2015: Year of the Mecanum

[Ether]

Originally Posted by Kevin Sevcik

You see those bumps called the scoring platforms? Those are going to going to cause all sorts of headaches for mecanums.

Has anyone looked at the field drawings yet? In the game video it looks like the platforms aren't that high, and there are ramps all around. How high is the platform, and what is the grade of the ramps?

[ATannahill]

Originally Posted by Ether

Has anyone looked at the field drawings yet? In the game video it looks like the platforms aren't that high, and there are ramps all around. How high is the platform, and what is the grade of the ramps?

The incline is 16 degrees, the height is two inches. This is from page 8 of the game manual. These values are nominal but the official values are in the field drawing.

[Jacob Bendicksen]

Originally Posted by Ether

Has anyone looked at the field drawings yet? In the game video it looks like the platforms aren't that high, and there are ramps all around. How high is the platform, and what is the grade of the ramps?

The angle of the ramp is 16 degrees, and the 'hypotenuse' is 7.125 inches. 7.125*sin(16) works out to 1.96 inches.

[Ether]

Originally Posted by Jacob Bendicksen

The angle of the ramp is 16 degrees, and the 'hypotenuse' is 7.125 inches. 7.125*sin(16) works out to 1.96 inches.

My guess is this won't be a major issue with a properly built and driven mecanum.

[Kevin Sevcik]

Originally Posted by Ether

My guess is this won't be a major issue with a properly built and driven mecanum.

For the record, we tried mecanums in 2008 and 2009, and just the plywood under the carpet would make things go wonky if you were trying to do a precise alignment.

I'm not saying they'll be undriveable, I'm just saying they're going to make auto and certain precision tasks a wee bit more challenging and error prone than they need to be.

[Ether]

Originally Posted by Kevin Sevcik

I'm not saying they'll be undriveable, I'm just saying they're going to make auto and certain precision tasks a wee bit more challenging and error prone than they need to be.

My prediction: There will be mecs that struggle mightily and those that dance like olympic figure skaters.

[hexane]

From our team's experience, the only time that mecanums have ever had troubles were on the bridges in 2012. Even then, the problem was the lower coefficient of friction rather than getting up on them, and we were still able to balance 2 robots better than most teams.

[chrisfl]

Originally Posted by hexane

From our team's experience, the only time that mecanums have ever had troubles were on the bridges in 2012. Even then, the problem was the lower coefficient of friction rather than getting up on them, and we were still able to balance 2 robots better than most teams.

It was the same for us. We used mechanum in 2012 and our only problem was staying in one place on the bridge. We had no problem going up and down it while at an angle.

[Bruceb]

never used macanums before but really considering it this year. what is the prefered gearbox for these?

[JosephC]

Originally Posted by Bruceb

never used macanums before but really considering it this year. what is the prefered gearbox for these?

If you have not prototyped mechanum or done it before, I would not recommend bringing it out this season. It doesn't seem difficult at first, but you will end up spending far too much time on your drive train instead of allocating proper time to your mechanisms.

[Brandon Zalinsky]

The biggest hitch in developing a mecanum drivetrain is code. It requires lots of code testing. The hardware is much easier. The wheels are placed in standard configuration and require very minor differences in hardware required from a 4wd skid. The biggest hitch in the hardware is that you need four separate transmissions.

1058 has used 9:1 transmissions for a few years on our mecanum drives.

[Peyton Yeung]

461 used toughbox minis last year with a 12.75:1 ratio on 6" wheels. The biggest issue we had was due to a lack of suspension, one of the wheels did not contact the floor like the others.

[AutodeskGeek]

Originally Posted by Brandon Zalinsky

The biggest hitch in developing a mecanum drivetrain is code. It requires lots of code testing.

For those teams that have used mecanum in the past, this is a non-issue. There's also plenty of help with algorithms online that teams trying it for the first time can use. Probably not too much testing unless you are implementing original drive styles with your mecanum wheels.

[Ben Wolsieffer]

Originally Posted by AutodeskGeek

For those teams that have used mecanum in the past, this is a non-issue. There's also plenty of help with algorithms online that teams trying it for the first time can use. Probably not too much testing unless you are implementing original drive styles with your mecanum wheels.

Yeah, the programming is not that difficult. WPILib for C++ and Java has a function for field oriented (or robot oriented) mecanum drive that works well. I don't know about Labview.

[Aedan Hawke]

Originally Posted by Bruceb

never used macanums before but really considering it this year. what is the prefered gearbox for these?

We've used mechanums for the last couple of years with success. Last year we made our own gearboxes and built them into our chassis. They worked exceptionally well but, obviously, were a huge drain on time. Other years we used Andymark ToughBoxes and those worked well for us. I'd recommend them unless you'd like the challenge of the custom gearboxes.