Pneumatics or Mecanum

[chaparoel]

What you think is better:
Pneumatics wheels or the Mecanum wheels ?
Why?

[Canon reeves]

It depends on your strategy, but:

Pneumatics:
- High traction

- Can act as shocks for the robot when crossing defenses

-Doesn't allow you to be pushed in a direction perpendicular to your wheels

-Allows for simpler drivetrain

-You only have to power two sides of your drivetrain, so better motor
allocation with 3 motor gear boxes

-Can climb over obstacles (depending on drivetrain)

-Defending your tower is always an option if something fails

Mecanum:
-Can strafe

-Can be pushed in any direction

-Likely not enough traction to go up the ramps, and definitely not over the defenses like the moat and bumpy road.

- Less dependable, more to go wrong

-If you use 4 wheels, the most power you can give to each wheel would likely be a CIM and miniCIM, so not as fast as a robot that uses 6 CIM motors in its drivetrain

-Little to no use on defense, most robots can push you around

Your team can choose which ever it thinks is best for your strategy, but I highly recommend not using mecanum wheels. If you think its worth it, just compare it to other drive trains using a decision matrix with objectives such as durability, multi-functionality, ease of build, and complexity.

[IndySam]

Mecanum:
-Can strafe yes

-Can be pushed in any direction Absolutely not true

-Likely not enough traction to go up the ramps, and definitely not over the defenses like the moat and bumpy road. "Definitely" Have you tested them?

- Less dependable, more to go wrong Absolutely false.

-If you use 4 wheels, the most power you can give to each wheel would likely be a CIM and miniCIM, so not as fast as a robot that uses 6 CIM motors in its drivetrain Maybe

[alicen]

Originally Posted by Canon reeves

It depends on your strategy, but:
Mecanum:
-Likely not enough traction to go up the ramps, and definitely not over the defenses like the moat and bumpy road.

I just wanted to say that unless you've tested this, it's all just hypothetical.
In 2010, my team used mecanums, and that ramp was a much greater angle than those seen on this year's field. We did not have any issues going up and over.

Don't entirely rely on other people's opinions, make your own judgements based on your experience and testing!

(I will forever have a love for mecanum, but I might be biased since my coffee table is mecanum drive )

[cglrcng]

Partial Quote:...."(I will forever have a love for mecanum, but I might be biased since my coffee table is mecanum drive)"

______________________

Lol...Now I know exactly what "Special Personal Project" I am going to order that wonderful tank chain tread for now! I'm going to turn my living room coffee table into a Stronghold Defense crossing capable coffee table. It may be too heavy for our robot, but it surely isn't for my future coffee table bot.

Our living room is small (the house overall is large though), and we have a matching very comfortable loveseat and large couch and a chair that are all seating position reclining, so everyone is always moving the coffee table a couple inches at a time, all about the center of the room (just a little bit, but I'm always straightening it up later-"anal type A" that I am), as feet get very close to it when reclining.

They will be able to move it about using a tethered controller and their smart devices, laptops, or ipads.

Thank's for that idea. (I would have never thought of doing that....ever!)

Just wait until my glass & tile squares topped wooden coffee table is going over and through all the team edition of the defenses with the practice bot before season end (besides the Low Bar of course), that the students have been putting together all week. (It certainly won't be FRC Legal, as it will certainly violate the 120" perimeter frame rule (I think I will just mount a nicely stained marching dark cherry wooden electronics shelf about a foot below the glass top), and I'm not putting the bumpers on it, or it certainly won't fit our living room space again. (Though I admit that it would look really cool w/ legal 8" each direction reversible Blue/Red bumpers perfectly in the bumper zone on each corner & our Team 60 numbers, so maybe I will notch the wooden legs so they can be added or removed on a whim).

[alicen]

Originally Posted by cglrcng

Our living room is small (the house overall is large though), and we have a matching very comfortable loveseat and large couch and a chair that are all seating position reclining, so everyone is always moving the coffee table a couple inches at a time, all about the center of the room (just a little bit, but I'm always straightening it up later-"anal type A" that I am), as feet get very close to it when reclining.

Might I suggest mecanums for this since it is moving in *all* directions,even just a little bit? Seems to solve the issue of lining up your table much more precisely!

Also, I've attached a picture of my coffee table
sorry for cruddy image quality!

[Dominick Ferone]

Originally Posted by alicen

Might I suggest mecanums for this since it is moving in *all* directions,even just a little bit? Seems to solve the issue of lining up your table much more precisely!

Also, I've attached a picture of my coffee table
sorry for cruddy image quality!

Do you sometimes get bored and drive your coffee table around the house?

[cglrcng]

Originally Posted by alicen

I just wanted to say that unless you've tested this, it's all just hypothetical.
In 2010, my team used mecanums, and that ramp was a much greater angle than those seen on this year's field. We did not have any issues going up and over.

Don't entirely rely on other people's opinions, make your own judgements based on your experience and testing!

(I will forever have a love for mecanum, but I might be biased since my coffee table is mecanum drive )

_______________________
There were a lot of mecanum's in Rebound Rumble and those ramps were a wicked angle, plenty of mecanum's last year in Recycle Rush (is the angle of the ramps really any different this year?) Low Bar, Sally Port, Drawbridge, and Portcullis are all ramped but flat going through Defenses. (If one could push down & climb the Rebound Rumble ramps, one should certainly be able to push down & climb the Cheval de frieze too I'd certainly think). Moat isn't that tough, Rock Wall ehhhhh - I don't know about that 1, or the Ramparts without some killer type suspension added. I wouldn't even attempt to tackle the Rough Terrain without same killer suspension added....Like Monster truck suspension added.

Put Mecanum's in an "X" pattern to shoot though and it does not push around as easy as many think (especially if backed by rail and wall right in front of the opposition alliances RH Drivers Station.

I'm willing to bet we see at least 1 Supershooter this year that figures out how to sit in the Spybot only position and shoots into top goal only (or maybe even top & bottom), using the curveball effect, and has not much of a drivetrain at all (just enough to crawl over to and climb on the Batter to Surround & or Scale and can collect from 2 sides so robot defense against it is a bit lessened.

We will probably see at least 1 Spybot Supershooter without any drivetrain at all...But, that bot will not make it out of the qualifying matches due to not being able to surround/scale the tower...And it will skew the RP results highly at that specific event! (I certainly could be wrong about not making it out of Q matches if it finishes a low team count event top 8 and ends up an alliance captain due to shooting very well and so many others helping them w/ Defense RP's and scoring high by making all shots high and accurate leading to high scoring auto & tele, while others fail to surround/scale against them).

Said bot will never move anywhere once placed in that Courtyard corner except during the last 30 or so seconds of a match. Count on it happening.

** Setting that X pattern once surrounding on the batter. Certainly No Rolling Off.

[TheJoe]

Originally Posted by cglrcng

There were a lot of mecanum's in Rebound Rumble and those ramps were a wicked angle, plenty of mecanum's last year in Recycle Rush (is the angle of the ramps really any different this year?) Low Bar, Sally Port, Drawbridge, and Portcullis are all ramped but flat going through Defenses. (If one could push down & climb the Rebound Rumble ramps, one should certainly be able to push down & climb the Cheval de frieze too I'd certainly think)

So much this. We had 8" mecanums in 2012 and were very, very fast with lowering and balancing on the bridge.

I also love mecanum wheels, but for our team this is just not the year to bring them out. Larger pneumatic tires or tank treads will be a lot better for our game strategy.

Originally Posted by cglrcng

I'm willing to bet we see at least 1 Supershooter this year that figures out how to sit in the Spybot only position and shoots into top goal only (or maybe even top & bottom), using the curveball effect

Teams might be capable, sure, but the game rules don't allow it.

[Dumper FTW 435]

I don't know why you're limiting to those two options. I think treads are worth considering if you haven't already.

In terms of those two, I would definitely say pneumatics for the same reasons Canon Reeves posted. Most of the advantages you get from mecanums are not going to help you very much this year, and this years fields really highlight the disadvantages of mecanums.

[Demonic_]

Originally Posted by chaparoel

What you think is better:
Pneumatics wheels or the Mecanum wheels ?
Why?

Pneumatics pros:[list]
Shock absorbers
Better traction
Pneumatics cons:

• Leaking is a constant threat

Also, you should consider using tank drive. It prevents the wheels from getting tangled too much, and can provide better traction.

[Team34Guy]

Pneumatics seem to be an obvious answer so far. The tread option is gaining traction(pun intended), but we've had limited experience with them in recent years. I love the maneuverability of the Mecanum, but, as other posters have already mentioned, they will have problems getting over obstacles. Off topic....
but I'm loving Stronghold so far. Our entire team is engaged in this endeavor right now...strategy, scoring, drive selection, etc. WTG First on Stronghold

[Kevin Thorp]

Umm... great discussion, but I think this technical category is intended for fluid power pneumatics: compressors, cylinders, valves, etc.

[Kevin Leonard]

For this game? I have no idea why you would even consider mecanum wheels unless the only defense you intend to be able to cross is the low bar.

Mecanum wheels are generally poor for traversing field obstacles, and the ability to strafe doesn't help you whatsoever in this game.

Pneumatic wheels are a great choice, but not the only choice for this game. Think about your team's priorities when making this decision.

[CalTran]

Originally Posted by Kevin Leonard

Mecanum wheels are generally poor for traversing field obstacles, and the ability to strafe doesn't help you whatsoever in this game.

For sake of discussion, an argument could be made that they help line up with taking shots on the goals and maneuvering around a possible defender in the courtyard.