Development of space end-effector with capabilities of misalignment tolerance and soft capture based on tendon-sheath transmission system

The essential requirements of the end-effector of large space manipulator are capabilities of misalignment tolerance and soft capture. According to these requirements, an end-effector prototype combining the tendon-sheath transmission system with steel cable snaring mechanism was manufactured. An analysis method based on the coordinate transformation and the projection of key points of the mechanical interface was proposed, and it was a guideline of the end-effector design. Furthermore, the tendon-sheath transmission system was employed in the capture subassembly to reduce the inertia of the capture mechanism and enlarge the capture space. The capabilities of misalignment tolerance and soft capture were validated through the dynamic simulation in ADAMS software. The results of the capture simulation and experiment show that the end-effector has outstanding capabilities of misalignment tolerance and soft capture. The translation misalignments in radial directions are ±100 mm, and angular misalignments about pitch and yaw are ±15°.     

大型空间机械臂柔性关节的微分几何算法控制器设计

大型空间机械臂负责空间站大型负载的运输、装配,而关节柔性会在一些工况下造成振动.因此设计了一种大型空间机械臂柔性关节控制器.针对谐波减速器的引入而带来的柔性,建立了柔性关节的动力学模型;采用基于微分几何反馈线性化方法对柔性关节模型做了精确线性化解耦处理.对于线性化后的系统,为了克服不确定性及提高鲁棒性,采用具有较高鲁棒性和抗干扰性的滑模变结构控制规律来实现轨迹的合理跟踪.在Matlab/simulink中实现了线性化过程和滑模控制过程,对给定输入信号进行跟踪仿真,改变滑模控制的控制参数,得到控制参数对系统影响,验证了滑模控制的高鲁棒性,并能很好地跟踪输入信号.仿真结果表明,反馈线性化与和滑模控制的结合可以很好地应用于柔性机械臂的控制.     

Modeling and simulations of orbital capture with space tether-net system

A new flexible tether-net space robotic system used to capture space debris is presented in this paper. With a mass point assumption, a dynamic model of the tether-net system was established in orbital frame by applying Lagrange Equations. In order to investigate the net in-plane trajectories after being cast, the non-controlled R-bar and V-bar captures were simulated with ignoring the out-of-plane libration, and the effect of in-plane libration on the trajectories of the capture net was demonstrated by simulation results. With an effort to damp the in-plane libration, the control scheme based on tether tension was investigated, then an integrated control scheme was proposed by introducing thrusters into the system, and the nonlinear close-loop dynamics was linearised by feedforward strategy. Simulation results show that the feedforward controller is effective for in-plane libration damping and enables the capture net to track an expected trajectory.     

自适应平方根中心差分卡尔曼滤波算法在捷联惯性导航系统大方位失准角初始对准中的应用

提出了一种自适应平方根中心差分卡尔曼滤波(ASRCDKF)算法,并应用于捷联惯性导航系统(SINS)大方位失准角初始对准中。ASRCDKF算法以中心差分变换为基础,基于平方根滤波能够克服发散的思想,利用协方差平方根代替协方差参加递推运算,并将自适应估计原理引入该算法中,不仅克服了扩展卡尔曼滤波产生线性化误差和计算雅可比矩阵的不足,而且减小了计算量,保证了数值稳定性。同时,ASRCDKF算法解决了传统滤波算法过度依赖系统动态模型和噪声统计特性先验知识的问题。最后通过滤波仿真证明了ASRCDKF算法在SINS大方位失准角初始对准中的有效性和优越性。     

Application of camera calibrating model to space manipulator with multi-objective genetic algorithm

The multi-objective genetic algorithm(MOGA) is proposed to calibrate the non-linear camera model of a space manipulator to improve its locational accuracy. This algorithm can optimize the camera model by dynamic balancing its model weight and multi-parametric distributions to the required accuracy. A novel measuring instrument of space manipulator is designed to orbital simulative motion and locational accuracy test. The camera system of space manipulator, calibrated by MOGA algorithm, is used to locational accuracy test in this measuring instrument. The experimental result shows that the absolute errors are [0.07, 1.75] mm for MOGA calibrating model, [2.88, 5.95] mm for MN method, and [1.19, 4.83] mm for LM method. Besides, the composite errors both of LM method and MN method are approximately seven times higher that of MOGA calibrating model. It is suggested that the MOGA calibrating model is superior both to LM method and MN method.     

Dynamic response of large increased pressure wind tunnel rotor-gear coupling system with parallel misalignment

To study the misalignment of gear coupling, this paper analyzed the distortion of the tooth of gear coupling on the base of gear coupling ＇ s motion under parallel misalignment, and derived the specific expression of additive radial force, which produced by the rotor＇ torque. The motion differential equations of the large in- creased pressure wind tunnel rotor-gear coupling system were derived by the finite element method. Newmark integral method was applied to calculate the dynamic response of the system with parallel misalignment. The nu- merical results show that： under the effect of additive radial force, the static misalignment can arouse 2X frequency component lateral vibration; the dynamic misalignment can arouse2X,4X,6X multiple frequency components lateral vibration. The 2X frequency component is obvious. The additive radial force of the gear coupling can arouse lateral vibration with even multiple frequency components.     

空间机械臂姿态运动规划的粒子群方法

空间自由漂浮的航天器系统在忽略外力矩的作用时,系统因对总质心的角动量矩守恒而成为非完整系统.基于这样的特性,讨论了带双臂航天器姿态运动的控制问题.利用粒子群算法确定最优控制输入信号,得到了系统非完整运动的优化轨迹.通过数值仿真,表明该算法解决空间机械臂非完整运动规划问题是有效的.     

基于C空间分解—路标法的机械手路径规划

针对核反应堆检修用多关节机械手的路径规划问题,提出了一种基于C空间分解-路标法的路径规划算法.由于该机械手C空间维数较高,因此将整个C空间分解成2组低维子空间,分别基于子空间建立路标图,并扩充成整个C空间内的路标图,从而将路标图的搜索维数由六维转化为三维,降低了路标图的搜索空间.同时为进一步提高路标图的质量,采用自适应变步长法来选取路标节点,根据前两时刻机械手各关节点距障碍物距离的变化情况来决定下一路标点的选择.仿真结果表明该方法不仅缩短了在线实时规划的时间,而且提高了路径规划的成功率.     

具有大型天线的卫星姿态大角度机动解耦控制

为了解决卫星-天线系统的耦合动力学问题,利用一种三自由度驱动与测量机构连接天线臂与卫星平台并控制天线指向.通过该机构在卫星姿态控制系统中引入前馈控制来补偿反作用力矩,从而实现卫星平台与天线之间的解耦控制.在卫星姿态大角度机动条件下建立带有解耦机构的卫星-天线系统动力学模型.以该模型为基础设计姿态大角度机动的控制方案并进行仿真验证.仿真结果表明解耦控制方法将卫星姿态稳定度提高了两个数量级.解耦控制方法能大幅增加天线振动的阻尼,有效提高卫星稳定度.     

A robotic laparoscopic tool with enhanced capabilities and modularactuation

Due to the improved treatment outcomes, research on robotic MIS(Minimally Invasive Surgery) thrived in the past decades. A benchmark example is the da Vinci system that dominates robotic laparoscopy via its technology excellence and strong holding of intellectual properties. This study provides an alternative approach to realize robotic laparoscopic surgeries, by presenting the development and experimentation of the SMARLT(Strengthened Modularly Actuated Robotic Laparoscopic Tool) for MIS. A dual continuum mechanism is used in the design to achieve enhanced distal dexterity, improved reliability, increased payload capability, and actuation modularity. With kinematics modelling and actuation compensation, the SMARLT can be manipulated by a generic manipulator to carry out typical laparoscopic MIS tasks, such as tissue peeling, suturing, and knot tying. Payload capability was also experimentally characterized. The SMARLT-manipulator system essentially formed a continuum-rigid hybrid structure that makes full use of the advantages from each component: the continuum mechanism as a wrist for distal dexterity and other rigid parts for position accuracy and payload capability. With the experimental demonstration of the desired functionalities, the SMARLT design can lead to promising opportunities for commercialization.     

大容差多柔性透镜组结构优化设计

为使透镜的面形精度在复杂工作环境下满足光学系统要求,利用CAE设计了多透镜组镜头的透镜柔性支座结构,并对其几何位置进行参数优化.首先,通过对比透镜支撑结构常用材料和加工制作工艺,选取透镜支座材料,根据光学设计结果采用定心车加工工艺保证光轴的直线度;然后,选取一适合柔性结构形式并根据其中心对称特点初步设计柔性支座;最后,...     

大型铁路站房结构健康监测研究现状评述

铁路站房作为大型公共建筑,具有结构体系复杂、人流高度密集、使用年限长等特点,一旦结构失效,将会造成严重的社会影响。为了有效监测站房结构的健康状况,及时发现站房结构的损伤,最大程度地保障铁路站房的结构安全,有必要对铁路站房结构进行健康监测。结合大型铁路站房工程案例,总结大型铁路站房的组成和结构特点,介绍站房健康监测系统的组成,考虑施工和运营2个阶段,从屋面层、无柱雨棚和承轨层3个部分,分析大型铁路站房主要监测对象和监测内容,并指出健康监测在铁路站房结构应用中有待解决的问题,以期促进健康监测在大型铁路站房结构中的应用和发展。     

不同大变形等级下层理角度对层状软岩隧道的影响

为探究不同大变形等级下层理角度对层状软岩隧道的影响,依托九绵高速全线软岩大变形隧道,通过岩石力学试验确定遍布节理模型参数,基于数值模拟,探究不同软岩大变形等级（轻微、中等、强烈）下层理角度对层状软岩大变形隧道围岩及支护体系受力变形的影响,并通过现场统计的层理角度与大变形情况对数值模拟结果进行验证。结果表明：1）层理小角度（0°、15°）与大角度（90°）围岩变形、支护结构受力变形较大,随着大变形等级的增大,层理角度引起的围岩支护变化效果越明显。2）随着层理角度的增大,围岩变形从拱底逐渐转移到右拱腰。围岩变形主要发生在隧道轮廓与层理面相切位置,其中拱底及左拱脚对层理角度变化较敏感。3）初支应力偏向及节理塑性区大致与层理弱面法向一致,随着层理角度的增大,节理的剪切塑性区由拱顶、拱底转移到左拱脚、右拱肩,最终偏移到左右拱腰上下位置;相比初支压应力,初支拉应力对层理角度更敏感,垂直节理增大了张拉剪切破坏塑性区贯通的风险,但剪切破坏塑性区半径反而有可能减小。4）现场的统计规律表现为小角度与大角度大变形等级较高,层理角度为60°以下时,岩层破坏发生在拱腰及拱肩处,随着层理角度的增大,有向拱肩发展的...     

Thermodynamic analysis of a space station remote manipulator with a harmonic drive that considers an integrated thermal protection layer.

To eliminate anomalies and improve the performance of a space station remote manipulator(SSRM) used in a dynamically changeable thermal environment, we analyze the thermodynamic behavior of an SSRM that considers an integrated thermal protection system(ITPS). Solar radiative heat gain and loss become equally significant as conductive heat transfers through the interior of the SSRM on orbit. A thermodynamic model of the SSRM with a sandwich ITPS structure is established on the coupling between harmonic drive and changeable thermal environment. A motion precision is proposed to evaluate thermodynamic behavior under continuously changeable thermal circumstances. Simulation results indicate that the ITPS with a corrugated sandwich structure reduces the maximum amplitude of angular position errors to 41.6%, which helps improve the motion precision of the SSRM. The feasible regions for the SSRM in the Low Earth Orbit(LEO) and Geostationary Earth Orbit(GEO) are analyzed, which shows that the proportion of feasible region in LEO is significantly larger than that in GEO.     

Mapping of ionospheric parameters for space weather predictions: A concise review

Reviewing briefly the recent progress in a joint program of specifying the polar ionosphere primarily on the basis of ground magnetometer data, this paper emphasizes the importance of processing data from around the world in real time for space weather predictions. The output parameters from the program include ionospheric electric fields and currents and field-aligned currents. These real-time records are essential for running computer simulations under realistic boundary conditions and thus for making numerical predictions of space weather efficient as reliable as possible. Data from individual ground magnetometers as well as from the solar wind are collected and are used as input for the KRM and AMIE magnetogram-inversion algorithms, through which the two-dimensional distribution of the ionospheric parameters is calculated. One of the goals of the program is to specify the solar-terrestrial environment in terms of ionospheric processes and to provide the scientific community with more than what geomagnetic activity indices and statistical models indicate.     

大空间卷烟制丝车间烟气控制性能化设计

为分析某大空间卷烟制丝车间(长203.9 m,宽72 m,高16.7 m)防排烟设计效果,对其典型可燃物进行实体火灾实验,得到其热释放速率为41.1~98.0 kW/m2,确定其火灾模型为慢速发展的t2火.然后用性能化消防设计的方法、运用FDS火灾模拟软件对其进行数值模拟,结果显示在不同火灾场景下火灾发展到2 400 s时车间2 m高度以下烟气温度、CO浓度均能满足人员生命安全的性能指标,而能见度指标在2 000 s之后低于10 m.多台风机同时排烟是导致烟气较快弥漫的主要因素,高大空间工业建筑设计机械排烟系统时宜划分防烟分区,并考虑分时段分区域启动,划分防烟分区的挡烟垂壁高度不宜小于0.7 m.     

基于多区模型的大空间空调温度场数值模拟

大空间建筑室内空调温度场的数值模拟中,CFD模拟结果的可信度极大地取决于能量方程边界条件的合理设定．探讨了一种基于多区热质平衡模型的边界条件确定方法．在大空间多区热质平衡模型研究基础上,建立了各宏观“大控制体”内的热质平衡方程．模型综合了墙体热传导、壁面对流热交换、壁面之间长波辐射热交换以及内部控制体之间的对流热交换过程．计算得到的壁面温度与热流直接加载到CFD模型的能量方程中,从而实现边界条件的精确化．这种方法是CFD模拟的一种辅助手段．     

采用积分流形与观测器的并联机器人轨迹控制

针对含柔性杆件并联机器人在高速运行时其末端存在弹性位移问题,以3RRR并联机器人为研究对象,提出一种基于积分流形与高增益观测器的柔性并联机器人轨迹跟踪复合控制算法.基于刚度矩阵引入小参数,将刚柔耦合动力学模型转为慢速与快速两个子系统.针对慢速子系统,采用反演控制,实现对末端刚体运动的跟踪控制,同时为避免杆件弹性变形与振动组成的弹性位移对机器人末端轨迹的影响,推导校正力矩,实现对弹性位移的补偿.针对快速子系统,采用滑模变结构控制,保证流形成立.为避免对曲率变化率的直接测量,引入高增益观测器对其进行估计.采用Lyapunov稳定性原理证明系统整体稳定性,并给出小参数上界.对提出的复合控制算法与奇异摄动及基于刚体动力学的反演控制算法进行仿真,从机器人末端振动抑制与轨迹跟踪性能两方面进行对比,验证了本文所提算法的控制效果.     

A review of structures,verification, and calibration technologies of space robotic systems for on-orbit servicing

Recently, with the rapid development of aerospace technology, an increasing number of spacecraft is being launched into space.Additionally, the demands for on-orbit servicing(OOS) missions are rapidly increasing. Space robotics is one of the most promising approaches for various OOS missions; thus, research on space robotics technologies for OOS has attracted increased attention from space agencies and universities worldwide. In this paper, we review the structures, ground verification, and onorbit kinematics calibration technologies of space robotic systems for OOS. First, we systematically summarize the development of space robotic systems and OOS programs based on space robotics. Then, according to the structures and applications, these systems are divided into three categories: large space manipulators, humanoid space robots, and small space manipulators.According to the capture mechanisms adopted, the end-effectors are systematically analyzed. Furthermore, the ground verification facilities used to simulate a microgravity environment are summarized and compared. Additionally, the on-orbit kinematics calibration technologies are discussed and analyzed compared with the kinematics calibration technologies of industrial manipulators with regard to four aspects. Finally, the development trends of the structures, verification, and calibration technologies are discussed to extend this review work.     

底层大空间剪力墙结构中框支柱弹塑性稳定性试验研究及理论分析

通过对三榀“π”型试件的试验研究，确认ＲＣ底层大空间剪力培结构中，框支柱在满足设计规范要求的情况下，仍存在失稳破坏的可能性，并提出了弹塑性稳定性分析方法。