Motion stable control for cable-driven parallel camera robots with high speeds

A method for motion stability control is proposed on the problem that it is difficult for the camera robot to achieve the high speed and steady movement. First, the dynamic model is established. Then, the trajectory of the camera robot to the stable tracking of high maneuverability target is planned. And, high order polynomial interpolation is performed to improve the stability of the start and stop motion for the camera platform. Furthermore, a hybrid controller based on the PD feed forward controller and disturbance observer is designed in order to achieve stable motion. Finally, the rapid turning motion is discussed by numerical simulation, and the validity of the proposed method is verified.     

超机动非线性自抗扰反演控制律设计

为提升建模不确定性下的超机动飞行控制性能,提出一种基于自抗扰反演的超机动非线性控制律设计方法.建立了具有大迎角特性的飞机六自由度非线性模型,通过由前至后递推的设计思想,逐步迭代设计Lypaunov函数与虚拟的控制输入量,实现强非线性飞机对象的控制.对建模不确定性给超机动控制性能带来的影响,将自抗扰控制方法中的扩张状态观测器与反演控制方法相结合,利用扩张状态观测器不依赖系统模型的特点,实时观测并补偿建模误差对飞行控制的影响.超机动数字仿真结果表明:所设计的超机动非线性控制律能够实现大迎角控制,在40%建模误差的影响下,迎角响应仍平滑稳定.基于自抗扰反演的超机动非线性控制方法具有优异的大迎角机动飞行控制性能.     

美国“快速全球打击”计划探讨与启示

美国"快速全球打击(prompt global strike,PGS)"计划是美国为适应其新时期军事转型,提高其远程打击能力,在本土从空间或通过空间(包括临近空间)对全球实施快速常规打击而开展的。介绍了"快速全球打击"计划由来、武器系统的现状和整个计划的趋势,并针对美国发展该计划所引发的思考,以及对我国发展军事航天研究的启示进行了阐述。     

Effectiveness-based orbital optimization for servicing spacecraft

Effectiveness-based system development is an essential technology developing concept advanced by some countries,such as the U.S.A.Making use of Analytic Hierarchy Process,this paper brings forward a methodology for orbital optimization based on effectiveness in the case of the orbital deployment for the Servicing Spacecraft(SSC),which needs to accomplish many types of tasks and whose orbit is affected by kinds of factors with contradictions in orbital parameter selection.Firstly,the possible tasks of SSC are decomposed and their degrees of importance are given by the times,probabilities,values of their applications.Then,the supporting capabilities are discussed from the viewpoint of orbit design,and the determination of their weights is put forward.Finally,the relationships between the orbital parameters and the effectiveness are established by using effective function,and three synthesizing methods for a single task and its capabilities are presented.     

Adaptive variable structure control based on backstepping for spacecraft with reaction wheels during attitude maneuver

An adaptive variable structure control method based on backstepping is proposed for the attitude maneuver problem of rigid spacecraft with reaction wheel dynamics in the presence of uncertain inertia matrix and external disturbances. The proposed control approach is a combination of the backstepping and the adaptive variable structure control. The cascaded structure of the attitude maneuver control system with reaction wheel dynamics gives the advantage for applying the backstepping method to construct Lyapunov functions. The robust stability to external disturbances and parametric uncertainty is guaranteed by the adaptive variable structure control. To validate the proposed control algorithm, numerical simulations using the proposed approach are performed for the attitude maneuver mission of rigid spacecraft with a configuration consisting of four reaction wheels for actuator and three magnetorquers for momentum unloading. Simulation results verify the effectiveness of the proposed control algorithm.     

机动目标断裂航迹粘连

针对目标跟踪系统中由于目标机动产生的断裂航迹,提出了量测缺失下的航迹粘连算法和有量测情况下的航迹粘连算法.首先,对新起始的航迹进行平滑处理.然后,利用转弯模型对断裂航迹进行外推,针对无量测情况,采用UT对转弯角速率进行估计;针对有量测情况,采用期望极大化的策略对目标状态及转弯角速率进行迭代优化.通过蒙特卡洛仿真验证了该方法能有效提高航迹连续性,减少虚假航迹数,降低目标状态估计误差.     

蒸汽发生器泵压供水方式试验研究

通过介绍国内外蒸汽发生器泵压技术的现状,说明泵压增压方式是大流量蒸汽发生器推进剂供应的发展趋势.提出一种蒸汽发生器水供应系统泵压增压方案,包括其组成、工作原理和控制方法,并在自行研发的大流量蒸汽发生器上进行冷调和点火试验.最后与挤压供水试验结果相比较,结果表明所提方法正确、有效.     

The role of navigation instruction at intersections for older drivers and those with early Alzheimer’s disease

AimsOur purpose was to explore the effect of navigation instruction on older drivers’ driving performance at left turn intersections. Left turns at intersections are particularly complex because they require many perceptive and cognitive abilities under considerable time pressure.MethodsFifty-four participants were recruited: 18 drivers with early-stage Alzheimer’s disease (AD), 18 neurologically healthy older drivers and 18 younger individuals. Various cognitive processes were measured, and 9 left turn maneuvers with or without navigation instruction were evaluated during an in-traffic road test. The psychomotor, planning and decision-making components involved in left turn were also analyzed closely.ResultsOnly older drivers (both healthy drivers and those with AD) were negatively affected by navigation instruction during the maneuver. The planning and decision-making components were more likely to be affected by the navigation instruction.ConclusionThis finding highlights the importance of carefully considering the use of navigation instructions when developing navigation systems. Adapting this instruction is necessary to simplify our understanding of the real-world driving environment and to avoid increasing the cognitive load of older drivers.     

用于机动目标跟踪的分段机动识别方法

分段轨迹识别方法是一种将目标轨迹分成若干段曲线,对每一段曲线进行参数估计进而估计目标状态的跟踪方法.基于分段轨迹识别方法提出了一种分段机动识别方法,使之能够适用于更多的目标机动类型.针对速度变化的目标,提出了新的曲线参数描述的模型以及新的优化跟踪性能的代价函数,改进了判断分段结束的条件以及起始新分段的方法.仿真结果表明:分段机动识别方法在稳态性能不变的情况下,能够更好地跟踪加减速目标;同时,分段机动识别方法对于高度机动目标的跟踪性能和准确构造的交互多模型算法相似,且远优于匀速直线运动模型下的卡尔曼滤波器.     

在轨服务多脉冲远程机动轨道设计与误差分析

针对在轨服务任务对远程机动轨道设计和机动误差展开研究,提出了服务航天器初始停泊轨道的部署原则,采用多脉冲远程机动策略设计了远程机动轨道,在此基础上对如项非球形摄动和大气阻力摄动影响下的服务航天器远程机动轨道进行误差分析,并与双脉冲机动进行了比较,仿真结果表明,在轨服务任务对时间要求不严格时,多脉冲机动优于双脉冲机动,从摄动误差方面考虑调整轨道高度的机动脉冲数为奇数次为宜。