太阳帆绳系小行星动力学与控制研究
发布时间：2019-05-12 12:01
【摘要】：近地小行星撞击地球虽是小概率事件,但其可能性不容忽视。为防御小行星,科学家们已提出多种缓解小行星威胁的方案。本文介绍了一种利用太阳帆—小行星绳系系统在不破坏小行星结构和成分的条件下改变小行星轨道的方法。文中首先在绳系质量块系统模型的基础上,加入太阳帆受到的太阳光压力,建立了太阳帆—小行星绳系系统的动力学模型。然后提出了以偏移距离最大为目标的连续时间最优控制问题,使用勒让德伪谱法将连续最优控制问题转化为非线性规划问题,并使用序列二次规划方法进行求解。仿真结果表明,利用太阳帆—小行星绳系系统能够有效地对小行星的轨道产生影响,使其偏离原始轨道,且能避免因太阳帆与小行星的相对运动引起的系绳缠绕问题;太阳帆的面积是影响太阳帆—小行星绳系系统改变小行星轨道能力的一个主要因素。为了解决小行星的自转给小行星探测、小行星防御等造成的困难,本文提出了使用绳系太阳帆减缓小行星自转的方案。首先对普通航天器在小行星旋转引力场中的运动学方程进行改进,得到了绳系太阳帆在小行星固连坐标系中的动力学模型。在利用绳系太阳帆减缓小行星的自转时,需要将太阳帆稳定在小行星的初始平衡点处以便于控制,于是使用PD控制方法求解使太阳帆稳定在小行星初始平衡点的控制律,并使用最优控制方法对控制变量进行了优化。仿真结果表明,使用绳系太阳帆能够有效地减缓甚至消除小行星的自转,同时,太阳帆的面积也是影响绳系太阳帆改变小行星自转角速度能力的一个主要因素。
[Abstract]:Although the impact of near-Earth asteroids on the earth is a small probability event, its possibility can not be ignored. To defend against asteroids, scientists have come up with a variety of plans to mitigate the asteroid threat. In this paper, a method of changing asteroid orbit by using solar sail-asteroid rope system without destroying the structure and composition of asteroid is introduced. In this paper, the dynamic model of the solar sail-asteroid rope system is established by adding the solar pressure of the solar sail on the basis of the mass block system model of the rope system. Then, a continuous time optimal control problem with the goal of maximum offset distance is proposed. The continuous optimal control problem is transformed into a nonlinear programming problem by Legendre pseudo-spectral method, and the sequential quadratic programming method is used to solve the problem. The simulation results show that the solar sail-asteroid rope system can effectively affect the orbit of asteroids, make them deviate from the original orbit, and avoid the problem of rope entanglement caused by the relative motion of solar sails and asteroids. The area of solar sails is a major factor affecting the ability of solar sail-asteroid rope system to change asteroid orbit. In order to solve the difficulty caused by asteroid rotation to asteroid exploration and asteroid defense, a scheme of using tethered solar sail to slow asteroid rotation is proposed in this paper. Firstly, the kinematics equation of the ordinary spacecraft in the asteroid rotating gravitational field is improved, and the dynamic model of the tethered solar sail in the asteroid fixed coordinate system is obtained. When using rope solar sails to slow down the rotation of asteroids, it is necessary to stabilize the solar sails at the initial equilibrium point of asteroids for easy control, so the PD control method is used to solve the control law to stabilize the solar sails at the initial equilibrium points of asteroids. The optimal control method is used to optimize the control variables. The simulation results show that the use of rope solar sails can effectively slow down or even eliminate the rotation of asteroids. At the same time, the area of solar sails is also a major factor affecting the ability of rope solar sails to change the rotation velocity of asteroids.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P185.7
，
本文编号：2475376
[Abstract]:Although the impact of near-Earth asteroids on the earth is a small probability event, its possibility can not be ignored. To defend against asteroids, scientists have come up with a variety of plans to mitigate the asteroid threat. In this paper, a method of changing asteroid orbit by using solar sail-asteroid rope system without destroying the structure and composition of asteroid is introduced. In this paper, the dynamic model of the solar sail-asteroid rope system is established by adding the solar pressure of the solar sail on the basis of the mass block system model of the rope system. Then, a continuous time optimal control problem with the goal of maximum offset distance is proposed. The continuous optimal control problem is transformed into a nonlinear programming problem by Legendre pseudo-spectral method, and the sequential quadratic programming method is used to solve the problem. The simulation results show that the solar sail-asteroid rope system can effectively affect the orbit of asteroids, make them deviate from the original orbit, and avoid the problem of rope entanglement caused by the relative motion of solar sails and asteroids. The area of solar sails is a major factor affecting the ability of solar sail-asteroid rope system to change asteroid orbit. In order to solve the difficulty caused by asteroid rotation to asteroid exploration and asteroid defense, a scheme of using tethered solar sail to slow asteroid rotation is proposed in this paper. Firstly, the kinematics equation of the ordinary spacecraft in the asteroid rotating gravitational field is improved, and the dynamic model of the tethered solar sail in the asteroid fixed coordinate system is obtained. When using rope solar sails to slow down the rotation of asteroids, it is necessary to stabilize the solar sails at the initial equilibrium point of asteroids for easy control, so the PD control method is used to solve the control law to stabilize the solar sails at the initial equilibrium points of asteroids. The optimal control method is used to optimize the control variables. The simulation results show that the use of rope solar sails can effectively slow down or even eliminate the rotation of asteroids. At the same time, the area of solar sails is also a major factor affecting the ability of rope solar sails to change the rotation velocity of asteroids.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P185.7
，
本文编号：2475376
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