pic: New swerve CAD from 2471

[Bryce2471]

Originally Posted by Dale

Very cool! Will this make it on a BunnyBot this year?

Also, what is your reduction off of the CIMs? It looks like it will be on the fast side but may be that's what you intended.

Thanks! Yes, the plan is to test this out on a BunnyBot this fall.

The reduction is quite fast, although it's a bit slower than what we ran last year. The final reduction is 3.6:1, or approximately 2.4 inches per revolution of the CIM shaft.

[kk052]

Hmmm... looks somewhat similar to one I've seen before...
just make sure the C brace the swerve's attach to are not shaved completly flat, or you might lose strength in the frame. also are you not worried that the belt might slip off the larger gear because its not flanged?
also most years bumpers must be supported every 8 inches do they mount on the swerves, or is there an additional bracket that is hidden?

[Dale]

Well you certainly won't be winning any pushing battles going that fast but on the up side, if it works as well as last year, maybe you won't need to!

[Tyler2517]

Originally Posted by Dale

Well you certainly won't be winning any pushing battles going that fast but on the up side, if it works as well as last year, maybe you won't need to!

We proved this year that you don't need to push back to win a pushing battle just not get pushed.

I still think its geared a bit high.

[asid61]

Originally Posted by Tyler2517

We proved this year that you don't need to push back to win a pushing battle just not get pushed.

I still think its geared a bit high.

It's geared for around 14fps adjusted it looks like. That's not too fast.
Even so, I would be worried about collisions at that speed on the modules. A hard hit on a corner could render you immobile, as well as costing a few hundred dollars. Even if nothing breaks mechanically, encoders are pretty fragile.
With frame perimeter rules, are you really gaining extra room this way?

[Dale]

It's also going to impact acceleration. I suspect being geared that high the robot will seldom actually get to top speed during a match before having to change direction. Usually robots geared that fast will have six CIM drive trains just for that reason.

[Bryce2471]

Originally Posted by Dale

It's also going to impact acceleration. I suspect being geared that high the robot will seldom actually get to top speed during a match before having to change direction. Usually robots geared that fast will have six CIM drive trains just for that reason.

I think you'll find that a robot geared for 14 fps on 4 cims will have plenty of power to accelerate quickly. Our comp bot did fine this year, and it was geared for about 18 fps. Our bunny bot was geared even faster that that, and it won. so obviously, it will depend on the game, but in my opinion, 14 fps isn't "too fast".

[Dale]

Your robots were certainly zippy! I'd love to know how long it took the robot to get to its terminal velocity (and what that velocity is.) Maybe that would be a good fall project for your software folks graphing speed vs time as measured by an encoder on your 2014 robot.

Going that fast will also impact power consumption during acceleration. I wonder what the peak current is.

[Bryce2471]

Originally Posted by Dale

Your robots were certainly zippy! I'd love to know how long it took the robot to get to its terminal velocity (and what that velocity is.) Maybe that would be a good fall project for your software folks graphing speed vs time as measured by an encoder on your 2014 robot.

Going that fast will also impact power consumption during acceleration. I wonder what the peak current is.

Yeah, that would be an interesting experiment. It would be hard to do either, maybe I'll get back to you with those numbers after our next shop meeting on Wednesday. You're right about power consumption. Our bunny bot pulled way too many amps when accelerating, and would often have a dead battery by the end of the match. Our comp bot wasn't so bad, but a battery would die after about 7-8 min of heavy practice. I'm just glad that we did't have to deal with our main breaker tripping!

[Bryce2471]

Originally Posted by asid61

...Even so, I would be worried about collisions at that speed on the modules. A hard hit on a corner could render you immobile, as well as costing a few hundred dollars. Even if nothing breaks mechanically, encoders are pretty fragile.
With frame perimeter rules, are you really gaining extra room this way?

Last years modules only costed about $220 each. I expect this years to be a little higher, but still not too bad. the encoders we are using are non contacting magnetic absolute encoders, so I doubt the would break. Although, if they did, they only cost about $10.
I'm not really sure what you mean by "With frame perimeter rules, are you really gaining extra room this way?"

[Andrew Schreiber]

Originally Posted by Bryce2471

Last years modules only costed about $220 each. I expect this years to be a little higher, but still not too bad. the encoders we are using are non contacting magnetic absolute encoders, so I doubt the would break. Although, if they did, they only cost about $10.
I'm not really sure what you mean by "With frame perimeter rules, are you really gaining extra room this way?"

Source on these absolute encoders @ $10 a pop?

[Bryce2471]

I forgot to post the estimated weight. According to inventor, these modules will be over a pound lighter that last year's model: Weighing in at 6 lbs each.
Including all that is pictured except the bumper, the drive base should weigh about 30.5 lbs.

[Gdeaver]

Absolute encoder. TT electronics 6127 series. .25 to 4.75 volt output. more like 11$ a piece. Used on our swerve for 3 years now. Like them.

[Bryce2471]

Originally Posted by Gdeaver

Absolute encoder. TT electronics 6127 series. .25 to 4.75 volt output. more like 11$ a piece. Used on our swerve for 3 years now. Like them.

Oops. I PMed Andrew about this, but I forgot it still looks like I left him hanging.

Yeah, we've used those encoders sense champs this year.

[Andrew Schreiber]

Originally Posted by Gdeaver

Absolute encoder. TT electronics 6127 series. .25 to 4.75 volt output. more like 11$ a piece. Used on our swerve for 3 years now. Like them.

Thanks, what's the rotate over point look like? Just a transition from high voltage to low? Can I simply map 0-360 to .25-4.75 and call it a day?