星上实时处理半实物测试系统的设计与实现

国产高性能处理芯片在卫星产品中的广泛应用,促进了星上实时处理技术的快速发展,同时对地面测试和验证系统的有效性提出了较高要求.针对卫星有效载荷分系统星上实时处理的需求,构建了以星上实时处理半实物系统为主体的测试环境,用于星上嵌入式软件开发的仿真验证,并自动地对处理结果进行对比和分析,完成效果评估,为卫星在轨可靠运行提供支...     

Multilevel Tests and Measurement Evaluation Methods for the Application of Composite Materials in Spacecraft Structures

With the implementation of new-generation launch vehicles, space stations, lunar and deep space exploration, etc., the development of spacecraft structures will face new challenges. In order to reduce the spacecraft weight and increase the payload, composite material structures will be widely used. It is difficult to evaluate the strength and life of composite materials due to their complex mechanism and various phenomena in damage and failure. Meanwhile, the structures of composite materials used in spacecrafts will bear complex loads, including the coupling loads of tension, pressure, bending, shear, and torsion. Static loads, thermal loads, and vibration loads may occur at the same time, which asks for verification requirements to ensure the structure safety. Therefore, it is necessary to carry out a systematic multi-level experimental study. In this paper, the building block approach (BBA) is used to investigate the multilevel composite material structures for spacecrafts. The advanced measurement technology is adopted based on digital image correlation (DIC) and piezoelectric and optical fiber sensors to measure the composite material structure deformation. The virtual experiment technology is applied to provide sufficient and reliable data for the evaluation of the composite material structures of spacecrafts.     

金属增材制造监测与控制技术研究进展

金属增材制造技术凭借其柔性化定制能力和复杂构件成形优势,有望成为提升航天领域设计与制造能力的一项关键核心技术,但现阶段该方法仍然存在制造过程稳定性不足、制造质量实时检测困难、工艺参数实时调节技术成熟度有待提升等问题。本文从增材过程信息感知、增材工艺优化决策、质量优化控制发展趋势三方面详细阐述了金属增材制造监测技术的研究进展,论证了高性能结构件增材成形过程中工艺变量-过程参量-成形质量调控的发展必要性,并就增材过程监测技术的发展趋势做出了思考与展望。     

一种天文导航信息导引的星间链路自主定轨算法

针对星间链路自主定轨算法稳定性差,故障无法自主恢复等缺点,提出了一种天文导航信息导引算法,以提升星间链路自主定轨算法的稳定运行能力。算法利用天文导航极高的稳定性与完全自主性,确定星间链路建链指向,以保证星间稳定建链。并且,算法在天文导航中加入强跟踪滤波环节,使在轨道信息出现偏差以致星间链路中断时,具备快速的自主轨道确定及建链恢复能力。经仿真测试表明,卫星平稳运行时,利用本文算法,星间链路仰角及方位角指向误差均小于0.1°。而在轨道机动产生链路中断后,算法可使卫星快速恢复链路建链。仿真测试验证了天文导航信息导引算法的有效性。     

能量最优的航天器连续动态避障轨迹规划

针对传统脉冲避障算法在航天器轨迹规划应用中存在对瞬时推力依赖性强且燃料消耗量大的问题,提出能量最优的连续动态避障算法。该算法首先基于线性相对运动方程与有限时间的能量最优模型,建立了相对运动能量最优模型,同时验证了模型最优性;其次将动态障碍物的 y 向运动误差偏移与正态分布概率引入避碰安全距离模型,修正了追踪航天器动态避障的范围,确定了安全距离矢量长度,增强了规避障碍的可靠性;最后通过障碍物速度矢量与追踪器航天器速度矢量夹角确定动态避障点方向,减少燃料消耗的同时提高了避障的有效性、准确性。通过仿真验证,该算法可以自适应选取规避障碍点,有效规避动态障碍;工质燃料消耗较小,有效延长航天器在轨寿命。     

压紧杆式太阳翼自动化加载设备设计与验证

基于对国内外太阳翼压紧释放机构预紧实施的现状及存在问题的研究,开展设备小型化、轻量化、可视化设计,研制了一种电机驱动拉伸压紧杆的力反馈型自动化加载设备。该设备采用特制的夹紧接口,并利用凸轮原理解决了狭小空间内压紧杆的的夹紧难题;采用拉力传感器和力反馈系统等将太阳翼压紧杆预紧力施加精度控制在5%以内,有效地解决了预紧力加载的精度问题和自动预紧问题。为验证设备性能,开展了预紧力误差分析,设计了一套采用电阻应变片实时测量预紧力的方案,得出设备工作时预紧力的变化情况。试验结果表明,自动化加载设备不受人员技能水平的影响,绝对精度最大值为3.11%,单次加载时间小于1 min。     

模块化热控技术及其在低轨卫星中的应用

Differently from traditional integration satellites, the modular satellites consist of several structurally independent modules and the heat dissipation is unevenly distributed, while the interface between modules should support repeatable connection separating. Therefore, the traditional thermal control design, which supports the independent heat dissipation of an integration satellite, cannot meet the thermal control requirements of the modular satellite. In this paper the modular thermal control technology is proposed. The carbon nanotube array on metal substrate is used as the thermal interface of the modules to realize the separable cross module heat transfer. The internal surface of structural panels is coated by graphene film to enhance the internal heat transfer in the modules with limited internal space. The smart thermal control coating is used at all the heat rejection surfaces to suppress the orbital heat flux variations. By using the technology, the thermal connection of the assembly and reconstruction system is built and the synergistic heat dissipation of the whole satellite is achieved. As to validate the proposed technology, the finite element model of the circular low earth orbit satellite is established and the in orbit temperature in the extreme working conditions is simulated. The result indicates that the modular thermal control technology proposed in this paper can satisfy the thermal control demand of the modular satellite.      

零泊松比蜂窝结构一维变形行为

为满足柔性蒙皮的变形需求,针对一种适用于柔性蒙皮的零泊松比蜂窝结构开展了一维变形行为的研究。首先通过考虑蜂窝胞壁轴向变形及弯曲变形,基于能量法建立了零泊松比蜂窝结构的等效弹性模量理论模型,并分别应用数值分析和试验方法验证了理论模型的正确性。然后分别以铝合金和钢材为基体材料,利用数值分析方法进一步分析了零泊松比蜂窝结构的非线性变形行为,并获得了蜂窝结构的变形量与残余应变的关系。结果表明:蜂窝变形过程中的力学行为与结构的几何参数以及母材的选择有关。因此,可以通过改变蜂窝结构的几何参数,实现蜂窝结构驱动力及残余应变的调节;同时,在选择基体材料时,为兼顾"面内"刚度和"面外"承载能力,不仅应该选用杨氏模量小的材料,减少其驱动力,还应该选用弹性段大的材料,减小残余变形。     

拉弯模具间隙对复杂截面型材成形精度的影响

采用有限元数值模拟方法对非对称复杂截面铝合金型材拉弯工艺过程进行研究,分析拉弯模具间隙对称和不对称两种情况对型材拉弯后的截面畸变及回弹的影响.结果表明型材拉弯后壁厚出现减薄,其最小厚度受间隙值影响较小,但左右间隙是否对称会影响截面畸变方向,左右间隙不对称时型材拉弯后其截面畸变方向会发生偏转,回弹后的扭转量也会有变化.以减小截面畸变和回弹量从而提高成形精度为目标,通过数值模拟分析对拉弯模具左右间隙值进行了优化,为合理设计拉弯成形模具提供理论依据,对制定生产工艺规范具有重要参考价值.     

超磁致伸缩作动器的率相关建模与跟踪控制

利用Hammerstein模型对超磁致伸缩作动器(GMA, Giant Magnetostrictive Actuators)进行建模, 分别以改进的Prandtl-Ishlinskii(MPI, Modified Prandtl-Ishlinskii)模型和外因输入自回归模型(ARX, Autoregressive model with exogenous input)代表Hammerstein模型中的静态非线性部分和线性动态部分,并给出了模型的辨识方法.此模型能在1~100 Hz频率范围内较好地描述GMA的率相关迟滞非线性特性.提出了前馈逆补偿和比例-微分-积分(PID, Proportional-Integral-Derivative)反馈相结合的复合控制策略.实时跟踪幅值为16 μm的单一频率和复合频率正弦参考输入信号, 均方根误差小于1 μm, 相对误差小于10%, 证明了控制策略的有效性.