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The motion of a variable-mass spacecraft is considered in the powered section of a descending trajectory. Approximate analytical solutions are obtained for the angles of spatial orientation of the spacecraft, which allows one to analyze the nutation motion and to develop recommendations on the spacecraft’s mass configuration, providing the smallest possible deviations of the longitudinal axis and thrust vector from specified directions. The errors of stabilization of the spacecraft’s longitudinal axis are calculated by means of numerical integration of complete models and using the obtained analytical solutions, the results being in good agreement. 相似文献
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航天器及其部件的热真空试验是航天器研制过程保证其可靠性的重要环节。由于复杂的物理和边界条件,单纯从传热的角度得到的航天器传热模型与真实情况存在差别。基于传热理论的基本方法,文章提出结合系统辨识的方法得到航天器热真空试验传热数学模型。这种方法可以推广到相似的试验中去,将加快试验进程和节省大量的试验经费。 相似文献
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微小航天器单相流体回路自主热控地面实验研究 总被引:2,自引:0,他引:2
单相流体回路是解决微小航天器热控问题的一种重要手段,但是由于其内热源功率密度高、轨道热环境变化复杂,要求其具有高度自适应控制能力。为满足开展微小航天器单相流体回路自主热控研究的需要,提出了一种单相流体回路核心部件-微机械泵的PWM控制策略及实现算法,设计并搭建了其地面等效模拟实验装置,实现了该单相流体回路包括微机械泵驱动电压-压差输入输出关系、热源载荷变化及微机械泵转速变化的开环动态特性实验研究,并在此基础上完成了所提出的单相流体回路自主控制方法控制效果的地面等效模拟实验研究,达到±0.5℃以内的自主控温效果。该控制策略除了可以实现高精度自主控温以外,由于机械泵功耗基本上与热载荷成正比,还可以减少热控系统运行能耗,因而在能量供应有限的微小航天器上具有广阔应用前景。 相似文献
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海事卫星系统在载人航天数据中继的应用 总被引:1,自引:0,他引:1
对海事卫星系统用于载人航天器数据中继的基本方法及可能性进行了讨论。从海事卫星系统的构成、链路能量和天线跟踪等方面论证了使用海事卫星系统中继载人航天数据的可能性。论述了工程实施中的关键技术和解决措施。提出了采用导频接收机来实施多普勒频移补偿的解决方案。最后认为使用海事卫星中继载人航天数据是可行的,可有效提高载人航天器的测控通信覆盖率。 相似文献
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近距离航天器相对轨道的鲁棒自适应控制 总被引:1,自引:1,他引:0
针对近距离航天器的相对轨道提出了一种鲁棒自适应控制律。在追踪星本体坐标系中考虑航天器的相对运动。首先,在转动惯量未知的情形下提出了自适应控制律,保证系统的全局渐近稳定性。其次,将两星地心引力加速度之差作为干扰加速度,并假设干扰有未知上界,对自适应控制律进行修正,提出了鲁棒自适应律,使得系统是全局一致最终有界稳定的。控制律的设计不需要绝对轨道信息,适用于任意轨道。对航天器编队飞行和空间交会两种情形分别进行了仿真分析,结果表明所设计的控制律是合理有效的。 相似文献
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This paper presents a general framework for synchronized multiple spacecraft rotations via consensus-based virtual structure. In this framework, attitude control systems for formation spacecrafts and virtual structure are designed separately. Both parametric uncertainty and external disturbance are taken into account. A time-varying sliding mode control (TVSMC) algorithm is designed to improve the robustness of the actual attitude control system. As for the virtual attitude control system, a behavioral consensus algorithm is presented to accomplish the attitude maneuver of the entire formation and guarantee a consistent attitude among the local virtual structure counterparts during the attitude maneuver. A multiple virtual sub-structures (MVSSs) system is introduced to enhance current virtual structure scheme when large amounts of spacecrafts are involved in the formation. The attitude of spacecraft is represented by modified Rodrigues parameter (MRP) for its non-redundancy. Finally, a numerical simulation with three synchronization situations is employed to illustrate the effectiveness of the proposed strategy. 相似文献
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The paper deals with energetically optimal multi-impulse transfer of a spacecraft in the central Newtonian gravity field near a planet. At the initial state of the transfer the distance from the spacecraft to the center of attraction, its radial and transversal velocity projections are known. At the end of the transfer the spacecraft must be located in the elliptical orbit with the given area and energy constants. The distance from the spacecraft to the center of attraction is bounded above and below, the transfer time being unspecified. The initial orbit intersects the inner boundary of the given ring.All the optimal solutions have been obtained by analytical way. A number of new solutions has been found for the given problem in comparison with the case of the transfer from the orbit at the free initial point.Up to five impulses can be applied on the optimal trajectories. The numerical simulation of the problem is carried out. It shows that all obtained solutions give not only local but global optimal energetic input on the corresponding conditions. 相似文献
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基于一致性理论,研究了多航天器系统相对轨道及姿态耦合的分布式协同控制问题。在仅有部分跟随航天器可获取领航航天器信息的情形下,针对各跟随航天器存在未建模动态以及外部环境干扰等问题,利用双曲正切函数的性质,提出了考虑输入饱和的分布式自适应协同控制律。首先,对于领航航天器具有时变状态的情形,为每个跟随航天器设计了3个滑模估计器,对领航航天器的状态进行估计。其次,针对跟随航天器间相对速度和角速度难以测量的问题,设计仅需领航航天器状态的切比雪夫神经网络自适应更新律。最后,设计考虑输入饱和的分布式自适应协同控制律保证各跟随航天器跟踪动态领航航天器。仿真结果表明了该算法的有效性、可行性。 相似文献
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