The Art of LEGO Design

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The Art of LEGO Design

• Alex Styler and Jason Geist
• Original version by Michael Rosenblatt
• January 31, 2007

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Sources

• The Art of LEGO Design, by Fred G. Martin
• LEGO kit instructions
• Internet
• ME! And other TAs, of course.

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Goals

• Build better robots
• Minimize mechanical breakdowns
• Build robots that are easy to control
• Encourage good design strategy
• Strive for elegant, clever solutions

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Know your Materials

• Quick facts
• Plastic bricks since 1949 (wooden blocks prior)
• On average, 2100 different parts each year
• Manufacturing tolerance 1/1000 of an inch
• Number of ways of combining six 8-stud bricks
  102,981,500
• Widely used by scientists and engineers as a
  rapid prototyping tool

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Geometry

• Three plates 1 brick in height

• 1-stud brick dimensions exactly 5/16 x 5/16 x
  3/8 (excluding stud height 1/16),
• This is the base geometry for all LEGO
  components

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Structure

• Common pitfall when trying to increase mechanical
  robustness

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Structure

• The right way

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Structure

• The right way

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Connector pegs

• Black pegs are tight-fitting for locking bricks
  together.
• Grey pegs turn smoothly in bricks for making a
  pivot

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Structure

• LEGO bricks are finicky
• They HATE duct tape.
• They HATE hot glue.
• They HATE super glue.
• They HATE epoxy.
• You should never need adhesives to build reliable
  LEGO structures

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Help!!!
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Drivetrain

• LEGO Gears

40T
8T
16T
Bevel
1T Worm
24T
24T Crown
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Worm Gears

• Pull one tooth per revolution

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1
2
Result is a 241 gearbox Not back driveable!
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Motors

• 9V Gear Motor
• 150 mA
• 300 RPM (no load)

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Motors

• 9V Micro Motor
• 20-30 RPM
• Internal two stage orbital gearbox (wow!)

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Mounting Motors
Note Bulge under motor
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Mounting Motors

• Add a gear

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Mounting Motors

• Use special 2x1 stud plate with wing

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Build for good control

• Slow vs. fast?
• Gear backlash
• Stability
• Skidding

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Wires

• Take pride in your wires!!!
• Wire management use zip ties!!

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Design Strategy

• Incremental
• Test components parts as you build them
• Drivetrain
• Sensors, sensor mounting
• Structure
• Dont be afraid to redesign
• KISS

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Design Strategy

• Drivetrain driven
• Chassis/structure driven
• Modular?

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Testing

• Dont wait until you have a final robot to test
• Interaction of systems
• Work division (work concurrently)
• Develop test methods
• Repeatability

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Philosophy

• Have fun
• Be creative, unique
• Strive for cool solutions, that work!
• Aesthetics its fun to make beautiful robots!