Drivetrain, what did you use?

[Joe3]

Team #365

# of years of participation? 4

# and type of motors? 2 Bosch's, 2 CIM's

# and type of drive wheels? 4 custom 6" aluminum wheels with neoprene wrapped around, attached by tie-wraps.

# and type of non-drive wheels? 0

Transfer system(chains, belts, etc.)? Chain, independent to each wheel

Transmission (not including supplied ones)? 2 custom, we geared the CIM's down to the same as the bosch's in the low setting.

Steering? Skid steering

Sensors? Two gyro's for autonomous, one for the turn to go up the ramp, one to stop the robot once we got off the ramp.

Success? Everything worked as planned. It was a fairly simple system, so, nothing major broke. Good combination of speed and torque.

Problems? The only problem we ran into was a chain falling off (twice).

Next year? We're looking into hovercraft, and a form of a mag-lev vehicle. No, but we're exploring several more advanced options.

[Austin]

Team #45

# of years of participation/since establishment of team? 12

# and type of motors? 2 Drill, 2 CIM

# and type of drive wheels? one belt/drive pully per side, tank style

# and type of non-drive wheels? ....about 6/7 idlers per side

Transfer system(chains, belts, etc.)? direct drive, gears

Transmission (not including supplied ones)? 2 custom shift-on-the-fly

Steering? Skid steering

Sensors? 4 light sensors for autonomous to tell us when we reached the HDPE

Success? won wm under the wing of 292...had hindering reliability problems the rest of the season

Problems? Gears breaking, shift-shaft broke, controller reseting, victors frying, auto-mode...etc...etc...lol not fun!

Next year? you'll just have to wait and see...try to guess!

[pras870]

- Team 870
- 3rd Year
- 2 Drill Motors set in high speed
- 6 9" Pneumatic Skyway wheels
- 2 6" Skyway solid wheels
- #35 chain with 60 tooth sprockets on wheels, (4) 14 tooth idlers, and 11 tooth sprockets on extended drill motor shafts
- Standard Drill Transmission
- Tank Drive
- None as of now
- Speedy, plenty of pushing power. Only problem is that it tends to bounce when doing a ZTR turn.
- Next Year: Would like to try a gear box incorporating the CIM and Drill Motors

[Tom Bottiglieri]

love doin that

[Jnadke]

Seeing as nobody else posted this...


I just wanted to hear what people used for their drive trains including:
-Team #? 269
-# of years of participation? 4
-# and type of motors? 2 CIM
-# and type of drive wheels? 2 Drive wheels (8" I believe)
-# and type of non-drive wheels? 2 Non-drive steering wheels (6")
-Transfer system(chains, belts, etc.)? Direct Drive gears
-Transmission (not including supplied ones)? No transmission. We did have a differential for steering (allows one wheel to move faster than the other), but was removed due to problems.
-Steering? We had Ackerman steering which allowed us to get to the ramp in 5 seconds consistently.
-Sensors? None
-Success? Seed 6th in Curie.
-Problems? Differential had problems with parts breaking, so we used a different drive system. It still worked, but didn't have the same high-traction drive wheels.
-Next year? Dunno.


Other than team 16, I don't think any other teams utilized a true Ackerman steering system. Correct me if I am wrong. I am not referring to casters. Ackerman steering is where the front wheels do the turning fully (usually unpowered, but they are powered by a front differential in AWD cars). The rear wheels are both set to go either full forward or full reverse.

If you want a really good demonstration, check out Curie Match 65 or Curie Match 115. Credit to Soap108.com. If we had higher traction wheels we could cut our time down because the robot actually goes through some acceleration-limiting code when the robot starts up (we were spinning wheels).

[Adam Y.]

We had Ackerman steering which allowed us to get to the ramp in 5 seconds consistently.

Edited for not reading the post. Edited again for not reading the post for the second time. So what differntial did you use?? It sounds like you used an underrated part.

[Adam Y.]

The problem wasn't in the differential itself (that worked flawlessly), but in transferring power to the differential. I noticed they were using 1/4" shafts and set screws...

Ahhh thanks by the way do you know where they got it??? The only differentials I have seen look like they would not work in a robot.

The rear wheels had less traction than the steering (front) wheels (which we were originally going to use), so there were no problems in turning even though both rear weels were operating at the same speed. Unfortunately we were pushed a little easier than we would have hoped.

Ahhhh I thought that may work. Thanks. Were you ever worried that if one of your wheels were up in the air that the robot would not move since all of the power would be going to that wheel?

[Jnadke]

Originally posted by wysiswyg
Stupid question but did you have a differntial on you drive shaft or did you just mount a chain to it directly???? I was wondering this.

We did originally have a differential on it, but we had many problems at the Midwest Regional, so we ended up dumping it and going with a drive system developed by one of our sister teams (with the help of our engineers). The other option was to replace the gears on the differential with a belt system. The problem wasn't in the differential itself (that worked flawlessly), but in transferring power to the differential. I noticed they were using 1/4" shafts and set screws...

The rear (newer) wheels had less traction than the steering (front) wheels (which we were originally going to use with the diff), so there were no problems in turning even though both rear weels were operating at the same speed. Unfortunately we were pushed a little easier than we would have hoped.


I'm just a college student/alumni that was helping to mentor them. I wasn't at nationals but I was at the Midwest Regional.

Ahhh thanks by the way do you know where they got it??? The only differentials I have seen look like they would not work in a robot.

The differential was actually a free-floating differential (also called an open differential - there are many different designs). It consisted of a nylon housing to which a large gear was attached (the drive gear). The housing was basically 4 bevel gears of the same size, to which 2 shafts were attached (the 2 that are perpendicular to the drive gear).

You can see a good picture here:
Differential
Steering

Unfortunately, I don't have any information as to whether they made it or bought it. If you look at the design, it wouldn't be that hard to make with a mill and drill press. All you need is a high-strength plastic like Delrin or Polyethylene. Take a square of it and mill out a perfect square inside. Drill 4 symmetrical holes on each side and mount the bevel gears (preferrably steel). They should all be mounted solid (can't move), 2 of which should be attached to the wheel shafts. Then attach a drive gear (or sprocket) to the housing (not to the wheel shaft). A bit more complex, but that's the basic idea.

At MR they replaced the nylon gears with steel one's. The differential worked nicely for a match, but then it broke again when a nut came out, so the decision was made to switch to the alternate, alternate drive system permanently (Plan A was nylon gears and hollow driveshaft, Plan B was steel gears and solid steel driveshaft, Plan C was belts, and Plan D was the drive system you see now). If you can get past all the kinks (using 3/8" steel shafts, keyways, and getting rid of those nuts), it'd be perfect.


There are many different kinds of differentials. There are differentials with bevel gears (open differentials). There are differentials with worm gears (Torsen differentials). There are even differentials with planetary gears (TrueTrac differentials). Open differentials are the simplest and most efficient, but if one wheel loses traction you're screwed. Torsen are the most complex and least efficient, but they have the ability of transferring torque to the wheel with traction. The TrueTracs are somewhere in the middle, but they require a little bit of initial friction to transfer the power to the other wheel (the slippage can't be instantaneous).

Were you ever worried that if one of your wheels were up in the air that the robot would not move since all of the power would be going to that wheel?

Yeah, that was a concern, but if you look at the steering picture, you can see that our it pivots on the vertical. It's semi-articulated so that both rear and front wheels are on the ground no matter what position the robot is in relation to the ramp. The only way we would have that problem is if a robot got under us.

[abeD]

We almost used a differential on our bot, till we thought that it wouldnt have helped us that much, and it ended up that just putting a 4 wheel tank in the back with two wheel steering the front(not casters but steered by a globe motor) worked great, ended up in 3.8 s autonomous and easy and fun drivability during matches.

here's a pic, u can see the 4 wheel tank in the back with the two wheel steering in the front,(no only the battery in the back is plugged in the other two are for weights to simulate the arm weight).
http://www.chiefdelphi.com/forums/pi...&quiet=verbose

[tatsak42]

Team #? 159
# of years of participation? 6? i dunno
# and type of motors? 4 drive motors, 2 drill and 2 Fischer Price (until we had to redo our drive @ regionals to 2 drill tank drive w/ casters >_<
# and type of drive wheels? 2 drive, 6 inch dia.
# and type of non-drive wheels? 2 casters >_<
Transfer system(chains, belts, etc.)? gears. custom gearboxes... ah will do better next year.
Success? Well, with just 2 motors, we still had quite a bit of power...
Problems? FP motors destroyed, aka, no translational
Next year? Ah well, work on that again... so that it works ;D

[Ricky Q.]

Originally posted by Adam Y.
Ahhh thanks by the way do you know where they got it??? The only differentials I have seen look like they would not work in a robot.

The differential that was orignally in our bot was designed and manufactured by our team. It was designed with the help of one of our new engineers from Harley-Davidson, he had much experience with the design of them, but not the assembly, so as Jnadke said, we had some issues with it and dumped it. It would have worked perfect if we would have had more time, we expect to work more on it in the summer. We went with the alternate drive and employed a software differential at Nationals and had little or no problems with the steering, it worked like a charm and made us pretty manuverable as opposed to tank drive robots, if your going to IRI head on over to our pits and check it out. We proabably will put a steering wheel on the controls to make it more car like, its a ton of fun to drive.

[Rob Colatutto]

Team 263
- 5 years participation
- 2 CIM (atwood, chippy, chalupa, etc)
- 2 custom 10 inch dia. 7 inch wide aluminum wheels, wrapped in neoprene, very good traction
- 0 non drive wheels, 2 hdpe (teflon in the past) skids in front. currently dubbed the sled bot by SBPLI judges
- 4:1 4:1 gear reduction, then 7:5 chain reduction
- no shifting...yet
- 2 wheel rear steering, no drag in the front of the robot
- 2 sensors to tell them robot in autonomous what side of the field its on to determine what turn to make
- 100% success with the drive train, no failures and ability to push most other robots
- problems... wheels were too wide and too big (although smaller dia than our previous wheels). combiner would have helped, had one last year but deemed it unneeded only to turn around and decide it does help to have one
- next year, swerve (crab like) drive (we hope) currently working on a prototype now, if successful it will become the model for next years and the robot cart. 2 drill in front with custom gearboxes, 2 chippy in the back with custom gearboxes. experimenting with window, globe, fp, and van door to turn the wheels, not sure what works the best yet

[Gobiner]

Team 753
2 years of participation
2 drills, 2 CIM motors
2 BrecoFlex belts, the red ones that tear.
Custom gearboxes linking CIMs with drill transmissions.
Tank style steering.
No sensors.
Very successful at Seattle, never met a robot we couldn't push. Geared to go about 8 ft/s with no load.
Had major trouble at Houston with the drill transmissions slipping into neutral, then with the clutch housing coming off the planetary gear housing.
Next year? Whatever next year's students want to do.