Drivetrain, what did you use?

[Tom Bottiglieri]

*Totally new design this year*
Team 195
8 Years
2 Drill
2 Treads Spanning over 32 inches of ground each
NO other wheels
Chains
Super Duper Gear Down Tranny using chains are gear reductions
2 joystick tank drive
no sensors
we have lots of sucesss with our down low tank designs
We have had problems with our past trannys (set screws vibrating loose)
only time can tell

[OneAngryDaisy]

whoa, someone totally brought back a dead thread. almost a year old too- i'd reccomend starting a NEW thread for 2004 instead of confusing half of the people here... (got me at first)

[SiliconKnight]

Team 824

Second year team

We attempted to manufacture our own gearbox. Shifter was taken off to make manufacturing schedule. All parts were student made - reliablity was good with 1 motor, but under 2 motor loads, reliabilty was a problem. (it exploded on the field at our very last match at PNW).

* Tank drive robot
* 2 "drive pods" modular drive system, on and off the robot very quickly.
* Optical encoders on driven wheel.
* Custom made aluminum wheels - attach just like a car's wheel with a wheel flange. Started out as a track system but the tracks kept falling off.
* Each pod contain 1 chip, 1 drill motor. There is a matching stage where the free spin RPMs are matched, then the output of that goes through the drill reduction box. Custom outtake shaft then drives the wheels.

Problems we encountered:

* Failure to account for the side load on the helical gear
* Bad construction quality on some of the press fits.
* Failure to calculate in the backlash - I used theoratical spacing for all the gears - that was a BAD mistake.
* Lack of tools and trained personnel (no one could weld, didn't have a knurling tool for press fits, no CNC trained operator to cut the bearing pockets, etc.

-=- Terence

[DougHogg]

Drivetrain, what did you use? (post #1)

I just wanted to hear what people used for their drive trains including:

Team 980
2nd year
Motors? 2 CIMs
Drive wheels? 8 wheels, 4 at a time.
# and type of non-drive wheels? 4 wheels on the ground at a time, and the other 4 spinning in the air
Transfer system(chains, belts, etc.)? Gear boxes and chains
Transmission (not including supplied ones)? 2 Custom Gear boxes. 8 full time spinning wheels. We used pneumatics to push a lever which rotated 4 large wheels down for high gear and 4 small ones for low gear.
Steering? Tank
Sensors? Gyro for autonomous movement, potentiometers for controlling the position of 3 arms.
Success? We have a 13 foot telescoping arm which was exceptional at taking down the stack from our starting position.
Problems? We had 3 arms, one 13 footer, and 2 for pushing and stacking bins. That left us short on weight for our drive system. In making everything light enough, the drive system was too flexible and we lost chains if pushed sideways. Later we found ways to reinforce it.
Problem 2: In 3 competitions, we tipped a total of 3 times (average of 1 per competition) when rammed by other robots.
Problem 3: After watching other robots in Houston, our acceleration could have been better. 4 motors would have helped. Also in high gear, our wheel base was short which made us rocky given our high center of gravity.
Next year? I would like 4 motors in the drive train, hopefully with shifting.

[Jared Russell]

-Team 341
-My second year, team's fourth
-2 drill motors
-4 drive wheels
-0 non-drive wheels
-Chain drive
-We welded ourselves into low gear
-Tank steer
-Sensors: gyro for autonomous position control, optical sensors to pick up top of the ramp.
-Success: +100% autonomous mode; +GREAT wheels (high traction); good tradeoff of speed and torque
-Problems: -Drill motor mounts; -Wish we were a little faster
-Next year: Expect 4 dedicated drive motors, almost certainly

[Matt D]

Team 254 (Cheesy Poofs)
# of years of participation? 5 years
# and type of motors? 2 drills this year
# and type of drive wheels? 4 6"X1" custom wheels with blue tread material (forgot where from)
# and type of non-drive wheels? caster dropped down with a pneumatic cylinder only for autonomous steering
Transfer system(chains, belts, etc.)? serpintine chain
Transmission (not including supplied ones)? none other than supplied drill transmissions, which we shifted with servos
Steering? during autonomous we dropped down an angled caster
Sensors? none
Success? yes! no breakdowns at Nats, we drove well, getting to the boxes in 3.8 s in auton, but by shifting could still outpush most robots
Problems?, a few problems with the transmissions at SVR
Next year? gears not chain (we broke a master link in a match at SVR and chain is a pain)

[Vu2000]

Team 812
2 years
2 Drill Motors
4- 9 x 2 skyways
No No No non-drive wheels
Chains that control the sides of the robot
Supplied Transmission with a few adjustments nothing to gears

Steering: 2 globe with Universal Joints to articulate wheels
3 types of steering-
Mode A: Where the rear and front turn in opposite directions like Chevy's truck commercial
Mode B: Where the rear and front steer same direction
Mode C: Tank

No sensors
Success: 6th at AZ 9th qualifying

Problems: Not that good because the wheels could only turn 30 deg, we had 10 deg of play to the left, design problem with the key always shearing under the globes DO NOT USE THE HOUSING FOR THE TRANSMISSION GIVEN, We had every possible problem happen to us at least 3 times at SoCal.

DONT USE TOO MANY CUSTOM PARTS, THEY"RE A REAL HASSLE AT COMPETITION ESPECIALLY IF THEY BReAK BETWEEN MATCHES

The team was planning on using chiaphua's with high reduction, the mechanics team and I wanna do and plan this summer a dual output, shifting on the fly with at least 4 gear ratios drive system.

Or maybe Servo?

[FotoPlasma]

Team number: 258

Years in FIRST: 5 years.

Drivetrain motors: 2 Atwood (CIM), 2 Drill, 2 Globe.

Driven wheels: 4 custom machined aluminum 6.5" wheels with MSC timing belt tread. (Picture of wheels and tread).

No non-driven wheels.

Transfer method: <Neo>Gears. Lots of gears.</Neo>

Transmissions: Four custom fabricated gearboxes, one for each of four drive motors (drills and Atwoods). Pictures. Pictures. and more pictures.

Steering: As Vu2000 stated, three distinct control schemes: 1) translational (all swerve modules are pointed in the same direction), 2) complementary (front and back sets of modules turn to complementary angles, in order to reduce the turning radius, as commonly seen on the GMC Denali (truck commercial with the object driving in a figure-eight so much that it makes you sick)), and 3) tank (both sets of modules are pointed straight forwards / backwards, and the robot is controlled as though there were no rotational component, whatsoever).

Sensors: Two potentiometers, without hardstops, which recycle at 360degrees. It took a good few hours digging around in local electronics surplus stores to find these babies, but I'll tell you, they were well worth it.

Success: I'd say that we were very successful. We seeded 5th at Silicon Valley, and had a great time. Quite the learning experience that FIRST intends us to have, if I do say so, myself.

Problems: Driver training was very difficult. Becoming oriented to the controls was definetly not the easiest thing to do, and we didn't have too much spare time to just drive around. Autonomous mode was rather interesting, seeing as though we only had it for the last few matches of the competition.

Next year: Well, there's lots of talk about a much more advanced system, but beyond that, I'm not at liberty to say, at this point in time.

Don't be afraid to IM or email me with questions or comments, or whatever.

[Andy A.]

Team 95

7 years (I think)

Drive motors: 2 drills, 2 CIM; one for each wheel

4, 8 inch skyway wheels, heavily modified.

2 window motors and 2 Globe motors for steering. Each wheel is independently driven and steered (full crab)

Drive was through worm gears. Steering was originally done with cable, but later changed to timing belt. Theoretically, we had full Ackermen steering and crabbing.

Sensors: no optics, we did use 4 pots to sense each wheel modules orientation.

Problems: Lots of them.

First, worm gears are very, very inefficient. Due to binding problems, this was even worse and we just lost to much power. Our speed was targeted to 8fps, it ended up being around 4.

Second, we had lots of issues regarding the pots. simply put, they drifted out of calibration after hard hits and just were never accurate enough.

Third, there was never enough time to get the custom circuit running. Because of this, all the calculations for steering was done on the RC. Because of the limitations of the RC, the math was very round about and filled every bit of memory we had. It's slow and inaccurate.

Fourth, the original design called for the wheel modules to be steered by motors connected via a capstan like cable setup. It actually worked and saved a good deal of weight. However, we found that in competition we would get rammed against the wall and the repeated blows would rip the cable out. So we replaced them with timing belts in Houston. But, because belts only come in 10 tooth increments sizing was a huge hassle.

Fifth, It was a bear to drive, and the complete lack of practice killed us. Ultimately, we got the mechanical problems pretty much figured out but our driver had never gotten the chance to play with it.

So ya, next time around we'll know what we are doing. It was a learning experience for sure. It's kinda tough to go from balls, which is something we know backwards and forwards, to making a complex drive train (past years have always been 2 drills end of story). It was easily the most complex thing we've ever made, and next time around it'll be fine.

-Andy A.

[Powers]

Team # : 710
3rd year participating
2 chips, 1 globe
drive wheels : 4 goped wheels
non-drive wheels: 2 pneumatic wheelchair wheels
4 wheel drive (back wheels)
2 wheel steering (front wheels)
chains connecting wheels in back
chips to drive
globe to steer

front steering wheel fell off in one match, but we re-inserted b4 the next match and it worked fine.

next year's plan is crab drive.

[Al Skierkiewicz]

Team #111

# of years of participation? 8

# and type of motors? 2 Drills, 2 FP, 2 Globe(steering)

# and type of drive wheels? 4-custom 6" dia. aluminum with conveyor belting, glued and riveted for tread. (Same as last year.)

# and type of non-drive wheels? 0

Transfer system(chains, belts, etc.)? DNA

Transmission (not including supplied ones)? 4 custom, optimized for motor type, one at each drive module. Modules independently replaceable, 4 screw mounting plus electrical connector.

Steering? 4 wheel crab. Two available (pneumatically controlled) feet to lift two wheels and allow conventional two wheel steering.

Sensors? optical for rotation sense, gyro for turning sense, pots for steering and wing control.

Success? All worked, rotation/gyro/software combo (interfaced at custom circuit board.)gives ability to program auto mode to anywhere on playing field within +/- 6 inches. Up to 11 programs can be stored on board. Select one at time of robot placement on field depending on alliance partner, opposition and field placement.

Problems? Slower than some, less push than some, best on carpet or ramp.

Next year? We will optimize for whatever the game requires and parts available.

[purplehaze357]

Team # 357

# of years of participation? 4 and counting

# and type of motors? 2 drills, 2 chips

# and type of drive wheels? 6 Inch pneumatic tires

# and type of non-drive wheels? 0 non-drivers

Transmission (not including supplied ones)? n/a

Steering? its a 4 wheel translational drive, essentially if you know what a crab steer looks like then you should be set.

Sensors? Opticals that read white tape and a sprocket inside the wheel assemblies to be used for distance in our auton period.

Success? We won this years regional Chairmans Award at the Chesapeake Regional, and we won the Delphi's Driving Tomorrows Technology award at the Chesapeake Regional. At the Philadelphia Alliance Regional we won the animation Award. We also made a stack of 3 totes in Philadelphia grabbing the bins off the top of the ramp and driving them down.

Problems? We discovered early on that our robot was comparable to bringing a ballerina to a mosh pit. Our drive train was fragile creating problems when battlebot style pushing would occur.

Next year? To build a robot and continue the Royal Assault on the FIRST competition.

[JVN]

Team 229 - Clarkson University "Division by Zero"
This is our teams 5th year.

Motors-
2x Drill, 2x Chiaphua

Wheels-
4x 6" skyway wheels, turned down and coated with "Kingman
Tread" (1.2 mu)

No dead wheels...

Chain-
Serpentine - 3/8" Chain

Tranny-
2x All-Custom, 2-speed, 2-motor, shift on the fly (pin style).

Steering-
Standard Tank Steering...

Sensors-
Custom Current Sensors measure Drive-Motor current draw. Protects us from popping breakers. 2x IR Wheels allow us to calculate wheel speed and robot position (vector addition).

Successes-
We felt the system was fairly successful. This was our team's first attempt at a custom gearbox, and we certainly aimed high. (A combiner, AND a shifter in our first try... what were we thinking!?!?!) With a lot of love, and some profanity we managed to get it running smoothly, and shifting like a champ.

Problems- Mostly mechanical failures... we had to work the bugs out of our system...
We were torsion fracturing 3/8" dia. steel output shafts. We ended up going to a 1/2" dia. shaft for nationals, and the problem went away.
We also had some problems with our idler system throwing chain. We managed to work the bugs out eventually.
The large loads involved destroyed some of the plastic skyway wheel-hubs we were using... we had to replace a few of those...

Next Year...Well...
We've got a shifting - swerve drive about half designed. (Swerve-ZER0)
We've got a 6-wheel omni-drive (like 343 - 2002) designed up.
We're playing with improving out current drivetrain. (Generation2)
Time will tell...
Regardless of the game, you'll probably see our Gen2.5 gearboxes on the robot in one form or another...


You might even see us playing around with some new technology at off-season comps...

[Gadget470]

Team #470
# of years of participation? 4th Year
# and type of motors? 2 CIM's
# and type of drive wheels? 4
# and type of non-drive wheels? 0
Transfer system(chains, belts, etc.)? Independant chains to each wheel
Transmission (not including supplied ones)? 12:1 Gearbox, no shift
Steering? Tank-style
Sensors? None
Success? We were a powerful pusher, but a little slow.
Problems? At nationals we had a chain fall off twice, but still drove and shoved people around with 3 powered wheels.
Next year? Designs are in talks, nothing decided yet, but it will be neat if I get my way.

[Solace]

Team 571
3rd year team
2x drills, 2x chippy
2x 8 inch pneumatic wheels
All chain drive
All chain transmission (no shifting)
Tank steering
no sensors

success: Very Fast (12ft/sec) but slightly underpowered, reasonably successful (always in the finals at regionals and championships, ranked 3rd at UTC)

problems: we initially had problems with the chains popping off, but we fixed those by pinning the adjusting mechanism in place.
next year - we're ditching the chain, gonna try to do a complete gear drive train. Plans for a 4 motor, 2 speed on the fly tranny are in the works.