D-LabDesign for Human Use

Ergonomics

• Ease of use• Ease of maintenance• Number of interactions• Novelty of interactions• Safety

Battery Maintenance

Design for as many target users as possible

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20

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60

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15-19 20-29 30-39 40-49 50-59 60-69

Age

Grip strength

male high

male low

Female high

Female low

Consequences of bad design

Ergonomics

• Ease of use• Ease of maintenance• Number of interactions• Novelty of interactions• Safety

Micro-Flail Time and Motion Comparison

Probing- 2-6 minutes

• Set up flail – 15 seconds• Walk away – 90 seconds• Run flail – 10

seconds• Walk back – 90 seconds• Finish operation – 15 seconds

Total ~4 minutes

split/shred bagasse

dry

load into kiln/oil drum

light

wait

cover

seal

wait

empty

crush

grate manioc

boil water

mix manioc w/ cold water

make porridge

let porridge cool

mix with charcoal

make briquettes

bake briquettes

Charcoal Briquette Making Time and Motion Study

Total = ~4 hours

Briquette Making

Original prototype in use

Break process into steps

1. Load charcoal2. Hammer3. Eject Briquette

Define the steps

1. Load charcoal – until hand releases scoop2. Hammer – until hand releases hammer3. Eject Briquette –until hand releases pin

Time study data(seconds)

Cycle # Load hammer eject total cycle1 8.3 7.4 10.5 26.12 9.0 6.3 9.5 24.83 7.1 6.4 11.7 25.24 10.8 5.6 36.5 52.85 9.1 6.5 13.6 29.26 9.2 6.8 11.9 28.07 11.6 6.2 13.2 31.08 10.5 9.3 11.0 30.99 9.3 6.8 14.3 30.4

10 12.4 7.2 11.7 31.311 10.9 7.3 12.9 31.012 9.2 6.4 47.1 62.713 9.5 7.2

Time trial data

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1 2 3 4 5 6 7 8 9 10 11 12

Briquette #

Seconds

LoadHammerEjectTotal

What took so long?

Eject, 42%

Cleaning, 17%

Load, 34%

Hammer, 24%

What took so long?Hammering

•Pick up hammer

•Pick up piston

•Insert piston

•Hammer

•Remove piston

•Set down piston

•Set down hammer

New designs•No corners in compaction area (no cleaning necessary)

•Piston hangs in top of tube (don’t remove and set down piston)

•One handed eject door (don’t set down hammer)

•Use hammer to open eject door (eliminate the closing pin)

Estimated speed = 5 Briquettes per Minute (BPM)

(old machine 2 BPM)

Alternate design: Two pistons

Estimated speed = 5.4 to 6.6 BPM, depending on the loading method.

Conclusion: second piston is not worth the added complexity

New machine 2.5x faster

New machine time breakdown

Load43%

Hammer24%

Eject33%

More people 5.5x faster

Comparison between machines

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1 2 3 4 5 6 7 8 9 10 11 12 13 14cycle#

Time per cycle (seconds)

Bottom Eject, 3 people

Side Door Eject

Bottom eject, one person

Linear (Side Door Eject)

Linear (Bottom Eject, 3people)Linear (Bottom eject, oneperson)

• External: Compare your product to other products to see what the benefits are (or are not).

• Internal: See if your product is efficient, and identify the best places for improvements.

Types of time studies: