Macro repositioning movements of pelvis and trunk during simulated driving tasks

Low back pain (LBP)³ is one of the most important features of discomfort in prolonged sitting postures. This is evidenced by an increase in the number of postural changes called macro-movements. The focus of study was the frequencies of macro repositioning movements in prolonged sitting posture resulting from the perception of discomfort caused by low-back pain. Eighteen (18) drivers performed driving tasks for a period of 90 min. The results indicate that LBP participants performed more movements (10.52 rep/h), compared to without low back pain participants (8.52 rep/h). However, the latter moved more than expected due to joint macro movements of the pelvis and trunk. LBP subjects generally performed macro-repositioning movements of the trunk only, while without low back pain (WLBP)⁴ subjects moved pelvis and trunk simultaneously. Although the WLBP participants moved less than those with LBP symptoms, they applied different movement strategies which should be considered in further research. Finally, the authors also propose that future research should be directed towards determining the influence of these lumbo pelvic movements when provided in a controlled manner, to improve comfort in seats and to help manufactures to offer better ergonomic seats.Relevance to industryAccording to the findings of this study, control of lumbo pelvic movements could be used to improve the design and production of ergonomic seats for driving activities.     

Practical way to measure large-scale 2D parts using repositioning on coordinate-measuring machines

In many situations it is required to perform an inspection of large flat parts on a coordinate-measuring machine (CMM) when it is impossible to probe all necessary surfaces from one position of the part. Or it is necessary to measure a large part which dimensions exceed the volume of an available CMM. For this purpose one needs to merge the data measured in two different positions of the workpiece into one coordinate system. Though most of geodesic software has out-of-the-box functionality to do that, a lot of popular CMM software lacks it. In this paper a practical approach is described to bring a repositioning functionality into a CMM software. The Calypso metrology software was studied. The proposed inspection method can be used both for the measurements of linear dimensions and location tolerances as common practice in Calypso.     

摆角铣头的动态误差及补偿技术

介绍了摆角铣头定位精度和重复定位精度的定义以及发生动态误差的原因。同时也介绍了定位精度和重复定位精度的检测原理方法以及检测工具,检测的最终目的是更好地对机构本身进行补偿使之提高自身精度。     

Changes in spinal curvature and proprioception of schoolboys carrying different weights of backpack

Despite evidence linking backpack carriage and back pain, previous studies to examine the effects of backpack carriage have focused on changes in physical performance rather than the direct effects on the spine itself. Spinal curvature and proprioception (in terms of spinal repositioning consistency) of 15 schoolboys during normal upright stance without a backpack and while carrying a specially adapted backpack loaded at 10, 15 and 20% of their bodyweight were measured and compared using repeated measures ANOVA. A significant flattening of the lumbar lordosis and the upper thoracic kyphosis was found with increasing backpack load, as well as a significant decrease in the thoraco-lumbar and lumbar repositioning consistencies. Carriage of a loaded backpack causes immediate changes in spinal curvature and appears to have a direct effect on the repositioning consistency. Further investigation of the changes in spinal curvature and repositioning consistency over time with prolonged backpack carriage is warranted. Daily carriage of a school backpack on the musculoskeletal health of children and adolescents has become an area of concern due to the association between backpack carriage and back pain. Data regarding the direct effect of backpack carriage on the spine in children are limited.     

自动光学检测设备重复定位精度测试与分析

为了对自动光学检测设备(A0I)的重复定位精度进行测试与分析,在介绍了其功能结构和工作原理的基础上,设计了一种针对其重复定位精度的简便有效的测试方法,然后根据正交试验设计思想,选取了算法类型、光源亮度和相机速度三个主要因素进行了试验,并借助极差分析法和方差分析法对试验数据进行了分析。结果表明:该测试方法简单快捷且准确可靠,该正交试验设计方案正确合理。     

NUM系统在CX300车铣加工中心中的回零及应用

回零是数控机床的重要功能。阐述了CX300车铣加工中心各个轴的回零方式，并实例介绍了回零在C轴与主轴切换后重新定位中的应用。     

Carry-over effects of backpack carriage on trunk posture and repositioning ability

Immediate effects of backpack carriage on spinal curvature and motor control in adults have been reported. However, there is a scarcity of evidence whether the effects would persist or not after the carrying load is removed. This study aimed to investigate the carry-over effects of backpack carriage on trunk posture and repositioning ability. Thirteen healthy adults were recruited and instructed to walk on a treadmill for 30 min with backpack (10% body weight) followed by 30-min unloaded walking. Participant’s trunk posture and repositioning ability were measured at different time points. During backpack carriage, reduction in lumbar lordosis and posterior pelvic tilt with significant increased cervical lordosis, thoracic kyphosis and trunk forward lean were observed. There was also a significant increase in repositioning errors in all spinal curvatures and trunk forward lean. After removal of the carrying load, there was a tendency for restoration of trunk posture and repositioning ability. However, the cervical lordosis and the repositioning error of all spinal curvatures could not be fully returned to the levels of the preload condition (all p < 0.05). The persistent changes in both spinal curvature and repositioning ability revealed an increased risk of spinal injury even after the backpack was removed, and the effects on the neck and back pain warrant future study.

Relevance to Industry

The effects of backpack carriage (10% body weight for 30 min) on the spine could not be fully restored after 30-min unloaded walking. The persistent changes in both spinal curvature and repositioning ability revealed an increased risk of spinal injury even after the backpack was removed. Proper postural reminder might be given to backpack users to alleviate the adverse effects induced after prolonged backpack carriage.     

数控机床的回零及应用

回零是数控机床的重要功能.阐述了NUM系统用于车铣加工中心各个轴的回零方式,介绍了回零在C轴与主轴切换后重新定位中的应用.