AN INTRODUCTION TO DRIVE TRAINS WELCOME Randy Hafner 2977 Sir Lancerbots Asst Coach Builddesign mentor since 2009 INTRODUCTION Terms Design considerations Drive Types Best Solution TERMS ID: 442710
Download Presentation The PPT/PDF document "DRIVE BASE SELECTION" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
DRIVE BASE SELECTION
AN INTRODUCTION TO DRIVE TRAINSSlide2
WELCOME
Randy Hafner
2977 Sir Lancerbots
Asst. Coach
Build/design mentor since 2009Slide3
INTRODUCTION
Terms
Design considerations
Drive Types
Best SolutionSlide4
TERMS
Wheelbase
Friction/Coefficient of friction
Torque
Center of mass/gravity
Power
GearingSlide5
Wheelbase
The distance from the center of the front wheel to that of the rear wheel in a motor vehicle, usually expressed in
inches
Also distance from one side to the otherSlide6
FRICTION
A force that resists the relative motion
or tendency
to such motion of two bodies or substances in contact.Slide7
Center of gravity
The point in a system of bodies or an extended body at which the mass of the system may be considered to be concentrated and at which external forces may be considered to be
applied
Need to keep in mind as you design a drivebase
A low center of gravity allows use of more powerSlide8
Center of gravitySlide9
Center of mass
The point in a system of bodies or an extended body at which the mass of the system may be considered to be concentrated and at which external forces may be considered to be
applied
Need to keep in mind as you design a drivebase
A low center of gravity allows use of more powerSlide10
Center of massSlide11
Torque
The moment of a force; the measure of a force's tendency to produce torsion and rotation about an
axis
Affects the ability to turn Slide12
Power
Strength or force exerted or capable of being
exerted
The
availability of power determines how much stuff your robot can do in a given span of time. Trade-off between doing a lot of stuff slowly or less stuff more
quicklySlide13
Gearing
A system of gears and associated elements by which motion is transferred within a
machine
Gears
Pulleys
Sprockets
Belts
ChainsSlide14
DESIGN CONSIDERATIONS
Motor selection
Gearing
Wheel type & size
WeightSlide15
Motor selection
FRC Approved list
Torque
CIM motors very popularSlide16
Gearing
Power vs. speed
Shifting gearbox?
Increased flexibility
Increased complexity
Increased cost
Pulleys & sprockets can also change gear ratioSlide17
Wheel Type & Size
Traction
Maneuverability
Wheel sizeSlide18
Weight
Limit by rules
Acceleration vs. top speedSlide19
DRIVE
TYPES
Tank drive
Omni drive
Mechanum
Swerve Drive
Holonomic
/
KilloughSlide20
Tank drive
2 WD
4 WD
6 WD
8+
Tank treadsSlide21
2 WD
Caster
DrivenWheel
+ Easy to design
+ Easy to build
+ Light weight
+ Inexpensive
+ Agile
Not much power
Will not do well on ramps
Less able to hold position
Motor(s)
Motor(s)Slide22
4 WDSlide23
6 WDSlide24
8+ Wheels & Tank Treads
At this point more wheels increases complexity without giving significant advantage
Tank treads might be useful to crawl over an obstacleSlide25
Tank TreadsSlide26
Omni DriveSlide27
Omni DriveSlide28
MechanumSlide29
MechanumSlide30
MechanumSlide31
Swerve DriveSlide32
Swerve DriveSlide33
Swerve DriveSlide34
Holonomic/
KilloughSlide35
Holonomic/
KilloughSlide36
RESOURCES
Know what:
You have available to you
Money
Time
You are capable of
You have time for
Trade offs are necessarySlide37
CONCLUSIONS
If you get the drive wrong nothing else matters
Your robot has to be in the right place at the right time to be competitive
The right drive is the one that best compliments your team strategySlide38
?’S