FTC Build a Better Robot

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29 Νοε 2013 (πριν από 3 χρόνια και 11 μήνες)

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FTC

Build a Better Robot

Cougar Robotics 4251

Design Principles and Strategies

Design Principles and Strategies


KISS

o
Keep It Super Simple


Tool Design First


Leapfrog Development

o
Never go backwards


Repetitive Testing

o
Repetitive
Testing

o
Repetitive Testing

o
Repetitive Testing


Competitive Development


Practical Applications

Chassis/Drivetrain


Stiff & Stable Frame


Maneuverability

o
Rocker in a 6 wheel tank
-
drive chassis

o
Omni wheels on corners or one end


Ability to go where you want/need to for the game


Going the right speed


Practice driving
before

the tournament

o
Be prepared to drive on all parts of the field

Other


Isolate your motors from impacts


Torque > Traction


Mechanical Alignment


8
motors, 3 lego motors, 12 servos

Motor Power Table

Motor Name

Speed (RPM)

Speed
(Radians/Sec
ond)

Torque
(oz/in)

Torque
(Newton/me
ters)

Power
(Watts)

DC 12 volt
Motor

150

16

300

2.12

33.26

PF XL

220

23

56

0.40

9.11

NXT Servo

170

18

70

0.49

8.80

PF M

405

42

15

0.11

4.49

180 Servo

60

6

84

0.59

3.73

PF E

780

82

5

0.04

2.88

Continuous
Servo

43

5

39

0.27

1.24

Double Drilled vs Regular

Tools, and Using them


Color coding tools


Good mechanics have their own tools


Removing cross
-
threaded machine screws

o
Vice grips

o
Drill out


Removing rounded out machine screws

o
Vice grips

o
Easy outs

Building Practices


Keeping screws and set screws in

o
Nylocks

o
Lock
-
tite and pre
-
nylon threaded set screws


Don’t transmit loads thru axles


Understanding friction/traction

o
Surface area doesn’t change friction

o

F=
µF
n


Components under tension & compression

Regular Wheel With Sprocket

Calculating Loads on Lever Arms


Margin of Safety

o
At least a 2:1


Exercise

o
Use a lever arm on your robot or make one
including:


A DC motor


At least one gear change


A lever arm on the end

o
Using your setup, calculate the reasonable max
weight your lever arm could elevate


Custom Parts

CAD Programs


PTC Creo Pro



Autodesk Inventor



Gear Generator

o
http://woodgears.ca/gear/index.html


Tools


Laser Cutter


CNC Machine


Sheet Metal Shear

o
Metal

o
Polycarb and PETG


Sheet Metal Brake


Machine Lathe

Steel and Plastic


When to use steel


Your best plastics

o
PETG

o
Delrin

o
Polycarbonate

3D Printing


When to print your own parts


Web order 3D printing (Shapeways)

o
Some companies can print steel




Useful Websites


Official Game Forum

o
http://ftcforum.usfirst.org/forum.php



Chief Delphi

o
http://www.chiefdelphi.com/forums/forumdisplay.php?f=146



ROBOTC Forum

o
http://www.robotc.net/forums/viewforum.php?f=52



Xander Soldaat

o
http://botbench.com/blog/



Cougar Robotics

o
http://cougarrobot.com/



Landroids

o
http://landroids.org



More Useful Websites


Hitechnic

o
http://www.hitechnic.com/



Lego Education

o
http://www.legoeducation.us/



Digikey

o
http://www.digikey.com/



McMaster
-
Carr

o
http://www.mcmaster.com/#


Contact Information


Coach Jamie
-

coach@cougarrobot.com


Coach Judy
-

scientist@cougarrobot.com


Kids
-


joey@cougarrobot.com


evan@cougarrobot.com


sean@cougarrobot.com


nathan@cougarrobot.com


reeve@cougarrobot.com