Re: Omni Wheels Vs. Mecanum Wheels
 

Team 3467 is using 4inx1in. Colson wheels in a 6 wheel tank drive configuration. We also have 6 CIMs with 2-speed VEXPro ball-shifters w/ third stage. Its a mouthful to say to pit scouters but we love it. Our bot has some serious pushing power.

I would recommend Colsons anyday over mechanum or omnis. If your driver knows how to drive mechanums like mechanums (and not like tank drive), mechanums are better than omnis, in my mind. The Windham Windup attend the Northeastern District event and I was blown away by Team 126's driver skills. They did some sliding which confused me because they were on mechanums, but they owned the mech. drive.

But what is interesting is that tank drive can go toe-to-toe against mechanums depending in driver skill. Basically anything can be a good drivetrain as long as you give your driver enough practice.

Re: Omni Wheels Vs. Mecanum Wheels
 

even this modified version is wrong if you ask me. It's also very simple to program, I do not understand why everyone thinks it's difficult. It uses basic trig functions(sin,cos,asin,acos) and nothing more complex. Is it harder than tank? sure, no where near swerve but it's actually very simple to program. Albiet it does require an additional sensor(we used compass) but even then it's very simple. Also in regards to ease to drive it should be the highest rating. The way ours is setup any first time driver can very easily control the robot. you point the stick in a direction and the robot goes that direction regardless of it's own orientation. I have video of first time drivers and it's almost indistinguishable from our experienced drivers it's soo simple. It's actually easier to drive than tank, arcade, or any of them frankly.

Re: Omni Wheels Vs. Mecanum Wheels
 

I would take a good mecanum drive over any other drive (excelt for swerve and octocanum) any day because I feel like I have much more maneuverability with mecanum wheels than with tanks or omni wheel drives. This is just my opinion, and it comes from having mainly driven mecanums and being most familiar with them (I have driven others, too so its not as if I only know one type of drive). Also, in our competition this past weekend I was able to out-maneuver most of the other robots and despite heavy defense, our robot received no damage. I was also able to play defense, too.

Re: Omni Wheels Vs. Mecanum Wheels
 

I think this may be some sort of record.



__________________________________________________ ______________
there is no "h" in mecanum

Re: Omni Wheels Vs. Mecanum Wheels
 

So how do you pronounce it?

Re: Omni Wheels Vs. Mecanum Wheels
 

Same way as you probably already do.

The name /Mecanum/ comes from the Swedish company Mecanum AB, where engineer Bengt Ilon came up with the idea in 1973

Re: Omni Wheels Vs. Mecanum Wheels
 

"mech-uh-num"
"mech-en-um"
"meh-can-uhm"
Or, without an "H" "Meh-sam-um" Or "Meh-sum-um"?
Which is " right"?
Any swedes in the thread?

Re: Omni Wheels Vs. Mecanum Wheels
 

Mec-anum like per anum

Re: Omni Wheels Vs. Mecanum Wheels
 

Re: Omni Wheels Vs. Mecanum Wheels
 

The poll needs an "other" option, our team uses Traction Wheels. :rolleyes:

Re: Omni Wheels Vs. Mecanum Wheels
 

Click on the speaker icon:
http://translate.google.com/#en/es/mecanum

Re: Omni Wheels Vs. Mecanum Wheels
 

Mecanum is the GIF of FRC

I don't mind either way (Mek-an-um) or (Meca-num) though I use the former

Re: Omni Wheels Vs. Mecanum Wheels
 

2 things.

1. I'd say arcade is easiest to drive, just because strafing is a concept of motion most people don't encounter. It's definitely harder to walk sideways than it is to rotate towards the direction you want to go, and start moving forward. I also guess through my many hours of playing video games as a kid, I just got used to driving arcade, since that's what many racing and shooter games used as a control scheme

2. Yes, it's that much harder to program and tune a mecanum drive, or any drive system with little turning scrub. You can rotate a mecanum drive along its axis of rotation by simply pushing it with one finger. Any imperfections in the fabrication of this chassis and weight distribution can cause a mecanum drive to refuse to drive straight. I've programmed a mecanum drive twice now, and both times the chassis refused to drive straight. Tuning the drive took encoders and a gyro, and even then the PID loop could not overcome the transition between carpet and plastic (We used a mecanum drive in 2012... not my proudest year). Accelerating without slipping in the 2009 game was one of the toughest challenges for some teams. Imagine doing that every year with a mecanum drive, because that's what I had to do to ensure our drivers wouldn't slip and "burn out" on the plastic and carpet in 2012.

Re: Omni Wheels Vs. Mecanum Wheels
 

Personally I would never consider a mecanum or slide drive. The loss of pushing power is just too much for me.
With 221's revolution swerve and the already-done swerve code to choose from, it is pretty easy to get a working swerve in 1-2 years. And while the revolution swerve is expensive, nothing's stopping teams from simply taking the CAD and optimizing it for thier robot.
While the center of gravity does go up a little, using 3.25" wheels offsets that.

That being said, I would first get a good working tank drive before going for swerve if I was a rookie team, or even an experienced team. Tanks drives are a good fallback.

Re: Omni Wheels Vs. Mecanum Wheels
 

We used a switching drive train this year too! We got the idea from Team Neutrino, but what we eventually came up with is a bit different than some of the others I've seen.

https://www.facebook.com/photo.php?f...type=3&theater

Instead of mounting the wheels in-line with each other, we put them side by side. This gives us a wider wheel base and thus a more stable robot when we are on our interior traction wheels. We use the traction set primarily for pushing so having that stability is a boon.

Another advantage to having them side by side is that it allows for the use of larger diameter wheels. We were able to use six inch vex mechanums, and four inch tractions. From what we've seen, small mechanum wheels don't always maneuver as well as larger mechanums, so having the ability to use those larger wheels was great.

The two downsides to this configuration are weight and complexity. Each of these four modules with the motor installed probably weigh around 10 pounds. And with one in each corner that's like a third of our weight allowance just in the drivetrain. Also we had to use 200 some spacers alltogether in our robot, so it was a ton of work to get them together.

But we managed to pull it off, and it has been working great for us this year! The design has won us two awards so far, and our team is definitely going to consider using switching drive trains in future games.