A guidance strategy for rendezvous and docking to the space station in the Earth-Moon NRHO orbit

With the development of space technology,it is possible to build a space station in Earth-Moon space as a transit for Earth-Moon round-trip and entering in the deep space.Rendezvous and docking is one of the key technologies for building an Earth-Moon space station.A guidance strategy for rendezvous and docking from the Earth orbit to the space station in the Earth-Moon NRHO orbit is proposed in this paper,which is suitable for engineering applications.Firstly,the rendezvous and docking process is divided into three sections,i.e.,the large-range orbit transfer section,far-range guidance section,and close-range approaching section.The suitable terminal of large-range orbit transfer is selected according to the eigenvalue of NRHO orbit state transition matrix.The two-impulse guidance method based on the relative motion equation in the three-body problem is adopted for the far-range guidance section.The impulse time and amplitude are solved with the optimization algorithm.The linear constant three-body relative motion equation is proposed for the close-range approaching section,and the rendezvous and docking is completed by a two-stage linear approximation.Finally,a simulation analysis is carried out,and the simulation results show that the adopted dynamics equations and the designed guidance law are effective,and the three flight phases are naturally connected to accomplish the rendezvous and docking mission from the Earth orbit to the space station on the Earth-Moon NRHO.

Dynamics and nonlinear control of space electromagnetic docking

Space electromagnetic docking technology, free of propellant and plume contamination, offers continuous, reversible and synchronous controllability, which is widely applied in the future routine on-orbit servicing missions. Due to the inherent nonlinearities, couplings and uncertainties of an electromagnetic force model, the dynamics and control problems of them are difficult. A new modeling approach for relative motion dynamics with intersatellite force is proposed. To resolve these control problems better, a novel nonlinear control method for soft space electro-magnetic docking is proposed, which combines merits of artificial potential function method, Lyapunov theory and extended state observer. In addition, the angular momentum management problem of space electromagnetic docking and approaches of handling it by exploiting the Earth＇s magnetic torque are investigated. Finally, nonlinear simulation results demonstrate the feasibility of the dynamic model and the novel nonlinear control method.

Confirmation of the Ball-Screw Force for the Differential Cushion System of Space Docking Mechanism

Based on the analysis of the differential cushion damping system kinematic relation and using principle of virtual work, a new kinematic function expression is established which is between six ball-screws and cushion components. At last the relationship between ball-screw force and attitude is intreduced.

China Accomplished Its First Space Rendezvous and Docking

At 1:36 am on November 3,China's Shenzhou 8 unmanned spaceship and Tiangong 1 space lab spacecraft accomplished the country's first space docking procedure and coupling in space at more than 343km above Earth's surface,marking a great leap in China's space program.

Research on Rigid-flexible Coupling Dynamics of Flexible Cone-probe Docking Mechanism

In this paper,a new kind of flexible cone composed of the thin-walled plates based on space probecone docking mechanism for small-sized spacecraft is presented.The theoretical model of docking impact dynamics,which takes into account the additional stiffness terms,is derived based on Lagrange Analytical Mechanics theory and Hertz contact theory.Finite element method is employed for the discretization of the thin-walled plate.The results show that the traditional dynamic model without considering the additional stiffness terms will be difficult to reach steady state.The method proposed in this paper can correctly predict the dynamic behavior of the system.

空间机器人在轨组装多模块单元的对接力控制与地面实验

将空间结构模块化单元呈堆叠式发射后通过空间机器人实施在轨组装,是构建大型空间结构颇具前景的一种方式.空间机器人在轨组装空间结构模块单元过程中存在动力学模型复杂、对接力控制难和对接过程干扰强等问题.针对上述难点,分析了多模块单元在轨组装接触情景,建立了空间机器人在轨组装的动力学模型和三维空间接触动力学模型,在此基础上采用了一种基于模型参考自适应阻抗控制的对接过程接触力控制方法.该方法根据力跟踪误差值实时调整顺应轨迹以适应复杂工况和抵抗外界干扰,从而使接触力准确跟踪期望值,以保证模块单元成功对接的同时避免物理接触对机械结构造成损坏.搭建了空间机器人组装模块单元的仿真平台和地面实验平台,对空间机器人动力学模型和控制方法进行了验证.实验结果表明自适应阻抗控制方法在多模块单元同步对接的复杂接触情景下,仍具有良好的力控制性能和环境适应能力.该方法可应用于(超)大口径太空光学组合镜组等空间大型结构在轨组装过程的力控制.

天舟货运飞船人控遥操作交会对接设计与验证

人控遥操作交会对接(RVD)是无人航天器与空间站自动交会对接的备份手段,提高了交会对接的可靠性与安全性。面向天舟货运飞船与天宫空间站,运用系统工程方法设计并验证了航天员遥操作交会对接与分离撤离功能,主要创新点包括:针对遥操作系统时延大的问题,采取精简系统信息主回路传输环节等措施,将系统总时延控制在1 s以内;针对船站近距离安全性的内在需求,提出了以安全性为核心、以状态转移图为工具的应急飞行方案设计方法,构建了飞行方案体系;针对遥操作交会对接系统复杂、大系统接口多的特点,提出了基于功能验证需求与地面验证条件匹配矩阵的系统级综合试验设计方法,构建了地面验证体系;针对交会灯功率不足导致阴影区远距离不能识别目标的问题,提出了空间站舱外泛光灯主动发光为主、交会对接敏感器合作目标被动反光为辅的方案。天舟二号货运飞船与天和核心舱在神舟十三号乘组操控下,圆满完成了遥操作交会对接与分离撤离在轨试验。

Design Schemes and Comparison Research of the End-effector of Large Space Manipulator

The end-effector of the large space manipulator is employed to assist the manipulator in handling and manipulating large payloads on orbit.Currently,there are few researches about the end-effector,and the existing end-effectors have some disadvantages,such as poor misalignment tolerance capability and complex mechanical components.According to the end positioning errors and the residual vibration characters of the large space manipulators,two basic performance requirements of the end-effector which include the capabilities of misalignment tolerance and soft capture are proposed.And the end-effector should accommodate the following misalignments of the mechanical interface.The translation misalignments in axial and radial directions and the angular misalignments in roll,pitch and yaw are ±100 mm,100 mm,±10°,±15°,±15°,respectively.Seven end-effector schemes are presented and the capabilities of misalignment tolerance and soft capture are analyzed elementarily.The three fingers-three petals end-effector and the steel cable-snared end-effector are the most feasible schemes among the seven schemes,and they are designed in detail.The capabilities of misalignment tolerance and soft capture are validated and evaluated,through the experiment on the micro-gravity simulating device and the dynamic analysis in ADAMS software.The results show that the misalignment tolerance capabilities of these two schemes could satisfy the requirement.And the translation misalignment tolerances in axial and radial directions and the angular misalignment tolerances in roll,pitch and yaw of the steel cable-snared end-effector are 30mm,15mm,6°,3° and 3° larger than those of the three fingers-three petals end-effector,respectively.And the contact force of the steel cable-snared end-effector is smaller and smoother than that of the three fingers-three petals end-effector.The end-effector schemes and research methods are beneficial to the developments of the large space manipulator end-effctor and the space docking mechanism.

Modeling of a space flexible probe–cone docking system based on the Kane method

Recent developments in micro- and nano-satellites have attracted the interest of the research community worldwide. Many colleges and corporations have launched their satellites in space. Meanwhile, the space flexible probe-cone docking system for micro- and nano-satellites has become an attractive topic. In this paper, a dynamic model of a space flexible probe-cone dock- ing system, in which the flexible beam technology is applied, is built based on the Kane method. The curves of impact force versus time are obtained by the Lagrange model, the Kane model, and the experimental method. The Lagrange model was presented in the reference and verified by both finite element simulation and experiment. The results of the three methods show good agreements on the condition that the beam flexibility and the initial relative velocity change. It is worth mentioning that the introduction of vectorial mechanics and analytical mechanics in the Kane method leads to a large reduction of differential operations and makes the modeling process much easier than that of the Lagrange method. Moreover, the influences of the beam flexibility and the initial relative velocity are discussed. It is concluded that the initial relative velocity of space docking operation should be controlled to a certain value in order to protect the docking system.

对接锁索驱轮系传动同步性及补偿研究

针对空间对接锁系装配采用目测采集数据,导致误差大、装配效率低的问题,依据索驱轮系传动结构,设计和搭建实验测试平台,并结合虚拟仪器技术利用LabVIEW软件开发轮系同步性测试系统,在不同预紧载荷作用下对索轮传动同步性进行测试。根据钢索形变、蠕变及系统测试的运动形变数据,提出一种轮系传动同步性补偿与控制方法。实验结果表明,利用开发的同步性测试系统可实现对索驱轮系传动误差的精确采集,提出的同步性补偿方法可为空间锁系装配效率的提高提供参考。

支持径向交会对接任务的宽波束中继方法研究

针对神舟飞船和天和空间站径向交会对接形成组合体的工作模式下,神舟飞船宽波束中继S终端对中继卫星视场缩小导致测控覆盖率降低的现象,提出一种基于组阵和时空分集技术的宽波束中继S链路的设计构想,通过在天和空间站宽波束中继S终端内部增设功分器和合路器,以及在组合体径向对接口的对接总线内部增设高频电缆。利用天和空间站的宽波束中继S发射天线和接收天线,传送神舟飞船的宽波束中继S信号。神舟飞船宽波束中继S终端,同时接收和处理组合体对接总线内部高频电缆和神舟飞船I/III象限收发的宽波束中继S信号,解决了中继卫星过顶遮挡导致的测控覆盖率降低的问题,提升了链路可靠性。经仿真分析,相比单独工作模式,测控覆盖率提升了25.3%。对于接收链路,采用时空分集技术,对3个方向的宽波束中继S信号进行互相关解算和最大比合并,获得信号合并增益,有效提升了接收信号的信噪比和有效带宽。

空间机器人在轨双臂辅助航天器对接力/位置嵌套双层滑模阻抗控制

为了实现空间机器人捕获航天器及辅助对接操作的柔顺化,对航天器对接装置的输出力与位姿的精确控制进行了研究,且在关节电机与机械臂之间添加了弹簧阻尼缓冲装置,以防止接触、碰撞时产生的巨大冲击力造成关节破坏。首先,结合Newton第三定律、捕获点的速度约束及闭链系统的几何约束,获得了捕获航天器后的混合体系统动力学方程,通过动量守恒关系计算了碰撞冲击效应与冲击力。接着,通过航天器对接装置相对载体坐标系的运动学关系,建立了对接操作过程中的阻抗模型。然后,设计了一种鲁棒自适应双层滑模控制策略,其与阻抗控制相结合,采用力加载随动控制系统实现对接装置的位姿与输出力的精确控制,以降低接触、碰撞时的冲击力。该控制策略具有双层滑模结构,其第一层保证混合体系统在有限时间内收敛,第二层用于解决控制的高增益问题。最后,通过Lyapunov定理证明了系统的稳定性;利用数值仿真验证了所提控制策略的有效性。仿真结果表明,在给定的速度下缓冲装置最大可将碰撞冲击力矩降低46.78%,输出力的控制精度优于0.5 N,位置、姿态的控制精度优于10^(-3)m,0.5°。

温度对空间对接机构扭矩测量的影响

分析高低温环境空间对接机构扭矩测量装置的设计方案,研究不同温度下轴系材料弹性模量变化对扭矩测量过程的影响,并通过热影响分析不同温度下同轴度变化对扭矩测量的影响。结果表明:由温度导致材料弹性模量变化对装置轴系的扭矩传递过程几乎没有影响,轴系热变形结果与温差呈正相关。通过对高低温环境下装置测量技术的分析研究,提高了扭矩性能测试工作的可靠性。

空间站实验舱对接与转位机构分系统技术及研制

受运载工具运载能力的限制,大型空间站须在太空对接组装。对接与转位机构在空间站组建过程中具有关键作用,用于实验舱与核心舱的对接及转位,实现空间站实验舱的组装。空间站实验舱对接与转位机构分系统是实施对接与转位任务的主动端,为复杂的空间机电热一体化机构产品,在正常模式下,由主动端实施分系统所有动作。在研制过程中,分系统充分论证系统方案,集中攻克关键技术,充分试验产品样机,并先后在轨圆满完成了实验舱Ⅰ和实验舱Ⅱ的对接与转位任务。论述空间站实验舱对接与转位机构分系统的研制技术,对后续空间机构产品研制具有启示作用。

一种空间对接机构的简化建模方法及其在实验舱侧向再对接中的应用

针对异体同构周边内翻式对接机构,从详细的传动原理及工程实践两方面说明可以建立简化的对接机构缓冲系统模型,既不损失对接机构性能特点,且简化了模型实现和计算。基于此,建立转位机构辅助实验舱侧向再对接仿真模型,给出仿真结果,并与试验结果进行对比,对比的数值和趋势一致性较好,运动量的误差值小于10%,模型仿真结果可以作为空间站侧向再对接流程设计的依据。这种简化的对接机构模型也可以用于机械臂辅助再对接动力学过程建模。

用于空间站的四重冗余对接控制系统设计

针对空间站所处太空环境的特殊性、对接机构对空间站正常运行的重要性,以及对航天器可靠性要求日益增加的问题,提出在对接控制系统中增加可靠性设计,实现整个机构的高质量、平稳运转。在完成正常控制功能的基础上,在系统中采用了四重冗余的工作机制,包括主备机双热备份、自动/手动控制模式切换、自动控制关闭指令双线发送和工作模式的三取二判断,对四重冗余设计的具体判断流程进行了详细的解释。对控制系统软件进行仿真验证,结果表明:本方法设计的对接控制系统具有高可靠性和故障容错能力。

城市货运配送车辆专用车位设置方案研究——以佛山市禅城区为例

为规范城市货运配送车辆停靠、提高货运配送效率、缓解城市交通拥堵、促进绿色低碳运输,该文首先基于场景分析,形成配送车辆专用车位设置必要性、可行性分析方法,继而在道路分段的前提下,提出配送停靠需求测算模型、专用车位规模测算模型和选址模型,并在佛山市禅城区进行示范应用,提出相应的配套措施,保障专用车位的便捷性和专用性。研究结果为城市货运配送车辆专用车位设置方案和管理措施的制定提供科学全面的理论依据。

精制透骨消痛颗粒防治骨性关节炎的计算机药理学

采用分子相似性分析、化学空间、分子对接、生物网络技术和药代动力学性质预测等计算机药理学方法研究中药精制透骨消痛颗粒中514个化合物的药理学机制.结果表明:该复方所含化合物在化学结构上具有多样性及大部分化合物在化学空间上具有类药性质;通过514个与35个骨性关节炎疾病相关的公认靶标的相互作用及它们在靶空间的分布上阐明了精制透骨消痛颗粒防治骨性关节炎的可能作用机理,发现了一些潜在的活性分子;通过分析药物库中骨性关节炎的药物-靶点的作用网络及精制透骨消痛颗粒中分子-靶点的作用网络的异质性值、特征路径长度等特征,揭示精制透骨消痛颗粒的多药物、多靶点、多途径分子作用机制.结果有助于理解中药精制透骨消痛颗粒的复杂作用机制.

空间对接半物理仿真原型试验系统

为研制用于对接机构地面测试的空间对接半物理仿真系统,建立能够体现其主要功能的原型试验系统。试验系统通过六维力传感器检测对接机构模拟元件的相互作用力和力矩,根据所建立的航天器动力学模型实时解算对接过程中两航天器的相对运动,并由6自由度运动平台模拟被动航天器来实现此相对运动。针对此原型试验系统,提出系统的动力学解算方案并据此构建动力学仿真大回路,着重对大回路仿真系统的稳定性进行分析,得到稳定性条件,讨论运动平台滞后对仿真的影响和解决方法。在此基础上,用所研究系统成功地模拟了航天器对接的全过程,从而为实际空间对接半物理仿真系统提供了必要的设计依据。

可重构星球探测机器人的空间对接研究

提出了以改装后的位置敏感传感器来引导机器人完成自动对接的方法,分析了具体工作原理。对可重构星球探测机器人在运动模式下完成对接的两种姿态进行了比较,分别用一般方法和改进后的规划方法计算出了对接工作空间,比较结果说明,机器人在运动模式下三角边着地有利于完成自动对接。对工作模式机器人在工作空间内的运动进行了静力学分析,分析结果表明,机器人在工作空间内可以自由运动。用VC和OpenGL搭建的平台对空间对接进行了仿真试验,试验结果验证了对接工作空间计算的正确性和完成空间自动对接的可能性。