Mecanum Drivetrains

[Brandon Zalinsky]

To add to Jay's post, we used 4x 30:1/11:1 supershifters with one CIM each. In the past, we have run each of a Jaguar, but we have blown out so many Jags that we have switched back to Victors.

If you want to get creative, you can do all kinds of crazy things with mecanums. For example, in 2011, 1058 built this simple 4-cim mecanum drive with a twist. Each wheel had a third mecanum plate with cut-up pieces of truck mud flap on it. This plate could be actuated into the rollers, freezing the rollers in place, but not the wheel. With these activated, the robot would be a high-traction 4WD that could push other robots around. At the press of a button this would switch to the normal mecanum drive, giving it unmatched speed and maneuverability.

Coming from one of the biggest mecanum fanboys in FIRST- have fun, drive fast, and forget the haters.

[Akash Rastogi]

Originally Posted by Flak-Bait

If you want to get creative, you can do all kinds of crazy things with mecanums. For example, in 2011, 1058 built this simple 4-cim mecanum drive with a twist. Each wheel had a third mecanum plate with cut-up pieces of truck mud flap on it. This plate could be actuated into the rollers, freezing the rollers in place, but not the wheel. With these activated, the robot would be a high-traction 4WD that could push other robots around. At the press of a button this would switch to the normal mecanum drive, giving it unmatched speed and maneuverability.

This sounds pretty creative! Do you have pictures or videos of it in action?

[Brandon Zalinsky]

Originally Posted by Akash Rastogi

This sounds pretty creative! Do you have pictures or videos of it in action?

Yep! They're around somewhere, i'll find them and post them tonight.

[Brandon Zalinsky]

Originally Posted by Akash Rastogi

This sounds pretty creative! Do you have pictures or videos of it in action?

Here's the design and implementation of the Locking Mecanum Drive 1058 built in 2011. I threw in some match footage for you guys too!

With regards to what Jay said about Field-Oriented Drive, here's a video for that.

[Madison]

Originally Posted by Flak-Bait

Here's the design and implementation of the Locking Mecanum Drive 1058 built in 2011. I threw in some match footage for you guys too!

With regards to what Jay said about Field-Oriented Drive, here's a video for that.

If I'm understanding this correctly, the rollers are stopped only be the pin / screw / post that goes through the 2nd hole you drilled near each rollers' axle?

[Brandon Zalinsky]

Originally Posted by Madison

If I'm understanding this correctly, the rollers are stopped only be the pin / screw / post that goes through the 2nd hole you drilled near each rollers' axle?

In the first shot in the video, the new hole that is being drilled is to help hold on a piece of rubber. The wheel itself is left unmodified, and we take a third mecanum plate and put one piece of rubber on each "wing" or flange of the plate. When the piston is activated, it pushes that aluminum bar you see in the video into that third plate, which is mounted parallel to the mecanum wheel. This pushes the rubber piece into the wheel, braking the roller.

The plates are on the same axle as the wheel and are spring loaded, so when the piston retracts, the plate comes off the wheel, unbraking the roller.

[Akash Rastogi]

Originally Posted by Flak-Bait

In the first shot in the video, the new hole that is being drilled is to help hold on a piece of rubber. The wheel itself is left unmodified, and we take a third mecanum plate and put one piece of rubber on each "wing" or flange of the plate. When the piston is activated, it pushes that aluminum bar you see in the video into that third plate, which is mounted parallel to the mecanum wheel. This pushes the rubber piece into the wheel, braking the roller.

The plates are on the same axle as the wheel and are spring loaded, so when the piston retracts, the plate comes off the wheel, unbraking the roller.

I have to admit, that is a great little feature! How well did it work out for you in a real match against defense?

[Brandon Zalinsky]

Originally Posted by Akash Rastogi

I have to admit, that is a great little feature! How well did it work out for you in a real match against defense?

Very well, even though we encountered very little defense focused solely on us. We'd do a "roll", where we'd activate the traction drive, plow into the side of the defensive robot, go back to mecanum mode, and push towards the goal while rotating the robot. This would cause us to roll off the side of the defending robot and get past them. In other situations, we could just outdrive them with the agility of the mecanum wheels. The biggest advantage of the locking mecanums is if an opposing robot is pushing you sideways, you can stop dead with a push of the button and, amusingly, confuse the hell out of the opposing robot's drivers.

[pfreivald]

Originally Posted by Flak-Bait

Very well, even though we encountered very little defense focused solely on us. We'd do a "roll", where we'd activate the traction drive, plow into the side of the defensive robot, go back to mecanum mode, and push towards the goal while rotating the robot. This would cause us to roll off the side of the defending robot and get past them. In other situations, we could just outdrive them with the agility of the mecanum wheels. The biggest advantage of the locking mecanums is if an opposing robot is pushing you sideways, you can stop dead with a push of the button and, amusingly, confuse the hell out of the opposing robot's drivers.

A lot of the same advantages of octocanum, though with octocanum you can do a 5:1 or greater downshift with little weight and cost built in.

[Lil' Lavery]

Being able to execute a "roll" maneuver is pretty much the tempts me towards omni-directional drivebases (and some fine tuning near goals like 2005, 2007, or 2011). That being said, I don't anticipate it happening anytime soon on 1712 and it's only useful if the field has enough space for it to be executed (so it rarely solves choke point defense). 1640's swerve drive roll maneuver is probably my favorite, though. So beautifully executed this season.

[pfreivald]

Originally Posted by Lil' Lavery

Being able to execute a "roll" maneuver is pretty much the tempts me towards omni-directional drivebases (and some fine tuning near goals like 2005, 2007, or 2011). That being said, I don't anticipate it happening anytime soon on 1712 and it's only useful if the field has enough space for it to be executed (so it rarely solves choke point defense). 1640's swerve drive roll maneuver is probably my favorite, though. So beautifully executed this season.

In terms of actual competitiveness, I wouldn't recommend straight mecanum for teams seeking to become elite. Some kind of omnidirectional drive combined with high-torque pushing is, I think, the best of both worlds, and of those kinds of drives, octocanum has been the best solution for us so far--it's certainly a lot simpler and lighter than swerve.

[wilsonmw04]

Originally Posted by pfreivald

In terms of actual competitiveness, I wouldn't recommend straight mecanum for teams seeking to become elite. Some kind of omnidirectional drive combined with high-torque pushing is, I think, the best of both worlds, and of those kinds of drives, octocanum has been the best solution for us so far--it's certainly a lot simpler and lighter than swerve.

no matter how accurate your statement is, mecanum is a great solution for many small teams. They are easy to build. They are easy to drive. They give young and/or small teams a reliable with a relatively small investment.

Octocanum is a wicked drive train. we developed a version last summer, Ran it with some success last year and perfected it this summer. I really hope the game allows us to use it this year.

[pfreivald]

Originally Posted by wilsonmw04

no matter how accurate your statement is, mecanum is a great solution for many small teams.

I disagree. They're a neat application for many small teams (trust me, it doesn't get smaller than 1551, or at least not by much). For competitive advantage, the KBOS is a better solution for those who can't to octocanum or some other variant which provides pushing/shoving/defense/plowing-through-defense capabilities.

Originally Posted by wilsonmw04

Octocanum is a wicked drive train. we developed a version last summer, Ran it with some success last year and perfected it this summer. I really hope the game allows us to use it this year.

It's a rare game that won't. We're very happy with ours, but I'd love to see how you've "perfected" it.

[yash101]

Team 1165's Mecanum Test! Mecanum is nothing but pure amazing, and it actually seems like magic, especially with the wheels covered up so no one can see them
http://www.youtube.com/watch?v=_Lrosi-WA7A

[BrendanB]

1058 is definitely one of those teams that has re-defined how to use mecanums effectively in the game. Their 2010 robot with the field oriented drive performed amazingly throughout the 2010 season. It was fast, responsive, very agile, and played some very mean mid-field offense!

I didn't get to see too much of their 2011 robot but I've heard a lot of stories about what they pushed.

Their 2007 and 2008 mecanum drives were also effective players of the game.

While mecanums still aren't my personal choice to use in a drivebase they can make for a great off-season project for a team. Plus they make excellent demo robots.

Use in a competition is a different story but every team needs to make decisions when they design their robots. There have always been times where being able slide sideways is advantageous and mecanums are a very easy way to achieve it. There are downsides that go with them but there are downsides of every mechanism you put on your robot.

In the end, no matter what drivebase you go with the best thing you can do is train your drivers and give them time to practice under realistic circumstances. While our team doesn't use multi directional drives we've trained our drivers to react faster so they can quickly maneuver around obstacles without us giving them another direction. We use old robots, chairs, trash cans, simulations, etc to keep them on their toes so when their path is blocked they don't stop moving while maneuvering.

Practice, practice, practice and the decisions you make at the beginning of the season will pay off no matter what drivebase you use.