Team 20`s Robot design.

[Corey Oostveen]

I talked to team 20 at nationals and I absolutly loved the design and was wondering if someone from team 20 that has access to the cad files could pm me.


thanks!

[MoniqueSays]

Thank you, we worked really hard on our design this year. I can talk to our CAD team and get back to you with the files.

[sgreco]

I don't have the CAD files, but I would like to comment on the Rocketeers robot.

I loved the mechanum drive. The speed of the robot was impressive and what seemed to be controlled drifting on the turns was amazing. It was a great design along with well prepared drivers. I liked watching your guys robot in Boston. Even though you knocked us out of elims, you guys deserved it. Congrats on a good season.

hope to see you next year in Boston.

[MCoughT-20]

Thanks on all of the Comments and I am part of the CAD team but i don't have any of the files they are at school on a locked account. But thanks for all of the positive feedback.

[commodoredl]

You can view pictures of Team 20's CAD files at Autodesk FIRSTbase.
http://firstbasefrc.autodesk.com/?nd=m_first_competition_inv2008_viewer&addlastlink=1
Second one down.

Amazing robot by the way, our team was in awe every time you guys played, both at FLR and Boston.

[EricVanWyk]

I'm thinking Team 20 could make a killing selling those mecanum wheels. Very cool.

[Mike M.]

I'm thinking Team 20 could make a killing selling those mecanum wheels. Very cool.

From the looks of it those are the 6in AndyMark mecanum (http://andymark.biz/am-0137.html) wheels so they are already commercially available.

MikeM.

[The Lucas]

From the looks of it those are the 6in AndyMark mecanum (http://andymark.biz/am-0137.html) wheels so they are already commercially available.

MikeM.

Almost, they where using the AndyMark wheels but bent the sides plates. So they milled new side plates out of solid aluminum and attached the AndyMark rollers.:D

[Mike M.]

Almost, they where using the AndyMark wheels but bent the sides plates. So they milled new side plates out of solid aluminum and attached the AndyMark rollers.:D

Learn something new everyday. Thanks :D

MikeM.

[MCoughT-20]

We did get a lot of publicity about the wheels and i don't know how many times i had to explain them to the people in the pits. I am on the Drive team and within the first 10 mins of driving on the andymark wheels on our practice field the side walls near the rollers collapsed in pitching the rollers so they would not roll , the bumps in the middle of the field was what did it. So we took the geometry from the andymark wheels and just redesigned them so they were reinforced. I dont have a picture but we will be at Battlecry.

[MCoughT-20]

We did get a lot of publicity about the wheels and i don't know how many times i had to explain them to the people in the pits. I am on the Drive team and within the first 10 mins of driving on the andymark wheels on our practice field the side walls near the rollers collapsed in pitching the rollers so they would not roll , the bumps in the middle of the field was what did it. So we took the geometry from the andymark wheels and just redesigned them so they were reinforced. I dont have a picture but we will be at Battlecry.

Here is a Picture i got from a mentor taken at the FLR in Rochester

http://i299.photobucket.com/albums/mm309/mcoughlin93/Mecanum.jpg

[Mike M.]

Here is a Picture i got from a mentor taken at the FLR in Rochester

http://i299.photobucket.com/albums/mm309/mcoughlin93/Mecanum.jpg

Those are some really nice looking hubs there. How much did they weigh?


MikeM.

[techtiger1]

Take if from someone who played against them, they were awesome this year. I have always liked this type of mechanum wheel for FIRST robots because it puts a lot more contact area on the floor then the other designs. AM,357,ETC. The draw back to this style is you can't really climb anything. Team 20 definitely had a great robot design though them and 39 made up a killer alliance along with 207.

[sanddrag]

Ah yes, I remember these wheels. I named them "machinist's worst nitemare" :D Do you have any pics of them during manufacturing? They certainly are some of the nicest machined pieces I've seen all season.

[MCoughT-20]

There is a video of it being made and one of our mentors has it so i will track it down and post it on youtube. But also regarding the weight of the wheels, they are about 8 pounds per wheel.

[AdamHeard]

There is a video of it being made and one of our mentors has it so i will track it down and post it on youtube. But also regarding the weight of the wheels, they are about 8 pounds per wheel.

..............per wheel?

really?

[MCoughT-20]

Ya it might be like 7.8 something but ballpark range of 8 pounds.

[Rick TYler]

Ya it might be like 7.8 something but ballpark range of 8 pounds.

:confused: The AndyMark 8" Mecanums are listed on their Website at 2.5 pounds per wheel, and the 6" wheels are only 1.25 pounds. Do yours really weigh three times as much as the 8-inch AMs? Just wondering...

For a comparison, a mid-90s aluminum 14-inch wheel (without tire) for a Mazda Miata weighs about 11 pounds, and a 14-inch BBS wheel for the same car only weighed 8.5 pounds. Those are MUCH bigger than your robot wheels. I'm guessing that your wheels weigh eight pounds for all four.

[MCoughT-20]

Nope they are. they were made by a 7x7 solid block of aluminum and was milled out. This also includes the rollers and the bolts that hold the rollers on.

[EEEric]

Hes right they are roughly 8 ponds per wheel.

[The Lucas]

Wow, 8lbs per wheel!

How did you guys make weight with both the Arm and the Puncher modules?

[Jetweb]

Wow, 8lbs per wheel!

How did you guys make weight with both the Arm and the Puncher modules?

my bet is that they saved a ton of weight by using those hokey sticks for there arm.

[MCoughT-20]

IT WAS CLOSE!! and we ended up not wanting to use the poker in nationals so we did not even get it weighed with robot so we had about 10 pound leeway. And the hockey sticks were a real weight saver. they are light and strong and has a little flex to them. But once again thanks for all of the positive feedback we worked really hard.

[Corey Oostveen]

I would really like the CAD files for the wheels. I talked to someone on the drive team and they said they could email them to me. so if someone...anyone could please contact me from team 20.

thanks

[MCoughT-20]

Coosty,


I justed emailed our CAD head mentor and if you could send me a message of your email i will give it to him and he can email you the files.

[MCoughT-20]

Also we have a back up wheel and if anyone is gonna be at Battle Cry at WPI you can see it at our pit.

[MCoughT-20]

CORRECTION!!!!!!! all of the info i have been getting it False and i have been getting it from EERic. The Wheels actually weigh around 2 pounds and eight all together. Sorry for all of the False information.

[keehun]

Do those macanums work well? What makes it different from other macanums? (I obviously see the difference, but any difference regarding why it works better?)

I've been hearing macanums slow down the robots, but I think this directly proves it wrong?

Thanks,
keehun

[thefro526]

Do those macanums work well? What makes it different from other macanums? (I obviously see the difference, but any difference regarding why it works better?)

I've been hearing macanums slow down the robots, but I think this directly proves it wrong?

Thanks,
keehun

I'm not on team 20 but I can answer a few of your questions. I don't think mecanum wheels are substantially slower and any speed lose comes from the lower efficiency of the wheels themselves.

[lukevanoort]

In theory, a robot using its mecanum wheels will travel at 71% the speed of one the using normal wheels (assuming both robots are geared the same, and the wheel sizes are the same), because wheel is designed to deliver force at a 45 degree angle to its axis of rotation, and thus some of it is being wasted pointing off in the wrong direction. On the other hand, a mecanum robot can travel forward, sideways and every 2-D vector in between, which provides it the maneuverability to get around obstacles much quicker than skid-steer or Ackerman robots.

In reality, the roller's bearings aren't perfect so a mecanum robot's forward speed tends to be a touch higher than its sideways speed. I don't know the actual difference, and it would be really dependent on loading and the specific wheel's bearings. I suspect if one used decent needle bearings on the rollers, the forward/sideways difference would all but disappear.

[MCoughT-20]

The Mecanum Wheels do help a lot. Not only can they go sideways but coming around the turn at high speed could cause a skipping effect and with the mecanum wheels it makes a drifting motion .

[Lil' Lavery]

In theory, a robot using its mecanum wheels will travel at 71% the speed of one the using normal wheels (assuming both robots are geared the same, and the wheel sizes are the same), because wheel is designed to deliver force at a 45 degree angle to its axis of rotation, and thus some of it is being wasted pointing off in the wrong direction. On the other hand, a mecanum robot can travel forward, sideways and every 2-D vector in between, which provides it the maneuverability to get around obstacles much quicker than skid-steer or Ackerman robots.

In reality, the roller's bearings aren't perfect so a mecanum robot's forward speed tends to be a touch higher than its sideways speed. I don't know the actual difference, and it would be really dependent on loading and the specific wheel's bearings. I suspect if one used decent needle bearings on the rollers, the forward/sideways difference would all but disappear.

Actually, Mecanums will travel with the same top speed as a standard wheeled robot, but only apply √2/2 (≈71%) of the force of a standard wheel. The top speed remains exactly the same as a traditional wheel of the same diameter. With reduced force (and thus torque), acceleration and pushing power will decrease though.

Many teams have also been able to balance their forwards and sideways motion through clever programming tricks and closed-loop control systems. It all depends on how well your machine is built, maintained, and programmed.

[Nikhil Bajaj]

Actually, Mecanums will travel with the same top speed as a standard wheeled robot, but only apply √2/2 (≈71%) of the force of a standard wheel. The top speed remains exactly the same as a traditional wheel of the same diameter. With reduced force (and thus torque), acceleration and pushing power will decrease though.

Many teams have also been able to balance their forwards and sideways motion through clever programming tricks and closed-loop control systems. It all depends on how well your machine is built, maintained, and programmed.

In addition, maximum force exerted on the carpet (which translates to maximum useful torque) is also typically reduced because the friction coefficients you can get with most rollers that I've seen are going to be less than you can get with better traction wheels.

[MCoughT-20]

WOW you guys know your mecanum wheels!