pic: New swerve CAD from 2471

[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!

[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?

[Bryce2471]

Originally Posted by Andrew Schreiber

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?

Yes, you can then call it a day. It's really simple to code, and we've found that the end behavior is surprisingly linear.

You can also get the flattened shaft version, so that set screws won't slip.

[Andrew Schreiber]

Originally Posted by Bryce2471

Yes, you can then call it a day. It's really simple to code, and we've found that the end behavior is surprisingly linear.

Thank you, just saved me a a fair bit of money in encoders.

[seanthompson]

Can you post the link to the encoders please?

[otherguy]

my guess is they are talking about this part:
http://octopart.com/6127v1a360l.5fs-...ogies-19910150

There are a number of different options it can be ordered in, see data sheet

Note these are rated at 500 RPM in the datasheet. So they likely more than sufficient for monitoring the position of a part - like the wheel's heading in this case. Without proper gearing they are likely not a good choice for use on things like a shooter wheel. If you're looking to monitor wheel rate of travel over ground, these aren't appropriate unless you've got wheels bigger than 6" or have geared the encoder down (assuming you're targeting a top speed or around 14fps).

[Dale]

Plus it's an analog output so in a high RPM application you'd be monitoring a saw tooth signal on the analog port.

[aaron_]

Looks very cool! And yes, I assume they are using this part http://componentsearch.com/search/se...127V1A360L.5FS