controlling method meets the accuracy demand of the satellite attitude control.Finally, we do researches on the correcting method of the measuring error for the three-axis magnetometer, which is the key attitude sensor in the satellite attitude determination and control system. We introduce the basic magnetic experiment equipment and the applied three-axis magnetometer. We analyze the error sources and build the correcting model. Then we test and verify the method through experiments. The experiment results show that the method promoted in this paper can improve the measuring accuracy largely and supply the small satellite attitude determination and control system with good sensor conditions.更多还原