An efficient posture recognition method using fuzzy logic

Computer-human interaction plays an important role in virtual reality. Glove-based input devices have many desirable features which make direct interactions between the user and the virtual world possible. However, due to the complexity of the human hand, recognising hand functions precisely and efficiently is not an easy task. Existing algorithms are either imprecise or computationally expensive, making them impractical to integrate with VR applications, which are usually very CPU intensive.In the problem of posture and gesture recognition, both the sample patterns stored in the database and the ones to be recognised may be imprecise. This kind of imprecise knowledge can be best dealt with using fuzzy logic. A fast and simple posture recognition method using fuzzy logic is presented in this paper. Our model consists of three components: the posture database, the classifier and the identifier. The classifier roughly classifies the sample postures before they are put into the posture database. The identifier compares an input posture with the records in the identified class and finds the right match efficiently. Fuzzy logic is applied in both the classification and identification processes to cope with imprecise data. The main goal of this method is to recognise hand functions in an accurate and efficient manner. The accuracy, efficiency and the noise tolerance of the model have been examined through a number of experiments.     

Adaptive Utilization of Optical Variables During Postural and Suprapostural Dual-Task Performance: Comment on Stoffregen, Smart, Bardy, and Pagulayan (1999).

T. A. Stoffregen, L. J. Smart, B. G. Bardy, and R. J. Pagulayan (1999) combined a postural task (upright stance) with a suprapostural task (visual fixation) to show that sway variability was not driven by optic flow in a task-independent manner (autonomous control) but governed by the demands of the supra-postural task (facilitatory control). The present study used a novel combination of Stoffregen et al.'s task conditions but obtained clear evidence of autonomous control and no indication of facilitatory control. The theoretical adequacy of the stabilization-by-looking versus stabilization-of-looking contrast was examined, as was emerging evidence that posture control and common cognitive tasks place concurrent demands on the same capacity-limited resources. An adaptive resource-sharing view of postural-suprapostural multitasking was proposed as an alternative to both the autonomous- and facilitatory-control views. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

具有越障功能的小型地面移动机器人

针对在危险环境下对移动机器人的运动要求，研究了机器人系统的总体设计，提出了一种具有越障功能的小型地面轮履复合式移动机器人，阐述了其机构设计度其实现。分析了谊机器人通过台阶、斜面、楼梯等障碍时的越障特性。研制完成的第一台样机具有结构简单、体积小、质量轻的特点，通过实验验证了该机器人运动灵活，具有很好的环境适应性和越障能力。     

Job enlargement and mechanical exposure variability in cyclic assembly work

Cyclic assembly work is known to imply a high risk for musculoskeletal disorders. To have operators rotate between work tasks is believed to be one way of decreasing this risk, since it is expected to increase variation in mechanical and psychological exposures (physical and mental loads). This assumption was investigated by assessing mechanical exposure variability in three assembly tasks in an electronics assembly plant, each on a separate workstation, as well as in a ‘job enlargement’ scenario combining all three stations. Five experienced operators worked for 1?h on each station. Data on upper trapezius and forearm extensor muscle activity were obtained by means of electromyography (EMG), and working postures of the head and upper arms were assessed by inclinometry. The cycle-to-cycle variance of parameters representing the three exposure dimensions: level, frequency and duration was estimated using ANOVA algorithms for each workstation separately as well as for a balanced combination of all three. For a particular station, the variability of trapezius EMG activity levels relative to the mean was higher than for extensor EMG: between-cycles coefficients of variation (CV) about 0.15 and 0.10, respectively. A similar relationship between CV applied to the parameter describing frequency of EMG activity. Except for head inclination levels, the between-cycles CV was larger for posture parameters than for EMG. The between-cycles variance increased up to six fold in the job enlargement scenario, as compared to working at only one station. The difference in mean exposure between workstations was larger for trapezius EMG parameters than for forearm extensor EMG and postures, and hence the effect of job enlargement on exposure variability was more pronounced for the trapezius. For some stations, job enlargement even implied less cycle-to-cycle variability in forearm extensor EMG parameters than working at that station only. Whether the changes in exposure variability associated with job enlargement were sufficient to imply a decreased risk for musculoskeletal disorders is not known.     

The influence of skill and low back pain on trunk postures and low back loads of shearers

Shearing is a rural occupation developing considerable spinal loads and carrying a high risk of low back pain (LBP). Although the workforce has a skill structure, interaction between skill, spinal loads and LBP is unknown. We examined whether skill and LBP influenced trunk postures and loads within a sample of 80 shearers representing shear skill levels. A progression from junior to open class demonstrated a 100% increase in productivity, less time in severe flexion, more time in neutral lateral bend, and more time in axially twisted postures, with no increase in cumulative compressive and anterior shear forces. LBP prevalence increased linearly from 10% for junior through to 76% for open class shearers. Shearers with a history of LBP generated greater cumulative right medio-lateral shear forces, greater left lateral bend and left axial twist moments. Skill-based training that reduces asymmetric forces may help reduce such high prevalence levels of LBP.

Statement of Relevance: Shearing is an important and physically demanding rural occupation. It requires sustained flexed postures that generate considerable spinal loads and a high risk of LBP. This research examines how skill and a history of LBP it carries interact to influence trunk postures and spinal loads within a sample of shearers.     

Notebook computer use on a desk,lap and lap support: Effects on posture,performance and comfort

This study quantified postures of users working on a notebook computer situated in their lap and tested the effect of using a device designed to increase the height of the notebook when placed on the lap. A motion analysis system measured head, neck and upper extremity postures of 15 adults as they worked on a notebook computer placed on a desk (DESK), the lap (LAP) and a commercially available lapdesk (LAPDESK). Compared with the DESK, the LAP increased downwards head tilt 6° and wrist extension 8°. Shoulder flexion and ulnar deviation decreased 13° and 9°, respectively. Compared with the LAP, the LAPDESK decreased downwards head tilt 4°, neck flexion 2°, and wrist extension 9°. Users reported less discomfort and difficulty in the DESK configuration. Use of the lapdesk improved postures compared with the lap; however, all configurations resulted in high values of wrist extension, wrist deviation and downwards head tilt.

Statement of Relevance: This study quantifies postures of users working with a notebook computer in typical portable configurations. A better understanding of the postures assumed during notebook computer use can improve usage guidelines to reduce the risk of musculoskeletal injuries     

汽车涂装中车身竖直输送技术的探讨

提出了在汽车涂装中采用车身竖直输送方式的设想。分析了车身竖直输送的优势:可以缩短生产节距和设备长度,提高生产节拍,降低投资成本,改善喷涂条件和提高产品质量。对车身竖直输送需要解决的问题进行了探讨。     

Standing

Abstract

The paper summarizes 12 papers by the authors over the last six years on various aspects of standing. This paper is divided into four sections. The anthropometry section discusses foot dimensions (including volume and footprints) and discusses leg-length discrepancy. The criteria section discusses the usefulness, for standing, of various physiological criteria and of body comfort votes. The floor surfaces section discusses concrete, rubber mats and carpet. The posture section discusses standing postures.     

公交司机肌肉骨骼损伤风险的工效学分析

通过问卷调查,结合Ovako工作姿势分析系统(OWAS)对城市公共汽车司机患肌肉骨骼损伤性疾病的风险进行了评估和分析。分析结果显示,公共汽车司机的颈部和背部存在较大的损伤风险,车辆进站、出站和转弯过程中不良姿势的比例较高。研究结果分别从主观和客观两个方面评估了城市公共汽车司机的职业负荷和可能的职业伤害,对城市公共汽车司机职业健康的促进和工作环境的改进具有一定的实践指导意义。     

Simulated effect of driver and vehicle interaction on vehicle interior layout

Digital human modeling is an essential tool to reduce cost and to save time in a design process where humans take the part of users of the design. Considering this phenomenon for a vehicle interior, the importance of the seat track location and adjustment ranges become important. This paper presents the effect of driver and vehicle interaction on vehicle interior layout based on simulation approach. This simulation method includes two optimizations. The first optimization problem is the physics-based seated posture prediction. In order to represent physical drivers, 4,500 virtual drivers are generated based on an anthropometric database-ANSUR. Interaction forces between the digital human and pedal, seat, ground, and steering wheel are incorporated in the physics-based posture prediction. Three different pedal reaction moments (0, 20, and 40 N m) are implemented into the formulation to examine the effect of pedal reaction moment on driver seat location and adjustment ranges. To study the effect of shear forces, the physics-based posture prediction is compared to kinematics-based posture prediction. After posture predictions are completed, individuals' preferred seat locations are used in a second optimization problem to predict the seat track location and adjustment ranges. For a specific vehicle with 20 N m pedal reaction moment, adjustment ranges are predicted as 223 mm and 82 mm in horizontal and vertical directions, respectively. Also, it was shown that shear force due to the interaction between the driver and the seat pan and the pedal reaction moment are both influential to the seat track location and adjustment ranges.Relevance to industryThe simulation model presented in this paper is useful in vehicle and seat design and can be easily used for virtual design assessment in vehicle design.