lego design
DESCRIPTION
LEGO Design. SIUE School of Engineering Fall, 2005. Goals:. Build better robots Minimize mechanical breakdowns Build robots that are easy to control Encourage good design strategy. Geometry. Three plates = 1 brick in height. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/1.jpg)
LEGO Design
SIUESchool of Engineering
Fall, 2005
![Page 2: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/2.jpg)
Goals:
• Build better robots– Minimize mechanical breakdowns– Build robots that are easy to control– Encourage good design strategy
![Page 3: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/3.jpg)
Geometry
• 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
• Three plates = 1 brick in height
![Page 4: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/4.jpg)
Structure
• Common pitfall when trying to increase mechanical robustness:
![Page 5: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/5.jpg)
Structure
• The right way:
![Page 6: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/6.jpg)
Structure
• The right way:
![Page 7: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/7.jpg)
A good robot starts with a good foundation. A robot whose body is not structurally sound will be fraught with problems for the designers. The first and most important is that the friction
between stacked bricks should not be relied upon for structural strength. We recommend using connector pegs to help create a "skeleton" like the one below. A design like this is both light
and strong but usually requires a number of rebuilds to get perfect.
![Page 8: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/8.jpg)
Structural supports like the ones shown below can be placed on almost any chassis design. Use this to your advantage. You can get by with fewer legos
and have a stronger chassis this way
![Page 9: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/9.jpg)
The picture below demonstrates a very structurally sound way of constructing a frame with legos. The 3 wide connector peg can be used for
one of the 3 join points, or an additional 4x1 brick can be used.
![Page 10: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/10.jpg)
The structure below demonstrates a very strong design
that will not come apart unless you take it apart.
![Page 11: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/11.jpg)
Connector pegs
• Black pegs are tight-fitting for locking bricks together.
• Grey pegs turn smoothly in bricks for making a pivot
![Page 12: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/12.jpg)
Connector Pegs
![Page 13: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/13.jpg)
Drivetrain• LEGO Gears
8T
16T
24T
40T
24TCrown
1T Worm Bevel
![Page 14: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/14.jpg)
Seesaw Physics
![Page 15: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/15.jpg)
Radius, Torque, and Force on a Gear
torque = r x F
![Page 16: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/16.jpg)
![Page 17: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/17.jpg)
3 to 1 reduction
![Page 18: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/18.jpg)
Since the forces between the teeth of the two gears are equal in magnitude but act opposite in directions, the torque exerted on the right axle is three times the torque
exerted on the left axle (since the radii of thee gears differ by a factor of three).
Thus this gear system as acts as a “torque converter”, increasing the torque at the expense of decreasing the rate at which the axle turns.
![Page 19: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/19.jpg)
9 to 1 reduction
![Page 20: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/20.jpg)
The torque at the “output shaft” is 9 times the torque provided on the left(‘input”) axle. The output shaft will of course spin 9 times slower than the input shaft, but it will be much harder to stall. Have someone grab the output shaft and try to “stall” your fingers as you spin the input axle. It’s not that easy!
![Page 21: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/21.jpg)
A three stage gear train with a gear ratio of 27:1
![Page 22: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/22.jpg)
Lego Drive Trains
![Page 23: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/23.jpg)
Lego Axle
![Page 24: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/24.jpg)
Sample Drive Train
![Page 25: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/25.jpg)
Gear Rack
![Page 26: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/26.jpg)
Worm Gears• Pull one tooth per revolution
1
2
3
4• Result is a 24:1 gearbox
![Page 27: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/27.jpg)
Axle Joiner
![Page 28: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/28.jpg)
Toggle Joint
![Page 29: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/29.jpg)
Caster Design
![Page 30: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/30.jpg)
Lego Legs
![Page 31: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/31.jpg)
Grippers
![Page 32: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/32.jpg)
Car Turn Problem
![Page 33: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/33.jpg)
Lego Differential Gear
![Page 34: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/34.jpg)
Differential Drive
The differential gear is used to help cars turn corners. The differential gear (placed midway between the two wheels) allows one wheel to turn at a greater speed than the other. Even though the wheels may be turning at different speeds, the action of the differential means that the torque generated by the motor is distributed equally between the half-axles upon which the wheels are mounted. Assuming the robot's weight is sufficient and distributed properly, the robot should be able to turn with its drive motors at full power without causing either wheel to slip.
![Page 35: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/35.jpg)
Motors
• 9V Gear Motor
• ~ 150 mA
• 300 RPM (no load)
• Polarity
![Page 36: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/36.jpg)
Motors• 9V Micro Motor
• 20-30 RPM
![Page 37: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/37.jpg)
Mounting Motors
Note Bulge under motor
![Page 38: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/38.jpg)
Mounting Motors
• Add a gear:
![Page 39: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/39.jpg)
Mounting the Motor
![Page 40: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/40.jpg)
Lego Sensors
![Page 41: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/41.jpg)
Light Sensor Mount
![Page 42: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/42.jpg)
This shows an interesting way to mount a photoresistor, as well
as how to sheild it from a dedicated light source.
![Page 43: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/43.jpg)
Touch Sensor Mount
![Page 44: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/44.jpg)
Changing Rotational Axis
![Page 45: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/45.jpg)
Changing Rotational Axis
![Page 46: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/46.jpg)
Spin x-y-z
See more examples at http://constructopedia.media.mit.edu/
![Page 47: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/47.jpg)
Lego RCX Brick
![Page 48: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/48.jpg)
RCX Brick withsensors & Motors
![Page 49: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/49.jpg)
Lego RCX Brick Display
![Page 50: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/50.jpg)
Build for good control
• Slow vs. fast?
• Gear backlash
• Stability
• Skidding (Tank-tracks vs. wheels)
• Differential Steering !!!
![Page 51: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/51.jpg)
Design Strategy
• Incremental– Test components parts as you build them
• Drivetrain
• Sensors, sensor mounting
• Structure
• Don’t be afraid to redesign
• Internet for design ideas
![Page 52: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/52.jpg)
Design Strategy
• Drive-train driven
• Chassis/structure driven
• Modular?
![Page 53: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/53.jpg)
Testing
• Don’t wait until you have a final robot to test– Interaction of systems – Work division (work concurrently)
• Develop test methods
• Repeatability
![Page 54: LEGO Design](https://reader036.vdocument.in/reader036/viewer/2022062305/56814bcb550346895db8a2dd/html5/thumbnails/54.jpg)
Competition Philosophy
• Have fun
• Be creative, unique
• Strive for cool solutions, that work!
• Aesthetics: it’s fun to make beautiful robots!