Bionic Attitude Transformation Combined with Closed Motion for a Free Floating Space Robot

In order to realize the small error attitude transformation of a free floating space robot,a new method of three degrees of freedom（ DOF） attitude transformation was proposed for the space robot using a bionic joint. A general kinematic model of the space robot was established based on the law of linear and angular momentum conservation. A combinational joint model was established combined with bionic joint and closed motion. The attitude transformation of planar,two DOF and three DOF is analyzed and simulated by the model,and it is verified that the feasibility of attitude transformation in three DOF space. Finally,the specific scheme of disturbance elimination in attitude transformation is presented and simulation results are obtained.Therefore,the range of application field of the bionic joint model has been expanded.

AN IMPROVED ROTATION VECTOR ATTITUDE ALGORITHM FOR LASER STRAP-DOWN INERTIAL NAVIGATION SYSTEM

The laser gyro is most su it able for building the strap down inertial navigation system (SINS), and its acc uracy of attitude algorithm can enormously affect that of the laser SINS. This p aper develops three improved algorithmal expressions for strap down attitude ut ilizing the angular increment output by the laser gyro from the last two and cur rent updating periods according to the number of gyro samples, and analyses the algorithm error in the classical coning motion. Compared with the conventional algorithms, simulational results show that this improved algorithm has higher precision. A new way to improve the rotation vector algorithms is provided.

Integrated modeling of spacecraft relative motion dynamics using dual quaternion

To realize high accurate control of relative position and attitude between two spacecrafts, the coupling between position and attitude must be fully considered and a more precise model should be established. This paper breaks the traditional divide and conquer idea, and uses a mathematical tool, namely dual quaternion to establish the integrated 6 degree-of-freedom(6-DOF) model of relative position and attitude, which describes the coupled relative motion in a compact and efficient form and needs less information of the target. Considering the complex operation rules and the unclarity of the current relative motion model in dual quaternion, necessary mathematical foundations are given at first, followed by clear and detailed modeling process and analysis. Finally a generalized proportion-derivative(PD) controller law is designed. The simulation results show that based on the integrated model established by dual quaternion, this control law can achieve a high control accuracy of relative motion.

Attitude control of spacecraft during propulsion of swing thruster

As for orbit transfer vehicle (OTV) with multiple satellites/payloads carried,the release of each payload will bring serious change to the mass center of OTV and the thrust produced by the swing thruster will form a rather large disturbance to the attitude of OTV. Steering the nozzle to track the estimated center of mass (ECM) of OTV can reduce but not remove the disturbance due to the difference between the ECM and the practical mass center (PCM) of OTV. The practical propelling direction will change with the internal motion during the propulsion process and attitude control system should be enabled to guarantee that the propelling direction is collinear with the command. Since the structural parameters have changed,which is due to internal motion and fuel consumption,the dynamic model have to be formulated to determine these time-varying parameters and the required attitude of OTV should be determined as well. Modulating attitude quaternion results in quasi Euler angles. Based on the resulting quasi Euler angles,a novel attitude switching control law is introduced to control the variable-mass OTV. Simulation results show that,even in the case of structural asymmetry,control torque matrix asymmetry,attitude disturbance and strong coupling between the channels,the attitude of OTV can be controlled perfectly,and the proposed attitude control law is effective for the variable-mass OTV with swing thruster.

Coordinated motion planning algorithm for multi-arm free flying space robot system

The motion planning problem of a free flying space robot (FFSR) is investigated and from the attitude disturbance characteristics of a multi arm FFSR, a new method based on the fixed attitude restricted (FAR) Generalized Jacobian Matrix of a multi arm FFSR is proposed to enable the coordinated motion of all the other arms while one arm is tracing a given path so that there is no disturbance on the body, and the problem of attitude disturbance with an operating multi arm FFSR is thereby better resolved. The simulation run with a dual arm FFSR system verifies the effectiveness of this algorithm.

MODEL OF CENTRIFUGAL EFFECT AND ATTITUDEMANEUVER STABILITY OF A COUPLEDRIGID-FLEXIBLE SYSTEM

The influences of nonlinear centrifugal force to large overall attitude motion of coupled rigid-flexible system was investigated. First the nonlinear model of the coupled rigid-flexible system was deduced from the idea of “centrifugal potential field', and then the dynamic effects of the nonlinear centrifugal force to system attitude motion were analyzed by approximate calculation; At last, the Lyapunov function based on energy norm was selected, in the condition that only the measured values of attitude and attitude speed are available, and it is proved that the PD feedback control law can ensure the attitude stability during large angle maneuver.

Micro-Doppler effect testing technique for attitude of projectile in space flight

To measure projectile attitude in space flight, based on continuous wave （CW） radar, a new micro-Doppler effect testing technique is developed in this paper. It also establishes radar testing model for attitude of flying projectile and resolve micro-Doppler effect of projectile motion attitude. By distinguishing and geting attitude parameters such as micro-motion period, this technique can in- tuitively estimate the flight stability of projectile, and the validity of this technique is proved accord- ing to flight tests.

Research on the Motion Track of Ocean Towing System

In this paper, a method for predicting the position of towline is presented. The location of the finite node is determined by installing fixed spaced attitude sensors in towline arrays, then the appropriate objective functions are selected for water depth profile and course profile respectively, and the interpolation fitting method is combined with the determined predicted positions. Through the hydrodynamic analysis of the existing towing cable’s underwater motion, the position of the towing cable under the steady state motion is obtained as the reference basis, and two methods are put forward, which are improved spline interpolation method, polynomial fitting method and multivariate nonlinear regression analysis. In the case of steady state motion, the two methods are compared and compared with the hydrodynamic simulation results. Finally, a more suitable method is selected as the basis of cable location inversion and applied to deep-sea towing operations.

多矢量姿态测量算法研究综述

将矢量测量转化为姿态测量,该问题在姿态估计中被称为Wahba问题。介绍了最小化Wahba问题的损失函数的不同算法,包括最优四元数估计器(ESOQ)、四元数估计器(QUEST)、快速最优姿态矩阵(FOAM)、矩阵的奇异值分解(SVD)等广泛使用的算法,以及基于快速线性四元数姿态估计器(FLAE)、黎曼流形等近年来提出的算法。给出了简单的计算原理与推导过程,并通过计算机仿真对照,归纳各类算法在计算旋转矩阵时的计算精度、鲁棒性。针对姿态测量算法应对当前应用场景的性能需求,简要介绍其在惯性测量单元(IMU)动态对准、协同集群视觉定姿、图像拼接等方面的适用可能和工作原理,并在此基础上简述了姿态测量算法当前的缺陷与未来的发展趋势。

基于CNN-GRU模型的USV运动姿态多步预测方法

针对单一模型在预测无人水面艇(Unmanned Surface Vessel,USV)运动姿态时精度不高的问题,提出一种基于卷积神经网络(CNN)和门控循环单元(GRU)的USV姿态多步预测模型。首先,使用滑动窗口法构造运动姿态数据集作为模型输入;然后,使用CNN模块挖掘时序数据的局部特征;最后,使用GRU模型进行多步预测。使用实测USV运动姿态数据进行预测实验,实验结果表明,该模型比XGBoost模型、单一LSTM模型和单一GRU模型具有更高的预测精度,各项评价指标表现更佳,具有重要的应用价值。

不同气囊压力气垫船空投入水研究

为保证气垫船在特殊情况的应用,对气垫船空投入水进行研究。应用Abaqus有限元分析软件对气垫船气囊建立空气弹簧模型,对气囊不同气压时气垫船入水过程的运动特性和姿态变化进行仿真分析。结果表明:气囊的运动因空气弹簧存在的原因较底板更为剧烈;气囊气压在0.2~0.3 MPa间的运动特性几乎一致,小于0.2 MPa时气囊的弹性势能较小,速度衰减较慢,入水后吃水更深;气囊气压在0.15~0.3 MPa内,气垫船入水的姿态由前倾变为后倾,气压为0.2 MPa时,气垫船入水全程的姿态变化不大。总的来说,气垫船气囊压力为0.2 MPa时入水运动特性较好,姿态始末变化不大。

船舶坐底运动姿态监测系统研发及应用

在船舶坐底过程中需要重点关注船舶的运动姿态变化,以便及时对船舶状态做出调整,保障船舶坐底安全。针对船舶坐底过程,自主研发了运动姿态监测系统,对船舶的六自由度姿态、三轴速度、三轴加速度、船舶四个角点的垂向速度和船底距海床的距离等参数进行监测。结果表明:运动姿态监测系统在船舶坐底过程中能够实时监测船舶运动姿态关键参数变化情况并进行安全提示,实现了对船舶坐底运动姿态的全程监测功能。

基于前端开发框架的舰船运动姿态数据监测系统

利用运动姿态监测结果为舰船可靠航行提供决策依据。为此,设计了基于前端开发框架的舰船运动姿态数据监测系统。系统设施层中,利用MEMS陀螺仪芯片与3轴MEMS加速度计采集舰船运动姿态信息,并将所采集信息传送至业务逻辑层;业务逻辑层利用控制子层和管理子层为用户提供姿态数据监测服务;控制子层中的姿态解算模块,依据传感器信息采集结果,利用卡尔曼滤波算法解算舰船运动姿态信息。基于此,利用Bootstrap的前端开发框架,通过viewport元数据标签完成前端UI设计,为用户提供可视化的人机交互界面,将姿态解算结果利用用户界面层为用户展示。测试结果表明,该系统对舰船航行运动姿态的监测结果与实际结果极为接近,适用于实际工作。

高动态姿态测量圆锥误差补偿算法改进及实时性分析

弹丸圆锥运动会对制导系统产生严重的控制干扰,为了补偿该误差,分析了一种新的圆锥误差补偿算法,以提高弹载姿态控制系统在高动态运动环境下的解算精度和实时性。结合四元数四阶龙格-库塔法和三子样等效旋转矢量法,利用修正型罗德里格斯参数改进基于角增量输出的三子样四元数姿态算法,推导相应的微分方程表达式,建立三子样四元数改进算法姿态求解数学模型。仿真结果表明,与传统圆锥误差补偿算法相比,改进算法能更有效的补偿圆锥误差,平均解算精度提高了约17.32%,减少了高动态环境下的计算量,实时性提升了约22.54%。

一种面向限制性三体问题的轨道-姿态运动模态构建方法

针对平动点附近的具有强非线性和耦合性的轨道-姿态动力学机理分析,以及如何利用其动力学特性完成相关任务操作等问题,提出了基于Floquet理论的轨道-姿态运动模态构建方法,并探讨了所构建模态的典型应用。首先,在平动点轨道-姿态周期解的基础上,对轨道-姿态状态转移矩阵进行分块,根据分块矩阵特征值特点,建立了姿态模态和姿轨耦合模态,与轨道模态共同构成完整的轨道-姿态运动模态。然后,对模态特性进行了相空间分析。最后,以平动点相对轨道-姿态运动解析、平动点轨道-姿态稳定性控制和平动点轨道附近姿轨编队设计为应用案例,相应数值仿真表明了所提出模态的正确性,以及在典型航天任务设计与控制中的应用价值。

轴对称矢量喷管运动学建模及运动轨迹分析

轴对称矢量喷管为复杂的空间多链路机构,是推力矢量技术的核心。为研究其运动规律,将空间机构位置分析法、解析几何法和环路矢量法相结合,建立了轴对称矢量喷管的空间运动学模型。利用数值仿真实现了其运动姿态的仿真,并通过与ADAMS仿真结果对比,验证了该模型的正确性,进而获得轴对称矢量喷管在不同驱动方式下的位姿以及喉口和喷口的面积变化规律。结果表明:喉口状态和喷管运动状态对喷管面积比均有影响,面积比随着A9作动筒的同步伸长呈明显单调递增状态;A9作动筒异步驱动时,喷管面积比变化较小,喷口矢量偏转角角速度与作动筒运动速度呈比例关系,截面形状由圆形逐渐变为空间上扭曲的椭圆形;拉杆尺寸对喷管机构的面积比变化范围有明显影响,拉杆每增大(或减小)1 mm,面积比变化区间整体上移(或下移)0.025。仿真结果有助于了解喷管的运动规律,可为喷管的参数化分析及优化设计提供理论依据。

基于运动约束的航姿系统误差自主补偿方法

为了提高车载捷联航姿系统的长航时定姿精度,提出利用载车的运动约束条件对航姿系统误差进行在线自主补偿。首先,对航姿系统的传感器误差、安装误差等进行分析与建模,选取航姿系统的各项误差作为误差补偿滤波的系统状态,建立系统状态方程。然后,根据发射车等特种车辆的运动特点,利用车辆运动约束条件,将载车行驶过程中航姿系统的速度输出在车体坐标系横向和垂向上的投影分量作为误差补偿滤波的量测,推导获得误差补偿滤波的量测方程。最后,采用卡尔曼滤波设计航姿系统误差在线估计算法。实验结果表明,所提方法能够自主有效地补偿航姿系统的积累误差,经过1200 s的跑车实验,系统的航姿误差始终保持有效收敛,其中航向精度优于3.4′,水平姿态精度优于0.4′。

基于Unity3D与MEMS惯性感知的运动监测系统设计

目的/意义构建人体模型,与实际人体运动数据绑定,实现对人体运动姿态的监测。方法/过程设计一种基于Unity3D和MEMS惯性传感器的运动监测系统。利用MEMS惯性传感器获取人体的运动姿态数据,利用欧拉角进行姿态解算,通过蓝牙无线传输协议将数据发送到计算机系统,以驱动虚拟动画人物的运动,实现人体动作的3D姿态实时展现。结果/结论经过实验测试,该模型能够准确监测和模拟人体的运动姿态,未来可为体育运动训练、肢体康复训练等应用领域提供有效的数据分析。

基于长时跟踪的滑雪教学姿态辅助矫正方法

在滑雪教学过程中,由于学员的迅速移动和姿态的大幅变化,导致以短时智能图像变化特征为主的姿态跟踪算法失效或不稳定,特别是在雪地条件恶劣或光线不足等复杂环境下,跟踪效果会受到较大的影响。为此,提出基于长时跟踪的滑雪教学姿态辅助矫正方法。使用递归最小二乘法(RLS)分类器训练得到学员姿态位置核相关滤波器(KCF)。计算最大的KCF响应值,精确检测学员的姿态位置。如果KCF结果低于经验阈值,表明目标丢失,启动再检测模块。利用光流法在前一帧学员姿态位置附近寻找当前帧中的姿态位置,以获取一个大致位置。在此位置重新应用跟踪器,获得精确的学员姿态位置,实现长时跟踪。依据得到的姿态位置数据,构建滑雪学员姿态误差补偿模型,提取学员身体的运动参数和姿态误差。通过计算身体运动参数,并结合KCF构建滑雪学员身体姿态辅助矫正模型,从而完成滑雪教学的姿态辅助矫正。实验结果表明,该方法在长时跟踪中展现出高度的有效性、可靠性和稳定性,其平均PCK指标达到92.3%,同时在目标跟踪效率上,参数量和计算量分别为30.24 MB和9.26 GFLOPs,速度达到142帧/s,实现了高效实时的跟踪,验证了该方法在滑雪教学姿态辅助矫正中的可行性。

管道机器人过T型管垂直爬坡动态性能分析

为进一步了解复杂管道的内部环境,设计一种全驱动轮式管道机器人。通过坐标旋转法,分析管道机器人通过T型管垂直爬坡时的姿态调整过程与运动状态变化,运用ADAMS动力学分析软件,分析管道机器人通过T型管时各驱动轮的受力情况和驱动轮质心运动速度变化。研究发现管道机器人通过T型管时,其各驱动轮先后经历悬空状态并失去管壁支撑,4个驱动轮与管壁的接触力总的变化趋势均是先减小到0 N,然后随着驱动轮与管壁发生接触碰撞,接触力迅速增大,幅值超过其稳态值;前后2个驱动模块的驱动轮质心运动速度不同,前驱动模块驱动轮质心运动速度变化规律为类似正弦变化,后驱动模块由于接触碰撞,上部驱动轮与管壁发生打滑,驱动轮运动速度先轻微增大后迅速减小。研究结果为管道机器人的结构设计提供参考。