Holonomic vs Mecanum Help!!

[kSniper]

Hello again, my team has been discussing pretty much every drive train method under the sun (including drift and ackermenn lol) but we have gotten stuck on Holonomic vs Mecanum and have a few questions that if you could help us with it would be much appreciated....

1. Would plastic molded wheels skid on carpet when trying to gain speed or push? How much so?
2. While trying to go from high speed to strafing around a corner would there be some diagnol skid?
3. What is your general thought on Mecanum vs Plastic Molded in terms of stability if we did the / \ design with Plastic?
4. The rubber on Mecanum...I have heard it is horrible for traction on carpet even compared to the plastic of say AndyMarks...is this true? or does the rubber help make the robot more capable of pushing or holding its ground.

And lastly when strafing with Mecanum ive been told you loose half the speed compared to straight aways....assuming thats true do you think thats really a bad thing or would that allow for better controllability?

Anyway if you guys could answer any or all of them It would be amazing thanks....Team303

[Alan Anderson]

I'm not really sure what your main question is. Using four Mecanum wheels gives you a holonomic drive base, so there's no "holonomic vs. Mecanum" issue in the first place.

Some of your other questions seem to assume something that I'm not aware of. You can make Mecanum wheels using whatever material you want for the rollers. Rubber is great for traction on carpet.

Mecanum drive doesn't necessarily have less power in the sideways direction compared to forward. It depends on how much friction there is on the small rollers.

[Tom Line]

Originally Posted by kSniper

Hello again, my team has been discussing pretty much every drive train method under the sun (including drift and ackermenn lol) but we have gotten stuck on Holonomic vs Mecanum and have a few questions that if you could help us with it would be much appreciated....

1. Would Holonomic wheels skid on carpet when trying to gain speed or push? How much so?
2. While trying to go from high speed to strafing around a corner would there be some diagnol skid?
3. What is your general thought on Mecanum vs Holonomic in terms of stability if we did the / \ design with holonomic?
4. The rubber on Mecanum...I have heard it is horrible for traction on carpet even compared to the plastic of holonomic...is this true? or does the rubber help make the robot more capable of pushing or holding its ground.

And lastly when strafing with Mecanum ive been told you loose half the speed compared to straight aways....assuming thats true do you think thats really a bad thing or would that allow for better controllability?

Anyway if you guys could answer any or all of them It would be amazing thanks....Team303

You've got your terms confused. You mean OMNI wheels vs. Mechanum wheels. Both result in a holonomic drive system, but use different methods.

The short version is, both are reasonably complex to program mechanum will result in a more highly geared robot for similar speed, and I'm really not sure which ends up with the best traction.

[kSniper]

apologies I was mixing up my terms, I had meant to make it more of a Meca vs Vertical Plastic Omni design.... There is no main question but rather i have several questions that all have to do with the stability and "pushing power" between the two designs

[Tom Line]

I would simply try to avoid pushing matches with either system. That's the point of the speed, and neither system pushes particularly well compared to a straight four wheel drive, crab, 6 wheel drive, or tread. Basically 3/4's of the bots will out-push you.

[GUI]

both systems are the same except that mecanum can goes faster forward and backward than omni (assuming everything else is the same). Mecanum can also make the chassis simpler, depending on the materials/methods you use.

[Jared Russell]

The same exact code can be used with either configuration.

Generally, 341 has used conventional omniwheels for holonomic drives, since the available wheels are of much higher quality (in my opinion) than off the shelf mecanum wheels. If you can make your own high-quality mecanum wheels, you can get away with a more normal looking frame.

[daltore]

I think it would be a little simpler to program mechanum reliably as apposed to omni, as with mechanum, you can have a regular tank drive operator interface with one of the controllers also controlling side-to-side motion on the x-axis of the joystick. This is fairly simple code, the hardest part is just telling the processor how to move the front wheels back and forth opposite the back wheels, but that's pretty easy. With omni holonomic/Kiwi/Killough the robot pretty much has to be programmed to know what's forward. From what I've seen in VEX, Mindstorms, and FRC, mechanum tends to lend itself to a slightly more powerful drive train, as omni holonomic has almost no resistance to movement, basically making it a hockey puck on wheels (note the incessant fishtailing of 2158's robot from 2007 FRC, where we only had 2 omniwheels, and were pushed around easily).

[StevenB]

Note: When I refer to omni, I mean a robot which has 90 degree omniwheels, one on each side of a square (or rectangle). That square can be rotated from the robot frame, meaning you have a wheel diagonally in each corner.

Originally Posted by daltore

I think it would be a little simpler to program mechanum reliably as apposed to omni

Unless I'm misunderstanding you, not really. As said before:

Originally Posted by Abwehr

The same exact code can be used with either configuration.

Originally Posted by daltore

From what I've seen in VEX, Mindstorms, and FRC, mechanum tends to lend itself to a slightly more powerful drive train, as omni holonomic has almost no resistance to movement, basically making it a hockey puck on wheels (note the incessant fishtailing of 2158's robot from 2007 FRC, where we only had 2 omniwheels, and were pushed around easily).

Power-wise, mecanum and 4-wheel omni are exactly the same. You get ~71% (sqrt(2)) power in one set of directions, and 50% in the directions 45 degrees from the first. Any differences are in the construction of the wheels.

[T3_1565]

you should go with the 1565 Linkage drive system (that's IMHO of course ) thats the best bet lol! (look it up!!)

[MrForbes]

Originally Posted by kSniper

And lastly when strafing with Mecanum ive been told you loose half the speed compared to straight aways....assuming thats true do you think thats really a bad thing or would that allow for better controllability?

I would consider this to be a feature, not a liability.

The hard part will be convincing those who haven't played with mecanum wheels that it is a fact