Optimal Design of the Modular Joint Drive Train for Enhancing Cobot Load Capacity and Dynamic Performance

Automation advancements prompts the extensive integration of collaborative robot(cobot)across a range of industries.Compared to the commonly used design approach of increasing the payload-to-weight ratio of cobot to enhance load capacity,equal attention should be paid to the dynamic response characteristics of cobot during the design process to make the cobot more flexible.In this paper,a new method for designing the drive train parameters of cobot is proposed.Firstly,based on the analysis of factors influencing the load capacity and dynamic response characteristics,design criteria for both aspects are established for cobot with all optimization design criteria normalized within the design domain.Secondly,with the cobot in the horizontal pose,the motor design scheme is discretized and it takes the joint motor diameter and gearbox speed ratio as optimization design variables.Finally,all the discrete values of the optimization objectives are obtained through the enumeration method and the Pareto front is used to select the optimal solution through multi-objective optimization.Base on the cobot design method proposed in this paper,a six-axis cobot is designed and compared with the commercial cobot.The result shows that the load capacity of the designed cobot in this paper reaches 8.4 kg,surpassing the 5 kg load capacity commercial cobot which is used as a benchmark.The minimum resonance frequency of the joints is 42.70 Hz.

Shape design of the reinforcement for bending load-carrying capacity of under-matched butt joint under four-point bending load

To improve the bending load-carrying capacity （ BLCC） of under-matched butt joint under four-point bending load in the elastic stage, the shape design of the reinforcement is studied based on the theoretics of mechanics of materials. The concept, criterion, realization condition and design proposal of equal bending load-carrying capacity （EBLCC） are put forward. The theoretical analysis results have been verified by the finite element method. The simulation results are coincident basically with the ones of theoretical analysis. The research results show that the shape design of the reinforcement of EBLCC can improve BLCC of under-matched butt joint and the unilateral-side type reinforcement can replace double-side symmetry

Lateral load-carrying capacity analyses of composite shear walls with double steel plates and filled concrete with binding bars

A method is developed to predict the lateral load-carrying capacity of composite shear walls with double steel plates and filled concrete with binding bars(SCBs). Nonlinear finite element models of SCBs were established by using the finite element tool, Abaqus. Tie constraints were used to connect the binding bars and the steel plates. Surface-to-surface contact provided by the Abaqus was used to simulate the interaction between the steel plate and the core concrete. The established models could predict the lateral load-carrying capacity of SCBs with a reasonable degree of accuracy. A calculation method was developed by superposition principle to predict the lateral load-carrying capacity of SCBs for the engineering application. The concrete confined by steel plates and binding bars is under multi-axial compression; therefore, its shear strength was calculated by using the Guo-Wang concrete failure criterion. The shear strength of the steel plates of SCBs was calculated by using the von Mises yielding criterion without considering buckling. Results of the developed method are in good agreement with the testing and finite element results.

Using a GIS to Assessment the Load-Carrying Capacity of Soil Case of Berhoum Area, Hodna Basin, (Eastern Algeria)

The concept of load-carrying capacity of the soil can be evaluated by two main components: permissible stress and permissible depth;and therefore, running it begins its assessment that allows an outline of exploitation. Nevertheless, the assessment of the load-carrying capacity made the object of several works of research and many models, based on the multi-criteria analysis, have been established. This work examines the contribution of GIS approach to assessment load-carrying capacity of the soil. This one has been finished in two practicums: 1) Assessment of the capacity of soil by a multi-criteria approach, using the Weighted Sum Model (WSM);2) It brought to use the GIS approach to evaluate and spatialize degree of soil bearing stresses resulting from the buildings, as well as load distribution. The method has been applied to the Berhoum area of Hodna Basin, in eastern Algeria, where each is characterized by its various natural properties and density of equipment. Final results are better in the classification of the degree of load-carrying capacity possible in each site. This results in allowing exploiters to program their optimal designs for the rational management of the area.

A Discusion on Limited Load-Carrying Capacity of Rectangular Plates

The elastic-plastic method is often used in designing the inner flat bulkhead plates of submarines, and the upper structure of ships and drilling platforms. Such bulkhead plates can bear the load only once. For the improvement of the load-carrying capacity or the reduction of the weight of plates, the yield line analytical method is employed in this paper to design the bulkhead plate to improve economy and increase the effiective load. Besides, a further sutdy of this method has been made theoretically and experimentally, and the data of the limited load-carrying capacity of the plate have been obtained. Furthermore, the safety coefficients for such a method are presented, which can be used as reference for related departments and staffs.

Boundary slippage for generating hydrodynamic load-carrying capacity

Boundary slippage is used to generate the load-carrying capacity of the hydrodynamic contact between two parallel plane surfaces. In the fluid inlet zone, the fluidcontact interfacial shear strength on a stationary surface is set at low to generate boundary slippage there, while in the fluid outlet zone the fluid-contact interfacial shear strength on the stationary surface is set at high enough to prevent the occurrence of boundary slippage. The fluid-contact interfacial shear strength on the entire moving surface is set at high enough to prevent boundary slippage on the moving surface. These hydrodynamic contact configurations are analyzed to generate the pronounced load-carrying capacity. The optimum ratio of the outlet zone width to the inlet zone width for the maximum load-carrying capacity of the whole contact is found to be 0.5.

Evaluation of the Residual Capacity of a Submarine for Different Limit States with Various Initial Imperfection Models

The current design philosophy for submarine hulls,in the preliminary design stage,generally considers as governing limit states material yielding along with various buckling modes.It is common belief that,beyond the design pressure,material yielding of the shell plating should occur first,eventually followed by local buckling,while global buckling currently retains the highest safety factor.On the other hand,in the aeronautical field,in some cases structural components are designed in such a way that local instability may occur within the design loads,being the phenomena inside the material elastic range and not leading to a significant drop in term of stiffness.This paper is aimed at investigating the structural response beyond a set of selected limit states,using nonlinear FE method adopting different initial imperfection models,to provide the designers with new information useful for calibrating safety factors.It was found that both local and global buckling can be considered as ultimate limit states,with a significant sensitivity towards initial imperfection,while material yielding and tripping buckling of frames show a residual structural capacity.In conclusion,it was found that the occurrence of local buckling leads to similar sudden catastrophic consequences as global buckling,with the ultimate strength capacity highly affected by the initial imperfection shape and amplitude.

Robust Optimization Method of Cylindrical Roller Bearing by Maximizing Dynamic Capacity Using Evolutionary Algorithms

Optimization of cylindrical roller bearings(CRBs)has been performed using a robust design.It ensures that the changes in the objective function,even in the case of variations in design variables during manufacturing,have a minimum possible value and do not exceed the upper limit of a desired range of percentage variation.Also,it checks the feasibility of design outcome in presence of manufacturing tolerances in design variables.For any rolling element bearing,a long life indicates a satisfactory performance.In the present study,the dynamic load carrying capacity C,which relates to fatigue life,has been optimized using the robust design.In roller bearings,boundary dimensions(i.e.,bearing outer diameter,bore diameter and width)are standard.Hence,the performance is mainly affected by the internal dimensions and not the bearing boundary dimensions mentioned formerly.In spite of this,besides internal dimensions and their tolerances,the tolerances in boundary dimensions have also been taken into consideration for the robust optimization.The problem has been solved with the elitist non-dominating sorting genetic algorithm(NSGA-II).Finally,for the visualization and to ensure manufacturability of CRB using obtained values,radial dimensions drawing of one of the optimized CRB has been made.To check the robustness of obtained design after optimization,a sensitivity analysis has also been carried out to find out how much the variation in the objective function will be in case of variation in optimized value of design variables.Optimized bearings have been found to have improved life as compared with standard ones.

延性抗震设计理念的发展及应用研究综述

延性抗震设计旨在通过结构发生较大弹塑性变形来降低结构地震响应。这一抗震设计理念广泛应用于大多数国家抗震规范中,其核心思路是通过使用强度折减系数对设防地震反应谱进行折减,使结构通过非弹性变形耗散地震能量。强度折减系数主要由延性折减系数和结构超强系数决定。同时,能力设计法是实现延性抗震的主要工具,该方法要求体系内的非延性构件在延性构件进入非线性阶段前后都保持弹性,以实现整个结构体系的延性设计。通过梳理延性抗震设计理念的研究历史,简要介绍了延性系数、结构周期、场地条件、阻尼比等因素对延性折减系数的影响,阐述了现有强度折减系数的组成和计算方法。最后,总结了中国、美国、欧洲、日本抗震规范中延性设计的应用情况。

塑料齿轮传动高承载技术发展与应用

围绕塑料齿轮承载能力及在动力传动领域应用的问题,介绍了塑料齿轮的失效形式与承载能力,给出了目前的材料与工艺水平下塑料齿轮承载的基础数据,从新材料应用、润滑等工况条件改善、材料结构工况协同设计等方面阐述了提高塑料齿轮承载能力的措施,介绍了高承载塑料齿轮在汽车发动机传动、轻型车辆主传动、小型航发附件机匣传动等动力传动场景的应用实践和潜力。

HRB600级钢筋混凝土柱偏压性能试验研究

为研究配置HRB600级钢筋混凝土柱的偏压性能,考虑偏心距与配筋率等因素影响,设计制作了6根高为2000mm的HRB600级钢筋C50混凝土柱。采用偏压加载的方式对试验柱进行静力试验,对其破坏形态、挠度曲线、极限承载力、钢筋强度设计值取值及裂缝宽度等展开研究,并对HRB600级钢筋混凝土柱纵向受拉、受压钢筋应变数据进行分析。研究成果显示:HRB600级钢筋混凝土偏压柱的受力形式以及破坏模式与普通钢筋混凝土偏压柱并无差异,其极限承载力仍然可以按照《混凝土结构设计规范》(GB 50010—2010)(2015年版)公式进行计算,但限定混凝土相对受压区高度x≥3.2a′s(a′s为受压区纵筋合力点至截面边缘的距离);对于此类偏压柱,建议HRB600级钢筋的屈服强度标准值取600MPa,抗拉强度设计值取520MPa,抗压强度设计值取460MPa;HRB600级钢筋混凝土柱最大裂缝宽度实测值与规范理论计算值在正常使用阶段吻合良好。

应力吸收层沥青混合料配合比设计

本文通过设计和优化应力吸收层沥青混合料的配合比,以提高道路表面的承载能力和抗裂性能。首先,通过对原料的选取和性能测试,确定了合适的沥青、骨料和填料。其次,采用马歇尔试验方法进行混合料的配合比设计,考虑到沥青含量、骨料粒径分布、填料种类和配合比的影响。通过不断调整配合比参数,以达到最佳的稳定度、流动性和抗裂性能,利用室内试验和现场试验对设计的混合料进行了验证。最后,对实验结果进行统计分析,并提出了进一步改进和优化的建议。研究结果表明,设计的配合比能够满足应力吸收层沥青混合料的工程要求,具有良好的承载能力和抗裂性能。

基于Kriging模型的锥形气体静压轴承优化设计

针对如何提升小孔节流式锥形气体静压轴承综合性能的问题,以气浮电主轴用锥形气体静压轴承承载力最大、气体消耗量最小为优化目标,考虑轴承尺寸和工况要求的约束条件,采用最优拉丁超立方法选取设计点,通过有限元法计算样本集,利用2种提高精度的加点策略构建针对优化目标的改进Kriging代理模型,最终使用非支配排序遗传算法获得最优解集。根据工况要求,通过权重系数法提出了3种优化方案,优化方案的气体消耗量分别降低至初始设计的28.85%,56.08%和73.87%;承载力则分别提升至初始设计的1.14,2.16和2.44倍;3种优化方案在中高转速下的性能提升会更加明显。另外,提高轴承锥度虽然能提升承载力,但同时也会增加气体消耗量。

中国天然气地下储气库重大理论、关键技术进展与展望

2019年中国地下储气库(以下简称储气库)进入高速发展期,气藏储气库面临着部分在役库达产率低、低渗泛连通气藏建库设计难度大等难题;盐穴储气库面临造腔速度慢和储气空间利用率低等挑战;油藏储气库建库机理与相关技术尚处于探索阶段,亟需攻关研究。为此,以破解气藏、盐穴、油藏不同类型储气库建库机理、储气空间优化设计等难题为目标,开展了系列理论研究与技术攻关。研究结果表明:(1)形成的在役库提高上限压力优化、大型低渗泛连通气藏建库、储气库群协同调峰优化等技术,助力气藏储气库高效建设与扩容增产;(2)建立的大井眼与水平井造腔、残渣空隙空间利用预测技术,指导了盐穴储气库高效造腔与储气空间利用最大化;(3)创建了气液高速交互滚动排驱仿真模拟与周期注采油气体系相行为模拟实验技术和油藏,形成了油藏建库驱替—传质耦合库容量预测方法,形成了油藏建库协同提高原油采收率的新模式;(4)复杂地质条件储气库高效建设运行和地下空间多元综合利用是未来增强储气保供能力和实现“3060双碳”战略目标的重要举措。结论认为,研究成果有力支撑了中国储气库快速发展,近5年来气藏、盐穴、油藏储气库建库能力全面提升,保障了储气库工作气量由100×10^(8) m^(3)向200×10^(8) m^(3)翻番增长,对我国地下储气库建设和地下空间综合利用具有重要指导和借鉴意义。

Bio-inspired Design and Inverse Kinematics Solution of an Omnidirectional Humanoid Robotic Arm with Geometric and Load Capacity Constraints

Inspired by the driving muscles of the human arm,a 4-Degree of Freedom(DOF)concentrated driving humanoid robotic arm is proposed based on a spatial double parallel four-bar mechanism.The four-bar mechanism design reduces the inertia of the elbow-driving unit and the torque by 76.65%and 57.81%,respectively.Mimicking the human pose regulation strategy that the human arm picks up a heavy object by adjusting its posture naturally without complicated control,the robotic arm features an integrated position-level closed-form inverse solution method considering both geometric and load capacity limitations.This method consists of a geometric constraint model incorporating the arm angle(φ)and the Global Configuration(GC)to avoid joint limits and singularities,and a load capacity model to constrain the feasible domain of the arm angle.Further,trajectory tracking simulations and experiments are conducted to validate the feasibility of the proposed inverse solution method.The simulated maximum output torque,maximum output power and total energy consumption of the robotic arm are reduced by up to 2.0%,13.3%,and 33.3%,respectively.The experimental results demonstrate that the robotic arm can bear heavy loads in a human-like posture,effectively reducing the maximum output torque and energy consumption of the robotic arm by 1.83%and 5.03%,respectively,while avoiding joints beyond geometric and load capacity limitations.The proposed design provides a high payload–weight ratio and an efficient pose control solution for robotic arms,which can potentially broaden the application spectrum of humanoid robots.

基于性能化设计的土木主体结构抗震性能研究

随着总体经济的迅速发展和人们生活的日益改善,人们对居住环境的需求也在不断增长。地震是一种具有巨大破坏力的天灾,虽然不能完全避免其发生,但可通过实施各种预防策略来减小地震造成的损害程度。因此,文章研究了基于性能化设计的土木主体结构抗震性能,以提高保证房屋建设的安全性和稳固性,进一步保障人们的生活质量和社会的和谐秩序。

企业视角下的当代工业建筑设计探索与实践

随着社会生产力的提高和社会认识的转变,传统工业建筑的设计方法及设计理念已不能满足如今企业的建设需求。文章首先分析了工业建筑设计的发展过程和现阶段设计中存在的问题,从社会认识、生产能力、审美观念等角度总结了制约工业建筑发展的原因。结合实际项目案例和经验,针对当下企业在工业建筑设计建设中所关注的要点,从生产能力保障、内外因素融合、建设成本控制三个方面对当代工业建筑的设计方法和策略进行了探索和研究。从缩短建设周期、提供可变空间、彰显地域特征和企业文化、降低建造成本等方面为工业建筑的设计提供了有价值的参考和帮助。

水利泵站增容扩建工程规划设计与稳定性分析

某灌区河道泵站增容工程的设计方法为在保留原有泵站的基础上,在河对岸根据设计所需的流量要求新建二号泵站,工程复杂性较高,且场地存在软弱土层和易于渗透破坏的砂性土对工程稳定性影响较大。为保障该工程的安全与质量,本文对其泵站增容设计要点进行阐述并对其稳定性进行详细分析,分析结果表明现有设计方案在抗滑稳定性与抗渗稳定性方面能够满足工程建设需求。本文研究结果对于本工程后续建设工作的开展具有一定指导意义。

基于增量内部收益率法的光伏电站容配比优化

光伏电站容配比的选择不仅取决于初始投资和发电量,而且取决于电价机制。以四川省某230 MW集中式光伏电站项目为例,按照四川省当前新能源电价机制计算综合电价和发电收入,然后根据每个方案的内部收益率确定备选方案,再采用增量内部收益率法进行方案优选。结果表明,项目的容配比最优值为1.307,相对于基本方案内部收益率提高0.52个百分点,对提升项目经济性具有明显的作用。此方法可应用于其他地区不同电价交易机制下光伏项目的容配比优选。

Selection of Weather Parameters for Air-Conditioning System Design for Buildings with Long Thermal Lag

Two building factors-a longer thermal lag of more than one hour for building envelops and a lag of indoor radiation to convert into cooling load-have impact on the instantaneous heat input and instantaneous cooling load.So the two factors should be taken into account when selecting the weather parameters for air-conditioning system design.This paper developed a new statistic method for the rational selection of coincident solar irradiance,dry-bulb and wet-bulb temperatures.The method was applied to historic weather records of 25 years in Hong Kong to generate coincident design weather data.And the results show that traditional design solar irradiance,dry-bulb and wet-bulb temperatures may be significantly overestimated in many conditions,and the design weather data for the three different constructions is not kept constant.