Chief Delphi

Chief Delphi (http://www.chiefdelphi.com/forums/index.php)
-   General Forum (http://www.chiefdelphi.com/forums/forumdisplay.php?f=16)
-   -   Mecanum wheels (http://www.chiefdelphi.com/forums/showthread.php?t=124193)

heisenburger 06-01-2014 17:12

Mecanum wheels
 
Hi, I was just wondering what is the purpose of the mecanum wheels, how do they work and are they worth the $400 for the set of 4, also if the sell them somewhere else cheaper than that could you give me the link?

cjl2625 06-01-2014 17:15

Re: Mecanum wheels
 
Mecanums have some nice maneuverability. They are able to strafe, for example. (you can find some videos of it on YouTube)

However, mecanum wheels will be weak for pushing power and can slide around.
You'll likely be pushed around a lot on the field if you use them

atucker4072 06-01-2014 17:17

Re: Mecanum wheels
 
Quote:

Originally Posted by heisenburger (Post 1322601)
Hi, I was just wondering what is the purpose of the mecanum wheels, how do they work and are they worth the $400 for the set of 4, also if the sell them somewhere else cheaper than that could you give me the link?

Where have you looked?

Also make sure you know what size you need. Don't use mecanum wheels just for a cool factor. Mecanum wheels are great for maneuverability, but when it comes to pushing they are worthless.

lethc 06-01-2014 17:29

Re: Mecanum wheels
 
Quote:

Originally Posted by heisenburger (Post 1322601)
Hi, I was just wondering what is the purpose of the mecanum wheels, how do they work and are they worth the $400 for the set of 4, also if the sell them somewhere else cheaper than that could you give me the link?

My team used mecanums last year and they worked well for sliding into place at the feeder station. However, they were terrible when we tried to cycle and were pushed extremely easily. This year may not be the best for mecanums simply because of the lack of safe zones - you can be pushed at any time with nowhere to retreat.

The choice is completely dependent on your team's strategy. Is your shooter reliant on consistent positioning? If so, you may not want to use mecanums because of the pushing issue.

azcalg 06-01-2014 18:21

Re: Mecanum wheels
 
In this game the only big advantage I see for them is with catching the ball from the truss, so unless that's a big part of your strategy, I wouldn't get them. Another downside to them is that they're quite heavy.

brennanvhoek 06-01-2014 18:23

Re: Mecanum wheels
 
Mecanum work well if they fit your game strategy. You can get a full set for much less then $400. Vex pro sells a set of 6" for 159.99 http://www.vexrobotics.com/vexpro/wh...um-wheels.html

Also, in my experience the vex wheels preform much better then the andymark equivalent.

jbsmithtx 06-01-2014 18:29

Re: Mecanum wheels
 
Try VEXpro. They have very affordable yet durable mecanum wheels. The other posters are correct in assuming that unless you are trying to catch, mecanums might not work well this year... However don't believe they are easy to push. We had to play defense with our mecanums last year in matches when our shooter failed and were fine. We could block lots of teams. I know this is contrary to popular belief, but a properly done mecanum drive base can in fact be very strong.

For anyone that wants to question our pushing abilites, we have video...

Oblarg 06-01-2014 18:33

Re: Mecanum wheels
 
Quote:

Originally Posted by jbsmithtx (Post 1322655)
Try VEXpro. They have very affordable yet durable mecanum wheels. The other posters are correct in assuming that unless you are trying to catch, mecanums might not work well this year... However don't believe they are easy to push. We had to play defense with our mecanums last year in matches when our shooter failed and were fine. We could block lots of teams. I know this is contrary to popular belief, but a properly done mecanum drive base can in fact be very strong.

For anyone that wants to question our pushing abilites, we have video...

Mecanum wheels, neglecting friction in the rollers, have an effective coefficient of friction that is a factor of sqrt(2)/2 reduced from that of a traction wheel made of the same material. You can verify this yourself by drawing a free-body diagram of a set of mecanum rollers in contact with the ground.

Whether or not this translates to "being pushed all over the field" depends critically on context (robot weight, weight/drive of opposing robot, weight distribution, manner in which you're hit, etc).

math311 06-01-2014 18:35

Re: Mecanum wheels
 
My team has used mecanum wheels for the last three competitions, and each time we had great success with our drivetrain.

The system is meant to give a robot high levels of maneuverability, and when it is allowed to move at high speed, it creates a formidable opponent. Having the range of motion provided by a mecanum drive can allow a driver to jump out of the way of onrushing defenders, all while maintaining a scoring opportunity

When discussing pushing and mecanum, it should not be forgotten that the goal of this drivetrain is maneuverability, not brute strength. Due to this, a pushing match with a robot designed for pushing will be lopsided. But that does not mean that this drivetrain is easy to push. I have seen our past mecanum drives stop six wheel drives dead, and win pushing matches. When we use mecanum, we maintain a balance of speed and pushing power, and ensure we are not compromising one for the other.

This quote sums the entire discussion up, and is good food for thought. "Mecanum drivetrains, like every other, have advantages and disadvantages" - Mr. B

Random42 06-01-2014 21:19

Re: Mecanum wheels
 
I have a quick question about mecanum wheels. Can they be placed in a trapezoidal configuration?

Has anyone tried this before? How well does it work?

cmrnpizzo14 06-01-2014 21:32

Re: Mecanum wheels
 
Quote:

Originally Posted by Random42 (Post 1322791)
I have a quick question about mecanum wheels. Can they be placed in a trapezoidal configuration?

Has anyone tried this before? How well does it work?

Could you describe the configuration you are thinking of? Do you mean something like this:

---[]----[]---


[]----------[]

where the [] are wheels and you have the front wheels in narrower (or the back wheels)?

Keegbot 06-01-2014 21:37

Re: Mecanum wheels
 
Quote:

Originally Posted by jbsmithtx (Post 1322655)
Try VEXpro. They have very affordable yet durable mecanum wheels. The other posters are correct in assuming that unless you are trying to catch, mecanums might not work well this year... However don't believe they are easy to push. We had to play defense with our mecanums last year in matches when our shooter failed and were fine. We could block lots of teams. I know this is contrary to popular belief, but a properly done mecanum drive base can in fact be very strong.

For anyone that wants to question our pushing abilites, we have video...

Our team used the VEXpro wheels last year, and I was very pleased with them. They lasted 2 competitions and multiple fundraisers until they started to fall apart. They are also quiet and light compared to the Andy Mark versions we have used in the past. We also had to be purely defensive in one competition and managed to place high because our mecanum drive allowed us to out-maneuver our opponents and get in front of them to block their shots.

Caleb Sykes 06-01-2014 22:03

Re: Mecanum wheels
 
I encourage anyone and everyone who thinks that they understand mecanum physics to read the whitepaper given here: http://www.chiefdelphi.com/media/papers/2759?

Random42 06-01-2014 23:01

Re: Mecanum wheels
 
Quote:

Originally Posted by cmrnpizzo14 (Post 1322800)
Could you describe the configuration you are thinking of? Do you mean something like this:

---[]----[]---


[]----------[]

where the [] are wheels and you have the front wheels in narrower (or the back wheels)?

Yes. Something very similar to this. The back wheels would be about 12in apart and the front about 24in apart. The front and back wheels would be about 30in apart.

BEN35678 06-01-2014 23:01

Re: Mecanum wheels
 
Quote:

Originally Posted by Keegbot (Post 1322805)
Our team used the VEXpro wheels last year, and I was very pleased with them. They lasted 2 competitions and multiple fundraisers until they started to fall apart. They are also quiet and light compared to the Andy Mark versions we have used in the past. We also had to be purely defensive in one competition and managed to place high because our mecanum drive allowed us to out-maneuver our opponents and get in front of them to block their shots.

Last year we used Andymark mecanum and this year we were looking at the vex pro mecanums, and a couple of our main mentors were worried about them cracking because they are plastic. Did you have anything that looked like it was about to crack or anything like that?


All times are GMT -5. The time now is 00:09.

Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Copyright © Chief Delphi