Ergonomics/Task Analysis/Human factors Learning Resource from Jayadeva de Silva

1. Guide lines for a
Task Analysis
Jayadeva de
Silva

2. Task Analysis
• To make something ergonomically sound you
need to understand three things.
You need to understand
• body mechanics,
• the tool, and
• the task being performed.

3. • A task analysis will help you understand what
you want to do.
• It will dissect a complex set of actions and
turn it into simple ones that can be evaluated
easily.

4. • Start the task analysis by breaking things
down into their basic steps.

5. • With the task broken down you can extract
two key elements.
• You can see what human-machine interfaces
are present.
• You can also see what actions are required for
each step.

6. • The human-machine interface will tell you
what body parts will actually touch, or
otherwise engage, the product/setup.
• The actions will determine what supporting
body structure is needed.
• It will also show you which steps take the
most effort and/or time.

7. Example –Vacuum
Cleaner
• Here is a quick example on vacuuming with a
typical upright vacuum cleaner.

9. Task:
• Power up and vacuum an area of carpet.

10. Steps:
• Uncoil power cord
• Plug in power cord
• Turn vacuum cleaner on
• Place vacuum cleaner in ready position
• Push, retract, and pivot vacuum cleaner over
carpet
• Turn vacuum cleaner off
• Unplug power cord
• Coil power cord

11. Human-Machine Interfaces:
• Power Cord
• Power Cord Plug
• Vacuum Cleaner Power Switch
• Vacuum Cleaner Handle
• Vacuum Cleaner Ready Position Release Lever

12. Actions:
• Uncoil/Coil Power Cord: Uses hands and arms to
uncoil/coil cord and back for bending over to reach
cord storage location. Cord needs to be
unwound/wound around guide posts a dozen times.
• Plug/Unplug Power Cord: Uses hand to hold and
push/pull plug into the power outlet and legs to walk
to the power outlet.
• Turn Vacuum Cleaner On/Off: Uses finger to press
switch.
• Place Vacuum in Ready Position: Uses foot to depress
release lever and hand to hold the handle.
• Vacuum Carpet: Uses hand to hold handle,
forward/backward motion of arm to move vacuum,
side to side motion of arm and wrist to turn vacuum,
legs to maneuver body behind vacuum.

13. • Ergonomics is all about making things
comfortable and efficient.
• So to make things comfortable you want to
make the human-machine interfaces nice.
• Nice means it plays to the strengths and does
not stress the body part interfacing with it.

14. • To make things efficient you want to limit the
actions as much as possible.
• Fewer actions equal less work which equals
more time to play

15. • If you are going to buy a vacuum you want to
find one that will make this task more
comfortable and efficient for you to complete.
• Then it will be an ergonomic vacuum cleaner.

16. • The power cord should be quickly accessible.
You should not have to move other pieces to
get to it.
• The area your hands and the cord needs to
travel around the guide posts should be free
or obstructions.

17. • A mechanism that lets the cord fall off of the
guide posts helps in efficiency.
• It adds two actions, pivoting the release
mechanism down to release and up to hold
the cord again, but it reduces the actions
needed to uncoil the cord to almost nothing.
• A retractable cord is also a plus.

18. • The plug should be easy to hold in your hand
with enough size and surface area to get a
good grip and remove from the outlet with
ease and plenty of room between you and the
prongs.

19. • The power switch should be easy to operate
with good feedback to let you know you
engaged it.
• It should click, light up, move and stay in a
different position, or some other action that
lets you know you turned it on or off.

20. • The switch should also be accessible without
having to move or reach around anything, or
bend over.
• The handle should be comfortable and sized so
that you have a good grip.
• Padding will help with comfort and to dampen
vibrations to your hand.
• Texture and shapes for your fingers to catch will
all help you maintain control through the handle.

21. • The handle should be at a height that allows you
to maintain a good standing posture, no
slouching, with your arm in a position of power.
• The middle of the range of motion for a joint is
typically the strongest.
• In this case you want your upper arm to hang
down with your elbow bent at 90 degrees.
• Since the vacuum cleaner does not require a lot
of strength to operate a good bit of deviation
from this position is allowable.

22. • The handle should be positioned so that you
can maintain a natural wrist position.
• The ready position release lever should be
easy to find and reach with your foot while
you maintain a good standing posture.
• Finally, the vacuum cleaner should be easy to
push/pull and rotate.

23. • There are many other tasks associated with a
vacuum cleaner.
• Storing, changing bags and adjusting carpet
height settings are all tasks you would want to
consider when looking at a vacuum cleaner.

24. • You can also use the task analysis to evaluate
your cleaning pattern.
• You can even go so far as to change your room
layout to minimize the amount of turning
needed to vacuum the area, although your
friends might look at you a little funny for
doing so.

25. • An affordance is often taken as a relation
between an object or an environment and an
organism, that affords the opportunity for that
organism to perform an action.
• For example, a knob affords twisting, and
perhaps pushing, while a cord affords pulling.

26. • Hope you are working on your assignment
• Wish You all the BEST