Possible configurations of a robot base and pros and cons of each Robotics 101 Robot Base Overview The robot Base generally has t hree major components Frame Drivetrain Controls Robot base construction ID: 442749
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Slide1
Drivetrain and Framing
Possible configurations of a robot base, and pros and cons of each.
Robotics 101Slide2
Robot Base Overview
The robot Base generally has
t
hree major components:
Frame
Drivetrain
Controls
Robot base construction
Standard KOP frame
Flexible, low cost, but heavy
Custom designed thin gage aluminum
Very lightweight, not flexible to changes, built from CAD
Good success with this style of
base in past years
Will use this base style again unless game requires something different
Climbing over
obstacles,
open front
for collector mechanism, etc.Slide3
Robot Base Overview
The robot “Drivetrain” has several major components:
Wheels or Tracks
Motor or Engine
Transmission/Gearbox
Chains/Belts
A
robot
needs a robust base
and drivetrain to:
Move
quickly and efficiently
Push
other robots out of the
way
Precisely control where it is so that it can perform
tasks
Provide stable base to mount scoring mechanism
Easy access to controls
and
battery change
Low center of gravity
#1 Rule-
Our robot should never tip overSlide4
Wheel Options
Traction wheels- coefficient of friction close to 1
AndyMark
standard KOP wheels
Low cost, good traction, can’t replace tread
Plastic wheel frame may
break
AndyMark Plaction wheels
Higher cost, excellent traction, replaceable treadPlastic wheel frame may breakAndyMark Performance wheelsMuch higher cost, excellent traction, replaceable treadVery durableVEXpro Colson wheelsLow cost, great traction, can’t replace treadVery durable for low price pointSlide5
Wheel Options
Lower Traction Wheels
Omni Wheels
Low sideways friction (rollers), decent forward/reverse
traction
Very easy to push robot around
Used when turning is more important than pushing
Mecanum Wheels
Rollers at 45 degree angle so robot can drive in all directionsHighly maneuverable but easy to push robot aroundDifficult to programSlide6
Drivetrain Layout Principles
Center of Gravity
Mass concentration and where it is acting on your robot
Center of Turning
Point at which the robot will rotate about
Effective Wheelbase
Wheelbase in contact with the
ground
WB
COG
COTSlide7
Axle Options
Cantilevered
Side Supported
“Live”
“Dead”Slide8
Drivetrain Options
6 Wheel Tank
D
rive with “Dropped” Center
A
xles
Relatively easy to turn and drive straight
Can turn in place with 2 CIM’s per side
Most popular choice among FRC teamsStandard design for Team 1507Slide9
Drivetrain Options
West Coast Drive (WCD)
Cantilevered
Axles
Direct Drive to One Wheel, #25 Chain to other Live Axles
Hex Axles
Fast Removable Wheels
Welded Tube
ChassisSlide10
Drivetrain Options
4 Wheel Swerve Drive
Robot can drive in all directions, incredibly maneuverable
Very complex to design, build, and program
Would require off-season to develop if we wanted to pursue this
optionSlide11
Drivetrain Options
4 Wheel Omni Drive
Wheels 45 Degrees in Corners of Chassis
Very Maneuverable
Loss of pushing force in all directions compared to a tank drive
Kiwi Drive
Wheels 120 Degrees apart
Very Maneuverable
Loss of pushing force in all directions compared to a tank driveSlide12
Drivetrain Options
Mecanum Drive
Wheels located in same orientation as a 4WD
Uses
Force Vectors from wheel rollers to translate
Expensive
Fairly easy to build with COTs wheels
Difficult to program effectively
Requires a lot of Driver TrainingSlide13
Six Wheel Robot Base
Linkage
Wheel
Wheel
Wheel
Wheel
Wheel
Wheel
Motor
Motor
Gearbox
Motor
Motor
Gearbox
High traction wheels
CIM Motors
Belts or Chains:
Transfer
Power
To Wheels
Transmission
/ gearboxSlide14
Gearbox Function
Gearbox
Wheel
Wheel
Wheel
Motor
Motor
Single speed gearbox
Standard KOP Ratio: 12:1
Torque From Motor Increased By 12X
Speed from Motor Reduced 12X
Gearbox Function:
Convert Motor Speed
to Wheel Torque through a series of gears
2 speed shifting speed gearbox
Low
gear = 6:1 ratio for pushing
High gear = 24:1 ratio for speed
Pneumatics used for shifting gearsSlide15
Team 1507’s Base and Drivetrain
CAD demo of last year’s robot
AndyMark Scavenger Hunt