A field comparison of neck and shoulder postures in symptomatic and asymptomatic office workers

Poor neck and shoulder postures have been suggested to be a cause of neck and shoulder pain in computer workers. The present study aimed to evaluate and compare the head, neck and shoulder postures of office workers with and without symptoms in these regions, in their actual work environments. The two all female subject groups reported significantly different discomfort scores across five trials repeated in a single working day. The results of repeated video capture and two-dimensional motion analysis showed that there were trends for increased head tilt and neck flexion postures in the symptomatic subjects (n = 8), compared to the asymptomatic subjects (n = 8). Symptomatic subjects also tended to have more protracted acromions compared with asymptomatic subjects and showed greater movement excursions in the head segment and the acromion. All subjects demonstrated an approximately 10% increase in forward head posture from their relaxed sitting postures when working with the computer display, but there were no significant changes in posture as a result of time-at-work.     

Technique,muscle activity and kinematic differences in young adults texting on mobile phones

The aim of this study was to investigate whether there are differences in technique between young adults with and without musculoskeletal symptoms when using a mobile phone for texting and whether there are differences in muscle activity and kinematics between different texting techniques. A total of 56 young adults performed a standardised texting task on a mobile phone. Their texting techniques were registered using an observation protocol. The muscular activity in six muscles in the right forearm/hand and both shoulders were registered by surface electromyography and the thumb abduction/adduction and flexion/extension were registered using a biaxial electrogoniometer. Differences in texting techniques were found between the symptomatic and the asymptomatic group, with a higher proportion of sitting with back support and forearm support and with a neutral head position in the asymptomatic group. Differences in muscle activity and kinematics were also found between different texting techniques. The differences in texting technique between symptomatic and asymptomatic subjects cannot be explained by them having symptoms but may be a possible contribution to their symptoms.

Statement of Relevance: There has been a dramatically increased use of mobile phones for texting especially among young people during the last years. A better understanding of the physical exposure associated with the intensive use is important in order to prevent the development of musculoskeletal disorders and decreased work ability related to this use.     

Neck/shoulder pain,habitual spinal posture and computer use in adolescents: the importance of gender

Neck/shoulder pain is a common complaint, with evidence suggesting rates in adolescence have increased in line with increased computer use. The study aimed to examine the influence of gender on relationships between computer use, habitual posture and neck/shoulder pain. Adolescents (n = 1483) participating in the 14 year follow-up of the Raine Study cohort were surveyed for computer use, habitual sitting posture and neck/shoulder pain. Females used computers less than males (52% vs. 45% used for up to 7 h per week). Females sat much more upright than males with greater anterior pelvic tilt (9.4° vs. 0.4°). Females reported a higher 1 month prevalence of neck/shoulder pain (34.7%) than males (23.1%). A multivariate model showed neck/shoulder pain risk was increased in females (OR 2.61, 95% CI 1.70–4.00) and with computer use (OR 1.19, CI 1.01–1.40). Computer use is related to neck/shoulder pain and posture in adolescents but this relationship is different in boys and girls.

Statement of Relevance: This study showed the confounding effect of gender on the relationships among computer use, posture and neck/shoulder pain and thus the need to consider genders separately in research and practice aiming to optimise young people's use of computers.     

Validity and reliability of the Spineangel® lumbo-pelvic postural monitor

Objective: to determine the reliability and the concurrent validity of the Spineangel^® lumbo-pelvic postural monitoring device. Methods: the dynamic lumbo-pelvic posture of 25 participants was simultaneously monitored by the Spineangel^® and Fastrak^TM devices. Participants performed six different functional tasks in random order. Within-task, within-session and between-day intraclass correlation coefficients (ICC(3,1), ICC(3,5), ICC(2,5), respectively) reliability were calculated for Spineangel^® measurements. Concurrent validity of the Spineangel^® was assessed by means of a Bland and Altman plot and by means of Pearson's correlation coefficient and paired t-test. Results: within-task, within-session and between-day ICC for the Spineangel^® were found to be excellent (>0.93). The Spineangel^® and Fastrak^TM pelvic measurements were found to have a good correlation (R = 0.77). Conclusion: the Spineangel^® is a reliable and valid device for monitoring general lumbo-pelvic movements when clipped on the belt or waistband of workers' clothing during various occupational activities.

Practitioner summary: The Spineangel^® can be used for assessing lumbo-pelvic posture during work or daily-life activities. This device was found to provide reliable and valid measurements for lumbo-pelvic movements. Further research is required to determine whether the use of this device is clinically relevant for patients presenting with low back pain.     

Inter-rater reliability of output measures for a posture matching assessment approach: a pilot study with food service workers

Despite the ongoing health problem of repetitive strain injuries, there are few tools currently available for ergonomic applications evaluating cumulative loading that have well-documented evidence of reliability and validity. The purpose of this study was to determine the inter-rater reliability of a posture matching based analysis tool (3DMatch, University of Waterloo) for predicting cumulative and peak spinal loads. A total of 30 food service workers were each videotaped for a 1-h period while performing typical work activities and a single work task was randomly selected from each for analysis by two raters. Inter-rater reliability was determined using intraclass correlation coefficients (ICC) model 2,1 and standard errors of measurement for cumulative and peak spinal and shoulder loading variables across all subjects. Overall, 85.5% of variables had moderate to excellent inter-rater reliability, with ICCs ranging from 0.30–0.99 for all cumulative and peak loading variables. 3DMatch was found to be a reliable ergonomic tool when more than one rater is involved.     

Exploiting eye–hand coordination to detect grasping movements

Human beings are very skillful at reaching for and grasping objects under multiple conditions, even when faced with an object's wide variety of positions, locations, structures and orientations. This natural ability, controlled by the human brain, is called eye–hand coordination. To understand this behavior it is necessary to study both eye and hand movements simultaneously. This paper proposes a novel approach to detect grasping movements by means of computer vision techniques. This solution fuses two viewpoints, one viewpoint which is obtained from an eye-tracker capturing the user's perspective and a second viewpoint which is captured by a wearable camera attached to a user's wrist. Utilizing information from these two viewpoints it is possible to characterize multiple hand movements in conjunction with eye-gaze movements through a Hidden–Markov Model framework. This paper shows that combining these two sources makes it possible to detect hand gestures using only the objects contained in the scene even without markers on the surface of the objects. In addition, it is possible to detect which is the desired object before the user can actually grasp said object.     

基于深度图像技术的手势识别方法

针对复杂环境下的手势识别问题,提出一种基于深度图像技术的手势识别方法。利用深度图像信息从复杂环境中提取手势区域,综合手势的表观特征,建立决策树实现手势的识别。对常见的9种手势在复杂背景条件下进行测试,实验结果表明,手势的平均识别率可达到98.4%,速度达到每秒25帧。     

基于多目摄像机的鲁棒眼动跟踪技术研究

为改进单个远程传感器采集眼动数据时存在视场小、容易被遮挡物遮挡的缺点,研究了一种多目摄像机眼动跟踪技术,以更好地采集眼动数据。应用多个摄像机对人体头部姿态和眼球信息进行采集,通过分割视频帧提取瞳孔图像和计算被测用户头部姿态角度,将瞳孔图像放入卷积神经网络进行训练得到注视点坐标,并基于头部姿态信息计算每个摄像机的注视点权重,从而加权融合得到更精确的注视点信息。研究结果表明：在头部姿态角较大时,多目眼动追踪技术的精度比单目传感器的精度高30%~50%。该技术具有灵活性和通用性,在驾驶舱设计、用户用眼习惯评估和驾驶学员眼动绩效分析中具有重要的应用和推广价值。     

基于QuaDRiGa的无人机非平稳信道模型

为了解决无人机信道模型非平稳参数空时不连续的问题,提出了一种支持三维运动及姿态旋转的无人机非平稳几何随机模型,用于描述和模拟无人机对地多输入多输出通信信道的真实特性。该模型借鉴QuaDRiGa中的“准确定性”思想,基于收发端拓扑关系更新时变信道参数,考虑路径生灭概率改进信道功率计算方法,引入姿态相位矩阵描述无人机姿态旋转,以实现无人机非平稳信道参数的平滑演进。数值仿真结果表明,本文提出模型能够保证功率和角度等参数的平滑演进,输出信道的自相关函数具有非平稳性且受无人机姿态影响显著,可用于无人机通信系统设计和算法优化等领域。     

小型断路器柔性装配中视觉识别系统的设计与应用

现代制造业对小型断路器（MCB）生产过程的效率和精度要求都在不断提高,传统的人工装配效率低且装配质量参差不齐,而传统基于振动盘上料的自动装配技术限制了制造的柔性化水平。针对上述问题以及未来的市场需求,提出了一种基于机器视觉的小型断路器柔性装配系统,该系统搭建专用的视觉识别模块,通过VGG-16架构的深度学习分类器和特征模板匹配方法,对小型断路器零件的种类、位置坐标、当前姿态进行识别,并将识别结果发送给工业机器人控制器,指导工业机器人对不同型号产品的不同零件类型通过机器人夹爪的灵活切换来完成不同的装配任务。实验表明,该系统对零件种类识别准确率为99.8%,坐标偏差在±0.3mm以内,旋转角度偏差在±0.8°以内,达到了MCB装配的精度要求,符合柔性化制造的需求。