Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

*polite cough* I think he was pointing our the quick maneuvering of the blue robot with the mecanum wheels. Not 1114 with their 8-wheel drive.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

You've got a good point... the FRC field is just too crowded for a mecanum to really open up and put its maneuverability to use repeatedly and consistantly. For years I've been hoping to see a larger field, but realize there are physical limits at the venues.

Ever since we built our mecanum, years ago, I've advocated that you don't build an omni-drive because of competitive advantages, but because of aesthetic ones. A well-driven mecanum (or other omni) is a thing of beauty that will be a joy to drive long after the competition is over.

Mind you, taking our torquey, tractiony, 8wd from last year and burning doughnuts and pushing cartloads of people down the hallway with it is kind of fun, too... but even through it was probably the superior drive train for competitive mobility it wasn't as magical as a mecanum.

Jason

"No fair. Using 1114 in ANY comparison is like arguing Mustangs vs Camaros and then posting a video of Bumble-Bee. "

Great analogy... even if they weren't specifically referring to 1114!

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

The 4WD bot they're defending is way too slow. Like 8 FPS max. If you can find a mechanum driving circles around a 16 FPS 6WD with competent drivers I'd be impressed.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

The too slow robot that was top seed at Ann Arbor and a first round pick at MSC and the CMP? They were geared for torque and couldn't take advantage. That said Chris spcifically asked for videos of mecanums against six wheels drives + and we didn't even score until the endgame.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

If you give us a couple of weeks we may be able to come up a video that either proves or disproves a Mecanum drive running circles around a 6 wheel drive.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

The real issue is driver practice. There were several mecanum robots at kc that got out maneuvered by skid steer robots. The main difference is driver practice, in 2009 we had 3 days to drive our robot and we ran circles around everybody except crab drive, that little bit of practice helped a lot. Any Drive system needs refinement time and practice. A lot of teams including us wait till the last second to put everything together. That drive time is critical.



I think that mecanum can out maneuver a skid steer but not run circles around it.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

The 2337 driver played excellent position defiense, positioning between 2619 and the bump and blocking the line to the goal. But watching the actual maneuvering, I see no maneuvers that any reasonable skid steer chassis couldn't do. The only intentional "strafe" move sideways I see is at the end when they position for the hang. The driver skill was key to this defense, not the drive base.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

The bottom line for me is that I don't think the drivetrain is the deciding factor in a competition. We use Mecanum's whenever possible because we just really like to use Mecanum's. We won KC last year, were runner up at 10,000 lakes, and came within 1 point of making the semi's at Newton - on Mecanum wheels. Our weakness wasn't the drivetrain - it was our ball control.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

Thank you Chris for this post!!! In theory Mecanum should be faster, but the complexity of control and their lack of precision makes them worse.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

Hmmm. Not exactly what you wanted, but to show the other side, here's a video of an 8wd running circles around mecanum drive.

2010 SVR, 971 vs 675:
http://www.youtube.com/watch?v=0X27bojZ26k

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

I'm looking for an offensive mecanum bot avoiding defense, not the other way around.

Also, with all due respect to 2337, they literally did not strafe the entire match. This match could have happened with a tank drive. They also played position defense rather than anything involving pushing.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

Convince? ;)

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

One other item (a bit off topic). Mecanums don't like split-mu. Our practice field is made up of several chunks of carpet and a lot of duct tape. The Mecanums spin out whenever we cross the duct tape. There's a lot of tape on this year's field...

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

This video is absolute abuse and a classic example of a team who has no clue how to use mecanum (which in my experience is a large majority of teams using mecanum).

I really like this thread because it just reinforces the fact that mecanums simply will not outmaneuver a "good" 6 or 8wd drivetrain. I'll take 254/968's drive against any mecanum any day.

IMO the only omni-directional drive worth pursuing is a swerve or crab, which brings with it a whole different set of problems, but when properly executed can be a big advantage.

Re: Video of Mecanum Drive Running Circles Around 6 Wheel Drives
 

A MASSIVE problem with mecanum drive this year, just as you could have had the issue in Breakaway last year with our mecanum bot, is the steel plates under the carpet.

Our build lead and I ran some simple vector addition, and realized that any mecanum wheel on a slight incline like the steel plates under the towers can and likely will cause 20% of the force lost on one wheel diagonally opposite to one on the incline, and transferred to the wheel on the incline. This will cause you to lose significant control of the robot, and in this case, a trip to your scoring lane can likely end up as a trip to the opponent's zone. It is very hard to right the bot after that, and can cause the rollers on the mecanum wheel to lock up.

Be wary of this.