Generalized Kinematics Analysis of Hybrid Mechanisms Based on Screw Theory and Lie Groups Lie Algebras

Advanced mathematical tools are used to conduct research on the kinematics analysis of hybrid mechanisms,and the generalized analysis method and concise kinematics transfer matrix are obtained.In this study,first,according to the kinematics analysis of serial mechanisms,the basic principles of Lie groups and Lie algebras are briefly explained in dealing with the spatial switching and differential operations of screw vectors.Then,based on the standard ideas of Lie operations,the method for kinematics analysis of parallel mechanisms is derived,and Jacobian matrix and Hessian matrix are formulated recursively and in a closed form.Then,according to the mapping relationship between the parallel joints and corresponding equivalent series joints,a forward kinematics analysis method and two inverse kinematics analysis methods of hybrid mechanisms are examined.A case study is performed to verify the calculated matrices wherein a humanoid hybrid robotic arm with a parallel-series-parallel configuration is considered as an example.The results of a simulation experiment indicate that the obtained formulas are exact and the proposed method for kinematics analysis of hybrid mechanisms is practically feasible.

Kinematics analysis for obstacle-surmounting capability of a joint double-tracked robot

A double-tracked robot is designed from mechanical and control perspectives,which consists of two segments connected with a swing joint. As the angle between the two segments of the robot platform can be changed,the robot can move like a four-tracked robot on many terrains. The center of gravity（ CG） kinematics model is established,which plays an important role in the process of traveling over obstacles and climbing up stairs. Using this model,the CG change situation and the maximal height of the climbable obstacle are obtained. Then the relationship between the robot pitch angle and the height of the obstacle is established. Finally,a reasonable system structure for the robot is designed and its kinematics analysis for obstacle-surmounting capability is conducted through experiments.

Configuration and Kinematics of a 3-DOF Generalized Spherical Parallel Mechanism for Ankle Rehabilitation

The kinematic equivalent model of an existing ankle-rehabilitation robot is inconsistent with the anatomical structure of the human ankle,which influences the rehabilitation effect.Therefore,this study equates the human ankle to the UR model and proposes a novel three degrees of freedom(3-DOF)generalized spherical parallel mechanism for ankle rehabilitation.The parallel mechanism has two spherical centers corresponding to the rotation centers of tibiotalar and subtalar joints.Using screw theory,the mobility of the parallel mechanism,which meets the requirements of the human ankle,is analyzed.The inverse kinematics are presented,and singularities are identified based on the Jacobian matrix.The workspaces of the parallel mechanism are obtained through the search method and compared with the motion range of the human ankle,which shows that the parallel mechanism can meet the motion demand of ankle rehabilitation.Additionally,based on the motion-force transmissibility,the performance atlases are plotted in the parameter optimal design space,and the optimum parameter is obtained according to the demands of practical applications.The results show that the parallel mechanism can meet the motion requirements of ankle rehabilitation and has excellent kinematic performance in its rehabilitation range,which provides a theoretical basis for the prototype design and experimental verification.

Biological Jumping Mechanism Analysis and Modeling for Frog Robot

This paper presents a mechanical model of jumping robot based on the biological mechanism analysis of frog. By biological observation and kinematic analysis the frog jump is divided into take-offphase, aerial phase and landing phase. We find the similar trajectories of hindlimb joints during jump, the important effect of foot during take-off and the role of forelimb in supporting the body. Based on the observation, the frog jump is simplified and a mechanical model is put forward. The robot leg is represented by a 4-bar spring/linkage mechanism model, which has three Degrees of Freedom （DOF） at hip joint and one DOF （passive） at tarsometatarsal joint on the foot. The shoulder and elbow joints each has one DOF for the balancing function of arm. The ground reaction force of the model is analyzed and compared with that of frog during take-off. The results show that the model has the same advantages of low likelihood of premature lift-off and high efficiency as the frog. Analysis results and the model can be employed to develop and control a robot capable of mimicking the jumping behavior of frog.

A Hyper-redundant Elephant’s Trunk Robot with an Open Structure:Design,Kinematics,Control and Prototype

As for the complex operational tasks in the unstructured environment with narrow workspace and numerous obstacles,the traditional robots cannot accomplish these mentioned complex operational tasks and meet the dexterity demands.The hyper-redundant bionic robots can complete complex tasks in the unstructured environments by simulating the motion characteristics of the elephant’s trunk and octopus tentacles.Compared with traditional robots,the hyper-redundant bionic robots can accomplish complex tasks because of their flexible structure.A hyper-redundant elephant’s trunk robot(HRETR)with an open structure is developed in this paper.The content includes mechanical structure design,kinematic analysis,virtual prototype simulation,control system design,and prototype building.This design is inspired by the flexible motion of an elephant’s trunk,which is expansible and is composed of six unit modules,namely,3UPS-PS parallel in series.First,the mechanical design of the HRETR is completed according to the motion characteristics of an elephant’s trunk and based on the principle of mechanical bionic design.After that,the backbone mode method is used to establish the kinematic model of the robot.The simulation software SolidWorks and ADAMS are combined to analyze the kinematic characteristics when the trajectory of the end moving platform of the robot is assigned.With the help of ANSYS,the static stiffness of each component and the whole robot is analyzed.On this basis,the materials of the weak parts of the mechanical structure and the hardware are selected reasonably.Next,the extensible structures of software and hardware control system are constructed according to the modular and hierarchical design criteria.Finally,the prototype is built and its performance is tested.The proposed research provides a method for the design and development for the hyper-redundant bionic robot.

PRINCIPLE, CONSTRUCTION AND KINEMATIC ANALYSIS FOR THE OMNIDIRECTIONAL MOBILE ROBOT——ICE-SKATER ROBOT

Three main basic types of locomotion for a mobile robot were introduced and the advantages and disadvantages of a legged mobile robot, a wheeled mobile robot and an articulated mobile robot were also discussed. A new type of leg wheeled mobile robot was introduced which combines the adaptability of legged robot with the stability of wheeled robot. On the basis of the structure of the wheels, the paper described the principle of the ice skater robot developed from Roller walker and ALDURO and its construction. The paper also established an inertia coordinate system and a wheel coordinate system, and analyzed the configuration or the posture and the related kinematic constraints of the robot according to some assumptions. Based on the motion principle, a logic based coordinated control system and corresponded flowchart were designed. At last, taking the ice skater robot as an example the paper expounded its application and the actual experiment proved its feasibility.

Robot inverse kinematics based on FCM and fuzzy-neural network

Presents a fast and effective method proposed by combining the fuzzy C means (FCM) and the fuzzy neural network for solving robot inverse kinematics, and its successful application to the robot inverse kinematics and concludes from simulation results that this new method not only has high efficiency and accuracy, but also good generalization, and it also overcomes the "dimension disaster" of fuzzy set in a fuzzy neural network fairly well.

Direct and Inverse Kinematic Analysis of a Leg-wheeled Passive Wheel Mobile Robot - Ice-skater Robot

A new passive wheel type of leg-wheeled mobile robot based on rolling principle was introduced. To enhance the stability and maintain vertical to the ground of wheels, four passive wheels were installed at the end of four legs respectively and parallel mechanisms were used as legs. And an inertia coordinate system and a robot coordinate system were established, the related kinematic equation of the robot was gotten according to some assumptions after the configuration or the posture of wheels and legs was analyzed. At the same time, the turning conditions of the robot were also obtained. Based on the motion principle, the VSS-based logic control system was designed and the skating straight experiments and the turning experiments were conducted. And some conclusions were drawn.

Configuration Design and Kinematic Performance Analysis of a Novel 4-DOF Parallel Ankle Rehabilitation Mechanism with Two Virtual Motion Centers

Aiming at the problem that the existing ankle rehabilitation robot is difficult to fully fit the complex motion of human ankle joint and has poor human-machine motion compatibility,an equivalent series mechanism model that is highly matched with the actual bone structure of the human ankle joint is proposed and mapped into a parallel rehabilita-tion mechanism.The parallel rehabilitation mechanism has two virtual motion centers(VMCs),which can simulate the complex motion of the ankle joint,adapt to the individual differences of various patients,and can meet the reha-bilitation needs of both left and right feet of patients.Firstly,based on the motion properties and physiological structure of the human ankle joint,the mapping relationship between the rehabilitation mechanism and ankle joint is determined,and the series equivalent model of the ankle joint is established.According to the kinematic and con-straint properties of the ankle equivalent model,the configuration design of the parallel ankle rehabilitation robot is carried out.Secondly,according to the intersecting motion planes theory,the full-cycle mobility of the mechanism is proved,and the continuous axis of the mechanism is judged based on the constraint power and its derivative.Then,the kinematics of the parallel ankle rehabilitation robot is analyzed.Finally,based on the OpenSim biomechanical soft-ware,a human-machine coupling rehabilitation simulation model is established to evaluate the rehabilitation effect,which lays the foundation for the formulation of a rehabilitation strategy for the later prototype.

Design of A Novel Wheel-Legged Robot with Rim Shape Changeable Wheels

The wheel-legged hybrid structure has been utilized by ground mobile platforms in recent years to achieve good mobility on both flat surfaces and rough terrain.However,most of the wheel-legged robots only have one-directional obstacle-crossing ability.During the motion,most of the wheel-legged robots’centroid fluctuates violently,which damages the stability of the load.What’s more,many designs of the obstacle-crossing part and transformation-driving part of this structure are highly coupled,which limits its optimal performance in both aspects.This paper presents a novel wheel-legged robot with a rim-shaped changeable wheel,which has a bi-directional and smooth obstacle-crossing ability.Based on the kinematic model,the geometric parameters of the wheel structure and the design variables of the driving four-bar mechanism are optimized separately.The kinetostatics model of the mobile platform when climbing stairs is established to determine the body length and angular velocity of the driving wheels.A pro-totype is made according to the optimal parameters.Experiments show that the prototype installed with the novel transformable wheels can overcome steps with a height of 1.52 times of its wheel radius with less fluctuation of its centroid and performs good locomotion capabilities in different environments.

六自由度上肢康复机器人机构设计及轨迹规划

本研究设计一款六自由度上肢康复机器人,机器人采用绳索驱动、串并联相结合的关节结构形式,能够牵引偏瘫患者的上肢实现多个关节且活动范围较大的康复运动训练。针对上肢康复机器人机构适用性问题,基于运动学理论和D-H坐标系法建立上肢康复机器人本体D-H参数模型,根据空间坐标向量之间的平移、旋转关系,对运动序列建模分析,求解正运动学,通过封闭解法求解逆运动学。基于运动学分析结果,提出五次多项式函数关节空间轨迹规划方法,对上肢提拉抬肘运动进行轨迹规划仿真,验证了康复运动过程中的运动能力。

气动肌肉驱动的上肢康复机器人动力学仿真

针对目前外骨骼机器人本体结构复杂,人机交互安全性不高的问题,结合驱动系统中气动人工肌肉的轻质、大驱动力、高柔顺性和接近人体肌肉的特性,提出一种基于气动肌肉的外骨骼上肢康复机器人。采用蒙特卡罗方法获得机器人的安全工作空间,并基于拉格朗日方程对外骨骼上肢康复机器人进行动力学建模,通过MATLAB软件对上肢康复机器人动力学特性仿真。

下肢外骨骼康复机器人仿真和试验分析

目的为了帮助下肢运动障碍者进行有序康复训练,设计一种下肢外骨骼康复机器人,动力源驱动下肢交叉摆动模拟人类正常步态行走,实现双下肢协调运动,帮助下肢运动障碍者完成康复训练。方法建立外骨骼机器人三维模型、下肢外骨骼机器人D-H模型,对下肢外骨骼康复机器人进行正、逆运动学分析,并将模型导入ADAMS,创建运动副与驱动函数进行运动学仿真,在此基础上制作样机并进行动力学测试试验分析。结果正、逆运动学验证了外骨骼康复机器人空间运动的合理性,ADAMS运动仿真结果与理论计算具有良好一致性,从而保证设计的下肢外骨骼结构与穿戴者下肢同步协调。仿真分析发现理论计算和仿真的误差主要来源于驱动函数误差,动作误差最大为2.15 cm。试验验证髋关节、膝关节运动与参考输入运动具有一致性。但是运动存在误差,髋关节平均误差为5.57°,膝关节平均误差为5.45°,实验发现电机扭矩不足是引起运动误差的首要因素,其次是零件加工误差和装配误差。结论通过理论计算、仿真与试验分析验证了方案的可行性,发现驱动误差、零件加工精度和装配精度可带来误差。研究结果可为进一步完善机器人性能和研究康复机器人动力学影响因素提供基础和参数依据。

一种双工位旋转式上甑机器人设计

上甑是白酒酿造的关键工序,为解决传统白酒酿造上甑过程中劳动强度大、酒质及产酒率不稳定等问题,依据上甑过程的工艺要求及标准,设计了一种双工位旋转式上甑机器人。该机器人采用3个旋转关节和撒料器实现上甑铺料的平面定位,平移关节实现撒料高度的控制。对机器人的正、逆运动学进行了解析求解和验证,采用Monte⁃Carlo法模拟了上甑机器人的工作空间;基于有限元方法对关键部件进行了强度及模态分析。通过物理试验样机的现场测试,表明样机上甑相比于人工上甑的出酒率提高了10%左右,尾酒度数降低了5°~7°,有效提高了上甑的效率,验证了设计的可行性。模拟仿真与样机测试结果表明:文中上甑机器人的结构及功能满足设计要求,可为上甑机器人的设计及后续性能优化提供参考。

仿生六足折纸机器人结构设计与运动分析

针对现有折纸机器人组成结构单一,运动不够灵活的问题,将折纸结构与多足机器人设计相结合,耦合三浦折纸和六折痕折纸,提出新型的仿螃蟹六足折纸机器人设计方案,扩展了折纸机器人的运动构型,提升了折纸机器人的运动灵活性.在面对称假设下,该机器人单足具有2个自由度,此时将机器人腿部顶点等效为关节,轴线折痕等效为连杆,建立机器人腿部的平面连杆等效模型,并以折面夹角为运动变量,通过仿真计算得出机器人足端的理论运动范围.利用楔形面板技术对折面增厚并避免相邻折面发生物理干涉,建模得到折纸仿螃蟹六足机器人的三维模型.基于平面连杆的等效模型,分析折面夹角与足端运动之间的联系,设计确定机器人的足端运动轨迹与运动步态.利用3D打印技术设计并制作折纸仿生六足机器人试验样机,基于STM32单片机控制实现了机器人三横向角步态运动.结果表明,该折纸仿生机器人可以实现平面构型到仿螃蟹构型的转换,在6条腿的协同运动下,机器人可以平稳地左右横向移动.

基于共形几何代数的工业机器人运动学分析

为解决工业机器人运动学求解复杂程度高、运算量大的问题,将共形几何代数(Confor-mal Geometric Algebra,CGA)方法引入到工业机器人运动学模型构建中。在正运动学求解过程中,利用CGA中平移算子和旋转算子列出各关节的运动表达式,求出机器人末端执行器的位姿;在逆运动学求解过程中,将构造的基本几何体进行外积计算,求得各关节点的位置,然后构造过关节点的线和面,并在CGA框架内做内积,得到所有关节角的余弦表达,求解得到机器人逆运动学的全部解;最后,以MOTOMAN-HP20D型6自由度工业机器人为例进行计算,并通过Matlab/Simulink软件验证了算法的准确性和有效性,为机器人后续的运动控制奠定了基础。

人体下肢康复装置的结构设计及运动学分析

介绍了一种基于平面五杆机构的人体下肢康复装置,旨在满足术后卧床的卒中患者的早、中、后期的下肢康复训练需求。该装置具有简单可靠的特点,可以在床尾侧放置或随患者行走移动。装置主要由下部移动平台、手动升降组件、上部动力传动机构及左、右训练机构组成,并在踝、膝关节通用的关节支架上附有传感器,患者的运动信息可以被实时采集和反馈。运动学分析及Adams软件仿真结果表明,调整该装置双曲柄的初始相位,可以改变关节点的运动轨迹,得到不同运动模式下人体下肢关节运动的范围,达到卧式训练及行走训练的目的,从而满足患者不同康复阶段的训练需求。

康复外骨骼机器人对脑卒中下肢运动功能障碍疗效的Meta分析

目的:运用Meta分析方法系统评价康复外骨骼机器人对脑卒中患者下肢运动功能的康复疗效,并比较不同下肢外骨骼机器人的疗效差异,为脑卒中下肢运动功能障碍患者选择适合的外骨骼机器人提供科学理论依据。方法:计算机检索Cochrane Library、PubMed、Web of Science、Embase、中国知网、维普和万方数据库的相关文献,收集从建库至2022年11月发表的关于探讨下肢康复外骨骼机器人改善脑卒中患者下肢运动功能的随机对照临床试验。由2名研究人员进行文献检索与筛选,使用Cochrane 5.1.0偏倚风险评估工具和Jadad量表对纳入文献进行质量评价。采用RevMan 5.4和Stata 17.0软件对结局指标进行Meta分析。结果:①最终纳入22篇文献,Jadad评分显示均为高质量文献,共865例患者,试验组436例、对照组429例。②Meta分析结果显示,与对照组相比,外骨骼机器人可显著提高脑卒中患者下肢运动功能(Fugl-Meyer Assessment of Lower Extremity,FMA-LE)评分(MD=2.63,95%CI:1.87-3.38,P<0.05)、平衡功能(Berg Balance Scale,BBS)评分(MD=3.62,95%CI:1.21-6.03,P<0.05)、站起-走测试量表(Timed Up and Go,TUG)评分(MD=-2.77,95%CI:-4.48至-1.05,P<0.05)和步频(MD=3.15,95%CI:1.57-4.72,P<0.05),但对功能性步行量表(Functional Ambulation Category Scale,FAC)评分(MD=0.30,95%CI:-0.01-0.61,P>0.05)和6 min步行测试(6-minute walk test,6MWT)评分(MD=3.77,95%CI:-6.60-14.14,P>0.05)的提高不明显。③网状Meta分析结果显示,FMA-LE评分:平地行走式外骨骼(MD=10.23,95%CI:3.81-27.49,P<0.05)和减重式外骨骼(MD=33.66,95%CI:11.49-98.54,P<0.05)与常规康复治疗相比均能改善FMA-LE评分,排序结果为减重式外骨骼>平地行走式外骨骼>常规康复治疗;BBS评分:减重式外骨骼(MD=79.86,95%CI:2.34-2725.99,P<0.05)与常规康复治疗相比能显著改善BBS评分,排序结果为减重式外骨骼>平地行走式外骨骼>常规康复治疗;FAC评分:平地行走式外骨骼(MD=1.38,95%CI:1.00-1.90,P<0.05)与常规康复治疗相比能显著改善FAC评分,排序结果为平地行走式外骨骼>减重式外骨骼>常规康复治疗;TUG评分:减重式外骨骼与常规康复治疗相比(MD=0.07,95%CI:0.01-0.51,P<0.05)能显著改善TUG评分,排序结果为平地行走式外骨骼>减重式外骨骼>常规康复治疗。结论:康复外骨骼机器人可以改善脑卒中患者平衡、步行以及日常生活活动能力,其中减重式外骨骼在提高下肢运动功能和平衡功能方面疗效更优,平地行走式外骨骼在提高功能性步行和转移能力方面疗效更佳。

外骨骼机器人辅助步行康复治疗脊髓损伤:研究热点的CiteSpace分析

背景:脊髓损伤危害严重,损伤后步行功能障碍最影响患者的日常生活能力,在该领域运用外骨骼机器人开展辅助步行康复研究日趋活跃。目的:应用CiteSpace可视化软件绘制脊髓损伤后外骨骼机器人辅助步行为主题的科学知识图谱,并探讨近10年该领域研究现状、热点及未来趋势,为该领域后续科学研究和临床运用提供借鉴。方法:利用Web of Science核心集数据库通过布尔逻辑运算符进行主题词检索,选择语种英语,检索策略:TS=“spinal cord injury OR SCI”AND“walk OR walking”AND“robot OR exoskeleton OR(exoskeleton-assisted walking)OR EAW”,利用知识图谱软件CiteSpace 6.2.R4对去重后获得的高质量文献进行发文量、国家/研究机构合作、高影响力作者/文献共被引、关键词共现/聚类/突现等主题热点、国际前沿趋势可视化分析,并绘制科学知识图谱。结果与结论:①共纳入544篇高质量文献,近10年该领域发文量、总被引频次呈增长趋势;②发文量排名前3的国家依次是美国、中国、意大利,发文量排名前3研究机构是美国退伍军人事务部、美国退伍军人健康管理局、瑞士联邦理工学院;③被引文献频次最高(167次)和中介中心性最高(0.13)的作者均为美国宾夕法尼亚Esquenazi A团队,在该领域具有较高影响力;④对被引频次、中介中心性前5共被引文献分析显示:目前针对脊髓损伤患者配备动力外骨骼设备步行康复研究重点包括在机构、家庭等真实环境中步行康复训练安全性判断、优势分析、个体化培训计划设计,动力外骨骼设备应用于胸椎及以下节段运动功能完全丧失脊髓损伤患者辅助步行效果优劣、影响因素及应用潜力等;⑤近年该领域研究热点集中于个体化(individuals)、步态(gait)、动力外骨骼(powered exoskeleton)、减重支持(body weight support)、功能性电刺激(functional electrical stimulation)、康复(rehabilitation)、辅助技术(assistive technology)、步行活动(ambulation)、恢复(recovery)等内容;⑥该领域研究早期多应用于脑卒中患者,前沿包括减重支持、往复式步态矫形器及功能性电刺激等技术手段,脊髓损伤外骨骼机器人辅助步行康复研究近年呈现上升趋势,关注点逐渐向以适应性控制为机制的医用下肢外骨骼设备研制、安全性提升、应用潜力挖掘等前沿方向转变,研究检测手段注重联合功能性近红外光谱成像等高端技术,而关注患者生活质量、提升运动训练能力及改善机体结构为该领域未来的研究热点。

仿生双爪式管道攀爬机器人设计与分析

针对燃气与管道工程等领域的高空作业,设计了一种永磁铁辅助式具有可调步距的蠕动和翻转两种步态的双夹持器仿生攀爬机器人。为防止机器人出现滑移和翻转倾覆失稳情况,对其进行了力学分析;根据机器人构型对其进行了运动学与攀爬步态分析;对蠕动攀爬步态进行直线路径规划,并在SOLIDWORKS MOTION环境下对其两种步态进行了运动仿真。样机试验说明了机器人在蠕动和翻转两种步态下均具有良好的稳定性,两种步态配合可实现障碍物的翻越。该机器人在高空管道领域作业方面具有较好的应用价值。