Effects of computer mouse design and task on carpal tunnel pressure

Computer mouse use has become an integral part of office work in the past decade. Intensive mouse use has been associated with increased risk of upper extremity musculoskeletal disorders, including carpal tunnel syndrome. Sustained, elevated fluid pressure in the carpal tunnel may play a role in the pathophysiology of carpal tunnel syndrome. Carpal tunnel pressure was measured in 14 healthy individuals while they performed tasks using three different computer mice. Participants performed a multidirectional dragging ('drag and drop') task starting with the hand resting (static posture) on the mouse. With one mouse, an additional pointing ('point-and-click') task was performed. All mice were associated with similar wrist extension postures (p = 0.41) and carpal tunnel pressures (p = 0.48). Pressures were significantly greater during dragging and pointing tasks than when resting the hand (static posture) on the mouse (p = 0.003). The mean pressures during the dragging tasks were 28.8-33.1 mmHg, approximately 12 mmHg greater than the static postures. Pressures during the dragging task were higher than the pointing task (33.1 versus 28.0 mmHg), although the difference was borderline non-significant (p = 0.06). In many participants the carpal tunnel pressures measured during mouse use were greater than pressures known to alter nerve function and structure, indicating that jobs with long periods of intensive mouse use may be at an increased risk of median mononeuropathy. A recommendation is made to minimize wrist extension, minimize prolonged dragging tasks and frequently perform other tasks with the mousing hand.     

Off-road machine controls: investigating the risk of carpal tunnel syndrome

Occupationally induced hand and wrist repetitive strain injuries (RSI) such as carpal tunnel syndrome (CTS) are a growing problem in North America. The purpose of this investigation was to apply a modification of the wrist flexion/extension models of Armstrong and Chaffin (1978, 1979) to determine if joystick controller use in oV-road machines could contribute to the development of CTS. A construction equipment cab in the laboratory was instrumented to allow force, displacement and angle measurements from 10 operators while they completed an ? 30-min joystick motion protocol. The investigation revealed that both the external fingertip and predicted internal wrist forces resulting from the use of these joysticks were very low, indicating that the CTS risk associated with this factor was slight. However, the results also indicated that, particularly for the ‘forward’ and ‘left’ right side motions and for all left side motions, force was exerted by other portions of the fingers and hand, thereby under-predicting the tendon tension and internal wrist forces. Wrist angles observed were highest for motions that moved the joysticks to the sides rather than front to back. Thus, the ‘right’ and ‘left’ motions for both hands posed a higher risk for CTS development. When the right hand moved into the ‘right’ position and the left hand moved into the ‘left’ position, the wrist went into extension in both cases. Results indicate that neither learning nor fatigue aVected the results.     

Touchable objects: attributes applied to the design of computer input devices

Among many important attributes, designers often seek to create products that are comfortable both in the sense of avoiding discomfort and providing a positive sense of comfort. Another way of looking at the design of hand-held products is to consider what attributes make a product enjoyable to touch, rather than just comfortable or uncomfortable. A series of focus discussions investigated the qualities of objects that are enjoyable to touch. Persons were asked to bring in one or two objects that said to them, ‘Touch me’ and ‘Keep touching me’. Discussion with the participants discerned their motivations for selecting the touchable objects. Observations noted the objects' sizes, weights, shapes, surfaces, and colours. This research about qualities of touchable objects influenced the designs of new designs of trackballs for computer navigation. Further hypothesis supposes that the attributes of touchable objects are based on human experience over time with nature.     

计算机实验室内鼠标的维护

鼠标器简称鼠标,是微型计算机的基本外设之一。鼠标器体积小巧,操作起来方便、自然,与其它指点设备相比(如光笔、触摸屏等),它更为便宜和方便,尤其是Windows的流行,对鼠标的普及起到了极大的推动作用。本文主要介绍了光机式鼠标的工作原理;机械式和光电式鼠标通常出现故障的种类以及常用的维护方法和如何有效的使用以延长其寿命。     

Multi-position ergonomic computer workstation design to increase comfort of computer work

This paper presents a new design of computer workstation that is aimed at increasing the comfort of a user working for long periods at a computer. As we have become a society that spends a lot of time working on computers, the computer workstation needs to provide comfort to users. Discomfort and an improper position can negatively affect overall health and productivity. A new type of ergonomic computer workstation, which allows users to sit in multiple working positions, is proposed in order to provide better comfort to people who spend a long time sitting at their workstations. We have designed and developed a new multi-position ergonomic computer workstation which has 19 degrees of freedom and which can accommodate from 5th to 95th percentile human size. Four types of working position (upright, lean-back, zero-gravity and lean-forward) are preset by choosing different angular positions of the workstation parts. Positions of the workstation parts can be changed by controlling the actuators. These four positions were used to evaluate the comfort of the workstation. Subjective and objective evaluations, including comparison of the prototype and standard computer setup, were carried out using human subjects and ergonomic principles. Results showed that the new workstation is much more comfortable, supporting the body in a balanced way. Users have the freedom to stretch and relax in different working positions before they feel any noticeable discomfort; as a result, it lets users work for a longer period without strain, thus resulting in higher productivity.     

Strength and range of motion of females with carpal tunnel syndrome

An experimental study was conducted to evaluate the grip and fingertip pinch strength, and range of motion of females with carpal tunnel syndrome (CTS). The range of motion of the wrist was measured in the sagittal, frontal, and transverse planes. Strength and range of motion measurements were also conducted on a control group. Results indicate that some strength and range of motion measures of the females with CTS were significantly different from that of the control group. Also, measurements in different planes caused significant differences in some range of motions of the wrist for both the CTS and the control groups.     

Effects of individual characteristics,organizational factors and task characteristics on computer programmer productivity and job satisfaction

Several individual characteristics of computer programmers (self- esteem, level of experience, and mathematical aptitude); four organizational factors (perceived supervisory initiated structure, perceived supervisor consideration, perceived level of performance feedback, and perceived degree of participation in organizational decisions); and five task characteristics (skill variety, task variety, task significance, autonomy, and feedback) are related to computer programmer productivity and job satisfaction. Measurement was accomplished via questionnaires; least squares multiple regression was used to test the hypotheses.     

Method for the analysis of posture and interface pressure of car drivers

Biomechanical study of car driver posture is one of the most referenced aspects for the ergonomic design process of the whole vehicle. The aim of this work is to present a multi-factor method for the analysis of sitting posture and the resulting interactions of the car driver body with the cushion and the backrest. The proposed method, based on the combined use of an optoelectronic system for motion capture and suitable matrices of pressure sensors, has allowed the measurement of a large set of car driver posture parameters and the identification of specific sitting strategies characterising the driving posture, despite the different behaviours of the analysed subjects.     

Effects of forearm and palm supports on the upper extremity during computer mouse use

The use of forearm and palm supports has been associated with lower neck and shoulder muscle activity as well as reduced musculoskeletal discomfort during keyboard use, however, few studies have investigated their effect during computer mouse use. Eight men and eight women completed several computer mousing tasks in six arm support conditions: Forearm Support, Flat Palm Support, Raised Palm Support, Forearm + Flat Palm Support, Forearm + Raised Palm Support, and No Support. Concurrently, an infrared three-dimensional motion analysis system measured postures, six-degree-of-freedom force-torque sensors measured applied forces & torques, and surface electromyography measured muscle activity. The use of forearm support compared to the no support condition was significantly associated with less shoulder muscle activity & torque, and the raised palm support was associated with less wrist extension. Forearm supports reduced shoulder flexion torque by 90% compared to no support. The use of either support also resulted in lower applied forces to the mouse pad. Participants reported less musculoskeletal discomfort when using a support. These results provide recommendations for office workstation setup and inform ergonomists of effective ways to reduce musculoskeletal exposures.     

Effects of keyboard tray geometry on upper body posture and comfort

The effects of a downward-tilting (DT) keyboard tray on wrist posture, seated posture and self-assessed musculoskeletal discomfort were investigated in a field experiment. Thirty-eight professional office workers were studied. A pretest assessed how they typed using either a conventional keyboard on a desk or on an articulating keyboard tray, and with or without wrist rests. Workers were randomly allocated to a control (n= 15) or test group (n= 23) that used their existing keyboard in a DT system. A post-test was conducted 3 weeks later. Results showed no significant changes in wrist posture, seated posture or reports of musculoskeletal discomfort for the control group, and ? 50% of typing wrist movements put the hand in a neutral zone. There were significant improvements in wrist posture, seated posture and upper body musculoskeletal discomfort for the test group using the DT system. Over 80% of typing wrist movements put the hand into a neutral zone with the DT arrangement. Reactions to using a conventional keyboard on a DT system were positive.     

计算机输入设备的频谱检测与分析

利用频谱分析仪对计算机输入设备工作时发射的辐射信号进行测试,获取输入设备辐射信号的频谱数据并进行相应的频谱特性分析。找出其泄漏的主要频段和特点,为输入设备的防护提供依据。     

Results of Finnish national survey on EU legislation concerning computer work

The European Directive on computer work (VDU 90/270/EEC) is implemented in the Finnish Government Decree. The aim of the present study was to evaluate the effects of the legislation and its applications in practice. The quantitative method used an online questionnaire. The respondents were employers (N = 934), employees (N = 1872) and occupational health care (OHC) units (N = 289). The majority of all these three groups considered the provisions clear and easy to understand, comprehensive, and easy to comply with. The provisions had a great impact on preventing mental overloading, arranging sight tests at the employer's cost, and on the refunding of eyeglasses for computer work. Most employers felt they did not need any more specific provisions, whereas half of the employees and OHC professionals would have liked the provisions to be more detailed. More explicit and specific regulations were also needed for practice applications in particular, as well as for the refunding of the costs of special eyeglasses for computer work. A total of 59% of the employers reported that costs of glasses are refunded, whereas the figure for employees was clearly lower (37%). OHC professionals reported that the costs of glasses were refunded in 82% of their customer workplaces. The practical conclusion is that employees' sight examinations and compensation for eyeglasses should be promoted in computer work. Moreover, ergonomic applications are best carried out in co-operation with OHC personnel.     

Effect of computer mouse gain and visual demand on mouse clicking performance and muscle activation in a young and elderly group of experienced computer users

The present study evaluated the specific effects of motor demand and visual demands on the ability to control motor output in terms of performance and muscle activation. Young and elderly subjects performed multidirectional pointing tasks with the computer mouse. Three levels of mouse gain and three levels of target size were used. All subjects demonstrated a reduced working speed and hit rate at the highest mouse gain (1:8) when the target size was small. The young group had an optimum at mouse gain 1:4. The elderly group was most sensitive to the combination of high mouse gain and small targets and thus, this age group should avoid this combination. Decreasing target sizes (i.e. increasing visual demand) reduced performance in both groups despite that motor demand was maintained constant. Therefore, it is recommended to avoid small screen objects and letters. Forearm muscle activity was only to a minor degree influenced by mouse gain (and target sizes) indicating that stability of the forearm/hand is of significance during computer mouse control. The study has implications for ergonomists, pointing device manufacturers and software developers.     

Effects of slanted ergonomic mice on task performance and subjective responses

The biomechanical benefits (e.g., muscular activity) of slanted ergonomic mice have been comprehensively identified; however, their effects on task performance and subjective responses have not been fully investigated. The present study examined the effects of two slanted mice (slant angle = 30° and 50°) in comparison with a conventional mouse (slant angle = 0°) in terms of task performance (task completion time and error rate) and subjective responses (perceived discomfort score and overall satisfaction score). Experimental results showed that all of the task and subjective measures worsened as the slant angle of the target mice increases. For example, the task completion time (unit: ms) and overall satisfaction score (unit: point) of the 30° slanted mouse (time = 0.71, satisfaction = −0.09) and 50° slanted mouse (time = 0.73, satisfaction = −0.79) significantly deteriorated than the conventional mouse (time = 0.65, satisfaction = 1.21). The slanted mice seem to compromise biomechanical benefits with task performance and subjective responses.     

Effects of mattress firmness on infant body pressure distribution

Infancy is a developmental stage in an individual's life. As an important part of infant development, sleep greatly influences the physiological and mental development of infants, and the health and comfort of infant sleep is a major public concern. From the viewpoint of ergonomics, this study investigated the effects of mattress firmness on the body pressure distribution of infants aged 0–3 years in the supine posture. Six types of mattresses with different firmness values were tested and 11 healthy infant subjects participated in the experiment. A Tekscan body pressure measurement system was used to record data. The body pressure distribution of infants was analysed using six pressure distribution indices including the maximum pressure, average pressure, contact area, maximum pressure gradient, average pressure gradient, and longitudinal pressure distribution curve. The results revealed that, in the supine posture, there is significant correlation between the body pressure indices and the mattress firmness. The average pressure has the strongest correlation with mattress firmness. The infants' buttocks zone had the highest pressure, while the pressure on the head and leg zones was relatively low. The recommended K value, which represents the mattress firmness, ranges from 267 to 669 mm².     

Effects of a thermal-insulating mouse pad on temperature of forearm and hand during computer tasks

This laboratory experiment studied the effects of a thermal-insulating mouse pad on arm temperature and comfort during computer work. Fourteen subjects performed two 20-min computer tasks (a mouse task and a combined task alternating keyboard and mouse use), under three conditions, namely with: 1) a thermal-insulating pad; 2) a placebo pad; 3) no pad (desktop). The temperatures of the forearm, wrist, hand and fingers were measured with four thermocouples. Comfort and discomfort were determined by two visual analogue scales. No arm temperature differences were found between the experimental conditions after performing the combination task in any location. After the mouse task, however, arm temperature decreased significantly less with the thermal-insulating mouse pad than with the placebo pad. The thermal-insulating pad was rated as more comfortable and less uncomfortable than a regular desktop during mouse tasks. A large size is recommended for the thermal-insulating pad.     

Variation in sitting pressure distribution and location of the points of maximum pressure with rotation of the pelvis,gender and body characteristics

The pressure distribution and the locations of the points of maximum pressure, usually below the ischial tuberosities, were measured for subjects sitting on a flat, hard and horizontal support, and at various angles of the rotation of the pelvis. The pressure data were analysed for force- and pressure-related quantities. Multiple regression was applied to explore relationships between these quantities and (i) a set of body characteristics and (ii) the pelvis rotation. The maximum pressure and the pressure gradient were mainly found to be explained by the ectomorphic index and the distance between the maximum pressure points by gender and the angle of rotation of the pelvis.     

路桥隧道承压报警传感节点的设计与实现

传统方法存在报警效率较低,能量消耗大等问题,提出了路桥隧道承压报警传感节点的设计。根据传感节点整体架构图,设计传感节点硬件,并对承压报警传感、无线单片机和传感单元及接口电路模块展开分析;利用嵌入式底层驱动进行信息交互,构建通信协议,通过无线传感方式采集数据,并对传感节点部署。通过实验验证结果可知,该设计方法充分考虑数据获取情况,具有报警效率高、能量消耗小的优势,可实现路桥隧道安全运营。     

Effects of precision demands and mental pressure on muscle activation and hand forces in computer mouse tasks

The objective of the present study was to gain insight into the effects of precision demands and mental pressure on the load of the upper extremity. Two computer mouse tasks were used: an aiming and a tracking task. Upper extremity loading was operationalized as the myo-electric activity of the wrist flexor and extensor and of the trapezius descendens muscles and the applied grip- and click-forces on the computer mouse. Performance measures, reflecting the accuracy in both tasks and the clicking rate in the aiming task, indicated that the levels of the independent variables resulted in distinguishable levels of accuracy and work pace. Precision demands had a small effect on upper extremity loading with a significant increase in the EMG-amplitudes (21%) of the wrist flexors during the aiming tasks. Precision had large effects on performance. Mental pressure had substantial effects on EMG-amplitudes with an increase of 22% in the trapezius when tracking and increases of 41% in the trapezius and 45% and 140% in the wrist extensors and flexors, respectively, when aiming. During aiming, grip- and click-forces increased by 51% and 40% respectively. Mental pressure had small effects on accuracy but large effects on tempo during aiming. Precision demands and mental pressure in aiming and tracking tasks with a computer mouse were found to coincide with increased muscle activity in some upper extremity muscles and increased force exertion on the computer mouse. Mental pressure caused significant effects on these parameters more often than precision demands. Precision and mental pressure were found to have effects on performance, with precision effects being significant for all performance measures studied and mental pressure effects for some of them. The results of this study suggest that precision demands and mental pressure increase upper extremity load, with mental pressure effects being larger than precision effects. The possible role of precision demands as an indirect mental stressor in working conditions is discussed.     

Control circuits simplification and computer programs design on bipedal robot

This study is expected to provide the best design of bipedal robot, which will help widen the application in the future. A new design system is presented through simplification of the control circuit, and the design of computer programs not only lowers the research barriers of the robots but also decreases the development costs. This design system can be used for various operations of manufacturing processes to make up the shortages of the flexibility for the robots. In recent years, the progress in electronics and the control technology has made the robots useful not only for dangerous and automatic tasks, but also for advanced and friendly people service. Thus, the robots have been used in the factories for automation and towards the general use in regular life. Of all robots, the bipedal robot attracts the most attention for its humanoid outlook, user-friendly design, and artificial intelligence for the human society. Many bipedal robots are developed to satisfy consumers’ needs. The control circuits and the program design are the key issues to make the bipedal robots. In this study, a synchronous robot controller for 31°-axis freedom is developed. The authors also equip a memory in the hardware architecture to store all moving commands of the bipedal robot. In terms of internal programs, the authors develop a human interface that synchronizes the movement of the robot and collects the pace data of the robot. The authors use the statistical method to analyze the data and establish a database of the robot's movement. With the database, one can finally drive the robot to walk and generate the pace design of the bipedal robots.