Mecanum wheels vs holonomics?

X drives may have a small amount of drift or rotation - your wheels and weight distribution are all a part of this. Using a gyro may help, but I can’t see an X-drive outperforming a “tank” in programming skills

So you’re saying it won’t make much of a difference?

how is it not better?
if “done right” the X has more maneuverability than the typical tank drive

the difference is just how much effort/difficult it would be to program

X = very maneuverable but hard
tank = not as maneuverable but easy

It would certainly be more work to program an X-holonomic autonomous, but if you have an encoder on each wheel (or a gyro and a couple encoders) you should be in pretty good shape. If done right, an X-holonomic should be better than a tank drive, but if done wrong a tank would be a lot more receptive of simple, intuitive code.

Thanks for clearing it up. So gyros might help it go straight because going straight is the only thing I am worrying about.

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Gyros will help for error-correcting, but encoders provide an easier-to-use feedback on how straight the robot is going. The only problem is that 4 encoders would take up 8 digital sensor ports…

would you advise against using only two encoders on a x-drive??

If you put the encoders on adjacent wheels, it would be impossible to differentiate between turning and one direction of strafing. If you had a gyro however, you would not have this problem and could get away with two encoders.
If you put the encoders on opposite wheels, it would be impossible to differentiate between strafing and driving straight (i.e. you wouldn’t know at which angle you were strafing).

So yes, I would advise against using two encoders to program a x-holonomic drive. Using three encoders should work, but you would end up having to solve for the rotation of the encoder-less wheel based on the rotation of the three encodered wheels.
I would therefore recommend putting encoders on two adjacent wheels and using a gyro in the middle of the robot to fill out the holes in the information from the encoders.

Always go for the more difficult, but I do have to agree that a free spinning rotation with a holonomic in an O shape would be desirably easier than in an X formation due to the orientation of the omni-wheels. Everything can be done though it’s not impossible.

In this game, if it was a choice between mecanums, holonomic, or X I would choose X-drive. Another additional advantage is that the motor placement will be out of the way of other things, where if a regular holonomic was used, the motors would be placed toward the inside of the chassis rather than outside the chassis. A bit confusing but if you build both you would get the point.

By “X-drive”, do you mean like this:

1 \ / 2
3 / \ 4

which wheels would you spin in which directions when you wanted to turn? =p

Normally “X drive” is like this

\ /
With the slashes being the wheels

Yes, and for a good reason.

I was replying to bgamsky’s post, which treats them as being different:

Ouch i didnt think of the turning at all. Sorry. N why would they call it an X drive if its shaped more like an O?

Probably because it sounds cooler, I guess. I don’t know where the term comes from but it’s possible it isn’t named after what the wheels look like.

i think because the other one is the “+” drive
and the X is essentially the + tilted sideways

“+” drive is also not shaped like a +, though, so that doesn’t really get us any closer to solving the mystery.

Edit: I found a clue, though:

Now THAT makes sense! Good input :smiley:

this would be the same if i decided to use Mecanum wheels right

yes, that’s correct