QUESTION 1
Discuss the major goals of Human Factor Ergonomics (HFE). Use relevant
examples to illustrate your answer. (15)
Three main goals of HFE:
The goal of safety – with regards to the goal of safety, the limitations of the operator
should be taken into consideration when designing tools, equipment or systems. To
determine the safety of the workplace, the limitations have to be compared to the
performance of the operator.
EXAMPLES
Protective gear for construction workings include:
helmets with head lights (for better illumination),
hardhats (deflects blows to the head),
safety goggles (protection against dust and sand)
Wearing a safety belt while driving.
Switching on headlights in fog, to improve vision.
The goal of productivity – 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 trade-off between the
two.
EXAMPLES emitted
New Technology
Ensure that equipment is in working order and user-friendly
Inform operators on their specific tasks and goals, to ensure that they know what
is expected of them.
The goal of operator satisfaction – The ultimate goal of ergonomics is to improve
and maintain the wellbeing of the individual worker. At the same time, the wellbeing
of the organisation will also be improved and maintained.
EXAMPLES
Ambient environment - better lighting, ventilation, noise reduction will reduce
stress
Improvement of the layout of the workplace.
By keeping the operator happy
QUESTION 2
According to Helander (2006), there are six common types of control coding.
Discuss these types of control coding. Also discuss the advantages and
disadvantages of each coding method and give practical examples of their
application. (20)
Controls can be coded by adding features to them. This makes them easier to
distinguish.
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There are six common types of control coding (Sanders & McCormick 1993):
1. Location
This is the most powerful principle, expectations are built by experience,
example, in a car the ignition have been standardised and drivers have clear
expectations of where to find this function.
Advantage – it is standardised.
Disadvantage – you need experience in using certain functions.
2. Colour
This consists of different colouring depending on function and task.
Advantage – Different colours can make it easier to distinguish.
Disadvantage - problem with colour coding is that it only works in a well-
illuminated environment. Needs longer reaction time as you need to reflect on
meaning of colour.
Some control colours have stereotypical meaning, e.g. commonly emergency
controls are made red like in South Africa all emergency signs and controls
are associated with red.
Example – the different colour wires in an electrical circuit, to identify which
colour is used for which function or purpose.
3. Size
To distinguish easily between different controls, size can be one coding
option. Small, medium and large controls are used in highly pressurised
situations.
Advantage – it is easy to identify controls when using its size specifications.
Disadvantage – the size of some controls can sometimes be a problem if it is
the same size and it is close to each other.
Example – the lever to open the boot and petrol tank is next to each other, but
the one is smaller than the other, so it is easy to identify which one is for the
petrol tank when you feel it at the bottom, as it is the smaller control.
4. Shape
Controls can be coded by shape.
Advantage - An operator can distinguish up to 12 different shape coded
control knobs under stress.
Disadvantage – when controls have the same shape it is difficult to distinguish
between them and can be a challenge to some users.
It is best when control shape represents the control function, for example the
round joystick control knob of a construction machine that are used to turn the
loader bucket around in different directions.
5. Labelling
Labelling can be used to describe the control, above, below or along side.
The labels must be clearly visible and text readable from left to right.
Advantage – they make the controls easy to identify.
Disadvantage - Labels don’t survive in some harsh environments.
Example – the label of the airbag on a vehicles dashboard, that is readable,
visible and not removable.
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6. Mode of operation
Each control has different feel or unique mode of operation.
Example - A car driver can distinguish between the accelerators and brake
because they have different control resistance, dampening, and viscosity.
Advantage - The operator can verify that the correct control has been
activated and also interrupt control activation if there is an obvious error.
Disadvantage - There are often usability problems with mode control.
QUESTION 3
Discuss the body dimensions regarded as important when designing, buying
or evaluating a workstation. Give reasons why the body dimensions you have
chosen are important. Also take into consideration the range of possible users
of the workstation and the different types of workstations.
Thigh height (popliteal height- the height from sole of the foot to the crease
behind the knee) and Knee height to determine required min height of space
below surface to accommodate legs of a seated user.
Sitting Eye Height (to determine height of visual display)
Arm length or reach (to determine the position of the input devices or controls)
Elbow height above seat surface (to determine height of work surface above
the floor)
Buttock knee height (to determine min horizontal knee room required
underneath work surface)
Shoe height
In the South African work situation, the likely range of users of an office
workstation would be males and females, from approximately the ages of 18 to
65, from all the various local population groups. In private homes, however, the
likely range of users could include anybody from as young as four or five years
old right up to somebody in their nineties! The greater the design range, the
greater the cost. It is more expensive to design for the 5th to 95th percentile
range than for the 10th to 90th percentile range.
It is common to design for the range from the 5th to the 95th percentile. In doing
so, one may have to add different anthropometric measures. For example, for a
sitting workstation with the table top at the elbow height it is necessary to add two
measures: popliteal height and sitting elbow height. Determining the height of a
standing workstation for a standing operator the elbow height of the worker as the
strongest hand forces and greatest hand mobility are between elbow and hip
height. The height of the workstation thus depends largely on the activities to be
performed with the hands, and the size of the object to be worked with. Sit-
standing workstations have become increasingly common in industry during the
last ten years. Sit-standing is convenient for many tasks, and there are
biomechanical advantages since the pressure on the spine and the lower back is
about 30% lower for sit-standing and standing as compared to sitting.
A handicap is not the same as a disability.It is also very important to remember
disabled people, such as somebody in a wheelchair. A work disability is a lack of
function in the vocation for which a person is trained. Handicapped people will
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