Proposed Dewbot V Chassis Clem McKown Team 1640 December 21, 2008.
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Transcript of Proposed Dewbot V Chassis Clem McKown Team 1640 December 21, 2008.
Proposed Dewbot V Chassis
Clem McKownTeam 1640
December 21, 2008
Why 6wd? This summer’s prototyping and follow-
up analysis demonstrated that 6 wheel drive robots have a significant advantage in maneuvering vis-à-vis a 4wd robot
Omni-wheels facilitate 4wd turning, but make a robot easier to push around
6wd middle wheels are key for turning performance
Also a plus for ramps
Good practices 6wd has no advantage in traction or
stability, but… For traction,
all wheels should be driven; robot should be at maximum weight;
and traction tread material should be used
For stability, Maximize wheelbase Keep center of mass low and central
The Specs
(6) 6” AndyMark Plactron Wheels (4) CIM Motors (2) modified 2-speed AndyMark
Shiftboxes 9.4:1 & 24:1 Overall Gear Ratios 14.8 & 8 ft/s maximum speed 24.26 x 30” wheelbase
Isometric View“Grease Guard”1/16” PC partitionto keep electronicscompartment clean
cRIO Controller
Battery
Isometric View (showing Jags)
Jaguar (PWM)motor controllersmounted onfront panel
Front / Rear Elevations
Right / Left Elevations
Plan View
Plan View (Showing Jaguars)
Direct drive to Middle Wheels
Middle wheels are direct, gear-driven from the gearbox
Front & Rear wheels are slave-driven via chains & sprockets from the middle wheel
Benefits Reliability Keeps motor & gearbox (and
center of mass) low Weight savings
Customized (Team 1640) Direct-Drive AndyMark Shiftbox
New front & back platesSprockets replaced w/ 20 tooth gear
Additional axle = wheel axlew/ 45 tooth drive gear
Spacer bolts (now¼-20) also serveas mounting bolts
Identical left & right drive units
We could build & bring a spare
Design Performance Acceleration
curves are with wheels slipping
High gear provides adequate power for turning (enough to make wheels slip)
velocity versus time
0
2
4
6
8
10
12
14
16
18
0 1 2 3 4 5
time (s)
v (f
t/s)
High Gear
Low Gear
Weight Current Mass is 68.9 lbm, which includes
Chassis w/ Drivetrain Pneumatic System up to & including Regulator Panel mounts for electronics Battery Mount cRIO controller with:
cRIO w/ 5 modules Alalog bumper Pneumatics bumper Digital side-car & cable Distribution Block Radio
Does not include: Jaguar (PWM) Motor Controllers Battery Bumpers (not the electronic bumpers) Oh, yeah, whatever we actually need to play the game
Center of Mass
4.4 in above grade
4.5 in aft of chassis center (w/ battery)
1 in left of chassis center (w/ battery)
A reminder
This is a still work in progress
Any suggestions or critique will be appreciated