Proposed Dewbot V ChassisClem McKownTeam 1640December 21, 2008

Why 6wd?This summers prototyping and follow-up analysis demonstrated that 6 wheel drive robots have a significant advantage in maneuvering vis--vis a 4wd robotOmni-wheels facilitate 4wd turning, but make a robot easier to push around6wd middle wheels are key for turning performanceAlso a plus for ramps

Good practices6wd has no advantage in traction or stability, butFor traction, all wheels should be driven;robot should be at maximum weight; andtraction tread material should be usedFor stability,Maximize wheelbaseKeep center of mass low and central

The Specs(6) 6 AndyMark Plactron Wheels(4) CIM Motors(2) modified 2-speed AndyMark Shiftboxes9.4:1 & 24:1 Overall Gear Ratios14.8 & 8 ft/s maximum speed24.26 x 30 wheelbase

Isometric ViewGrease Guard1/16 PC partitionto keep electronicscompartment cleancRIO ControllerBattery

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 WheelsMiddle wheels are direct, gear-driven from the gearboxFront & Rear wheels are slave-driven via chains & sprockets from the middle wheelBenefitsReliabilityKeeps motor & gearbox (and center of mass) lowWeight savings

Customized (Team 1640) Direct-Drive AndyMark ShiftboxNew front & back platesSprockets replaced w/ 20 tooth gearAdditional axle = wheel axlew/ 45 tooth drive gearSpacer bolts (now-20) also serveas mounting bolts

Identical left & right drive unitsWe could build & bring a spare

Design PerformanceAcceleration curves are with wheels slippingHigh gear provides adequate power for turning (enough to make wheels slip)

WeightCurrent Mass is 68.9 lbm, which includesChassis w/ DrivetrainPneumatic System up to & including RegulatorPanel mounts for electronicsBattery MountcRIO controller with:cRIO w/ 5 modulesAlalog bumperPneumatics bumperDigital side-car & cableDistribution BlockRadioDoes not include:Jaguar (PWM) Motor ControllersBatteryBumpers (not the electronic bumpers)Oh, yeah, whatever we actually need to play the game

Center of Mass4.4 in above grade4.5 in aft of chassis center (w/ battery)1 in left of chassis center (w/ battery)

A reminderThis is a still work in progressAny suggestions or critique will be appreciated