Bionic lightweight design of limb leg units for hydraulic quadruped robots by additive manufacturing and topology optimization

Galloping cheetahs,climbing mountain goats,and load hauling horses all show desirable locomotion capability,which motivates the development of quadruped robots.Among various quadruped robots,hydraulically driven quadruped robots show great potential in unstructured environments due to their discrete landing positions and large payloads.As the most critical movement unit of a quadruped robot,the limb leg unit(LLU)directly affects movement speed and reliability,and requires a compact and lightweight design.Inspired by the dexterous skeleton–muscle systems of cheetahs and humans,this paper proposes a highly integrated bionic actuator system for a better dynamic performance of an LLU.We propose that a cylinder barrel with multiple element interfaces and internal smooth channels is realized using metal additive manufacturing,and hybrid lattice structures are introduced into the lightweight design of the piston rod.In addition,additive manufacturing and topology optimization are incorporated to reduce the redundant material of the structural parts of the LLU.The mechanical properties of the actuator system are verified by numerical simulation and experiments,and the power density of the actuators is far greater than that of cheetah muscle.The mass of the optimized LLU is reduced by 24.5%,and the optimized LLU shows better response time performance when given a step signal,and presents a good trajectory tracking ability with the increase in motion frequency.

基于CFD和热阻网络法的C型舱LEG船温度场分析及热应力计算

为解决C型舱LEG船进行温度场计算时,CFD方法难以计入结构细节以及热阻网络法处理热对流精度较低的问题,提出将2种方法相结合的船体结构温度场计算方法。在CFD计算时,只考虑主要结构,将计算结果作为热阻网络法的输入,而在热阻网络法中考虑结构细节。实船计算结果显示,该方法高效可靠,避免了2种方法的缺点,可以合理地求解船体结构的温度场,是一种工程上实用的方法。计算还表明,对于温度梯度大的关键结构区域,结构强度评估需要考虑热应力。

Inverted Modelling:An Effective Way to Support Motion Planning of Legged Mobile Robots

This paper presents an effective way to support motion planning of legged mobile robots—Inverted Modelling,based on the equivalent metamorphic mechanism concept.The difference from the previous research is that we herein invert the equivalent parallel mechanism.Assuming the leg mechanisms are hybrid links,the body of robot being considered as fixed platform,and ground as moving platform.The motion performance is transformed and measured in the body frame.Terrain and joint limits are used as input parameters to the model,resulting in the representation which is independent of terrains and particular poses in Inverted Modelling.Hence,it can universally be applied to any kind of legged robots as global motion performance framework.Several performance measurements using Inverted Modelling are presented and used in motion performance evaluation.According to the requirements of actual work like motion continuity and stability,motion planning of legged robot can be achieved using different measurements on different terrains.Two cases studies present the simulations of quadruped and hexapod robots walking on rugged roads.The results verify the correctness and effectiveness of the proposed method.

A molecular toolkit to boost functional genomic studies in transformation-recalcitrant vegetable legumes

Dear Editor Legumes,the second-largest family of crops,contribute over one-third of human dietary proteins.Soybean(Glycine max L.),common bean(Phaseolus vulgaris L.),pea(Pisum sativum L.),and cowpea(Vigna unguiculata L.)are among the most widely culti-vated crop legumes for grain and vegetable and are essential for food security globally.

Task-Oriented Topology System Synthesis of Reconfigurable Legged Mobile Lander Integrating Active and Passive Metamorphoses

To explore hostile extraterrestrial landforms and construct an engineering prototype,this paper presents the task-oriented topology system synthesis of reconfigurable legged mobile lander(ReLML)with three operation modes from adjusting,landing,to roving.Compared with our preceding works,the adjusting mode with three rotations(3R)provides a totally novel exploration approach to geometrically matching and securely arriving at complex terrains dangerous to visit currently;the landing mode is redefined by two rotations one translation(2R1T),identical with the tried-and-tested Apollo and Chang'E landers to enhance survivability via reasonable touchdown buffering motion;roving mode also utilizes 2R1T motion for good motion and force properties.The reconfigurable mechanism theory is first brought into synthesizing legged mobile lander integrating active and passive metamorphoses,composed of two types of metamorphic joints and metamorphic execution and transmission mechanisms.To reveal metamorphic principles with multiple finite motions,the finite screw theory is developed to present the procedure from unified mathematical representation,modes and source phase derivations,metamorphic joint and limb design,to final structure assembly.To identify the prototype topology,the 3D optimal selection matrix method is proposed considering three operation modes,five evaluation criteria,and two topological subsystems.Finally,simulation verifies the whole task implementation process to ensure the reasonability of design.

Effect of Specific Verbal Instructions on the Identification of Pain Location during a Passive Straight Leg Raise Test

Musculoskeletal pain is common. Because pain is subjective, objectively describing it is crucial. However, pain assessment may cause distress in patients;therefore, physical therapists (PTs) should conduct these tests quickly and accurately. Simple and clear instructions are recommended for pain assessment. However, few studies have provided evidence to support this hypothesis. Correspondingly, this study aimed to confirm the effectiveness of specific verbal instructions for pain location during five consecutive Passive Straight Leg Raise (PSLR) tests. The 28 asymptomatic participants (age 27.4 ± 9.6 years) who provided informed consent received five consecutive PSLR tests: three without and two with specific verbal instructions to ascertain pain intensity, quality, and location. The participants drew pain locations on a body chart and described the pain intensity and quality after each test. All participants were interviewed regarding the differences they noted in the presence and absence of specific verbal instructions. Each pain location was classified into one of ten areas for statistical analysis. The proportion of participants who changed the pain location was compared between the tests using McNemar’s test, and the kappa coefficient was confirmed for consistency of pain location. There was a significant difference in the proportion of participants who changed their pain location between the second and third tests and from the third to the fourth test (McNemar’s test: p = 0.003). Kappa coefficients had low consistency (κ = 0.28) just after receiving the specific verbal instructions in the fourth test compared to the third test. Consistency improved in the fifth test (κ = 0.57);93% of the participants answered that the pain location had become clearer. This study revealed the effects of specific verbal instructions in identifying pain locations. This detailed information may help PTs provide appropriate treatment and contribute to reducing pain in clinical settings.

Investigation of the mechanism of action of Sanwu Huangqin Tang in the treatment of restless leg syndrome based on network pharmacology,molecular docking technology and molecular dynamics simulation

Background:Through the use of network pharmacology and molecular docking approaches,this study will examine the pharmacological effects of Sanwu Huangqin Tang on restless legs syndrome in order to better understand the mechanism of action of Traditional Chinese medicine(TCM)on RLS.Method:Utilise the TCMSP database to collect and select the drug components of Sanwu Huangqin Tang,and the Uniprot database to identify pertinent targets;RLS-related disease targets were obtained from GeneCards,DrugBank,and OMIM databases;and STRING and Cytoscape 3.9.1 software were used to generate an interaction network.KEGG pathway analysis and GO enrichment analysis were performed utilizing the DAVID database.Use Autodock for analyzing the relationships between targets and core components.Result:By using a network pharmacology approach,83 active ingredients and 50 drug-disease intersecting targets were derived for Sanwu Huangqin Tang.The molecular docking results showed that the drug components had strong affinity with the average target targets.Conclusions:This study provides new insights into the mechanism through which Traditional Chinese Medicine(TCM)treats Restless Legs Syndrome(RLS).Furthermore,it lays the foundation for additional research into the mechanism of treatment for RLS through the intervention that addresses various targets and pathways using the active ingredients identified by Sanwu Huangqin Tang.

Design and Analysis of a Multi-Legged Robot with Pitch Adjustive Units

The paper proposes a novel multi-legged robot with pitch adjustive units aiming at obstacle surmounting.With only 6 degrees of freedom,the robot with 16 mechanical legs walks steadily and surmounts the obstacles on the complex terrain.The leg unit with adjustive pitch provides a large workspace and empowers the legs to climb up obstacles in large sizes,which enhances the obstacle surmounting capability.The pitch adjustment in leg unit requires as few independent adjusting actuators as possible.Based on the kinematic analysis of the mechanical leg,the biped and quadruped leg units with adjustive pitch are analyzed and compared.The configuration of the robot is designed to obtain a compact structure and pragmatic performance.The uncertainty of the obstacle size and position in the surmounting process is taken into consideration and the parameters of the adjustments and the feasible strategies for obstacle surmounting are presented.Then the 3D virtual model and the robot prototype are built and the multi-body dynamic simulations and prototype experiments are carried out.The results from the simulations and the experiments show that the robot possesses good obstacle surmounting capabilities.

灰色系统理论对LEG船货舱温度的预测

应用灰色系统理论中 GM( 1,1)预测模型的原理和方法对 LEG船货舱温度预测进行了计算 ,结果表明该 GM( 1,1)预测模型计算简单、结果可靠 ,此模型可应用于船舶各种设备的运行状态预测。

供应链合作伙伴关系分类:基于LEG模型的实证研究

建立供应链合作伙伴关系分类评价模型,以国内典型制造企业为研究对象,结合问卷调查分析制造型企业供应链合作伙伴关系现状,运用聚类分析法对合作伙伴关系进行分类,为企业有效实施供应链合作伙伴关系管理提供依据,帮助制造型企业提高管理效率,节约管理成本,更合理地分配资源。

Optimal Load Balancing Leveling Method for Multi-leg Flexible Platforms

The working platforms supported with multiple extensible legs must be leveled before they come into operation.Although the supporting stiffness and reliability of the platform are improved with the increasing number of the supporting legs,the increased overdetermination of the multi-leg platform systems leads to leveling coupling problem among legs and virtual leg problem in which some of the supporting legs bear zero or quasi zero loads.These problems make it quite complex and time consuming to level such a multi-leg platform.Based on rigid body kinematics,an approximate equation is formulated to rapidly calculate the leg extension for leveling a rigid platform,then a proportional speed control strategy is proposed to reduce the unexpected platform distortion and leveling coupling between supporting legs.Taking both the load coupling between supporting legs and the elastic flexibility of the working platform into consideration,an optimal balancing legs’ loads(OBLL) model is firstly put forward to deal with the traditional virtual leg problem.By taking advantage of the concept of supporting stiffness matrix,a coupling extension method(CEM) is developed to solve this OBLL problem for multi-leg flexible platform.At the end,with the concept of supporting stiffness matrix and static transmissibility matrix,an optimal load balancing leveling method is proposed to achieve geometric leveling and legs’ loads balancing simultaneously.Three numerical examples are given out to illustrate the performance of proposed methods.This paper proposes a method which can effectively quantify all of the legs’ extension at the same time,achieve geometric leveling and legs’ loads balancing simultaneously.By using the proposed methods,the stability,precision and efficiency of auto-leveling control process can be improved.

Development and Analysis of a Closed-Chain Wheel-Leg Mobile Platform

Current research concerning legged platforms and wheeled platforms primarily focuses on terrain adaptive capability and speed capability,respectively.Compared with wheeled platforms,legged platforms with a closed-chain mechanism still present deficiencies regarding speed ability.To integrate the advantages of these two types of platforms,a wheel-leg mobile platform with two modes based on a closed-chain mechanism is proposed.First,a closed-chain mechanism that generates a high-knee trajectory in legged mode is designed and analyzed based on kinematic analysis.To improve the platform’s obstacle-surmounting performance,the dimensional parameters of the closedchain mechanism are optimized and the design requirements for the platform’s frame are analyzed.In addition,the particular structure of the leg group is designed to realize transformation between legged mode and wheeled mode.The mobility of the constructed platform is calculated through an obstacle-surmounting probability analysis.The performances of the two motion modes are analyzed and compared by conducting dynamic simulations.Finally,experiments are carried out to verify both the theoretical analyses and the prototype performance.This study proposes a new approach to designing wheel-leg platforms with prominent speed ability and mobility based on a closed-chain mechanism.

Free gait generation method for omnidirectional locomotion on abrupt terrain with multi-legged biomimetic robot

In order to achieve omnidirectional locomotion on rough terrain with multi-legged biomimetic robot,a free gait generation approach is proposed based on local rules.The phase coordinates of each operation leg was established according to the motion task and a universal depiction of leg-end locomotion was implemented;the mathematical relation of gait pattern and walking velocity of multi-legged robot was put forward;combined polynomial curve was adopted to generate the leg-end trajectory,which was capable of accomplishing walking missions and accommodating to landform conditions;a distributed network of local rules for gait control was constructed based on a set of local rules operating between adjacent legs.In the simulation experiments,adaptive regulation of inter-leg phase sequence,omnidirectional locomotion and ground accommodation were realized.Moreover,statically stable free gait was obtained simultaneously,which provided multi-legged robot with the capability of walking on irregular terrain reliably and expeditiously.

37 500 m^(3) LEG船液罐吊装精度数字仿真分析

以37500 m^(3)液化乙烯气(Liquefied Ethylene Gas,LEG)船货舱区液罐吊装为研究对象,对液罐吊装前的干涉检查和数据匹配等工作进行梳理,建立一套完整的液罐吊装模拟匹配流程,并对实际吊装过程出现的问题提出解决方案,旨在为后续同类大型液罐的吊装提供参考、积累经验。

基于uClinux的嵌入式CIP-I Leg控制器设计

CIP-I Leg是国内首个智能仿生人工腿原型机。智能仿生人工腿的摆动是依靠膝关节内一个空压气缸的活塞的伸缩来实现的。空压气缸尾部有一个电机可以控制气缸内一个针阀的开度,改变针阀开度可以调节膝关节弯曲和伸展的阻尼,从而达到改变人工腿摆动速度的目的。以前研制的智能人工腿,在三个方面存在不足:第一,用于控制气缸内针阀开度的控制器采用的是由步进电机所构成的开环系统,位置精度不高;第二,它的CPU多采用8位或16位的单片机,运行速度不能满足高级算法的需要;第三,原裸机系统开发难度大,可扩展性差。针对以上不足,提出了基于嵌入式系统的智能仿生人工腿CIP-I Leg控制器解决方案。在软件实现部分,uCinux由于其内核精简而高效、可修改性和可移植性被选作为嵌入式系统的操作系统,软件设计包括开发环境的建立、BootLoader引导加载程序的实现、内核的配置与移植、设备驱动程序和应用程序的开发与移植等。

斑马鱼leg1直系同源基因mu-leg1在小鼠中的表达谱分析

基因leg1(liver-enriched gene 1)首先在斑马鱼中作为肝脏富集表达基因被鉴定。进一步的研究揭示leg1编码的Leg1蛋白代表一类新型外分泌蛋白,它在斑马鱼胚期肝脏生长发育过程中起关键作用。小鼠leg1(mu-leg1)是斑马鱼leg1(zb-leg1)的直系同源基因,二者编码的蛋白氨基酸序列相似性为31%。文章通过巢式PCR从成年小鼠肝脏中成功克隆了mu-leg1的cDNA序列,并对该基因在成年小鼠不同组织中的表达特征进行分析和鉴定。Northern印迹杂交和半定量RT-PCR分析结果显示,mu-leg1在成年小鼠小肠中而非肝脏中富集表达。此外,用制备的mu-Leg1多克隆抗体进行Western印迹杂交,结果显示mu-Leg1也是一个分泌蛋白。同时,还建立了mu-leg1基因条件性剔除杂合子小鼠。这些材料为今后深入研究和探讨mu-Leg1蛋白的生化功能奠定了基础。

基于leg-by-leg机动的两级采样被动跟踪方法

针对被动声呐方位-频率观测情况下粒子滤波检测前跟踪算法中高维采样效率低的问题,该文提出一种利用leg-by-leg机动可观测性特点的两级采样方法。首先,对leg-by-leg机动的可观测性进行分析;然后,建立极坐标系下的目标运动状态模型,以粒子相对观测站的距离和法向速度均匀分布为准则,提出将极坐标系下的目标状态向量映射至直角坐标系的方法;最后,为改善滤波收敛性,提出根据粒子的空间分布特征自适应地调整过程噪声协方差矩阵。仿真结果表明,对于典型的水下目标跟踪场景,所提方法可使滤波收敛率增大约47.6%,距离估计误差减小约329 m,滤波收敛时间缩短约450 s。

Leg-by-leg机动条件下纯方位跟踪的观测站机动策略

针对观测站机动前目标距离未知导致无法计算Fisher信息矩阵(Fisher information matrix,FIM)的问题,从粗估目标初始距离和减小粗估误差对FIM行列式影响两方面着手,提出在转向前计算FIM进而设计机动策略的方法。首先,在修正极坐标系下建立系统模型,描述了观测站leg-by-leg机动模式下FIM的计算方法。其次,通过假设目标速度实现目标初始状态粗估,提出使归一化初始距离粗估误差最小的目标速度假设方法。然后,对FIM行列式进行近似及多项式展开,通过控制前后leg段比例以减小状态粗估误差对FIM行列式的影响。最后,利用仿真验证了所提机动策略设计方法的可行性和有效性。结果表明,对于典型的水下目标跟踪场景,FIM行列式的有效估计概率为76.7%,平均的相对估计误差为0.12。

LEG可倾瓦径向轴承的特性分析

介绍LEG可倾瓦径向轴承的结构特点,计算并分析LEG可倾瓦径向轴承的静特性和动特性,并对LEG可倾瓦径向轴承和浸润式可倾瓦径向轴承进行了比较,显示出应用直接润滑技术轴承的优越性。

LEGPRESS测试系统对速度滑冰专项力量训练价值的理论研究

研究leg press系统对速度滑冰专项力量训练的价值,采用视频、表面肌电和直线等速运动同步对王北星、于静和张虹蹬伸过程中的力学和肌电参数进行研究。结果表明:(1)冰刀对下肢力和功有较大限制,应进行穿刀力量训练以提高专项力量训练效果;(2)有刀支撑时的电-力关系较独特,且有刀支撑时对胫骨前肌的刺激加大,体现了穿刀力量训练的必要性;(3)直线等速蹬伸对速度滑冰的专项力量训练价值主要体现在最大力量训练的全程性、多关节复合运动性,以及力量训练的专项性和安全性。建议:从特制冰鞋和速度控制等角度降低穿刀等速训练的危险性,逐步提高运动员穿刀等速蹬伸训练的能力,尽快体现该系统在速度滑冰专项力量训练上应有的价值;在该系统应用于训练实践后,应及时进行各速度最大力值变化与运动成绩、加速能力关系的量化研究,实证该系统对速度滑冰专项力量的训练价值。