IOP2603 GREAT NOTES TO HELP YOU GET ABOVe 90% .

IOP2603 - Ergonomics. IOP2603 - ERGONOMICS STUDY NOTES AND EXAM QUESTIONS. Explain the 2 principles or guidelines, namely that the primary purposes of HFE are the design of tools and workstations and that an interdisciplinary approach is necessary in the design and analysis of tools or systems. 1 st guideline – explore together is that design is the primary purpose of ergonomics 2 nd guideline – we should explore is that an interdisciplinary approach is necessary in the design and analysis of tools or systems. Interdisciplinary knowledge is required in ergonomics in HFE design for the following reasons:  formulate system goals  understand functional requirements  design a new system  analyze a system  implement a system In your own words, explain what Human Factors and Ergonomics (HFE) are: Helander define human factors and ergonomics as:  Considering environmental and organizational constraints  Use knowledge of human abilities and limitations  To design the system, organization, job, machine, tool or consumer product  So that it is safe, efficient, and comfortable to use. Word ergonomics is derived from the word Greek words ergo (work) and nomos (laws). Main purpose is design. Primary purpose is to understand and model human behavior – but not to design. Definition: Ergonomics is scientific discipline concerned with the understanding of interactions among humans and other elements of a system, and profession that applies theory, principles, data and methods to design in order to optimize human well-being and overall system performance. The focus of ergnomics HRE is the applied field of Industrial and Organisational Psychology that focuses on the interaction between human beings and the  Products  Equipment  Facilities  Procedures  Physical environment and  Psychological environment Used at work and in everyday living. The emphases is on people and how the design and laytout of above aspects influence them. Discuss the 3 major systems goals of HFE (15) Use relevant examples to illustrate your answer (15) x 3 Three goals of HFE are:  Increased safety of the user or operator  Enhanced productivity  Operator satisfaction Goal of safety –  Make a comparison between performance requests of the environment with the performance restriction of the operator.  Limitations of the operator should be taken into consideration when designing tools, equipment or systems. Ergonomics is a design methodology that used to arrive at safety, productivity and satisfaction.  Injuries and accidents are relatively rare in some workplaces. Rather than waiting for accidents to happen, it can be analyzed by other indicators such as operator errors subjective assessments, physiological response variable. Example: construction and mine workers wearing helmets, protective head cover against falling bricks and rocks. The goals of productivity –  Design a system which improves performance affordances through efficient design as the system, the operator can excel in exercising his or her skills.  Such system design makes it possible to perceive quickly, make fast decisions, and exercise efficient control.  Increase the efficiency and effectiveness with which work and other activities are performed, thereby increasing productivity.  Safety must be considered when focusing on productivity; there is usually a tradeoff between the two. Example: upgrading the memory of employee’s personal computers so that processing time improves. The goal of operator satisfaction –  The work satisfaction as well as user satisfaction. The ultimate goal of ergonomics is to improve and maintain the wellbeing of individual worker.  The wellbeing of the organization will also be improved and maintained. Different people have different needs and different expectations and vary substantially between countries and cultures. Example: power steering in a vehicle of reducing fatigue and increasing comfort. Give a simple definition and explain the focus and objectives of Ergonomics. Make us of appropriate diagram of the objectives of ergonomics to show advantages for the individual worker and the organization (15) x 2  The ultimate goal of ergnomics is to improve and maintain the well-being of the individual worker.  Same time the well-being of the organisation will also be improved and maintained.  Ergnomics has certain advantages for the individual worker, such as an improvement in the following: o Health o Safety o Comfort o Satisfaction o Convenience  For the organisation, on the other hand, there will be an improvement in the following: o Performance o Productivity o Effectiveness o Efficiency o Quality of the product or service  In this process there will be a drop in absenteeism and labour turnover, an increase in worker involvement, more commitement to change, as well as increase in work motivation and purcahse of the companys products or services. OBJECTIVES OF ERGONOMICS EMPLOYEE ORGANISATION Improvement in: Improvement In: Health Performance Safety productivity Comfort effectiveness Satisfaction efficiency Convenience quality Less: Absenteeism, labour turnover More: Involvement, commitment to change Increased: motivation, purchase WELLBEING OF EMPLOYEE WELLBEING OF ORGANISATION Explain what is meant by holistic approach. Illustrate your answer with 2 practical examples (5) A holistic approach, where all aspects in the work environment are addressed, should be followed when ergonomics is applied to the design and layout of work environments and facilities. Example: noise in house will have an effect on study room. What about your neighbor’s. The total environment should be considered and not just what is happening in your immediate environment, which in this case is the study environment. Simple ergonomics model Explain in your own words what the human – technology – workspace – environment model refers to –describe the workplace aspects of a human – technology system of your choice (10) Take human-technology system where a person is working on a computer, for an example, aspects of workplace will include the size, height and layout of the desk and chair, legroom underneath the desk, keyboard and mouse on the desk work surface. These factors will have an effect on the body position, body posture, viewing distance, viewing angle and reach distance of the user and consequently on his or her comfort and efficiency. Important aspect is whenever a person uses a product, equipment or tool we refer to this interaction as a human technology system.  A system comprises a number of parts or components that interact with each other so that movement in one part of the system leads in a predictable way to movement in other parts.  Systems are open to environmental inputs and as a result are continually fluctuating. Given the 2 points above about what a system is an example of a human technology system is a person working on a computer. From a mechanical point of view, the person receives information, based upon which he or she takes certain actions. Interaction between person and technology always takes place in a certain workspace which is located in a certain physical and psychological environment. Workspace is described in terms of size and layout of chairs, tables, desks, consoles and other equipment. Factors like size and layout will have an effect on the body position, body posture, reach distances of the expected user population and consequently on their comfort and efficiency. Environment can be described in physical terms such as temperature, lighting, noise, vibration, ambient environment. The ambient environment also includes presence and effect of chemical and biological agents. Organizational environment can include psychological aspects such as teamwork, management structure, shift conditions and psychological factors. The human-technology-workspace-environment model is useful in identifying the factors that will have an effect on comfort, task performance and safety. Describe the workspace aspects of your chosen human-technology system. Discuss the process of information flow in your chosen example. If we take the human-technology system where a person is working on a computer for e.g. Aspects of workspace will include the size, height and layout of the desk and chair, legroom underneath the desk, and the positioning of the computer screen, keyboard and mouse on the desk work surface. These factors will have an effect on the body position, body posture, viewing distance, viewing angle and the reach distance of the user and consequently his or her comfort and efficiency. Information flow will be as follows:  Information is presented on the computer screen, is observed by the user  The information is processed,  A decision is made and input is provided to the computer by using the keyboard or the mouse.  The computer processes this input information and displays the results on the screen for the user to observe, and then the whole process repeats itself again. Describe the relevant physical and psychological environmental aspects of your chosen human technology system. The physical environmental aspects will include temperature, lightning and noise. Psychological environmental aspects may include teamwork, management structure, privacy, concentration and sosio-psychological factors such as culture and religion. Explain why a cost – benefit analysis is needed in the human factors and design A redesign or change in a system will only occur because of a perceived need or benefit that can be achieved. Even if there is a strong perceived need for redesign or reengineering it is important not to just start with the redesign, because redesign will cost money. It is important to investigate the benefits thoroughly and weight them against the costs. If the benefits such as improved productivity, quality, safety and worker comfort out weight the costs, then the effort of redesign might be worth it. To investigate the costs and benefits of a redesign it is important to obtain information from different sources such as the following:  Discussion with management  Plant walk-through, inspection and not taking  Discussion with operators  Discussion with first line supervisors  Measurements in the plant or office of illumination, noise and design of the workstation. These measurements values should be recorded and documented in a systematic fashion, so that comparisons can be made between different workstations and before and after comparison can be made. Explain work, environment and personal factors to be considered in workstation organization (15)  Illumination levels  Special lightning for special tasks  Job rotation and shift overlap  Personal music  Ergonomics chairs  Operator communication and feedback  Material handling  Automation of monotonous jobs  Housekeeping  Noise reduction  Ergonomic training  Continuous flow manufacturing  Evaluation of safety equipment. Your management at work requests you to investigate a way to improve health, safety, productivity in a certain section of your workplace. Identify and discuss sources of information you would need to conduct an HFE investigation (10) To investigate the costs and benefits of a redesign to obtain information from different sources such as following:  Discussion with management – they can give more details about what the focus of the study should be and explain what the problem is from their perspective.  Plant walk-through, inspection and not taking – from this information about how the manufacturing is and how the material flow is organized can be obtained  Discussion with operators – how they perform their tasks? How long does it take to learn a new task? What are the problems that newly employed workers have?  Discussion with first line supervisors – often these are able workers who have been promoted. They are a great source of information.  Measurements in the plant of illumination, noise and the design of the workstation. Explain the main benefits of usability testing (5)  Usability testing is a method for reducing the difficulty and time for performing a task on a computer.  Basically a process whereby people such as future users analyze the system by trying it out and suggesting improvements on it. It is one of the specialist’s areas of HFE defined by the international association as the field human – computer-interaction (HCI) research.  Can improve the quality of a work with respect to productivity and also with respect to job satisfaction.  As task has an easy and smooth work flow is simply more interesting and more satisfying to perform. Main benefits of usability testing  Usability testing can dramatically improve the quality of work with respect to productivity and also with respect to job satisfaction.  A task that has an easy and smooth work flow is simply more interesting and more satisfying to perform. Positive effects of usability testing for an organization  Product design and product performance will improve  User satisfaction will increase  Since usability errors can be detected much earlier in the systems development cycle, the development time and he development cost for the interface will be reduced.  As a result of the improved software design, sales and revenue will increase.  Because interface is easier to handle it will take less time to train employees  There will also be reduced maintenance costs, reduced personnel costs, and improved user productivity. STUDY UNIT 2 – DESIGNING FOR VISION AND ILLUMINATION The aging eye- make a list of facts that should know about changes that take place in the eye when one grows older and the implications of these changes for industrial work A supervisor is worried that many workers are getting on in years, which may have a negative impact on their sight (the aging eye) to assist the supervisor, provide a list of facts that she should know about the changes that take place in the eye when one grows older and the implications of these changes for industrial work. Also explain the use of indirect or reflected lighting and any corrective measures that could be taken (15) For older individuals there are several physical changes to the eyes. The important loss of focusing power of the lenses in the eye. This because with increasing age the eye lenses lose some of their elasticity, and therefore cannot bulge or flatten as much as before. Older persons cannot focus well because the eye lenses cannot change shape easily as they lose elasticity:  Long sighted people move away from their task, while near-sighted people move closer to it, often resulting in poor work posture  Corrective glasses therefore often solve postural problems. They should be specifically customized for the task at hand  Items in the workplace should be placed not only within the reach but also in the area of functional vision.  Limited range of clear vision makes it necessary that items in workplace are put at a distance where they can be seen clearly. For an individual with no refractive errors a young person, the near point moves further away, while far point may stay at infinity. Another problem is that the vision becomes increasingly clouded, making older persons very sensitive to glare and stray illumination. To prevent:  Avoid lights that shine directly into the operators eyes  Avoid reflections or indirect glare from other surfaces in the work area  Use task illumination: lights with a restricted light cone that shine directly on the task from above Explain the following terms: (10)  Illumination o Light falling on a surface o Measured in lux  Luminance o Reflected illumination o Light emitted by a computer screen o Measured in candela per square metre or nits  Contrast is o The difference in luminance between two objects next to each other  Contrast ration is o A ration of the luminance of area A and area B Explain the role illumination plays at work A well-designed illumination system is important for industrial productivity and quality, as well as operator performance, comfort, and convenience. Improved illumination is not just a matter of installing more lights, but also of how this is done. There are several ways of improving the quality of illumination, for example. By using indirect lighting. Such lightning can be important since it reduces the amount of glare. Visual inspection can be enhanced by using special-purpose illumination, which makes flaws more visible.  Examples of high and low contract in the workplace (black and white printing, computer screens)  The reason why a workstation should not be placed facing a bright window  Reasonable contrast ratio (10:1 or 1:10)  Maximum contrast in an office environment of 40:1  The basic use of functioning of a photometer  The importance of paying attention to the contrast setting between characters and the background on computer screens or video displays terminals. Have you notices, for instance, that the latest mobile phone technology it is possible to choose certain backgrounds that make it nearly impossible to read the screen, although they look very nice?  The problem determining appropriate illumination levels for different tasks, especially the importance of checking legislation and other recommended sources for the latest recommended levels, as these change from time to time, usually as a result of new technology or the pitfalls of both laboratory and field studies in determining illumination levels. Explain use of indirect and direct lightning and any correction measures that could be taken (15) The following is another list of points that you could tell the supervisor about to overcome vision problems. Generally the main vision related difficulties an older person faces in the workplace are dimness, reading small print, distinguishing similar color, and coping with glare. Corrective measure that could be taken is:  Supplying proper glasses  Ensuring a higher intensity of lightning, but  Shielding bright lights to reduce glare  Increasing color contrasts  Using large characters with high contrast and enough white space between them  Avoiding light and color screens  Using red and yellow, not green and blue  Avoiding tasks that require following movement, especially on the edges of the field of vision  Placing things in the centre of the operators vision Explain how to use indirect and reflected lightning in the workplace The use of indirect lighting minimizes both direct glare and indirect glare. It minimizes direct glare because the light is directed towards the ceiling rather than the operators eyes, and it minimizes reflected glare because the light reflected from ceiling is not directional, and will therefore generate so called diffuse reflection. Indirect lighting is mostly suitable for offices and cleans manufacturing workplace where the ceilings do not become soiled. Indirectly lightning would probably not be effective for dirty manufacturing processes, since the light sources and light fixtures become covered with dirt and is it necessary to clean luminaires and paint ceilings at regular intervals. Disadvantages of indirect lightning, the loss of light when it is reflected from the ceiling. It is preferable to use a white ceiling with a high reflectance value. Indirect lightning is mostly suitable for offices and clean manufactures workplaces where the ceilings do not become soiled. STUDY UNIT 4 – DESIGN OF CONTROLS, DISPLAYS AND SYMBOLS Explain the principles underlying the design of controls Appropriateness of manual controls Manual controls should be selected so that they are appropriate to the task and intuitive to use. Some controls can make a task easy to perform, whereas others make a task difficult. Controls can be classified by the number of settings and by the force required to manipulate the control. For example, if a control does not require much force and there are only two discrete settings, the recommended types are goggle switch, pushbutton, or key lock. If there are several control settings, a rotary selector would be a good choice. If a large actuation force is necessary, one should select a control where it is easy to apply force. Hand pushbuttons, foot pedals, levers, or cranks could be used. Presently many controls are programmed and they have become inexpensive, for example male urinals with sensors for flushing, if the sensor is put too high it might not pick up that someone just used the urinal and not flush, therefore height adjustment must be appropriate. Standardization of controls Over the years many controls have become standardized. In driving a can we are so accustomed to steering wheels and foot pedals, that it would be difficult to imagine any other arrangements. Examples of standardized controls include:  Steering wheel for steering  Joystick for airplanes  Foot pedals for braking and acceleration  Manual lever for aircraft throttle  Lever control for gear shift A user would be confused and annoyed to find other types of controls. With technological advancement, some systems are no longer controlled manually. You do not have to manually turn on some water taps. If there are hands in front of them they open the water. Selection of computer input devices There has been much research on the design of input devices, such as the mouse, the track-ball, the joystick, the touch screen, the light pen, and the graphics tablet. Different input devices have different advantages and disadvantages. For touch screens and light pens, one has to point with a finger or a stylus; this provides excellent hand-eye coordination. Pointing is a very direct way of expressing preference. This is such basic behavior that training is not necessary. Touch screens and light pens are therefore the most direct devices. There are, however, disadvantages. The pointing will partly obscure the view of the display, and the input resolution is poor. For the touch screen the resolution is the width of the finger, and for the light pen it is the width of the pen. Touch screens are particularly appropriate for use in public environments, such as information displays at train stations and ticket vending machines at airports. This type of device has no moving parts, and it is sturdy and robust. The mouse, the track-ball, and the joystick have the best input resolution; therefore they are the best for accurate pointing. This is because the input resolution can be programmed by changing the gear ratio between the device movement and the cursor movement. For some devices there is flexibility with respect to placement on the work table. The track-ball and joysticks are excellent in this respect, because they are small and easy to move. One disadvantage with the mouse and the graphics tablets is that they occupy prime table space to the right of the keyboard, in the space where users like to write. Operators of touch screens and light pens sit with an extended arm, which could induce muscle fatigue. The input devices described above are the most common. The best device would be the one that requires the least time and produces the least number of errors in performing the task. Control movement stereotypes People have expectations about what to do with controls. In the U.S., a light switch is moved upwards to turn on the light. For a person raise in SA, it is the opposite expectation – the switch is turned down. Control movement stereotypes are trained expectations, and many have been learned since childhood. The stereotype for opening the traditional tap is always to turn the control counter clockwise, and to turn the control clockwise to close the tap. This is a clear stereotype since there is a one to one correspondence between the movements of the control and the controlled element. Why is Control-response compatibility an important ergonomics principle in designs (5) The problem with the design of the stove top is that there is no clear control response compatibility. Ideally, there should be a one-to-one relationship between the controls and the responses (burners). It would be easy to redesign the stovetop so that there is control-response compatibility. For example, the rear burners can be offset slightly to the side. The controls can then be lined up one-to-one with the burners, and the association is immediate. The stovetop represents a familiar and common problem in control-response compatibility. In manufacturing, it would be expected that workstations should be designed with similar considerations. In designing a workstation for manual assembly one must line up part bins so that they are compatible with the assembly process. Discuss 5 common types of control coding (discuss different types of codes. Provide appropriate examples (10) Coding of controls Controls can be coded by adding features to them. This makes them easier to distinguish. There are six common types of control coding: 1. Location 2. Colour 3. Size 4. Shape 5. Labelling 6. Mode of operation These principles apply to controls in automobiles and airplanes, as well as industrial and office environments Coding by location Coding by location is the most powerful principle e.g. in a car. Coding by colour In colour coding, items are coloured differently depending upon the function and the task. One potential problem with colour coding is that it only works in a well illuminated environment. Colour coding requires a longer reaction time than location coding, since it is first necessary to reflect on the meaning of the colour before the task can be performed. This typically involves a double reaction time.