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.

Topology Search of 3-DOF Translational Parallel Manipulators with Three Identical Limbs for Leg Mechanisms

Three-degree of freedom（3-DOF） translational parallel manipulators（TPMs） have been widely studied both in industry and academia in the past decades. However, most architectures of 3-DOF TPMs are created mainly on designers＇ intuition, empirical knowledge, or associative reasoning and the topology synthesis researches of 3-DOF TPMs are still limited. In order to find out the atlas of designs for 3-DOF TPMs, a topology search is presented for enumeration of 3-DOF TPMs whose limbs can be modeled as 5-DOF serial chains. The proposed topology search of 3-DOF TPMs is aimed to overcome the sensitivities of the design solution of a 3-DOF TPM for a LARM leg mechanism in a biped robot. The topology search, which is based on the concept of generation and specialization in graph theory, is reported as a step-by-step procedure with desired specifications, principle and rules of generalization, design requirements and constraints, and algorithm of number synthesis. In order to obtain new feasible designs for a chosen example and to limit the search domain under general considerations, one topological generalized kinematic chain is chosen to be specialized. An atlas of new feasible designs is obtained and analyzed for a specific solution as leg mechanisms. The proposed methodology provides a topology search for 3-DOF TPMs for leg mechanisms, but it can be also expanded for other applications and tasks.

准连续c切Er,Yb:YAl_(3)(BO_(3))_(4)激光器的偏振操控

通过构建谐振腔模型,分析了各向同性固体激光器中两个本征模式相干叠加后的光斑奇异特征。并且实验验证了在不使用任何特定的腔内光学偏振选择元件的情况下,在二极管泵浦的准连续c切Er,Yb:YAl_(3)(BO_(3))_(4)激光器中可以有效操控1.6μm输出激光的偏振态。实现了从部分偏振态转化成稳定的线偏振态,其线偏振方向为可切换的正交特殊情况,均具有21 dB的偏振消光比。同时通过光斑对比,验证了激光器的线偏振输出来源于两个正交本征模式的相干叠加。文中为c切Er,Yb:YAl_(3)(BO_(3))_(4)激光器线偏振光的直接输出与偏振态的调控提供了可靠的方案。

Trajectory tracking control based on linear active disturbance rejection controller for 6-DOF robot manipulator

The trajectory tracking control for a 6-DOF robot manipulator with multiple inputs and outputs,non-linearity and strong coupling is studied.Firstly,a dynamical model for the 6-DOF robot manipulator is designed.From the view point of practical engineering,considering the model uncertainties and external disturbances,the robot manipulator is divided into 6 independent joint subsystems,and a linear active disturbance rejection controller(LADRC)is developed to track trajectory for each subsystem respectively.LADRC has few parameters that are easy to be adjusted in engineering.Linear expansion state observer(LESO)as the uncertainty observer is able to estimate the general uncertainties effectively.Eventually,the validity and robustness of the proposed method adopted in 6-DOF robot manipulator are demonstrated via numerical simulations and 6-DOF robot manipulator experiments,which is of practical value in engineering application.

4-RRR冗余驱动并联机器人的驱动力协调分配对比研究

应用于3D打印的冗余驱动可以有效降低并联机器人的瞬时最大驱动功率,提高机构的承载能力。但影响其实现的关键因素是驱动力的协调性及其控制方法,因此本文以4-RRR冗余驱动并联机器人为对象展开研究。首先,求解机构的位置逆解以及机构末端与关节速度、加速度之间的映射关系。其次,采用虚功原理构建动力学模型,分别采用4种方法优化以最大瞬时驱动力矩为优化目标对并联机器人动力学逆解进行对比研究。最后,通过仿真对最优驱动力矩优化方法的峰值力矩降低效果进行验证对比。仿真结果表明:加权最小二范数法在降低机构最大瞬时驱动力矩方面具有优越性,呈明显降低趋势且驱动力分配均衡,为提高并联机器人面向3D打印功能的运动精度及后续的应用奠定了理论基础。

Topology optimization design of the main structure of 6-DOF manipulator based on the variable density method

In order to solve the problems of too large mass,too complex structure and poor flexibility of the 6 DOF manipulator,the topological optimization theory based on variable density method is applied to the 6-DOF manipulator,the topology optimization of the main structural components of the manipulator is carried out with the help of the finite element software ANSYS,and the optimized structure is simplified according to the density distribution of the units and the requirements of manufacturability.the results are compared and analysed by static mechanics.It shows that the whole mass of the 6-DOF manipulator is reduced by 47.23%without changing the original mechanical properties after topological optimization,and the optimized model can meet the requirements of manufacturability,the optimization effect is signifcant,which can be used as a reference for the structure optimization of the 6-DOF manipulator.

新型4-DOF并联机器人位置和工作空间分析

提出研究新型4-DOF并联机器人的位置和工作空间的问题,利用计算机辅助几何法构造4-DOF并联机器人模拟机构,基于并联机器人的模拟机构,分析出一种4-DOF并联机器人的位置和工作空间。模拟结果表明,计算机辅助几何法的应用不但大大简化了并联机器人机构分析位置和工作空间难度,而且快捷直观,值得推广。

葡萄采摘4-DOF机械臂设计与虚拟样机仿真

为实现篱架式栽培的食用葡萄自动化采摘,设计了一种关节型四自由度(4-DOF)机械臂,并利用DH参数法建立机械臂的连杆坐标系。通过MatLab里的Robotics Toolbox建立机械臂的数学模型,对机械臂的正、逆运动学进行仿真,对末端执行器走直线轨迹进行了轨迹规划。利用ADAMS建立机械臂的虚拟样机,将轨迹规划仿真数据作为驱动,进行动力学仿真,获得夹持2kg葡萄时腰关节、肩关节、肘关节及腕关节所需驱动力矩分别为95、52、48、12N·m,从而为采摘机械臂的物理样机制造与采摘试验提供了技术依据。

Research on the operating characteristics of parallel 4-DOF electric platform with 4TPS-PS structure

The 4TPS-PS parallel platform designed for a stabilization and automatic tracking system is a novel lower-mobility parallel mechanism. In the first part of this paper, the structure of the platform is described and the kinematics model is built. The workspace of the platform is defined as the full reachable rotation workspace when the Z coordinate dimension of the upper plate varies continuously. A fast searching method of the full reachable workspace is presented, after which the inverse kinematics of the platform is deduced. The forward and inverse solutions of the speed and force of the platform are deduced. According to the characteristic of the 4TPS-PS platform’s structure, a fast searching algorithm of the maximum generalized speed and maximum generalized force output by the upper plate is put forward based on the forward and inverse solutions of the platform’s speed and force. The 4TPS-PS platform prototype built by the State Key Laboratory of Fluid Power Transmission and Control of China is taken as the research subject. The full reachable rotation workspace of the prototype is computed out and analyzed. The curves of maximum generalized speed and maximum generalized force of the prototype are computed out and plotted. Finally, the com- puting and analyzing results of the operating characteristics are confirmed through the experiment.

4-DOF串联仿生机械臂动力学建模方法

串联机械臂在仿生机械、工程机器人中得到广泛应用,如何建立有效的串联机械臂系统动力学模型,解决好模型求解的精度和实时性问题是深入开展机械臂运动控制研究的基础。分别采用牛顿-欧拉法、基于动能积分法的拉格朗日方程和基于等效动能法的拉格朗日方程3种求解机械臂动力学模型的方法,对某仿生螳螂前臂四自由度机械臂进行建模研究,通过具体求解过程对比分析了上述3种方法的实时性、精确性和通用性,为该串联机械臂的运动控制研究提供支撑。

Molecular and atomic manipulation of metal-organic framework-derived LiCoMnO_(4):An oxygen-deficient strategy for advanced lithium storage

As a novel class of high-voltage cathode materials,spinel lithium transition metal oxides have been faced with demerits including pronounced structural instability caused by Jahn-Teller distortion(especially at the lower voltage region)and severe capacity degradation despite their intriguing electrochemical properties.To extend their functionalities as broad-voltage cathodes,the sacrificial template method has been regarded as a promising way to realize structural and compositional control for desirable electrochemical behaviors.Herein,we report a synthetic protocol to directionally prepare Li Co Mn O_(4)(LCMO)using carboxyl-based metal-organic frameworks(MOFs)as self-sacrificing templates.Impressively,LCMO derived from Co Mn-BDC(H_(2)BDC=1,4-benzenedicarboxylate)displays superior electrochemical performances with a specific capacity of 151.6 m Ah g^(-1)at 1 C(150 m A g^(-1))after 120 cycles and excellent rate capacity of 91.9 m Ah g^(-1)at 10 C due to the morphology control,microstructural modulation,and atomic manipulation of the MOF precursor.Bestowed by the optimized atomic and electronic structure,abundant oxygen vacancies,and the nanostructure retained from MOF precursors,LCMO materials display extraordinary electrochemical properties,which have been extensively verified by both experimental and theoretical studies.This work not only provides guidelines for the directional design of spinel materials at molecular and atomic levels but also sheds light on the practical use of LIBs with broad range voltage.

4自由度轮式悬架移动机械手动力学研究与仿真

针对4自由度轮式悬架移动机械手(平面)动力学问题进行了系统研究。该轮式移动机械手由2自由度线弹性-阻尼悬架系统的移动载体和2自由度机械手所组成,并假定移动载体以恒速通过不规则路面(路面以正弦函数描述)。综合利用拉格朗日原理和牛顿-欧拉方程,并采用Cartesian坐标,建立了该轮式移动机械手系统的完整动力学模型(正、逆动力学模型)。该动力学模型综合考虑了由路面和悬架对整体系统动力学的耦合影响,最后采用数值的方法分别给出了考虑悬架与不考虑悬架工况的该动力学模型逆解的仿真结果。该模型为后续系统控制策略的选取提供了相应的理论依据。同时该动力学模型由于采用Cartesian坐标,致使该动力学模型的推导具有通用性,为移动机械手动力学研究提供了相应借鉴。

4自由度串联式机械手轨迹运动学的分析

为了实现4自由度串联式机械手的轨迹控制,为实验室设计一种4自由度串联式机械手的结构,基于D-H坐标变换理论,建立了该机械手位置运动学模型,研究了该模型的正、逆解问题。通过计算机仿真,验证了该模型及其正解的正确性。以此为基础,分析了该4自由度串联式机械手的工作空间,并导出该模型逆解的解析式,为实现该机械手的轨迹的精确控制奠定了基础。

可实现空间取放作业的4自由度并联机器人机构综合

本文旨在解决非过约束4自由度并联机构综合这一机构学难题.在总结已有的4自由度并联机器人综合结果的基础上,结合运动子群的概念和螺旋理论的方法,技术性地解决了约束数目和支链数目之间存在的矛盾.利用解析的手段给出了一套全新的非过约束对称4自由度并联机构设计方法.定义了一系列便于综合该机构的概念,分析了该类机构必须具有的拓扑结构,得出两种类型的该类并联机构.给出了满足设计条件的运动副组成情况及空间装配条件,最后给出了典型机构的设计范例.

基于FPGA的4自由度机械臂控制系统设计及实现

以FPGA为核心控制器，选用高效的空心杯电机、高精度的电机驱动器及高性能的增量式光电编码器设计了一个连杆结构的4自由度机械臂。在QuartusⅡ软件平台中，设计了FPGA与上位机PC的串行通信接口及光电编码器信号采集电路．对编码器输出的信号进行了滤波、四倍频和鉴相设计。基于VC＋＋设计了上位机PC人机交互控制界面，实现了对机械臂单关节和多关节联动的控制。实际应用表明，设计的4自由度机械臂能较稳定、灵活地完成用户指定的动作及目标物体的抓取和搬运．证明了设计的合理性。

L_(3-4)椎间盘突出症手法治疗临床疗效观察

目的观察脊柱定点旋转复位手法治疗L_(3-4)椎间盘突出症的临床疗效。方法 L_(3-4)椎间盘突出症56例为A组,L4-5及L5-S1椎间盘突出症60例为B组,均采用脊柱定点旋转复位手法治疗,治疗前及治疗结束后用VAS评分,评价治疗效果,并进行统计分析。结果 A、B组手法治疗后VAS评分与治疗前VAS评分比较均减小,差异均有统计学意义(P<0.01);A组与B组相比,手法治疗后的VAS差异无统计学意义(P>0.05)。结论 L_(3-4)椎间盘突出症可以运用脊柱定点旋转复位法手治疗,其临床疗效与L4-5和L5-S1椎间盘突出症相比差异无统计学意义。

模拟腰椎旋转手法抑制瞬时感受器电位离子通道香草素受体4/一氧化氮疼痛转导通路的作用研究

目的观察模拟腰椎旋转手法对腰神经根疼痛模型大鼠背根神经节(dorsal root ganglion,DRG)内瞬时感受器电位离子通道香草素受体4(transient receptor potential vanilloid 4,TRPV4)表达、一氧化氮(Nitric Oxide,NO)含量变化的影响,探讨手法抑制TRPV4/NO疼痛转导通路的作用。方法2017年3月至2018年10月,将144只雄性SD大鼠随机分为假手术组、模型组、模型+钌红组,每组各48只。其中假手术组只在相应椎节(L5 6)左侧做局部软组织切开,未建模;模型组通过手术在特定椎节(L5 6)左侧建立L5神经根疼痛模型;模型+钌红组在建模后向L5背根节注射TRPV4抑制剂钌红0.1 nmol。所有组别均施行统一量化的模拟腰椎旋转手法,频率1次/隔日,治疗期为3周。每组各取24只大鼠于术后第9、21天时取出手术同侧的L5 DRG,其中18只用于TRPV4通道蛋白表达的检测;6只用于NO代谢产物亚硝酸盐含量的检测。结果经蛋白质印迹法条带比较,发现模型组TRPV4为高表达,模型+钌红组TRPV4表达比模型组减弱,但仍强于假手术组。经腰椎旋转手法干预后,在术后第9、21天时模型组亚硝酸盐含量均值(9.17 nm/mL,5.31 nm/mL)均明显低于模型+钌红组(14.36 nm/mL,9.45 nm/mL),均明显高于假手术组(6.23 nm/mL,3.84 nm/mL)(均P<0.001)。结论TRPV4/NO通路是调控神经根疼痛敏感状态的重要信号转导通路之一。腰椎旋转手法可能是通过调控DRG神经元上的TRPV4/NO通路,来达到迅速缓解DRG神经痛敏的作用。

Precise semi-analytical inverse kinematic solution for 7-DOF offset manipulator with arm angle optimization

Seven-degree-of-freedom redundant manipulators with link offset have many advantages,including obvious geometric significance and suitability for configuration control.Their configuration is similar to that of the experimental module manipulator(EMM)in the Chinese Space Station Remote Manipulator System.However,finding the analytical solution of an EMM on the basis of arm angle parameterization is difficult.This study proposes a high-precision,semi-analytical inverse method for EMMs.Firstly,the analytical inverse kinematic solution is established based on joint angle parameterization.Secondly,the analytical inverse kinematic solution for a non-offset spherical-roll-spherical(SRS)redundant manipulator is derived based on arm angle parameterization.The approximate solution of the EMM is calculated in accordance with the relationship between the joint angles of the EMM and the SRS manipulator.Thirdly,the error is corrected using a numerical method through the analytical inverse solution based on joint angle parameterization.After selecting the stride and termination condition,the precise inverse solution is computed for the EMM based on arm angle parameterization.Lastly,case solutions confirm that this method has high precision,and the arm angle parameterization method is superior to the joint angle parameterization method in terms of parameter selection.

Workspace Analysis of the 4RRR Planar Parallel Manipulator with Actuation Redundancy

In order to overcome the drawbacks of 3RRR non-redundant parallel manipulators,a redundantly actuated planar parallel manipulator,the 4RRR manipulator,was examined.In the current study,three types of workspace were analyzed.In the analysis of the reachable workspace,the shape of the workspace of 4RRR PMs was illustrated,and the relationship between the parameters of parallel mechanisms（PMs） and this kind of workspace was discussed.In the analysis of the m-orientation workspace,a procedure for calculating this type of workspace was presented,and the relationship between this type of workspace and the requirement of rotational displacement was revealed.In the analysis of the nonsingular workspace,the singularity of 4RRR PMs was discussed,the boundary of the singularity was illustrated,and a scheme to maximize the nonsingular workspace was presented.Depicting the properties of 4RRR PMs from different perspectives,the analyses of these three kinds of workspace can serve as helpful references for the structure design and mechanism control of 4RRR PMs.

A hybrid biogeography-based optimization method for the inverse kinematics problem of an 8-DOF redundant humanoid manipulator

The redundant humanoid manipulator has characteristics of multiple degrees of freedom and complex joint structure, and it is not easy to obtain its inverse kinematics solution. The inverse kinematics problem of a humanoid manipulator can be formulated as an equivalent minimization problem, and thus it can be solved using some numerical optimization methods. Biogeography-based optimization （BBO） is a new biogeography inspired optimization algorithm, and it can be adopted to solve the inverse kinematics problem of a humanoid manipulator. The standard BBO algorithm that uses traditional migration and mutation operators suffers from slow convergence and prematurity. A hybrid biogeography-based optimization （HBBO） algorithm, which is based on BBO and differential evolution （DE）, is presented. In this hybrid algorithm, new habitats in the ecosystem are produced through a hybrid migration operator, that is, the BBO migration strategy and Did/best/I/bin differential strategy, to alleviate slow convergence at the later evolution stage of the algorithm. In addition, a Gaussian mutation operator is adopted to enhance the exploration ability and improve the diversity of the population. Based on these, an 8-DOF （degree of freedom） redundant humanoid manipulator is employed as an example. The end-effector error （position and orientation） and the ＇away limitation level＇ value of the 8-DOF humanoid manipulator constitute the fitness function of HBBO. The proposed HBBO algorithm has been used to solve the inverse kinematics problem of the 8-DOF redundant humanoid manipulator. Numerical simulation results demonstrate the effectiveness of this method.