health and safety executive - iosh.com · ergonomic design principles. ergonomic design principles...
TRANSCRIPT
Health and Safety Executive
Health and Safety Executive
Humans Factors in
workstation design
Why:
Is better than:
Sock drawer Human Factors
And how to achieve it
Marie Kondo Human Factors
Correct design vastly improves performance (by up to 800% in certain cases)
Numerous disasters have been attributed to poor panel design e.g. Kegworth 757 crash
Reduces errors and improves performance
Why putting things in the right
place is important
Fa
tig
ue
Time of Day
‘Working
hard’‘Normal’
Fatigue (ish)
‘Work requirement
threshold’
‘Marie Kondo tolerance
limit’
Efficiency is good for everyone
The next 50 minutes
• How to get thing physically in the right
place
• How to get thing cognitively in the right
place
NIOSH 1988
Deviations from Neutral
Postural Ideal – “Neutral Posture”
Workplace Posture
Anthropometry
(the scientific study of the
measurements and proportions
of the human body).
People adapt to their task environment but
often this more difficult than necessary, by the
poor design of the workplace, resulting in:
• injuries and strains from poor postures
• less spare capacity to deal with
emergencies
• greater probability of accidents and errors
Anthropometry &
Workplace Design
Adaptation
The problem (#1)
Variability ‘between’ groupsAge; Gender; Nationality
e.g.
Average male stature in USA = 178cm
Average male stature in Vietnam = 167cm
A car designed for USA would comfortably fit
around 10% of Vietnamese population !
Applied Anthropometry
dimension (e.g. stature)
nu
mb
er
of p
eo
ple
average
largesmall
The problem (#2)
Variability ‘within’ groups
Within any sizeable group, body dimensions are distributed
along a bell-shaped curve.
Applied Anthropometry
Fre
qu
en
cy o
f o
ccu
rre
nce
Normal frequency distribution
dimension (e.g. stature)
nu
mbe
r of
pe
op
le50th percentile
95th percentile5th percentile
dimension (e.g. stature)
nu
mbe
r of
pe
op
le
95th percentile5th percentile
Range of adjustment needed for 90%
of the population
Bodyspace (Pheasant and Haselgrave, 2010)
Design for the 5th and 95th percentile ranges or “extreme individuals”
e.g. minimum clearance (of doorway) for large user
e.g. maximum reach to top shelf for small user
Let the small person reach
Let the large person fit
How to use the data
Applied Anthropometry
How to use the data
Design for ‘average’ when adjustability is not feasible
but NEVER use ‘average’ for clearances, reach or
strength
Applied Anthropometry
A
A Door height
(assume no shoes)
B
B Window height
(assume no shoes)
C C Handle height to top
and bottom
(elbow height best)
(assume no shoes)
Applied Anthropometry
A Door height
A Pallet stack height
Needs to be higher than tallest person
= tall (95th percentile) male stature
= minimum door height of 1855mm to the top
A
Applied Anthropometry
B Window height
Needs to be reached by short person
= small (5th percentile) female eye height
= maximum window height of 1405mm
B
Applied Anthropometry
C Handle length
Needs to be reached by both short and tall people
= small female to tall male elbow height
= bottom height of 930mm top height of 1180mm
C
Applied Anthropometry
A Hole for the thumb
(male and female users)
Applied Anthropometry
Needs to fit the largest thumb
= large (95th percentile) male
Applied Anthropometry
Applied Anthropometry
a
b
(assume no shoes)
(male and female
workforce)
A range for height of
glove ports
= elbow height + 10cm
(task dependent)
A range for width of
glove ports
Applied Anthropometry
= elbow height of 930mm top height of 1180mm + 100mm
Applied Anthropometry
Applied Anthropometry
= 95th % male bideltoid – 5th % female biacromial
= 510 – 325 mm (plus task requirements)
Workplace Design
Movement and access
Human Scale 8 - Dreyfus
• recommended space
to access low shelf or
area
91cm
Standing workstation:
Working Heights
Pheasant 1986
Correct working heights depend on trade-off between visual tasks
and muscular tasks
Reach Envelopes
Maximum working area
Normal working area (Barnes 1958)
Pheasant 1986
Minimum area under a
standing workstation that
should be left free for legs and
feet.
Standing workstation:
Leg Room
Dul & Weerdmeester 2001
Sit / Stand Workstation
Allows worker to chose when to sit or when to stand.
Ergonomics - Part 2
Putting things cognitively in the
right place
One or more of four task criteria should be satisfied
when designing things together.
Sequence Frequency Importance Function
These basic criteria make up about 30% of ergonomics design and evaluation criteria.
Apply this to workstations, manufacturing processes, environment layouts, control panels and sock drawers.
Ergonomic Design Principles
Ergonomic Design Principles
Sequence Frequency Importance Function
• Some tasks always follow a fixed sequence of operations.
e.g. setting a video recorder timed record function
e.g. pilot checking flight systems before take off
• Where the sequence of the task is important, the controls and
displays should be set out in the order that reflects the sequence.
Ergonomic Design Principles
Sequence Frequency Importance Function
1
2
3
Ergonomic Design Principles
Sequence Frequency Importance Function
Ergonomic Design Principles
Sequence Frequency Importance Function
1
2
3 45
Ergonomic Design Principles
Sequence Frequency Importance Function
This makes the task easier to perform:
▪ The user does not have to remember the order of the task but simply follow the order of the controls.
▪ Task time will be reduced.
▪ Fewer errors are made.
Ergonomic Design Principles
Sequence Frequency Importance Function
1
2
3
45
Ergonomic Design Principles
Sequence Frequency Importance Function
• Controls / Displays that concern the primary functions of a system are placed near to the operator or central to the panel.
• Most frequently used controls and displays should be placed nearest the operator or central to the panel.
Ergonomic Design Principles
Importance FunctionSequence Frequency
• e.g. a computer keyboard is central to the workstation user, but the phone is off to one side.
Minimises the search time for the most frequently used control/display, enhances comfort and reduces error.
Ergonomic Design Principles
Importance FunctionSequence Frequency
e.g. speedometer is directly in front of the driver
radio is placed down and central.
Ergonomic Design Principles
Importance FunctionSequence Frequency
Minimises the search time for the most frequently used control/display, enhances comfort and reduces error.
• Usually important and
frequent are the same.
• But there are cases where the
most important functions are
the least likely to occur.
• e.g. emergency indicators
Ergonomic Design Principles
Importance FunctionSequence Frequency
• Important controls and displays should be placed near the operator or central to the panel.
Pendolini Class 390
Ergonomic Design Principles
Importance FunctionSequence Frequency
Ergonomic Design Principles
Importance FunctionSequence Frequency
• Frequently, groups of controls/displays are associated with a particular function.
• e.g. numerical keys on a computer keyboard
• Whenever control/displays have a similar function, they should be grouped together.
• Indication should be given of their functional similarity
Ergonomic Design Principles
Importance FunctionSequence Frequency
• This greatly reduces search time for desired functions
Ergonomic Design Principles
Importance FunctionSequence Frequency
• It is not always possible to satisfy the criteria of sequence,
frequency, importance and function simultaneously, they
may give conflicting results.
• In some cases, it may be that one criterion is more
important than the others, which will largely determine the
final layout.
The task carried out by the
control/displays must be clearly
understood, as must the
consequences of error.
Ergonomic Design Principles
Importance FunctionSequence Frequency
Is sequence of operation
simple & straight through?
Design Panel Layout to match
the sequence of operationYES
NO
List displays/controls/by:
ANALYSIS DESIGN ‘RULES’
Sequence Frequency Importance Function
3.) Subsequence
Design by placing controls in:
Central unique locations}1.) Frequency of use
2.) Importance for safety/efficiency
In rows & columns
In groups4.) Functionally related sets
Link Analysis design rules
summary:
Any questions?
Subjects in an
experiment made
less than half
the number of
errors of
operation
with layout 4
than with layouts
2 and 3.
1 2
3 4
A B
C D
C A B D
A B
C D
CA B D
A B
C D
C A BD
A B
C D
CA BD