pic: Light Weight Swerve Module

[Bryce2471]

loading photo ...

[Tyler2517]

Is that with the motor weight?

[Bryce2471]

I tried to match the motors to actual weight by changing the materials in inventor.

here's a breakdown of weights as inventor sees them.
cim: 2.78lbs
Planetary: 0.4 lbs
AM 912: 0.51lbs
Other: 1.56lbs

[Munchskull]

Looks great. Are you going to use it on any of your robots?

[jman4747]

Originally Posted by Bryce2471

I tried to match the motors to actual weight by changing the materials in inventor.

here's a breakdown of weights as inventor sees them.
cim: 2.78lbs
Planetary: 0.4 lbs
AM 912: 0.51lbs
Other: 1.56lbs

You can key in a custom weight for an individual part or assembly.

[asid61]

5.25lbs with the motors, shifting gearbox, AND module!
You win swerve. Seriously, this weighs less than a WCD. If you make a 4-cim, 4 minicim version then there would be very little disadvantage to using this apart from the programming and driving. I also think you could make this into a shifting version without too much trouble.
How are you tensioning the belt? If it just slides along the track you have and is clamped by screws, I would defintiely change that to having something similar to 192's gearbox wehre you have seperate holes for each tension. Sliding tensioers with friction holds are sketchy IME. That was the primary reason why our drivetrain failed this year. It might not be as bad on the cim, but it won't add weight to change that slot to holes.
How much ground clearance for the cim and module? Why banebots over versaplanetary? A BAG motor and that massive gear reduction will allow you to use a single-stage versaplanetary for the turning motor.
Where is the top plate? If it's not present, that should be okay, but testing this would be of high importance IMO.

If you could release the CAD, that would be a boon, but I understand if you don't want to.

EDIT: Wait, is that CIM held on by only two standoffs? That seems very insecure; add at least one more for strength..

[cadandcookies]

What would the clearance be for the CIM wires?

[Chris Endres]

Wow, that's amazing! Just a few question though. Do you feel that the standoffs will hold-up on the potential forces acted on the assembly, especially if they're that long? Why is there a bushing on the swerve module without a supporting plate? And how is the rotation gear held onto the bottom plate, just by the part where the CIM powers the wheel, or is it not in the CAD yet? What is the calculated FPS? What is the estimated cost?

[Caleb Sykes]

Originally Posted by asid61

If you make a 4-cim, 4 minicim version then there would be very little disadvantage to using this apart from the programming and driving.

And building.

[asid61]

Originally Posted by inkling16

And building.

Well yes, but I would presume that getting the drivetrain machinined could happen before the manipulators, thus making the assembly have much less of an impact. Driver training would be slightly shorter, but any driver of swerve should really have many hours of driving swerve under their belt pre-season.

EDIT:
The banebots planetaries are 0.5lbs according to the website, not 0.4lbs. Just a quick heads up.

[Bryce2471]

Looks great. Are you going to use it on any of your robots?

To minimize the time commitment required to build swerves, our team built four swerves last year in the off season that then got reused on the practice bot for the competition season. This year, we are in a notable money crunch, so we've decided to do limited off season swerve building. Because of that, the odds of us putting this to use in the build season are minimal.

You can key in a custom weight for an individual part or assembly.

Great! I did't know that you could do that. I'll have to look it up.

How are you tensioning the belt? If it just slides along the track you have and is clamped by screws, I would defintiely change that to having something similar to 192's gearbox wehre you have seperate holes for each tension.

It has a single hole on one side, and a curved track on the other. I like this setup because it is adjustable enough to allow for different gear ratios without changing the belt.

Why banebots over versaplanetary? A BAG motor and that massive gear reduction will allow you to use a single-stage versaplanetary for the turning motor.

The bane bots is cheaper, smaller, and lighter. I couldn't find a configuration that would allow for a single stage planetary without being really large.

Wait, is that CIM held on by only two standoffs? That seems very insecure; add at least one more for strength..

There are three standoffs. I'll try to get the CAD up here pretty soon I suppose.

Where is the top plate? If it's not present, that should be okay, but testing this would be of high importance IMO.

I'm not sure what you mean by "top plate."

What would the clearance be for the CIM wires?

0.59"

Do you feel that the standoffs will hold-up on the potential forces acted on the assembly, especially if they're that long?

I'm pretty sure they will be fine. The forces on them are from holing up the CIM motor and encoders, and from the CIM torque.

Why is there a bushing on the swerve module without a supporting plate?

There isn't. I think you are referring to the 3D printed encoder gear.

how is the rotation gear held onto the bottom plate, just by the part where the CIM powers the wheel, or is it not in the CAD yet?

there is an integral trust bearing cut into the turning gear, and bottom plate. It's much like what team 16 has done in the past. Basically there is a track for a 0.25" ball bearing cut into the bottom of the plate and the top of the gear.

What is the calculated FPS? What is the estimated cost?

It's currently geared at 3.22 to 1 on a 2.75in wheel. So about 16fps, although it's easily changeable.

Thanks for all the great questions and comments, I hope my answers make sense.

[asid61]

Originally Posted by Bryce2471

To minimize the time commitment required to build swerves, our team built four swerves last year in the off season that then got reused on the practice bot for the competition season. This year, we are in a notable money crunch, so we've decided to do limited off season swerve building. Because of that, the odds of us putting this to use in the build season are minimal.

Great! I did't know that you could do that. I'll have to look it up.

It has a single hole on one side, and a curved track on the other. I like this setup because it is adjustable enough to allow for different gear ratios without changing the belt.

The bane bots is cheaper, smaller, and lighter. I couldn't find a configuration that would allow for a single stage planetary without being really large.

There are three standoffs. I'll try to get the CAD up here pretty soon I suppose.

I'm not sure what you mean by "top plate."

0.59"

I'm pretty sure they will be fine. The forces on them are from holing up the CIM motor and encoders, and from the CIM torque.

There isn't. I think you are referring to the 3D printed encoder gear.

there is an integral trust bearing cut into the turning gear, and bottom plate. It's much like what team 16 has done in the past. Basically there is a track for a 0.25" ball bearing cut into the bottom of the plate and the top of the gear.

It's currently geared at 3.22 to 1 on a 2.75in wheel. So about 16fps, although it's easily changeable.

Thanks for all the great questions and comments, I hope my answers make sense.

That tensioning method could be unreliable. Testing would be paramount, and easier would be to have discrete mounting holes for each tensoning distance.
By "top plate" I mean an upper support. Right now, the only thing keeping the module in place is the weight of the robot. You need to have some kind of way to secure the module from above as well, either by means of a plate on top of the module or by using some kind of loose clamp on the bottom plate.
As for gearboxes, I see what you mean. I'm cadding one like this but shifting right now, and the banebots is considerably lighter than the versaplanetary. However, I hear that they can be unreliable.

[Bryce2471]

Originally Posted by asid61

That tensioning method could be unreliable. Testing would be paramount, and easier would be to have discrete mounting holes for each tensoning distance.
By "top plate" I mean an upper support. Right now, the only thing keeping the module in place is the weight of the robot. You need to have some kind of way to secure the module from above as well, either by means of a plate on top of the module or by using some kind of loose clamp on the bottom plate.
As for gearboxes, I see what you mean. I'm cadding one like this but shifting right now, and the banebots is considerably lighter than the versaplanetary. However, I hear that they can be unreliable.

Wow! That was a fast response time.

We ran a swerve drive with a setup much like this last year but with two straight slots instead of a hole and a curved slot. We didn't have any issues with it. Truth is, you don't want a whole lot of tension in the first stage of reduction because it will cause resistance.
The caster is held from falling out of the robot is the snap ring groove above the timing pulley. (The groove is hard to see in this render)
I'll look into the reliability of the banebots. Thanks for the heads up.
I think this could be modified to make a great shifting design. I might CAD one up next time I get a notable block of free time.

[asid61]

Originally Posted by Bryce2471

Wow! That was a fast response time.

We ran a swerve drive with a setup much like this last year but with two straight slots instead of a hole and a curved slot. We didn't have any issues with it. Truth is, you don't want a whole lot of tension in the first stage of reduction because it will cause resistance.
The caster is held from falling out of the robot is the snap ring groove above the timing pulley. (The groove is hard to see in this render)
I'll look into the reliability of the banebots. Thanks for the heads up.
I think this could be modified to make a great shifting design. I might CAD one up next time I get a notable block of free time.

Ah, so that's how it's held. Very interesting.

[Kevin Ainsworth]

Great design!!!
The more designs someone does the more they learn and the better they get.
Your designs get more compact and innovative every time, keep them coming.

What is shifting the gears? I don't see an air cylinder or servo in there.

I prefer the Vex Versa gearboxes also, due to the fact the output shaft has a flange. The Banebots gearbox doesn't have a flange on the output shaft and that can cause problems if not used correctly. We tried using a round sleeve and a screw/washer to pull the gear up against the Banebots gearbox bearing with bad results last year. We switched to clamp collars and everything ran smooth after that. I agree they're lighter and that's a benefit.

I am a little nervous about retaining the steering balls with a single clip at the top. We went through a discussion about using a clip on our 8WD setup and found they can take about 600lbs of force for a 1/2" shaft so the clip isn't the issue. I am more concerned with the strength of the upper plate that will be seeing that load. I think there are more forces there than you are considering. In normal operations the weight of the robot will bear down on the balls and this will be a non-issue. When the robot is pushed to the side and the balls try to climb out of their grooves you will see vertical load that might cause issues. Again you might be fine.

The other consideration is contamination getting into the steering ball tracks. We had issues with aluminum chips from drilling on the robot, debris from the field and the carpet fibers getting kicked up from the tires getting in the steering grooves. This is the reason that we are switching to sealed ball bearing on our 2nd generation swerves. We disassembled our units and replaced the balls multiple times last year. I would guess Bomb Squad doesn't have this issue because they leave the steering bearing setup above the wheel and not right next to the carpet. I would be interested to hear from them if they have seen this issue also. Maybe consider a labyrinth seal (a winding path to the balls instead of a straight slot between the plates). I was considering using two opposing L-shaped walls instead of two round grooves.