ftc build a better robot

FTC Build a Better Robot

Cougar Robotics 4251

Design Principles and Strategies

Design Principles and Strategies

• KISSo Keep It Super Simple

• Tool Design First• Leapfrog Development

o Never go backwards

• Repetitive Testingo Repetitive Testingo Repetitive Testingo Repetitive Testing

• Competitive Development

Practical Applications

Chassis/Drivetrain• Stiff & Stable Frame

• Maneuverabilityo Rocker in a 6 wheel tank-drive chassiso 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 tournamento 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/Second)

Torque (oz/in)

Torque (Newton/meters)

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 gripso Drill out

• Removing rounded out machine screwso Vice gripso Easy outs

Building Practices

• Keeping screws and set screws ino Nylockso Lock-tite and pre-nylon threaded set screws

• Don’t transmit loads thru axles• Understanding friction/traction

o Surface area doesn’t change frictiono F=µFn

• Components under tension & compression

Regular Wheel With Sprocket

Calculating Loads on Lever Arms

• Margin of Safetyo At least a 2:1

• Exerciseo 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 Generatoro http://woodgears.ca/gear/index.html

Tools

• Laser Cutter• CNC Machine• Sheet Metal Shear

o Metalo Polycarb and PETG

• Sheet Metal Brake• Machine Lathe

Steel and Plastic

• When to use steel• Your best plastics

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

• ROBOTC Forumo http://www.robotc.net/forums/viewforum.php?f=52

• Xander Soldaato http://botbench.com/blog/

• Cougar Roboticso http://cougarrobot.com/

• Landroidso http://landroids.org

More Useful Websites

• Hitechnico http://www.hitechnic.com/

• Lego Educationo http://www.legoeducation.us/

• Digikey o http://www.digikey.com/

• McMaster-Carro 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