Guide lines for a Task Analysis Jayadeva de Silva

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.

• 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.

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

• 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.

• 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.

Example –Vacuum Cleaner

• Here is a quick example on vacuuming with a typical upright vacuum cleaner.

Task:

• Power up and vacuum an area of carpet.

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

Human-Machine Interfaces:

• Power Cord • Power Cord Plug • Vacuum Cleaner Power Switch • Vacuum Cleaner Handle • Vacuum Cleaner Ready Position Release Lever

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.

• 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.

• 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

• 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.

• 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.

• 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.

• 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.

• 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.

• 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.

• 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.

• 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.

• 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.

• 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.

• 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.

• Hope you are working on your assignment

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Wish You all the BEST