Analysis of coordinate time series of DORIS stations on Eurasian plate and the plate motion based on SSA and FFT

This study focuses on analyzing the time series of DORIS beacon stations and plate motion of the Eurasian plate by applying Singular Spectrum Analysis(SSA)and Fast Fourier Transform(FFT).First,the rend terms and periodic signals are accurately separated by SSA,then,the periodic seasonal signals are detected using SSA,and finally,the main components of the time series are reconstructed successfully.The test results show that the nonlinear trends and seasonal signals of DORIS stations are detected successfully.The periods of the seasonal signals detected are year,half-year,and 59 days,etc.The contribution rates and slopes in E,N,and U directions of the trend items of each beacon station after reconstruction are obtained by least-square fitting.The velocities of these stations are compared with those provided by the GEODVEL2010 model,and it is found that they are in good agreement except the DIOB,MANB,and PDMB stations.Based on the DORIS coordinate time series,the velocity field on the Eurasian plate is constructed,and the test shows that the Eurasian plate moves eastward as a whole with an average velocity of 24.19±0.11 mm/y in the horizontal direction,and the average velocity of it is1.74±0.07 mm/y in the vertical direction.

Motion Planning Based Coordinated Control for Hydraulic Excavators

Hydraulic excavator is one type of the most widely applied construction equipment for various applications mainly because of its versatility and mobility. Among the tasks performed by a hydraulic excavator, repeatable level digging or flat surface finishing may take a large percentage. Using automated functions to perform such repeatable and tedious jobs will not only greatly increase the overall productivity but more importantly also improve the operation safety. For the purpose of investigating the technology without loss of generality, this research is conducted to create a coordinate control method for the boom, arm and bucket cylinders on a hydraulic excavator to perform accurate and effective works. On the basis of the kinematic analysis of the excavator linkage system, the tip trajectory of the end-effector can be determined in terms of three hydraulic cylinders coordinated motion with a visualized method. The coordination of those hydraulic cylinders is realized by controlling three electro-hydraulic proportional valves coordinately. Therefore, the complex control algorithm of a hydraulic excavator can be simplified into coordinated motion control of three individual systems. This coordinate control algorithm was validated on a wheeled hydraulic excavator, and the validation results indicated that this developed control method could satisfactorily accomplish the auto-digging function for level digging or flat surface finishing.

Terminal sliding mode control for coordinated motion of a space rigid manipulator with external disturbance

The control problem of coordinated motion of a free-floating space rigid manipulator with external disturbance is discussed. By combining linear momentum conversion and the Lagrangian approach, the full-control dynamic equation and the Jacobian relation of a free-floating space rigid manipulator are established and then inverted to the state equation for control design. Based on the terminal sliding mode control （SMC） technique, a mathematical expression of the terminal sliding surface is proposed. The terminal SMC scheme is then developed for coordinated motion between the base＇s attitude and the end-effector of the free-floating space manipulator with external disturbance. This proposed control scheme not only guarantees the existence of the sliding phase of the closed-loop system, but also ensures that the output tracking error converges to zero in finite time. In addition, because the initial system state is always at the terminal sliding surface, the control scheme can eliminate reaching phase of the SMC and guarantee global robustness and stability of the closed-loop system. A planar free-floating space rigid manipulator is simulated to verify the feasibility of the proposed control scheme.

Adaptive neural network control for coordinated motion of a dual-arm space robot system with uncertain parameters

Control of coordinated motion between the base attitude and the arm joints of a free-floating dual-arm space robot with uncertain parameters is discussed. By combining the relation of system linear momentum conversation with the Lagrangian approach, the dynamic equation of a robot is established. Based on the above results, the free-floating dual-arm space robot system is modeled with RBF neural networks, the GL matrix and its product operator. With all uncertain inertial system parameters, an adaptive RBF neural network control scheme is developed for coordinated motion between the base attitude and the arm joints. The proposed scheme does not need linear parameterization of the dynamic equation of the system and any accurate prior-knowledge of the actual inertial parameters. Also it does not need to train the neural network offline so that it would present real-time and online applications. A planar free-floating dual-arm space robot is simulated to show feasibility of the proposed scheme.

Structure design and coordinated motion analysis of bionic crocodile robot

Crocodiles,one of the oldest and most resilient species on Earth,have demonstrated remarkable locomotor abilities both on land and in water,evolving over millennia to adapt to diverse environ-ments.In this study,we draw inspiration from crocodiles and design a highly biomimetic crocodile robot equipped with multiple degrees of freedom and articulated trunk joints.This design is based on comprehensive analysis of the structural and motion characteristics of real crocodiles.The bionic crocodile robot has a problem of limb-torso incoordination during movement.To solve this problem,we used the D-H method for both forward and inverse kinematics analysis of the robot's legs and spine.Through a series of simulation experiments,we investigated the robot's motion stability,fault tolerance,and adaptability to environments in two motor patterns:with and without spine and tail movements.The experimental results show that the bionic crocodile robot exhibits superior motion performance when the spine and tail cooperate with the extremities.This study not only demonstrates the potential of biomimicry in robotics but also underscores the significance of understanding how nature's designs can inform and enhance technological innovations.

Case Studies on an Approach to Multiple Autonomous Vehicle Motion Coordination

This paper conducts a series of case studies on a novel Simultaneous Path and Motion Planning (SiPaMoP) approach [1] to multiple autonomous or Automated Guided Vehicle (AGV) motion coordination in bidirectional networks. The SiPaMoP approach plans collision-free paths for vehicles based on the principle of shortest path by dynamically changing the vehicles’ paths,traveling speeds or waiting times,whichever gives the shortest traveling time. It integrates path planning,collision avoidance and motion planning into a comprehensive model and optimizes the vehicles’ path and motion to minimize the completion time of a set of tasks. Five case studies,i.e.,head-on collision avoidance,catching-up collision avoidance,buffer node generation and collision avoidance,prioritybased motion coordination,and safety distance based planning,are presented. The results demonstrated that the method can effectively plan the path and motion for a team of autonomous vehicles or AGVs,and solve the problems of traffic congestion and collision under various conditions.

Coordinating control of multiple rigid bodies based on motion primitives

This paper studies the problem of coordinated motion generation for a group of rigid bodies. Two classes of coordinated motion primitives, relative equilibria and ma- neuvers, are given as building blocks for generating coordi- nated motions. In a motion-primitive based planning frame- work, a control method is proposed for the robust execution of a coordinated motion plan in the presence of perturba- tions. The control method combines the relative equilibria stabilization with maneuver design, and results in a close- loop motion planning framework. The performance of the control method has been illustrated through a numerical sim- ulation.

Dual-manipulator Coordinate Motion Planning Scheme for Robot Satellite

A scheme of dual-manipulator coordination motion planning for robot satellite (RS) is proposed.Based on the analysis of RS motion characteristics in micro-gravity environment, two manipulators are divided into main manipulator and assistant manipulator. Then, four kinds of coordination modes for dual-manipulator RS, namely,stablizing function, counterbalancing function, adjusting function and coorperative operation are presented. Motion planning algorithm for dual-manipulator is also presented.Finally, computer simulation results of the four kinds of coordination modes for a RS experimental model capturing target operation in micro-gravity environment are given.Simulation experiments show that the coordination modes and planning algorithm proposed in this paper are effective.

COORDINATION OF THE MOTION PARAMETERS WITHIN STEP-BY-STEP INTEGRATION FOR DYNAMIC EQUATION

A method is presented that coordinates the calculation of the displacement, velocity and acceleration of structures within the time-steps of different types of step-by-step integration. The dynamic equation is solved using an energy equation and the calculating data of the original method. The method presented is better than the original method in terms of calculating postulations and is in better conformity with the system's movement. Take the Wilson-θ method as an example. By using the coordination process, the calculation precision has been greatly im proved (reducing the errors by approximately 90% ), and the greater part of overshooting of the calculation result has been eliminated. The study suggests that the mal-coordination of the motion parameters within the time-step is the major factor that contributes to the result errors of step-by-step integration for the dynamic equation.

Improvement of Computation Method of Fault Motion Coordination Ratio and Analysis of Earthquake Cases

According to the concept of the fault motion coordination ratio( FCR),this paper discusses the effect of the starting point on the result of FCR calculation and puts forward the calculation method for FCR using the sliding window and the index for evaluating the dispersion. Earthquake cases analysis shows that at the Lijiang site across the fault: the FCR value varied greatly and its distribution was dispersive before the MS7. 0 Lijiang earthquake,while the value was stable and less dispersive after the earthquake,which reflects the strain accumulation of the fault during the seismogenic process and the poor movement coordination between the motion of the three components. After the earthquake,the fault was in a free activity state,the accumulated strain energy released, and the movement of the three components was coordinated mutually. At present,FCR dispersion of Lijiang is at a low value,and fault strain accumulation is at a low level.

Canonical Treatment of Elliptical Motion

The constrained motion of a particle on an elliptical path is studied using Hamiltonian mechanics through Poisson bracket and Lagrangian mechanics through Euler Lagrange equation using non-natural Lagrangian. We calculate the generalized momentum pθ and we find that this quantity is not conserved and the conjugate θ coordinate is not a cyclic coordinate.

基于坐标时间序列的地心运动分析与预测

地心运动会影响地球参考框架原点的准确性,是地球参考框架进行非线性维持必须考虑的因素之一,因此提出对地心运动进行多尺度的建模和预测,以实现毫米级地球参考框架的建立和维持。采用网平移法计算的地心运动、全球地球物理流体中心(global geophysical fluids center,GGFC)和国际GNSS服务(international gnss service,IGS)第三次重处理(IGSR03)提供的3组地心运动数据,首先对其一致性和差异进行了分析,然后分别利用谐波模型和Diff-LSTM模型对地心运动进行了长期和短期的建模与预测,结果显示,GGFC地心运动的预测精度优于1.5 mm,而Diff-LSTM模型的地心运动预测结果在短期内优于谐波模型,当预测步长为17时,GGFC和IGSR03的地心运动预测精度均能达到甚至优于1 mm。表明地心运动的预测精度能够满足基于地球质量中心(center of mass of the total earth system,CM)的瞬时地球参考框架的建立与维持。

基于谱压缩的大斜视TOPS BP图像自聚焦算法

在机动平台大斜视TOPS模式SAR成像时,通过使用地平面直角坐标系BP成像算法,能够在短时间内获取地距平面无畸变的宽幅SAR图像,但实际应用中如何对BP图像快速完成运动误差补偿与旁瓣抑制仍是一个难点。针对此问题,提出了一种改进的谱压缩方法,基于此能够快速实现机动平台大斜视TOPS模式地平面BP图像自聚焦等后续操作。首先,考虑到传统BP谱压缩方法仅适用于聚束成像模式,结合大斜视TOPS SAR虚拟旋转中心理论与波数谱分析,推导出了改进的精确谱压缩函数,能够通过全孔径压缩获得无模糊的地平面TOPS模式BP图像频谱。在此基础上,利用相位梯度自聚焦(PGA)能够快速完成全孔径运动误差估计与补偿。此外,基于提出的改进谱压缩方法得到的无模糊对齐BP图像频谱,可以在方位频域统一加窗实现图像旁瓣抑制。最后,通过仿真数据处理验证了所提算法的有效性。

基于双矩阵编码混合蛙跳算法的多焊接机器人任务分配

焊接工艺是整车制造的重要环节之一,多机器人焊接工艺问题涉及任务分配、多机协调与运动规划等多个子问题,这些子问题之间的耦合关系导致工艺规划问题求解困难。针对车身复杂结构焊接过程中多机器人运动空间狭窄、焊接节拍受限等问题,综合考虑机器人的可达性、机器人与静态环境无碰与多机器人无冲突等条件,提出一种面向多焊接机器人协调运动规划的任务分配新方法。首先,构建候选轨迹库与轨迹冲突表,在此基础上建立面向焊点任务分配与焊接轨迹协调规划的优化模型,提出基于双矩阵编码的改进混合蛙跳算法进行优化求解。通过加入两种交叉算子、一种变异算子与贪婪放置策略,获得多机器人焊接任务近似最优规划结果。最后,通过某白车身焊接案例验证了所提方法有效性。同时,结果证明,工位焊接周期平均下降16.26%,多机器人运行时间一致性提升30.87%。

露天矿无人驾驶自卸车横-纵向协同控制研究

露天矿无人驾驶自卸车面临道路等级低且坡道弯道多、车辆载质量大且变化范围宽等恶劣运输工况,现有车辆运动控制策略多面向普通道路环境,无法直接将现有车辆控制策略应用于矿山自卸车。针对上述问题,提出了一种基于预瞄误差与分层反馈的露天矿无人驾驶自卸车横-纵向协同控制系统。横向控制以线性二次型调节器(LQR)为基础,运用前馈控制器降低稳态误差,采用模糊控制器实现自适应调整预瞄距离,以提高路径跟踪控制精度;纵向控制建立分层反馈式纵向速度控制器,分别采用模型预测控制和模糊PID反馈控制,并建立车辆驱动及制动逆向模型,降低自卸车载质量与道路坡度改变对纵向速度追踪的影响。仿真结果表明:(1)车辆实际速度和期望速度误差在2%以内,说明自卸车在空载下坡与满载上坡2种工况下的速度跟踪效果能够满足要求。(2)由于横-纵向协同控制能够针对路径曲率的不同实时调节车辆速度,在2种工况下,自卸车横-纵向协同控制器相比于单一横向控制都获得了更高的路径跟踪精度,同时也提高了自卸车的操纵稳定性。实验结果表明:(1)空载下坡时的横向误差峰值为0.0199 m,方向误差峰值为0.1840 rad,误差增大均发生在弯道处,但误差波动范围较小,能够保证试验车对期望路径的跟踪。(2)负载上坡时的横向误差峰值为0.0168 m,方向误差峰值为0.0714 rad,误差变化趋势与空载下坡试验相反,但误差仍在合理范围内,试验车的跟踪效果良好。(3)2个误差峰值均小于空载下坡试验,验证了不同速度对横向控制精度的影响规律。

结合动作捕捉的外骨骼座椅协调性评估

外骨骼座椅在工业中的应用日渐流行,但部分外骨骼座椅的协调性仍有待提高。为全面评估外骨骼座椅在动静态下的协调性,12名受试者在穿戴和未穿戴外骨骼座椅的条件下,模拟了快递流水线作业的动静态任务。运用光学动作捕捉设备采集髋膝踝关节的运动数据,并使用SPSS对其进行Wilcoxon秩和检验,最后通过五级李克特量表问卷采集主观评估数据,验证主客观结果的一致性。结果显示,在动态行走任务中,双腿膝关节角均有所下降,髋膝踝关节的速度和加速度也呈现下降趋势,在快走时尤为明显:在静态坐姿下,臀部和大腿上侧易产生不舒适感,调整坐姿容易发生倾倒。结论,该外骨骼座椅的整体协调性较差,限制了各关节的运动:在辅助坐姿时,易产生不稳定感和不舒适感。主客观数据结果表现一致,该方法能有效地定量评估外骨骼座椅的协调性,为进一步优化提供定量参考。

基于图像超分辨的巡检机器人运动路径自动追踪方法

复杂的场景可能使巡检机器人采集到的图像质量下降,导致机器人运动路径追踪时的精度下降。对此,提出基于图像超分辨的巡检机器人运动路径自动追踪方法。首先,通过图像超分辨技术提升运动图像质量,确保机器人在复杂环境下仍能清晰识别路径。然后,进行机器人运动路径配准,精确计算设备坐标系与基准坐标系间的平移和旋转关系。最后,利用模糊控制器进行机器人运动路径的动态追踪。结果表明,设计方法能够有效提升路径追踪精度,具有实用性。

小型水库大坝无人机巡检和行人定位方法

针对小型水库大坝缺少准确的坐标转换参数,无人机识别的行人目标难以精确三维定位的问题,提出无人机坐标系与坝体局部坐标系的转换方法。实际工程应用结果表明,坐标转换后生成的点云与激光扫描点云基本一致,对坝顶目标的非接触测量精度优于10cm。提出方法可以从任意角度和位置准确测量小目标行人在坝体结构上的位置,为小型水库大坝无人机常规巡检和建立电子围栏等提供高效且经济的方法。

基于拓扑表征优化的多机器人协作运动泛化

针对多机器人无碰协调操作的运动生成问题,提出了一种基于拓扑表征优化的多机器人运动泛化方法。首先,对示范多机器人系统进行节点化及网格化,利用拉普拉斯坐标构建网格化的多机器人图模型,使用网格的拓扑关系表征多机器人间的空间关系语义;然后,通过示范多机器人系统与泛化多机器人系统间拓扑关系语义的保持,将针对泛化机器人系统复杂的多机器人运动生成问题转化为两个机器人系统间的网格/图变形优化问题,求解该优化问题即可得到新系统的协调运动;最后,通过两个双机器人系统的泛化实验,展示和分析了所提方法的实现流程和仿真结果。实验结果表明,所提方法能生成与示范数据相似的构型序列,实现多机协作的运动泛化,验证了所提方法的有效性及泛化性。

基于PID搜索算法的永磁同步电机振动抑制研究

针对某款新能源汽车永磁同步电机在急加减速、扭矩突变等工况下,引起的噪声增大及转速变化等影响驾驶及乘坐舒适性的指标进行研究。通过对永磁同步电机进行运动及动力学建模,列出动力学方程并对其进行坐标变换及简化,得到简化及单一控制变量。基于PID搜索算法(PSA)对永磁同步电机的变频器输出电流进行控制。设计电机测试及采集设备,并通过在电机上布置的加速度传感器采集永磁同步电机阶跃载荷及冲击载荷振动加速度信号,布置在电机周围的麦克风采集电机的噪声信号,通过测功机采集转速信号,对加速度及噪声信号时域到频域进行变换。试验结果表明PSA控制方法相对于传统PID控制方法,永磁同步电机振动加速度、转速及噪声均有明显的改善,在电机3000 r/min时加载100 N·m的阶跃扭矩时,其平均噪声由68.7 dB(A)降低到62.5 dB(A);最大加速度由0.645 m/s^(2)降低到0.247 m/s^(2),降低了61.7%,速度波动最小值由2675 r/min升高到2740 r/min,最大值由3255 r/min降低到3155 r/min。其他转速及扭矩下均有同等的改善效果,验证了该控制方法及控制模型对永磁同步电机振动抑制及噪声有明显的改善效果。