|
Too much traction
We have run into a little snag. Turing can be really hard for our bot due to the fact we are using 4 IFI Traction wheels with a 4X4 set up. We can turn, but we got to be also moving backwards or forwards. It has been really bugging me cause I'm one of the drivers of the bot. I would love to put Omni wheels on the front, but the bot is already shipped. I was wondering is anyone else had any suggestions. The fix has to be able to be done at regionals during our tuning time. Any suggestions would be very helpful.
Here is a pic of your chassis if this will help at all:  |
Re: Too much traction
Sounds like you're having the same problem we had last year. Later you'll find the traction will be totally lost (after competition though so don't worry), anyway You could either drive with a lot of jerking forward and quick switching into a turn or you could probably modify the wheels with those omni-wheels or the smooth rubber tires that come in the kit (with the shifters and those rubber wheels strafing in high gears was A-M-A-M-A-Z-I-N-G!!!)
Hope this helps. |
Re: Too much traction
put zip ties on either the front 2 wheels or the back 2 wheels
|
Re: Too much traction
We ran into this problem. If your going to do omni wheels, put them in the front and DON'T power them, trust me. Or, we found this out by breaking a chain, if power two wheels on the right side and one on the left side, just power the right more and it turns real nice.
|
Re: Too much traction
If adding omnis isn't possible, just reduce the distance between the drive wheels so the wheelbase is significantly wider than it is long. Some casters may be necessary to add to the robot for balance. Actually, if you had casters on the front and rear with drive wheels in the middle, you might (depending on drive wheel squishiness) be able to raise/lower the casters a few mm to reduce the normal force on your drive wheels. Another option might be switching to lower traction tread on a pair of wheels. McMaster-Carr has a wide variety of conveyor belt materials, I'm sure you can find a lower traction one that can be adapted to your wheels (like the PVC or Nitrile Incline conveyor belting). In my opinion, your best bet is to move the front wheel back to a couple of holes after where the idler currently is, and then move the other wheel a few more holes back to get a centered drive system with a width of 1.5*length. Casters at the ends would restore balance.
|
Re: Too much traction
I believe you can still order omni wheels and bring them in to the competition, as they are COTS.
|
Re: Too much traction
Thank you everyone, like i said any ideas will be helpful
Quote:
Quote:
|
Re: Too much traction
Adding Omni Wheels will definitely help with your maneuverability. This years game is not so much about pushing and shoving as it is about being able to move around easily.
If you can put omni wheels on I would suggest you put them on the REAR not the front. The reason for this is to allow you to make turns very easily and quickly. This will allow you to literally turn on the pivot of one front wheel. Think: Forklift units in your local home store. The front wheels are the drive wheels and the rear wheels allow it to maneuver easily around obstacles. If omni wheels are not an option I would suggest you change out the rear wheels with the kit of parts wheels. These have less of a surface area in contact with the carpet along with a lower CoF and should allow you to makes turns easier. Good Luck! |
Re: Too much traction
Maybe try flipping the wedgetop/roughtop tread around such that the "back" side is facing "out" and the wedgetop/roughtop is against the metal rim on one end (front or back)?
|
Re: Too much traction
I would say that omni's would your best bet. ideally, you could make it a 6 wheeled robot (they dont all have to be powered) with the center wheel slightly (about an 1/8" or so) lower that the other wheels. this will allow you to turn with relative ease. however, with weight and time being an issue this prolly wouldn't help, but just an idea.
|
Re: Too much traction
We have the weight to spare, but this year we really wanna get in a lot of practice matches.
|
Re: Too much traction
Quote:
Are you going to a first week regional? If so, then I'm not sure about the rules on upgrade parts. I'm pretty sure omni wheels, in your case, would be considered upgrade parts. If you're going to a regional after the first week, then you are allowed to bring upgrade parts. It's really lame how first week regionals can't bring in upgrade parts, but every other regional can. What's the reason for that? |
Re: Too much traction
Thankfully FLR is week 2.
|
Re: Too much traction
Quote:
|
Re: Too much traction
what does COTS stand for =P
|
Re: Too much traction
Quote:
|
Re: Too much traction
I can't tell how you have the wheels aligned on the shaft from the picture but...
http://andymark.biz/am-0104.html The AndyMark Coolie Dualie Wheels have the same diameter center hole and hole pattern as the IFI Tractions (if I remember correctly) and would probably be the easiest to switch to at a regional (if you do decide you want to switch the wheels out). |
Re: Too much traction
1 Attachment(s)
[quote=InfernoX14;705454]Too bad surface area doesn't affect traction :rolleyes:
[quote] No offense meant here but if surface area doesn't affect traction then: Why do drag racers use really wide tires? |
Re: Too much traction
Quote:
|
Re: Too much traction
[quote=Brian C;705462][quote=InfernoX14;705454]Too bad surface area doesn't affect traction :rolleyes:
Quote:
|
Re: Too much traction
Quote:
As for the turning issue, take a dremel to the roughtop tread and remove strips of tread to reduce the traction of the wheel. Should take about 5 minutes total. |
Re: Too much traction
Thank you very much everyone, I was just talkign to a mentor and we now have a few things we will try:
1) Move the center wheels to change the wheelbase 2) Use a 1” wide wheel for 2 of the wheels which will reduce the friction (less wheel tread on the carpet) 3) Raise or lower the casters. 4) Install larger casters 5) Replace a wheel set for a pair of omni wheels 6) Change the wheel tread to lower friction type 7) Change the gear ratio of the drive 8) Install larger wheels on the left side of the robot (old dirt track stock car trick) Number 8 is my personal fav cause it keeps in the spirit of the bases of this years game |
Re: Too much traction
There are many different ways to help your turning problem, including adding the omni's, changing your wheelbase a bit, or just reducing the traction on two of your wheels. We (Team 378) will be at the Finger Lakes Regional and would be glad to add our help if you want/need it.
|
Re: Too much traction
Are you using cims to drive your robot? If so how many?
|
Re: Too much traction
Quote:
Quote:
|
Re: Too much traction
how many feet per sec is your robot going??? aka what is it geared to.
|
Re: Too much traction
idk the gears but i do know it goes from 12 to 13fps and we could ramp it up to go faster then that
|
Re: Too much traction
Be careful. You can quickly go from too much traction to too little.
Instead of grinding off the roughtop, add wide zip ties sideways around the wheels through the holes in the rims. If that's not enough - add omni's in the front. We made the mistake of adding omnis in the rear. It was a nightmare to control. When we hit the gas, the weight transfer to the back wheels would reduce the friction on the front ones, and it made hard acceleration a bear to control. |
Re: Too much traction
Last year we had 6 IFI traction wheels, all powered. With 42 teeth sprockets on the wheels and a 25? tooth output sprocket, we outpushed everyone. But, like you, we couldn't turn. So we flipped the front traction strips over and re-riveted them so the wedgetop was facing the aluminum wheel itself. It worked like a charm. We still outpushed everyone and, more importantly, we were able to turn.
|
Re: Too much traction
Yu could also check FIRST if you need anything to be approved by the rules. [off_topic]
Also I can't seem to get to FIRST are "remodeling" their site? [/off_topic] |
Re: Too much traction
You should try the omni wheels. they work really well for us. In the past we had the same problem. This year we bought the Andy mark aluminum omni's. Our set up is omnis in front and 2 inch wide wheels in back. Front and back are powered. It has worked really well. At the Suffield scrimmage we were really fast going around the track, at the same time we could push fairly well. If you cant get the omnis try the KOP wheels. they might work well also.
|
Re: Too much traction
go omni or i don't no if this is a good idea but take the robot and jack it off the ground and sand down those wheels i never used those wheels so i don't no if that is possible... and be careful if you do this.
|
Re: Too much traction
Thank you everyone, with all of these we will find a solution to your prob.
|
Re: Too much traction
Heres a simple solution. Order some AM Plastic Omniwheels. Bring them to the competition. They work with the same bearings as the traction wheels I believe and have the same sprocket mounting pattern. Put omni's on two of the corners (front left and back right or FR+BL) and it should help turning without being really wild. If you still don't have the turning you like, then put the omni's on the front. You shouldn't break chain unless you didn't align them correctly.
I would advise finding the drawings for the plastic omniwheels on Andymark's site and comparing dimensions with the IFI Traction wheels you are using so you can make new spacers before the competition. |
Re: Too much traction
we had exactly the same problem last year. if you can't replace the wheels once you get to regionals, would either flip over the tread on the front or back wheels. wrapping them in duct tape, and putting lots of zipties around them might work even better. hope you can fix it once you get there, ours were simply a disaster last year.
|
Re: Too much traction
Quote:
1> Will work as long as the movement is to shorten the wheelbase 2> Reducing the wheel width will not gain much as Coefficient of friction has not changed 3> Will work, but be careful of reducing the contact of your wheels or you may go too far and end up with no traction on your center wheels (and end up hitting the walls). 4> Same as 3 with no adjustability 5> This wil work for turning ... but be careful if you do this with your wheels in the center of your bot as you may end up just swinging the rear out when you turn with little control at higher speeds 6> Will work, but will need some experimentation to find a good CoF wheelset 7> Will work as long as it's a slower gear ratio 8> :D Will make the bot difficult to drive straight. Good luck, I'd suggest changing the center tires to ones with a lower CoF |
Re: Too much traction
Quote:
|
| All times are GMT -5. The time now is 01:04. |
Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Copyright © Chief Delphi