NAME / MATRIX NO.
MUHAMMAD FARHAN BIN JAHRONI / 15DKA11F2052
MOHAMMAD FAIZ BIN / 15DKA11F2080
Contents
Introduction 2
Objective 3
Methodology 4
Conclusion 14
References 15
Ergonomics About Mouse
Introduction
Ergonomics is concerned with the ‘fit’ between the user, equipment and their environments. It takes account of the user's capabilities and limitations in seeking to ensure that tasks, functions, information and the environment suit each user.
To assess the fit between a person and the used technology, ergonomists consider the job (activity) being done and the demands on the user; the equipment used (its size, shape, and how appropriate it is for the task), and the information used (how it is presented, accessed, and changed). Ergonomics draws on many disciplines in its study of humans and their environments, including anthropometry,biomechanics,mechanical engineering,industrial engineering,industrial design,information design,kinesiology,physiologyandpsychology.
Typically, an ergonomist will have a BA or BS or BD in Psychology, Industrial/Mechanical Engineering or Industrial Design or Health Sciences, and usually an MA, MS or PhD in a related discipline. Many universities offer Master of Science degrees in Ergonomics, while some offer Master of Ergonomics or Master of Human Factors degrees.
According to theInternational Ergonomics Associationwithin the discipline of ergonomics there exist domains of specialization:[1]
§ Physical ergonomics: is concerned with human anatomy, and some of the anthropometric, physiological and bio mechanical characteristics as they relate to physical activity.
§ Cognitive ergonomics: is concerned with mental processes, such as perception, memory, reasoning, and motor response, as they affect interactions among humans and other elements of a system. (Relevant topics include mental workload, decision-making, skilled performance, human-computer interaction, human reliability, work stress and training as these may relate to human-system andHuman-Computer Interactiondesign.)
§ Organizational ergonomics: is concerned with the optimization of socio technical systems, including their organizational structures, policies, and processes.(Relevant topics include communication, crew resource management, work design, design of working times, teamwork,participatory design, community ergonomics, cooperative work, new work programs, virtual organizations, telework, and quality management.)
Objective
Abstract Computer users who experience repetitive wrist movements and awkward hand positions are prone to developing upper extremity disorders. Manufacturers have designed various ergonomic mice in response to complaints of pain and discomfort related to computer mouse use. The objective of this work was to validate the use of surface electromyography (sEMG) in assessing the design of non-keyboard input devices (computer mice). While holding the computer mouse in different grasp positions sEMG of the forearm and hand were recorded during a set of static tasks.
The sEMG signal provided information regarding the level of muscle activity and the varied combinations of muscular effort needed to position the hand in a specified posture. A significant decrease in the level of sEMG activity was observed for the pronator muscles when subjects were tested using ergonomic computer mice. The sEMG-based method was validated to be sensitive to the impact of subtle differences in shape/design on the amplitude of the surface EMG data. We also proved a significant effect of hand size and grasp position on the level of muscle activity associated with different mice.
Methodology
Twenty-one healthy subjects were recruited in this study. Age ranged from 20 to 38 years with a mean and standard deviation of 26.3 +/- 5.8 years. Ten of the subjects were female. Subjects were recruited in order to cover a range of hand sizes from the 5th percentile of the female population to the 95th percentile of the male population
Muscle selection in this study was based on several criteria. The first criterion was that the muscle of interest had to be detectable by surface electrodes. Secondly, the recorded activity was reproducible in any environment and eventually could be applied to a field investigation. EMG signals were recorded from the following muscles of the forearm and the hand: Extensor Carpi Ulnaris (ECU), Extensor Digitorum (ED), Pronator Quadratus (PQ), Pronator Teres (PT), Flexor Digitorum Superficialis (FDS), First Dorsal Interosseus (FDI), and Second Dorsal Interosseus (SDI) muscles. These muscles were chosen because they are the dominant muscles that control the handto assume the three tested positions. Fig. 1 shows the position of the electrodes on the forearm and hand of one subject. A single and double differential electrode is
Fig. 1. Electrode placement on the forearm.
implemented based on the muscle of interest zone (Fig.2).
Fig. 2. Single and double differential electrodes
When measuring activity of the wrist/finger extensor muscles that are in close proximity with one another it is ideal to use double differential electrodes. The double differential also called three-bar electrode is preferred for localized areas because it removes neighboring muscle signals from the signal of interest. Single differential electrodes are used when high selectivity is not a main concern (bicep, quadriceps, calf, etc.). The sEMG signals were detected with a Bagnoli- 8- channel system (Delsys Inc.). In order to provide an output range of 0.1-1 V (peak to peak) the sEMG signals were amplified with a gain of 1000 or 10,000. The sEMG signal was then filtered at a bandwidth of 20 to 450 Hz and sampled at 1024 Hz using a 12-bit Analog to Digital conversion board. The modified signal was then stored in computer memory.
The study was performed using the following four computer mice: Logitech Mouse, Logitech Mouse Man, Microsoft IntelliMouse and Microsoft IntelliMouse Pro. The Logitech Mouse and Microsoft IntelliMouse were chosen because they are commonly found at college computer terminals and are standard in desktop computer packages. The criterion for choosing the Microsoft IntelliMouse Pro was its ergonomic feature. Logitech was the first to provide slanted mice to reduce the flat, handsdown posture (forearm pronation) typical with mouse use. As a result we decided to test the Logitech Mouse Man.
In order to compare computer mouse designs it was necessary to specify hand positions that were the same across tests performed with different computer mice. Three static positions of the hand, corresponding to three different ways of holding the computer mouse, were tested: 1) rest [Fig. 3]; 2) side grip [Fig. 4]; 3) grab position
Fig.3. Rest
Fig.4. Side Grip
Fig. 5. Grab
10 Tips for Using a Computer Mouse
The following tips should help you avoid a mouse-related musculoskeletal injury. The same posture principles apply to other input devices (e.g. trackball, touchpad, pen, digitizing puck etc.). Postural variation is a key factor for good ergonomics. Try to regularly vary your posture when you work with a mouse, and in this way you will help to minimize the risk of ergonomic problems. remember, the best ergonomic mice are designed to allow you to vary your posture while working with the mouse.
1. Mouse Grip - don't throttle your mouse (it's already dead)! Hold the mouse gently to move it over a mousing surface.
2. Mouse from the Elbow - don't skate or flick the mouse with your wrist. Make controlled mouse movements using your elbow as the pivot point and keep your wrist straight and neutral.
3. Optimal Mouse position- sit back in your chair, relax your arms then lift your mousing hand up, pivoting at the elbow, until your hand is just above elbow level. Your mouse should be positioned somewhere around this point. Don't use a mouse by stretching to the desk or out to the side of a keyboard. With a flat mouse platform, position this 1-2" above the keyboard and over the numeric keypad if you are right handed - you can easily move it out of the way if you need to access these keys. With a downward sloping mouse platform, position this close to the side of the keyboard so that you can use the mouse in a neutral wrist position. Position adjustable mouse platforms are commercially available (e.g. Humanscale, Flexrest, 3M etc.)
4. Protect your wrist - if you look at the anatomy of the wrist it is curved away from any contact surface (you can easily see this by resting your hand/arm on a flat surface - you'll see light under the wrist and can probably even pass a thin pen under this). The forearm is shaped liked this for the wrist to remain free of surface pressure contact.
5. Avoid restricting circulation - For may people there are exposed blood vessels near the skin at the wrist, which is where the pulse is often taken. Any pressure in this region will disrupt circulation into the hand and this will increase the risks of injury.
6. Don't use a Wrist Rest - research has shown that using a wrist rest doubles the pressure inside the carpal tunnel, because the floor of the tunnel is a more flexible ligament that transmits external pressure changes directly into the carpal tunnel (the roof of the tunnel is bone so the pressure doesn't get transmitted on through the hand). Indeed, one test for carpal tunnel syndrome (CTS), know as Tinel's sign, simply involves tapping on the palmar surface of the wrist, which is enough to cause tingling and numbness in someone developing CTS.
7. Avoid Restricting Arm Movement - with a softly padded wrist rest, especially one that is rounded, or a soft chair arm rest the forearm becomes "locked" into position and this encourages people to make mouse movements by flicking the wrist, which also increases intracarpal pressure.
8. Keep the Mouse Free Moving - The base of the palm of the hand is the part of the body designed to support the hand when resting on a surface. For keyboard use a broad palm support is best. However, mouse use is different from keyboard use. With a keyboard the best posture is for users to float their hands over the keyboard when typing and then to rest on the palm support in microbreaks between typing bursts. You can use rest-breaking software (e.g.Break reminder etc) to help track and advise on your mouse use. With mousing this doesn't happen. A mouse is used by moving its position over a surface, and resting usually occurs when mouse movements stop but with the mouse still being held in the hand. Mouse movements should be made using the elbow as the pivot point, not the wrist. Anything that impairs free movement of the forearm/hand and mouse will increase injury risks.
9. Mouse shape - choose a mouse design that fits your hand but is as flat as possible to reduce wrist extension. Don't use a curved mouse. Use a symmetrically shaped mouse. Consider a larger mouse and there are several new interesting products on the market , such as the Whale mouse or the Perfit mouse, that encourage arm rather than wrist movements or that encouirage postural variety and one or two-handed use. Pen-based mice designs also allow a more comfortable grip. Some types of mouse palm support can be attached to the mouse, such as the Mouse Bean.
10. Load sharing - if you want to load share between your right and left hands, that is using the mouse for some of the time with each hand. For this you need to choose a mouse platform that can easily be configured to the left or/and right, and a symmetrical shaped mouse that can be used by either hand.
Other input devices- whether you choose a different mouse design, a trackball, a joystick, a pen, a touchpad, a multitouch pad or some other input device, make sure that your position this comfortably, and that your wrist is in a neutral position when using the device.
It is believed by many researchers that by keeping your wrist and hand in line with your forearm in astraight and neutral position, you reduce stress and strain on tendons and muscles.
When cradling the mouse, use your index and middle fingers for clicking the right and left mouse buttons, respectively.
Make sure, when handling the mouse, to keep your hand in a straight line with your forearm, and not surrender to any urge to bend the palm at the writs; either to the left or right, or up or down.
If your wrists form an unhealthy angle when using the mouse, it can easily cause many aches and pains, as well as joint and/or tendon infections.
Even though there is no problem using a standard mouse in a correct and healthy way,severalnew models of ergonomic micehave been designed. The most successful ergonomic mice of all time are, of course, the tracking ball mice series by Logitech, which is used by moving a ball by one’s thumb instead moving the entire mouse. There are some newer advances, such as thejoystick styled mouse by 3Mand the new patentedEvoluent mouse.
Some ergonomic practical tips:
· The mouse should be held loosely and should fit naturally under the palm of your hand. Avoid the use of a wrist pad.
· Movement of the mouse should come from the whole arm and shoulder, not just the wrist.
· The mouse should be positioned at the same height as the keyboard and directly adjacent to avoid reaching (if there is at a wider angle than 110 degrees between your arm and forearm, this is considered reaching).
· Avoid holding the index finger elevated between clicks.
Whether you spend five minutes or five hours using your mouse or trackball, these suggestions can help you stay comfortable and productive.