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.

采用37.5■锦纶开发多功能弹力Legging面料

文章以37.5■锦纶科技纱线4.4 tex/34 f消光DTY为主纱,夹入2.2 tex黑氨纶材料,采用双面互锁的织造方式,开发出一款集抗菌、凉感、远红外、吸湿速干、防紫外线功能为一体的多功能弹力Legging针织面料。详细介绍该面料的原料选择、织造工艺以及染整工艺,并对面料的基本性能进行测试。结果表明,该面料具有较好的多项功能以及优良的包覆性能,可以满足女子多场景的运动与穿着舒适性的相关需求。

“腿(leg)”隐喻在汉英表达中的认知语言学阐析

身体部位在人类认知体系中处于基础性地位,在获取身体体验的过程中具有独一无二的作用。身体部位之腿(leg)更是人们感知外部世界的重要工具之一。汉英表达中均广泛存在以腿(leg)为源域的腿(leg)隐喻表达。从认知层面的意象角度具体分析腿(leg)的隐喻可知,腿(leg)的意象分为两大类:一类是以腿(leg)的基本外形和功能为主的具体意象,另一类是由其基本外形和功能而衍生出来的抽象意象。汉英民族因为具有相同的身体结构和生理特征,产生了相近的身体体验,而趋近的体验也产生了对等的心理阐释和语言表述,因此汉英语言表达中存在众多相仿或趋同的腿(leg)隐喻。隐喻作为各民族典型的语言现象,势必与不同民族的文化意蕴密不可分。汉英表达中腿(leg)的隐喻义都颇为丰富,有相同之处,也存在典型差异,这主要是由各自的社会文化背景、思维方式、词法规则、词语搭配、主体指代关系和民族特色差异所造成的。

Prevalence of Bacterial and Fungal Infected Chronic Leg Ulcers at a Teaching Hospital in Ghana

Background: Chronic ulcers are responsible for considerable morbidity and significantly contribute to the escalation in the cost of health care. Chronic leg ulcers (CLUs) are susceptible to microbial infections and serious complications such as tissue necrosis and osteomyelitis, can result without the timely control of infections. Recent studies have also reported an increase in the association of fungal infections with chronic non-healing ulcers. Aim: To determine the prevalence of bacterial and fungal infections among patients reporting with chronic leg ulcers in participants without co-morbidities. Methods: A prospective cross-sectional study was conducted among patients with chronic leg ulcers at the National Reconstructive Plastic Surgery and Burns Centre, Korle-Bu Teaching Hospital (NRPS/BC-KBTH) and those who consented were enrolled. Characteristics of the wound as well as micro-organisms cultured from wound swabs were recorded. Results: A total of 50 participants were enrolled for the study with the mean (SD) age of 40.7 (10.7) years. Eighty percent of the participants presented with post traumatic leg ulcers with 80% being artisans and traders in the age group 31 - 50 years. There was no statistically significant association between sex and the organism cultured for post traumatic and cellulitis (p-value > 0.05). The prevalence of bacterial and fungal infection was 79.3% and 20.7% respectively. Pseudomonas species was the most isolated bacteria (61.5%) while Aspergillus niger was the most isolated fungi (41%). Conclusion: From this study, fungal infections should be included in managing chronic leg ulcers, especially among artisans, famers and gardeners even though there was a significantly higher burden of bacterial infections.

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.

Comparative Analysis of a Jack-up Drilling Unit with Different Leg Systems

The jack-up unit is one of the best drilling platforms in offshore oil fields with water depth shallower than 150 meters.As the most pivotal component of the jack-up unit,the leg system can directly affect the global performance of a jack-up unit.Investigation shows that there are three kinds of leg structure forms in the world now:the reverse K,X,and mixing types.In order to clarify the advantage and defects of each one,as well as their effect on the global performance of the jack-up unit,this paper commenced to study performance targets ofa deepwater jack-up unit with different leg systems(X type,reverse K type,and mixing type).In this paper a typical leg scantling dimension and identical external loads were selected,detailed finite element snalysis(FEA)models were built to simulate the jack-up unit's structural behavior,and the multi-point constraint(MPC)element together with the spring element was used to deal with the boundary condition.Finally,the above problems were solved by comparative analysis of their main performance targets(including ultimate static strength,dynamic response,and weight).

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.

新修订的IGC规则对37500m3LEG运输船破舱稳性的影响研究

新修订的IGC规则对液化气船压载航行状态的破舱稳性提出了明确的要求,针对压载工况纳入破舱稳性计算中初始工况的问题,对江南造船(集团)有限责任公司自主研发的全球最大型液化乙烯气体运输船——37500m3 LEG运输船进行了破舱稳性方面的计算研究,得出了新要求对该船的破舱稳性计算结果的影响,并通过调整压载水装载方案,对不满足新修订的IGC规则的破舱稳性的工况作出了改进,并满足了这一新的基本要求,保持了江南造船在液化气船研发领域的技术领先优势,为江南造船的后续接单做好了技术准备。

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.

Expression of GHR, IGF-I, IGF-IR and IGFBP-3 Genes in Leg Muscles of Taihu Goose and Wanxi White Goose and Correlation between Their Expression and Carcass Traits

[Objective] This study aimed to explore the effects of IGFs system on the growth of goose skeletal muscles. [Method] Quantitative fluorescence PCR technique was adopted to study the variety- and gender-specificity in the expression of GHR, IGF-I, IGF-IR and IGFBP-3 genes in leg muscles of 70-day-old Taihu goose and Wanxi white goose, and the correlation between their expression and carcass traits was also investigated. [Resull] There was no variety difference in the expression of GHR, IGF-t, IGF-IR and IGFBP-3 genes in leg muscles of Taihu goose and Wanxi white goose, but there were significant variety differences in the body weight and leg muscle weight. There were no gender difference in the body weight, leg muscle weight and the rate of leg muscles; except IGF-I mRNA level that was significantly higher in male Taihu goose than in female ones（P=0.032）, there was no gender dif- ference in the expression of other three genes. Among the four tested genes, only IGFBP-3 mRNA exhibited an extremely significantly positively correlation with the rate of leg muscles, suggesting that IGFs may play a role in regulating the growth of leg muscles via IGFBP-3 system in 70-day-old goose. [Conclusion] This study provides theoretical basis for research in the skeletal growth and development.

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。