Failure treatment strategy and fault-tolerant path planning of a space manipulator with free-swinging joint failure

Aiming at a space manipulator with free-swinging joint failure, a failure treatment strategy and fault-tolerant path planning method is proposed in this paper. This method can realize failure treatment of a space manipulator with free-swinging joint failure through determination of the optimal locked joint angle and dynamics model reconfiguration. Fault-tolerant path planning is realized by the establishment of the degraded workspace with integrated kinematics performance (DWWIKP) and an improved A-Star (A1) algorithm. This paper has the following contributions. The determination of the optimal locked joint angle can ensure that the manipulator is able to continue follow-up tasks while maximizing the workspace of the manipulator after locking the fault joint. Underactuated control of a high degree-of-freedom (DOF) manipulator can be effectively solved through dynamics model reconfiguration. The analysis process of the dynamics coupling relationship can be applied to cases where the active joint and the passive joint are parallel or perpendicular to each other. The establishment of the DWWIKP can demonstrate the kinematics performance of the manipulator in both joint space and operation space comprehensively. The improved A1 algorithm based on the integrated kinematics performance index (IKPI) can search a fault-tolerant task trajectory that satisfies the requirements of reachability and the overall kinematics performance simultaneously. The method proposed in this paper is verified by a 7-DOF manipulator, and it is available to any DOF manipulator with free-swinging joint failure.     

基于拉格朗日插值法的ATS射频信号衰减修正研究

对自动测试系统中射频信号通路的衰减修正进行了研究。为解决现有修正方法操作复杂、后期维护困难的问题,提出了基于拉格朗日插值的方法来实现射频信号衰减的修正,在保证修正数据准确度的前提下既减少了修正的工作量又降低了系统后期维护的难度,并通过算例和验证了该方法的可行性。     

Scientific Objectives and Payloads of Chinese First Mars Exploration

China plans to implement the first Mars exploration mission in 2020. It will conduct global and comprehensive exploration of Mars and high precision and fine resolution detection of key areas on Mars through orbiting, landing and roving. The scientific objectives include studying the Martian morphology and geological structure characteristics, studying the soil characteristics and the water-ice distribution on the Martian surface, studying the material composition on the Martian surface, studying the atmosphere ionosphere and surface climate and environmental characteristics of Mars, studying the physical field and internal structure of Mars and the Martian magnetic field characteristics. The mission equips 12 scientific payloads to achieve these scientific objectives. This paper mainly introduces the scientific objectives, exploration task, and scientific payloads.      

控制力矩陀螺驱动空间机器人的角动量平衡控制

针对V构型控制力矩陀螺(CMGs)驱动的冗余空间机器人的CMGs角动量饱和问题,提出一种角动量平衡控制方法。该方法从平衡使用机械臂各臂杆CMGs角动量的思想出发,定义了角动量平衡指标,并使用加速度分解技术和逆动力学方法设计了角动量平衡控制器。该控制器可在保证机械臂跟踪工作空间轨迹的同时,利用机械臂的空转运动使得角动量平衡指标尽量减小,即各臂CMGs的角动量使用趋于平均,从而降低某些臂杆的CMGs先行饱和的可能性,充分利用CMGs的控制能力。基于平面三自由度冗余机械臂的数值仿真结果验证了所设计的控制器的有效性。     

月面巡视探测器任务规划顶层设计与实现

针对巡视器月面任务规划工程的可实现性,开展了巡视器任务规划顶层设计方法的研究,主要内容包括:任务规划技术特点的梳理与归纳;任务规划输入条件与约束条件的整理,规划变量的统一;任务规划框架的设计,巡视器行为序列与上行控制指令的衔接,针对巡视器行为序列的大模式套用小模式的动态设计等。通过巡视器任务规划工程实现的介绍,说明在巡视器任务规划的顶层设计中,任务的不确定性、部分约束与输入信息的模糊性,是任务规划框架设计以及在后续工程实现过程中需要重点考虑的内容,是与任务规划的工程可实现性直接相关的。     

跨音速压气机转子内三维流场数值模拟

采用多步Runge-Kutta与有限差分相结合的格式,离散叶轮机械内三维欧拉方程,应用代数法生成了压气机转子三维网格。用此方法模拟了NASA Rotor37跨音速压气机转子流场,计算得到的流场与试验结果进行了对比。结果表明,该方法收敛速度快,实用可行,计算简单省时。并且,该方法为研究叶轮机械内部流场计算提供了很好的基础。在此基础上进行更深层次的研究会变得很容易。     

控制力矩陀螺群奇异角动量超曲面仿真分析

用角动量超曲面仿真分析了控制力矩陀螺构型奇异的产生机理。基于控制力矩陀螺群动力学总角动量和输出控制力矩,讨论了典型构型奇异存在的状况,并确定了奇异点存在的判断依据,对五棱锥构型的显奇异和隐奇异进行了角动量超曲面仿真,发现能通过零运动脱离奇异状态的隐奇异点,为控制力矩陀螺群的操纵律设计提供了重要依据。控制系统数学仿真结果表明该分析法有效。     

月球车全局路径规划中的A＊算法改进

考虑月球车全局路径规划的应用要求,针对传统A＊算法搜索速度慢和返回路径不够优化的缺点,对算法流程进行改进,减少其时间和空间复杂度,提高其搜索速度,并对返回路径进行优化,有效地缩短了路径。对于存在凹形障碍的地图,采用后退一尝试的方法解决规划失败的问题,并在一次搜索的基础上使用二次搜索策略来实现规划路径的优化,使之绕过凹形障碍趋向目标,从而达到输出最短路径的目的。     

基于虚拟现实的空间机器人遥操作在维护作业中的应用

研究了变时延遥操作环境下的预测仿真技术、基于虚拟现实的机器人遥操作系统组成、遥操作系统的自主学习技术和虚拟操作环境建模技术。开发了基于虚拟现实的机器人遥操作演示系统和自学习功能。实现了基于虚拟现实的临场感遥操作,在5～8s模拟时延条件下完成了推开故障太阳翼,擦拭受污染的镜头和拉动调整出现故障的卫星天线等作业。