FIRST Robot Drive Bases

1
FIRST Robot Drive Bases

• Andy Baker, team 45
• Phil Perdan, team 135

2
Drive Base Design

• Guidelines
• Off-Season Work
• Define Your Strategy
• Choose Type of Drive System
• Timing
• Debug
• Rules of Thumb
• Summary and KISS

3
Guidelines

• Know FIRST rules stick to them
• Know your resources
• Materials, equipment, tools
• Design capabilities talent
• Reliability is key (KISS)
• Rely on a mentor ask for help
• Decide early and stick with it
• Take risks early try things out
• Watch your weight (low c.g. is good, but allow
  for other mechanisms)

4
Slow and steady wins the race. - Aesop, The Hare
and the Tortoise
5
Your robot will break down.Winning is inversely
proportional to the amount of break downs your
robot experiences.
6
Inanimate objects are classified scientifically
into three major categories - those that don't
work, those that break down and those that get
lost. - Russell Baker
7
Off-Season Work

• Veteran teams focus on drive train
• Develop foundation
• Train students
• Study competition
• Learn from mistakes

8
Define Your Strategy

• How do you want to play?
• Power
• Speed
• Maneuverability
• Mixture of all?

9
Types of Drive Systems

• 2 Wheel Drive
• Casters / Ball
• Wheels 2003 kit drive w/ 21 ratio
• Crab
• Simple two position - Team 868
• Full 360 degree - Team 135
• Tank
• Wheels
• Tread
• Innovative alternatives / additions
• Modified kit drive to 4 wheel
• CVTs, shifting drills or on the fly, two drives

10
2 Wheel Drive
DrivenWheel
Motor(s)
Motor(s)

• Easy to design
• Easy to build
• Light weight
• Inexpensive
• Agile
• Not much power
• Will not do well on ramps
• Less able to hold position

Caster
11
4 Wheel Drive
DrivenWheel
Motor(s)
Motor(s)

• Easy to design
• Easy to build
• Inexpensive
• Powerful
• Can hold its position
• Not agile
• More binds and
• inefficiencies

12
4 Wheel Drive (Modifications)
Large Sprocket
Large Sprocket

• Medium to design
• Medium to build
• Inexpensive
• Efficient Powerful
• Can hold its position
• Not agile
• More binds and
• inefficiencies

Difficult Next Step Replace Motor(s) with a
Motor(s)
Motor(s)
Motor(s)
Transmission
Large Sprocket
Large Sprocket
13
4 Wheel Drive / 4 Wheel Steering
Motor / Cylinder

• Highly Maneuverable
• Agility
• Powerful
• Can hold its position
• Difficult to design
• Difficult to build
• Difficult to maintain
• Expensive
• More binds and
• inefficiencies

Motor
Motor
Motor / Cylinder
14
Timing

• Use non-competition drive bases for software
  debug
• Drive by week 3
• Give drivers a week to test a robot
• Keep driving non-competition drive bases after
  competition robot is shipped

15
Debug

• Give electrical and software room time to work
• The earlier you break your robot, the earlier you
  fix your problems
• Give yourself room to speed up or slow down 30
• Make it easy to change ratios
• Make spare parts as you go

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Rules of Thumb

• Bow your treads
• Align your wheels
• No cantilever shafts!
• Build it, break it, build it, break it, build it,
  build it, break it, WIN!
• Wires have resistance. Use large gauges and keep
  em short
• Dont drive a light robot test it at 130
• Keep chains and belts tight
• More traction leads to higher gear ratios
• Reduce friction and binding everywhere possible

17
Summary

• KISS
• Know your limitations
• Rules, materials, machining capabilities
• Know your objective
• Write down all ideas
• Dont be afraid to try something
• When in doubt, ASK SOMEBODY for HELP
• Build and test quickly - especially drive train

HAVE FUN!!!!