chassis ideas swerve

[staplemonx]

I really liked how 1717 drove this year. So I am trying to improve on the chasis I saw this year with some guess work since i didn't get to really dive in and get to know it. pnuematic super shifter chain linked to drive shafts and window motor chain linked to drive collar. Electrical bay on the botom. 1/8 aluminum rivitied together. Assum the total chassis weight is 25lbs with rivits.

Is this about right?

Would you use banenot motors instead of window motors for steering?

Is the super shifter gear box over kill?

How much pushing power would this have?

How fast would this be with 2 or 4 cims?

[Aidan S.]

I would not suggest using banebots on your steering. They have a tendency to short circuit and cause your robot to time out in matches for about 30 seconds. Putting them in the drivetrain would just worsen this problem because they would be exposed to a lot of debris, which is the cause of this problem. it's really easy to fix the shorts on the banebots, but they would be difficult to access in your drive system and you would have to fix the short every match because of the level of dirt and debris they would be exposed to.

[R.C.]

Originally Posted by Hawkeye610

I would not suggest using banebots on your steering. They have a tendency to short circuit and cause your robot to time out in matches for about 30 seconds. Putting them in the drivetrain would just worsen this problem because they would be exposed to a lot of debris, which is the cause of this problem. it's really easy to fix the shorts on the banebots, but they would be difficult to access in your drive system and you would have to fix the short every match because of the level of dirt and debris they would be exposed to.

Not necessarily true. When you say banebots, what you do mean?

The gearboxes? The motors? The entire package?

The 2 main issues with banebots is:

-The gearbox blowing itself apart on high reductions (ex: 256:1)
-The 775 case shorting (not the 550/540/395)

-RC

[Aidan S.]

I was referring to the case shorts on the 775s. Our team experienced many problems with the 775s on our arm at our later competitions this year. Team 2056 showed us a method to fix the problem by attaching the positive battery lead to the positive terminal, and the negative lead to the case, and then moving our motor. That seemed to fix the problem, but it was still pretty consistent. The problem would be more apparent if the motor was on the drivetrain, which would be time consuming to fix after every match

[rocknthehawk]

Everyone on 1717 was super nice about explaining their robot and actually showing us up close how it works. I was totally impressed!

[11douglash]

Stricly speaking, the maximum speed would vary upon any gearing / sprocket + chain ratios.

[staplemonx]

Originally Posted by rocknthehawk

Everyone on 1717 was super nice about explaining their robot and actually showing us up close how it works. I was totally impressed!

Thanks for the photos, are those pnuematic motors attached to the steering belts or the drive belts.

[staplemonx]

Originally Posted by 11douglash

Stricly speaking, the maximum speed would vary upon any gearing / sprocket + chain ratios.

Makes sense. I was curious about a general 2 speed transmision. is swerve strictly for mobility + speed? Or can it get high torque and friction to the ground and push?

[staplemonx]

Originally Posted by Hawkeye610

I would not suggest using banebots on your steering. They have a tendency to short circuit and cause your robot to time out in matches for about 30 seconds. Putting them in the drivetrain would just worsen this problem because they would be exposed to a lot of debris, which is the cause of this problem. it's really easy to fix the shorts on the banebots, but they would be difficult to access in your drive system and you would have to fix the short every match because of the level of dirt and debris they would be exposed to.

Thanks for the heads up. Would the window motors work? Or should we go with pnuematic motors like 1717?

[EricH]

Originally Posted by staplemonx

Thanks for the heads up. Would the window motors work? Or should we go with pnuematic motors like 1717?

Window motors ought to work, though they might be a bit heavy.

Oh, and swerves can push. They just tend to try to avoid pushing matches by using their mobility.

[staplemonx]

Originally Posted by EricH

Window motors ought to work, though they might be a bit heavy.

Oh, and swerves can push. They just tend to try to avoid pushing matches by using their mobility.

Good to know

[Mark Sheridan]

Originally Posted by staplemonx

Thanks for the photos, are those pnuematic motors attached to the steering belts or the drive belts.

I talked to 1717 for a bit about how their drive train works. Until someone from their team posts, I will do my best to fill you in.

The pneumatic parts you see are for their shifters. They put the shifter mechanism on the opposite side of where the Andy-Marks are placed. I don't know the full story behind this but I have a hunch that they did this because originally they were going to have each CIM have its own gearbox and each module independently steered.

From my conversations with one of their mentors, they choose not to go that route to conserve two banebot motors. So they have two CIMs for each gearbox

So the belts you see by the pneumatics are for drive and the ones the cross are for steering. The drive left wheels together and right wheel together. For steering, the front right wheel is connected to the back left wheel and vice versa. This means to rotate the robot, they have to come to a stop but they specifically designed their robot to minimize the need to rotate.

For my opinion, you can get away with a standard andymark shifter. The supershifter has a extra gear reduction you don't need. You will defiantly want to use all 4 CIMs if you want to cover the field as fast as 1717 does.

Another great team to look up is 1640: wiki.team1640.com/

[Andrew Schreiber]

Originally Posted by staplemonx

I really liked how 1717 drove this year. So I am trying to improve on the chasis I saw this year with some guess work since i didn't get to really dive in and get to know it. pnuematic super shifter chain linked to drive shafts and window motor chain linked to drive collar. Electrical bay on the botom. 1/8 aluminum rivitied together. Assum the total chassis weight is 25lbs with rivits.

Is this about right?

Would you use banenot motors instead of window motors for steering?

Is the super shifter gear box over kill?

How much pushing power would this have?

How fast would this be with 2 or 4 cims?

JJ, it was nice meeting you in St Louis.


Both motors work for steering. Really I would suggest using the window motors if only because we have a very limited amount of high power motors (CIM, FP, BB) and using 6 of them in the drive train may not be the best use of those resources.

I have only ever seen 1 shifting swerve drive and that was from 118. Check for their 2007 video if I recall. Aside from acceleration I don't really see a point in doing that. Swerve systems are more mobile than many other platforms. This allows them to drive around obstacles rather than pushing through. Unfortunately I don't see many teams using them this way.

As for how fast it would be, perhaps take a peek at JVN's mechanical design calculator.


Now, the part you didn't ask for... If this was just a thought experiment then cool. From what Akash has told me about 3553's resources, and from my general opinions of most teams, doing a swerve drive isn't the best option in my opinion. I would feel that mastering a 6wd style base would be a very good use of time and resources. Train some phenomenal drivers and make it bullet proof. The key to a successful season is a robust and reliable drive system. Additionally, swerve systems require massive allocation of resources including driver practice (meaning you need 2 bots) and programming. The software for a swerve system is difficult and, if done wrong, can result in your system being unusable or not performing to your expectations.

The above being said, if you decide to go this route I will make two suggestions:

Prototype in Vex/FTC/Any Other Small Scale. - I cannot stress this. It will save thousands of dollars and most of the concepts will apply at the large scale.

Build two robots. - Driver practice is key with swerve, you can't just point a direction and go, there is a delay.

If you need any help (I'm not an engineer, just a programmer) Akash has all my contact info. Hope to see 3553 out on the field next year.

[staplemonx]

Originally Posted by Andrew Schreiber

JJ, it was nice meeting you in St Louis.



Now, the part you didn't ask for... If this was just a thought experiment then cool.

Thanks for all of the info. I know akash wants to go the 6 wheel route for next year so that is probably where we will end up. But i want to try and design and prototype a drive base for each drive train options just to learn. Also, since we have to get kids up to speed on this stuff quickly next year i wanted them to help us build a few chassis over the summer so they can see what all of the different drive trains can do. Resources will always limit what we do so will see if we get to the swerve. You will see a few more threads like this on the other drive trains.

[rocknthehawk]

Originally Posted by Mark Sheridan

I talked to 1717 for a bit about how their drive train works. Until someone from their team posts, I will do my best to fill you in.

The pneumatic parts you see are for their shifters. They put the shifter mechanism on the opposite side of where the Andy-Marks are placed. I don't know the full story behind this but I have a hunch that they did this because originally they were going to have each CIM have its own gearbox and each module independently steered.

From speaking to the mentors/students, the gearboxes were designed/built in house.

As explained, you can see the left side and right side are both powered from 2 cims each on a 2 speed gearbox. The two cross belts control steering between left front/right rear and vice versa.

Mark, could you explain why they would need to stop to rotate? From watching their matches on Curie, I never saw them really stop moving.
I haven't been able to find many videos, but you can see them here: http://www.youtube.com/watch?v=n63CaX1W-pU (the red alliance robot with the black lift)

(Team 126 is looking into building a similar drivetrain for the off season)