行人腿部保护汽车前部结构优化

为减少人车碰撞事故中对行人的伤害,采用LS-DYNA软件模拟人车碰撞过程,分别模拟了刚性腿型和柔性腿型的碰撞情况,得到行人小腿的伤害规律。同时,针对柔性腿型的分析结果,对汽车前部结构从三个方面进行优化:改进泡沫刚度,行人腿部总得分值提高了10.01%;改变小腿支撑,行人腿部总得分值提高了10.37%;改进保险杠横梁,行人腿部总得分值提高了17.63%。通过改进汽车的前部结构,柔性小腿的碰撞性能得到了优化,为行人保护方面的汽车前部结构设计提供了参考。     

Study on Roller-Walker — Improvement of Locomotive Efficiency of Quadruped Robots by Passive Wheels

Abstract

Roller-Walker is a leg–wheel hybrid mobile robot using a passive wheel equipped on the tip of each leg. The passive wheel can be transformed into sole mode by rotating the ankle roll joint when Roller-Walker walks on a rough terrain. This paper discusses the energy efficiency of locomotion in wheeled mode. We define a leg trajectory to produce forward straight propulsion, and discuss the relationships between the parameters of the leg trajectory and energy efficiency of the propulsion using a dynamics simulator. We find optimum parameter sets where optimization criterion is specific resistance. The results indicate that faster locomotion achieves higher energy efficiency. We then carry out hardware experiments and empirically derive the experimental specific resistance. We show that wheeled locomotion has an 8-times higher energy efficiency than the ordinary crawl gait. Finally, we compare the specific resistance of Roller-Walker with other walking robots described in the literature.     

HYSY901#平台桩腿齿条损坏的原因分析及改进措施

HYSY901#平台在建造完成后进行首次升降船试验,降船过程中3#桩腿靠近船尾一侧的齿条发生了折断和严重的变形损坏。初步的原因分认为,是桩腿齿条由于焊接时火工校正导致性能降低或材料性能本身不足所致,但在破坏部位的取样做机械性能试验并不能证明这判断。在随后的现场调查中,发现是升降液压系统的原因导致破坏的产生。文中对破坏发生的原因进行了分析,并提出了相应的解决办法。     

六足步行机器人的设计研究

迈步行走方式是一种具有广泛应用前景的地面推进方式。本文提出了一种采用液压驱动的缩放式腿机构的结构设计，并针对六足行走方式，完成了液压驱动原理设计及PLC控制设计。     

Numerical analysis of jacking operations for a self-elevated jack-up unit

Localized failure and collapse of a jack-up unit may take place during installation on site, especially under severe sea state conditions. To minimize the loss, structural behavior is predicted before construction. When the hull of a unit is elevated from sea water level, the structure system varies with time. This means that normal structural analysis is difficult to satisfy the relevant requirements. To capture the system status at different times, an innovative method is proposed and incorporated into Finite Element Analysis (FEA). With a full model of a jack-up unit having been built and with the techniques developed, behavior such as Rack phase difference (RPD), vertical reaction forces of the pinions and footing reactions, etc., under different loads and boundary conditions can be determined by FEA in the time domain. These valuable data would be helpful in re-designing the unit, and also provide guidance for site installation. To determine the general characteristics of a jack-up unit, casestudies on a practical design have been done, with some important findings concluded.     

The nutrient composition of three cuts obtained from P-class South African pork carcasses

The shoulder, loin and leg from P-class pork carcasses were used to determine the nutrient composition of both raw and cooked cuts. Significantly lower fat content were observed in the current study for the leg (5.21 g/100 g) and loin (6.99 g/100 g) compared to the shoulder cut (10.32 g/100 g). The overall percentage fat for all three cuts was less than 10% which is recommended by the South African Heart Mark. The cooked loin cut contained the most protein (27.50 g/100 g) of the three cooked cuts. When compared to other meat products (beef, mutton and chicken) it is clear that pork is a good source of B vitamins, especially vitamin B₃. The cooked loin cut contained the least vitamin B₁ (0.22 mg/100 g), B₂ (0.02 mg/100 g) but the most vitamin B₃ (7.09 mg/100 g), of the three cooked cuts. The 100 g cooked shoulder, loin and leg cuts provide on average 40.11% protein, 5.19% magnesium, 3.37% calcium, 24.29% phosphorus, 18.22% zinc, 22.33% iron and 22.50% vitamin B₁, 2.57% vitamin B₂ and 42.6% vitamin B₃ of Recommended Daily Allowances for males, age 25–50. Energy from a 100 g portion provides 5.81% of the Recommended Daily Allowances. To conclude, the pork cuts are undoubtedly a good source of nutrients that is required for good health because it is high in protein, have a low fat content and are a nutrient-packed choice for the family and compares favourably with the fat, energy, and cholesterol content of many other meats and poultry.     

张力腿平台张力腿焊接工艺

依托中海油拟建的流花16-2/11-1张力腿平台(Tendon Leg Platform,TLP)建造项目,对TLP平台的关键结构——张力腿的焊接技术进行初步研究。针对张力腿结构及母材特性、焊接工艺要求及强度韧性指标等一系列要求,结合国内外张力腿焊接研究现状及青岛公司现有场地资源,对张力腿的焊接工艺进行研究,经验证,该工艺满足相关技术指标。     

辅助老人抬腿上床装置设计

为了解决老人上床及起身困难等问题,设计了一种辅助老人上床的装置.对老人腿部上床轨迹进行分析,基于数学建模,以球面和圆锥面的相交圆锥截交线来模拟腿部抬升轨迹,设计了一种空间连杆机构来实现腿部抬升;进行了具体结构设计及运动仿真分析.仿真结果说明,该装置能够实现腿部抬升轨迹并且运行状态平稳,验证了其理论可行性.进行实物搭建并...     

Evaluation of work-rest schedules with respect to the effects of postural workload in standing work

The influence of four work-rest schedules (60-min shift-15-min break, 45-15, 30-15, 30-30) on acute effects of physical workload in the back and legs due to standing work was investigated in 12 poultry inspectors. Subjective discomfort in the legs and back, and swelling in the distal lower leg were significantly affected, with the 60-15 schedule leading to a higher postural load as compared with the other schedules. No effect on spinal shrinkage was found. It was concluded that the 60-15 schedule should be avoided. An optimal work-rest schedule considering visco-elastic deformation of the spine would probably involve frequent short breaks, whereas longer breaks would seem more effective considering leg swelling.     

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 experi-ments show that the robot possesses good obstacle surmounting capabilities.