UAV-based transient electromagnetic 3D forward modeling and inversion and analysis of exploration capability

Unmanned aerial vehicle transient electromagnetic(UAV-TEM)is a novel airborne exploration method that offers advantages such as low cost,simple operation,high exploration efficiency and suitability for near-surface exploration in complex terrain areas.To improve the accuracy of data interpretation in this method,the authors conducted a systematic three-dimensional(3D)forward modeling and inversion of the UAV-TEM.This study utilized the finite element method based on unstructured tetrahedral elements and employed the second-order backward Euler method for time discretization.This allowed for accurate 3D modeling and accounted for the effects of complex terrain.Based on these,the influence characteristics of flight altitudes and the sizes,burial depths,and resistivities of anomalies are compared and analyzed to explore the UAV-TEM systems’exploration capability.Lastly,four typical geoelectrical models of landslides are designed,and the inversion method based on the Gauss-Newton optimization method is used to image the landslide models and analyze the imaging effect of the UAV-TEM method on landslide geohazards.Numerical results showed that UAV-TEM could have better exploration resolution and fine imaging of nearsurface structures,providing important technical support for monitoring,early warning,and preventing landslides and other geological hazards.

An Analysis of the Inverse Kinematics for a 5-DOF Manipulator

This paper proposes an analytical solution for a 5-DOF manipulator to follow a given trajectory while keeping the orientation of one axis in the end-effector frame. The forward kinematics and inverse kinematics for a 5-DOF manipulator are analyzed systematically. The singular problem is discussed after the forward kinematics is provided. For any given reachable position and orientation of the end-effector, the derived inverse kinematics will provide an accurate solution. In other words, there exists no singular problem for the 5-DOF manipulator, which has wide application areas such as welding, spraying, and painting. Experiment results verify the effectiveness of the methods developed in this paper. Keywords Inverse kinematics - modeling and control - 5-DOF manipulator This work was supported by the National High Technology Research and Development Program of China (No. 2002AA422160), and the National Key Fundamental Research and Development Project of China (973, No.2002CB312200)De Xu graduated from Shandong University of Technology (SUT), China in 1985. He received a Masters degree from SUT in 1990, and a Ph.D. degree from Zhejiang University, China in 2001. He has been with the Institute of Automation, at the Chinese Academy of Sciences (CASIA) since 2001. He is an associate professor with the Laboratory of Complex Systems and Intelligence Science, CASIA. He worked as on academic visitor in the Department of Computer Science, at the University of Essex from May to August 2004. He is a member of the IEEE. His research interests include robotics and automation, especially the control of robots such as visual and intelligent control.Carlos Antonio Acosta Calderon received a B.S. degree in Computer Science Engineering from Pachuca Institute of Technology, Mexico in 2000, and a M.Sc. degree in Computer Science (Robotics and Intelligent Machines) from the University of Essex, UK in 2001. He is currently pursuing a Ph.D degree in Computer Science at the University of Essex, UK. His research interests have focused on mobile robots, in particular, the coordination of multi-robot systems, mobile manipulators, and learning by imitation. He is a member of IEEE.John Q. Gan received a B.Sc. degree in electronic engineering from Northwestern Polytechnic University, China in 1982, a M.Eng. degree in automatic control and a Ph.D degree in biomedical electronics from Southeast University, China in 1985 and 1991, respectively. He is a Senior Lecturer in the Department of Computer Science at the University of Essex, UK. He has co-authored a book, and published over 100 research papers. His research interests are in robotics and intelligent systems, brain-computer interfaces, pattern recognition, signal processing, data fusion, and neurofuzzy computation.Huosheng Hu is a Professor in the Department of Computer Science, at the University of Essex, and head of the Human Centered Robotics Group. His research interests include autonomous mobile robots, human-robot interaction, evolutionary robotics, multi-robot collaboration, embedded systems, pervasive computing, sensor integration, RoboCup, intelligent control, and networked robotics. He has published over 200 papers in journals, books, and conferences, and received two best paper awards. He is a founding member of the IEEE Society of Robotics and Automation Technical Committee of Internet and Online Robots, and a member of the IASTED Technical Committee on “Robotics” for 2001–2004. He was a Conference Chairman for the 1st European Embedded Systems Conference in Paris, 1996, and has been a member of the Program Committees for many international conferences such as IROS (2005–2006), IASTED Robotics and Applications Conferences (2000-present), and RoboCup Symposiums (2000–2004). Dr. Hu is a Chartered Engineer, a senior member of IEEE, and a member of IEE, AAAI, ACM, IASTED and IAS.Min Tan graduated from Tsing Hua University, China in 1986. He received a Ph.D. degree in 1990 from CASIA. He is a professor with the Laboratory of Complex Systems and Intelligence Science, CASIA. He has published over 100 papers in journals, books, and conferences. His research interests include robotics and complex system theory.

Three-dimensional forward modeling and inversion of borehole-to-surface electrical imaging with different power sources

Borehole-to-surface electrical imaging （BSEI） uses a line source and a point source to generate a stable electric field in the ground. In order to study the surface potential of anomalies, three-dimensional forward modeling of point and line sources was conducted by using the finite-difference method and the incomplete Cholesky conjugate gradient （ICCG） method. Then, the damping least square method was used in the 3D inversion of the formation resistivity data. Several geological models were considered in the forward modeling and inversion. The forward modeling results suggest that the potentials generated by the two sources have different surface signatures. The inversion data suggest that the low- resistivity anomaly is outlined better than the high-resistivity anomaly. Moreover, when the point source is under the anomaly, the resistivity anomaly boundaries are better outlined than when using a line source.

Real-time forward modeling and inversion of logging-while-drilling electromagnetic measurements in horizontal wells

Based on the pseudo-analytical equation of electromagnetic log for layered formation,an optimal boundary match method is proposed to adaptively truncate the encountered formation structures.An efficient integral method is put forward to significantly accelerate the convergence of Sommerfeld integral.By asymptotically approximating and subtracting the first reflection/transmission waves from the scattered field,the new Sommerfeld integral method has addressed difficulties encountered by the traditional digital filtering method,such as low computational precision and limited operating range,and realized the acceleration of the computation speed of logging-while-drilling electromagnetic measurements(LWD EM).By making use of the priori information from the offset/pilot wells and interactively adjusting the formation model,the optimum initial guesses of the inversion model is determined in order to predict the nearby formation boundaries.The gradient optimization algorithm is developed and an interactive inversion system for the LWD EM data from the horizontal wells is established.The inverted results of field data demonstrated that the real-time interactive inversion method is capable of providing the accurate boundaries of layers around the wellbore from the LWD EM,and it will benefit the wellbore trajectory optimization and reservoir interpretation.

The Forward and Inverse Problem Based on Magneto-Acoustic Tomography with Current Injection

The Magneto-acoustic Tomography with Current Injection (MAT-CI) is a new biological electrical impedance imaging technique that combines Electrical Impedance Tomography (EIT) with Ultrasonic Imaging (UI), which possesses the non-invasive and high-contrast of the EIT and the high-resolution of the UI. The MAT-CI is expected to acquire high quality image and embraces a wide application. Its principle is to put the conductive sample in the Static Magnetic Field(SMF) and inject a time-varying current, during which the SMF and the current interact and generate the Lorentz Force that inspire ultrasonic signal received by the ultrasonic transducers positioned around the sample. And then according to related reconstruction algorithm and ultrasonic signal, electrical conductivity image is obtained. In this paper, a forward problem mathematical model of the MAT-CI has been set up to deduce the theoretical equation of the electromagnetic field and solve the sound source distribution by Green’s function. Secondly, a sound field restoration by Wiener filtering and reconstruction of current density by time-rotating method have deduced the Laplace’s equation that caters to the current density to further acquire the electrical conductivity distribution image of the sample through iteration method. In the end, double-loop coils experiments have been conducted to verify its feasibility.

TriMule机器人并联机构运动学分析与仿真

针对并联机构运动学模型求解困难的问题,以TriMule并联机构为研究对象对其正向运动学与逆向运动学进行了分析与仿真,并通过样机平台的加工工艺参数评价了运动学算法的正确性与稳定性。根据TriMule机器人机构特点,基于矢量法与连杆长度差迭代法建立机器人并联机构的运动学逆解及正解模型,推导机器人驱动支链长度与动定平台位姿关系;在机器人运动空间中选取样本位姿,应用MATLAB对所建立TriMule机器人并联机构运动学模型进行仿真验证,结果表明运动学模型求解算法正确稳定。最后搭建TriMule机器人搅拌摩擦焊实验平台验证运动学算法控制稳定性。

A modified forward and backward reaching inverse kinematics based incremental control for space manipulators

Forward and backward reaching inverse kinematics(FABRIK)is an efficient two-stage iterative solver for inverse kinematics of spherical-joint manipulator without the calculation of Jacobian matrix.Based on FABRIK,this paper presents an incremental control scheme for a free-floating space manipulator consists of revolute joints and rigid links with the consideration of joint constraints and dynamic coupling effect.Due to the characteristics of FABRIK,it can induce large angular movements on specific joints.Apart from that,FABRIK maps three dimensional(3D)problem into two dimensional(2D)problem by a simple geometric projection.This operation can cause infinite loops in some cases.In order to overcome these issues and apply FABRIK on space manipulators,an increments allocation method is developed to constrain the angular movements as well as to re-orient the end-effector.The manipulator is re-positioned based on the momentum conservation law.Instead of pure target position tracking,the orientation control of the end-effector is also considered.Numerical simulation is performed to testify and demonstrate the effectiveness and reliability of the proposed incremental control approach.

一种基于重力正演理论的海底地形反演迭代算法

重力数据反演海底地形的方法是获取全球海底地形数据的重要途径。针对传统地形反演算法需要间接引入经验参数的问题,本研究以不采用经验公式为原则,从空间域方法入手,结合重力正演公式,建立重力异常与地形之间的解析观测方程,采用最小二乘方法进行求解。为了得到观测方程最优解,建立牛顿迭代关系,引入正则化参数,增强方程组的收敛性。顾及边缘效应对正演的影响,采用双线性插值算法对原始重力异常数据进行加密处理和无约束网格扩充以削弱误差。在太平洋海域(155°E~156°E,16°N~17°N)构建了1′×1′分辨率的海底地形模型,并通过船测水深数据验证。相比于传统空间域算法——重力地质法,本研究方法的均方根误差降低了12.7%,验证了其可行性与准确性。

刚柔耦合串并联康复机械臂运动特性分析

针对目前大多数上肢康复机器人在结构上存在的不足,首先,设计了一种兼具绳索驱动和并联机构优点的4自由度刚柔耦合串并联康复机械臂。其次,在基于此康复机械臂绳索空间和关节空间映射关系的条件下,运用D⁃H坐标法建立了康复机械臂的运动学模型。最后,在Matlab环境下,仿真分析了各关节角与绳长、速度随时间变化的关系曲线。分析结果表明,该刚柔耦合串并联康复机械臂结构设计的合理性,也为分析康复机械臂的轨迹规划问题提供理论基础。

基于高精度重力勘探对地下空洞的探测研究

地下空洞埋藏浅、规模小不易探测,随着重力感应技术的发展,给准确快速获取微重力变化为探测地下空洞带来新机会,对小规模地下空洞的探测能力具有广泛的研究和实用价值。本文从重力基础理论、重力探测技术、重力数据处理及反演3方面对地下空洞进行系统的分析研究。在给定形体大小、重力数据精度的情况下,通过二分法计算出了重力探测的最大埋藏深度;将高密度采集、高精度重力探测方法用于某区客运站地下人行通道实际探测,获得一套高精度重力格网数据,理论研究和实测结果表明,现有重力仪器具有探测地下空洞的能力;采用最小曲率位场分离方法、2.5D人机交互反演和靶区识别三维物性快速反演方法,得到地下人行通道近SN向的分布,埋藏深度大致2.5~5 m,这与实际情况相符。本次研究为地下空洞探测摸索出一套完整的重力勘探流程,具有一定的参考价值。

航天员舱外操作载荷分析的逆运动学建模方法

针对航天员舱外活动中操作动作对扶手和脚限制器约束点造成的载荷进行精细化分析。对失重环境下航天员的运动特点进行了总结,采用逆运动学算法对航天员上肢操作动作进行建模;引入运动耗能、关节角与施力能力的关系、航天服活动反力矩等条件作为冗余系统约束;并考虑身高、体重、工作位点距离等精细化因素对操作载荷的影响。对沿扶手行走和搬运大质量物体典型算例的分析表明,此方法利用最小耗能准则进行出舱活动复杂运动的逆运动学求解具有可行性,基于本方法分析模型精细化参数影响,分析了操作力和力矩载荷与航天员体重、身高和工作位点距离的关系,并可据此开展更加精确的出舱活动操作载荷预测,为有关结构设计提供参考。

CSAMT在巴音戈壁盆地铀储层识别中的应用

在电磁法数值模拟中,正演模拟是认识各种地电条件下的大地电磁响应特征的良好途径,模型正演得到的结论,对于资料处理、反演、解释具有积极的指导作用。通过在巴音戈壁盆地开展可控源音频大地电磁测量(CSAMT),结合巴音戈壁盆地已知钻孔资料,建立了初始地电模型,进行模型正演计算得出正演数据,通过对正演数据进行反演计算,确定合理的反演模型和反演参数,提高资料反演的准确性,最后根据对实测数据的反演计算、资料解释、综合分析结果,推断研究区铀储层巴音戈壁组的空间展布特征,解释结果得到钻孔资料的验证,在砂岩型铀矿勘查中取得较好的效果。

以全球导航卫星系统为辐射源的前向散射雷达发展综述

前向散射雷达(FSR)可获得高水平雷达截面积(RCS)的特性使其在反隐身中占据重要地位。利用全球导航卫星系统(GNSS)作为辐射源,具有全天时全天候全地域覆盖的优势,通过部署多个接收节点可构建地面/海上/空中目标监视网络。该文针对基于GNSS的FSR发展现状,从目标检测、目标参数估计、阴影逆合成孔径雷达(SISAR)成像及目标分类识别等方面对关键技术和现存问题进行概述,并从组网探测、多目标定位、布站优化和极化信息获取等方面对基于GNSS的FSR发展趋势提出展望。

基于粒子-人工蜂群算法的3RPUP_(c)-UPS并联机构运动学正解研究

针对3RPUP_(c)-UPS并联机构运动学正解求解困难的问题,对新型3RPUPc-UPS并联机构的运动学特性进行了研究,并构建出位置正解求解模型,进而提出了一种基于粒子-人工蜂群算法(P-ABC)的并联机构运动学求解方法。首先,根据机构的拓扑特性,计算得到了方位特征集、自由度和耦合度;然后,根据机构的几何特征,基于姿态变换矩阵和动平台投影方程,建立了机构的运动学逆解方程,并对比了MATLAB和SOLIDWORKDS的仿真结果,验证了逆解分析的正确性;最后,将运动学逆解方程转化为最小化求解问题,构建出了适合优化算法的运动学正解模型,并利用MATLAB的软件交互界面(GUI)功能,开发出用于计算并联机构运动学正解的软件,分别基于粒子群算法(PSO)、人工蜂群算法(ABC)和P-ABC算法,对该并联机构的运动学正解进行了计算。研究结果表明:P-ABC算法单次求解时间在0.5 s内,求解误差级别为10-20,相对于ABC算法,运行时间缩短了50.02%;而相对于POS算法,其求解精度提高了10个数量级。P-ABC算法能够用于求解该并联机构运动学正解,具有计算速度快、精度高的特点,可以为研究并联机构运动学正解提供新方法。

基于Maxwell模型的压电驱动系统前馈控制方法

为了提高外腔可调谐半导体激光器的测量精度,基于Maxwell模型提出了用于消除其压电驱动系统迟滞非线性的前馈控制方法.基于经典Maxwell力学模型,建立了描述非凸、非对称迟滞环的静态迟滞模型;根据频率与位移幅值的关系建立了率相关系数矩阵,与静态迟滞模型耦合得到率相关迟滞模型,实现了不同频率下压电驱动系统迟滞非线性的精准预测;构建了迟滞逆模型,对压电驱动系统进行前馈补偿控制.实验结果表明,率相关迟滞模型具有较高的精度,1 Hz下模型均方根误差为0.049μm, 50 Hz下模型均方根误差为0.252μm.基于迟滞逆模型的前馈控制方法能够明显提高系统输出位移的线性度,增大线性度范围,线性相关系数R2由0.971 58提高到了0.999 77.

基于变差分系数的变网格弹性波全波形反演

全波形反演充分利用地震波传播的振幅、相位和旅行时等信息,相较于旅行时层析能够获得分辨率和精度更高的反演结果。当浅层介质速度较低时,为了保证正演模拟精度,通常需要使用较细的网格对低速层进行采样。然而,对整个模型用细网格剖分会导致巨大的计算量以及存储量,同时模型的高速区域也会产生过采样现象,这些问题会在全波形反演过程中被进一步放大。为了避免这些问题,引入了一种基于变差分系数的变网格弹性波动方程有限差分正演模拟方法。首先,基于Taylor展开式推导了变网格波场模拟的差分系数,实现了变网格波场模拟;其次,将变差分系数正演模拟方法应用于全波形反演中的正演模拟、残差反传和波场重构中,实现了基于变差分系数的变网格弹性波全波形反演。在全波形反演时,分别采用多尺度反演策略和常规的共轭梯度法迭代求解。使用细网格剖分速度较低的浅部低速层和粗网格剖分速度较高的中深层,既可以保证浅层的反演精度,又可以避免中深层的过采样。模型数据反演结果表明,基于变差分系数的变网格全波形反演相较于均匀粗网格全波形反演可以更有效实现低速异常体的准确刻画。含噪数据测试表明,提出的全波形反演方法具有较强的抗噪性。

基于多自由度机械臂的乒乓球平衡控制算法研究

以板球系统模型为基础,提出了使用多自由度串联机械臂控制乒乓球平衡的方法。首先,从板球控制系统出发,分析这类平衡算法的优缺点;其次,对六自由度串联机械臂进行运动学分析;最后,通过Matlab软件和Webots软件对机械臂进行仿真试验,验证其准确性。仿真结果表明:在一般的应用场景下,使用多自由度串联机械臂控制乒乓球平衡的方法具有一定的通用性。

人体复合训练设备的逆运动学分析及仿真

针对传统的三轴人体离心机,提出了一种新型的四轴双臂人体短臂离心机。阐述了人体复合训练设备的基本结构及功能特点。根据逆运动学,提出了在给定3个方向上的人体过载值Gx、Gy、Gz时,可确定俯仰角度α和旋转角度β,以及主轴电机转速n和有效回转半径R之间的关系的控制要求。采用旋转矩阵坐标变换的方法,对设备的多自由度运动过程进行了分析,建立了数学模型,应用逆运动学求解了α、β、n、R。通过MATLAB仿真验证了分析方法的正确性,得出了Gt在Ox、Oy、Oz方向上的影响规律。总体的结构设计和模型建立与前人所设计的设备对比,轴的控制从三轴增加到了四轴,解决了逆运动学模型和模拟算法太过复杂的问题,用简单且计算量小的模型实现了给定人体过载值,确定离心机各轴的运动状态的目的,适合实际的运动控制应用,为电机选型以及控制系统设计提供有效的依据。

南堡凹陷火山岩喷发模式及火山碎屑岩分布

渤海湾盆地南堡凹陷中深层火山岩纵向多期次发育,厚度大,分布广泛,是油气富集有利区带,但火山岩储层薄,横向变化快,地震资料无法直接识别及刻画,影响着有利目标落实。为了有效刻画火山岩优势储层甜点发育区,针对火山碎屑岩有利储层预测问题,开展了火山岩区域分布规律研究、火山喷发模式建立、火山机构精细解剖、正演模型分析、融合属性及地质统计学反演工作。研究结果表明:1)火山喷发具有多期次性,单一期次火山岩喷发形成多个独立火山岩体;2)基性喷发岩之上发育火山碎屑岩,是火山岩岩性组合有利储层发育段;3)火山碎屑岩储层越发育,上覆地层地震波振幅变弱特征越明显;4)火山碎屑岩测井曲线表现为中声波时差和中伽玛特点。以上成果认识,详细描述了不同期次下火山岩顶面构造形态及火山碎屑岩有利储层分布,对南堡凹陷中深层火山岩进一步勘探具有一定指导意义。

哈萨克斯坦南图尔盖盆地Doshan斜坡带岩性油气藏储层预测方法

综合利用钻井、测井、地震等资料,分析了哈萨克斯坦南图尔盖盆地Doshan区块中部斜坡带沉积特征,并提出了一种岩性油气藏储层预测方法,识别出岩性圈闭,地震属性分析验证了储层预测结果的可靠性。研究结果表明:(1)哈萨克斯坦南图尔盖盆地Doshan斜坡带中—下侏罗统沉积时构造活动强烈,发育少量断裂,以湖相沉积为主,可分为SQ4—SQ6共3个沉积期,分别对应埃巴林组(J_(1)ab)、多尚组(J_(2)ds)和卡拉甘塞组(J_(2)kr),SQ6时期发生大规模湖侵,扇三角洲呈裙带状展布在边缘断层一侧,半深湖范围扩大;三角洲前缘为岩性圈闭发育的有利相带。(2)储层预测方法为以井-震标定结果确定地层界线,以基于声波曲线重构的岩石物理分析校正井径的影响,以基于调谐厚度的正演模型分析识别砂体,以高分辨率岩性储层地震反演技术对单砂层进行识别。(3)研究区岩性圈闭主要分布于中—下侏罗统,发育于坡折控砂条件下的一系列构造带上。地震属性分析结果与沉积特征吻合度较高。(4)研究区中—下侏罗统的坡折位置发育一系列岩性圈闭,在高分辨率地震剖面上表现为强振幅、高阻抗特征,是勘探有利区。