pic: Butterfly Drive Concept

[hectorcastillo]

I'm actually not all that sure what the advantages are over octanum. I know that mechanums are a little trickier to code. I also know that some people just don't like mechanums for whatever reason (not really a valid argument).

I'm definitely not the best person to answer this question. I curious to see what other advantages people can think of.

[Knufire]

Originally Posted by hectorcastillo

mechanums

Originally Posted by Mecanum Wheel

Hello Mark. Mecanum is a commonly misspelled word. There are multiple ways to say it but only one way to spell it. If you have any questions, feel free to ask. Until then, you may refer to this handy chart:

[hectorcastillo]

Everything I thought I knew has been nothing but a lie...

[BBray_T1296]

Originally Posted by Knufire

I was hoping Mecanum Wheel would reply, but quoting "it" is just as sufficient

By the way, Mecanum AB is the company that either invented or popularized the wheel, but is nonetheless where the name came from

[RoboticDaymon]

Originally Posted by orangemoore

With Mecanum you have to run each wheel individually. Here they can run each side resulting in the ability to run 3 cims per side.

Yep this is why it was designed like this. Also I wanted to ability to have a 2 speed shift with the wheels at a 1:1 ratio so this seemed like the simplest solution. Also the next iteration of the design will (probably) have the traction and omni flipped.

[asid61]

Originally Posted by RoboticDaymon

Yep this is why it was designed like this. Also I wanted to ability to have a 2 speed shift with the wheels at a 1:1 ratio so this seemed like the simplest solution. Also the next iteration of the design will (probably) have the traction and omni flipped.

You do lose some functionality compared to making the traction wheel smaller, but do you think the loss pushing resistance of this drive is worth the lower gear in omni mode?
Might want to rethink that 6-cim drivetrain. The Roborio browns out so easily...

[hectorcastillo]

Originally Posted by asid61

You do lose some functionality compared to making the traction wheel smaller, but do you think the loss pushing resistance of this drive is worth the lower gear in omni mode?
Might want to rethink that 6-cim drivetrain. The Roborio browns out so easily...

Can you explain "browning out" or share share thread that explains this?

[Dunngeon]

Originally Posted by hectorcastillo

Can you explain "browning out" or share share thread that explains this?

Google is a great way to answer your own question, click here.

Click the first result

[Knufire]

Originally Posted by asid61

Might want to rethink that 6-cim drivetrain. The Roborio browns out so easily...

Agreed. Software current monitoring/control, good monitoring of battery health, and a bulletproof electrical system are essential to effectively use a 6 CIM drive in a normal (i.e. not RR) game on this control system.

[RoboticDaymon]

For the 6(7) cim I agree for most circumstances it is probably overkill. if this were to be manufactured I would probably just leave a cim out of each of the 2 speed gearboxes or use current monitoring code or both. Realistically this would probably be assembled with 2 cim in each 2 speed and 1 mini cim for the center wheels.

[philso]

Have you designed this so that the complete butterfly module can be removed and installed as a single complete assembly or do the butterfly modules have to be assembled in the chassis? We did it the later way in 2014. It typically took an hour or more to change a wheel. 148 did it in 2014 the first way and it would take them 5 minutes or less to change out a whole butterfly module.

[RoboticDaymon]

Originally Posted by philso

Have you designed this so that the complete butterfly module can be removed and installed as a single complete assembly or do the butterfly modules have to be assembled in the chassis? We did it the later way in 2014. It typically took an hour or more to change a wheel. 148 did it in 2014 the first way and it would take them 5 minutes or less to change out a whole butterfly module.

The modules should be able to be installed as a complete assembly. They were designed to be put together outside the robot then slide into place. The only parts that might need to be assembled while on the robot are the pneumatics and the drive axles directly off the gearbox.

On a different note after some feedback from my team today there are a few different variations on the design i will be working on. I will post these revisions as soon as i finish the CAD for it.

[Chak]

Originally Posted by RoboticDaymon

The modules should be able to be installed as a complete assembly. They were designed to be put together outside the robot then slide into place. The only parts that might need to be assembled while on the robot are the pneumatics and the drive axles directly off the gearbox.

Are you direct driving one of the wheels straight off the gearbox? If so, you might want to consider how hard it would be to slide the module onto the drive axle. You can't completely assemble the module separately if the gearbox output shaft is required to hold the module together. the direct driven wheel and everything floating in the module would have to line up perfectly to slide the module on. That's really annoying, especially if you're using hex. BTW, I'm assuming these things because it's a COTS gearbox.

My team had a similar design for our octocanum modules this year, and I regret not considering assembly when we designed it. I always chose to assemble half the module on the robot instead of frustratingly trying to lining up all 5 hex components.