pic: 2996 Octocanum Prototype

[Liquid_Science]

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[AdamHeard]

I'd be concerned about the slender shafts that front and rear of the cylinders attach to. They might not have enough stiffness.

[thedude019]

This looks great! Is the weight an issue? Ive seen some really heavy octocanum drives before.

[Liquid_Science]

Originally Posted by thedude019

This looks great! Is the weight an issue? Ive seen some really heavy octocanum drives before.

We managed to get the weight right around 54 pounds with everything needed to run the bot (electronics, pnematics, ect.)

[JoshWilson]

Originally Posted by Liquid_Science

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looks pretty cool, but I'm not exactly sure how that type of drive train is beneficial, could you explain? I've never seen or heard of it before, so I don't know anything about them.

[Ari423]

Originally Posted by JoshWilson

looks pretty cool, but I'm not exactly sure how that type of drive train is beneficial, could you explain? I've never seen or heard of it before, so I don't know anything about them.

The idea is that you get the best of both worlds: mecanum wheels for maneuverability and traction wheels for pushing. The main downsides are weight and complexity.

[jnicho15]

What was your reason for putting the traction wheels on the pivot? In my team's design, we placed the mecanums on the pivot because then, when you retract the traction wheels, you don't need as much cylinder force to hold them off the ground. For traction mode, the mecanums barely need to be off the ground or can be slightly touching- the cylinders don't need to support nearly as much weight. In your design, the cylinders need to hold the whole weight of the robot up off the ground so only the mecanums are touching.

[Liquid_Science]

Originally Posted by jnicho15

What was your reason for putting the traction wheels on the pivot?

The biggest reason is we wanted to use 4in casters and 6in Mecanums. The cylinders we used should be plenty enough to lift even a fully weighted robot, since the boar on each is 1.5" with a 1" stroke, and there are 4 of them. Aslo, we wanted the casters to be the default wheel if something failed. The two wheels can easily be switched around, if we wanted to run 6in casters and 4in mecanums; depends on the game really.

[Chris is me]

Originally Posted by jnicho15

What was your reason for putting the traction wheels on the pivot? In my team's design, we placed the mecanums on the pivot because then, when you retract the traction wheels, you don't need as much cylinder force to hold them off the ground.

Two great reasons to pivot about the traction wheels. First is that traction wheels will see a lot more force in all directions than the mecanums will, especially when being pushed from the side. Pivoting about the traction wheels means these wheels are more rigidly supported by the whole frame. Additionally, mecanum wheels seem to behave better when on a suspension, and the cylinders will serve as a form of a suspension, helping to ensure all of the wheels are touching the ground. The amount of cylinder force for holding one wheel off of the ground instead of the other really shouldn't change in either case.

[JesseK]

How does this drive train plan to handle bumpers?

[T3_1565]

I really enjoy looking at these types of drive trains. Back in my days these types of drives were never heard of. I made something to try and accomplish what this does.

These are cooler to see people make for sure.

[JesseK]

Originally Posted by T3_1565

I really enjoy looking at these types of drive trains. Back in my days these types of drives were never heard of. I made something to try and accomplish what this does.

These are cooler to see people make for sure.

You should provide a link. That type of drive train hasn't been seen since. It was really cool for its time, IMO.

[nuclearnerd]

Wow, pretty!

I would really recommend extending the outer plates that join your pivot points all the way out to the front and back plates if you can. I'd be worried about cantilevering those huge assemblies off the side of a pair of bearings that are only < 1" apart! Doing so would also let you support your side bumpers for more of their length (the 2014 rules required support every 8").

[T3_1565]

Originally Posted by JesseK

You should provide a link. That type of drive train hasn't been seen since. It was really cool for its time, IMO.

I dont want to hijack the thread lol. Search 1565 Linkage if your interested.

I feel like these types of drives came from what that drive was. Opened up the door for pneumatics manipulating wheels. Before that it was only Swerve Drive.

[T3_1565]

I am curious though. Is there a reason that you need 4 cylinders to move the wheels? Can you put a push bar from 1 pod to another and use a wider diameter piston in the middle of the bot? That way you only need 2 pistons and less chance of there being problems with switching wheels?

As I said I'm old and not up to date on these drives lol. There may be a really easy reason why you need them seperate that I'm missing