pic: Team 148 - 2011 - Raptor

[Dad1279]

Originally Posted by Chris is me

While it can be done with less resources, I'd be worried about these low resource teams trying this, mainly because wheel pod side loading is a pretty big concern with this style of drivetrain.

By the way, the above blog post refers to large performance gains with the removal of the 5th wheel. What are those gains?

Not to hi-jack, but that's how we did it, Drill press and bandsaw. Only machined parts are the two plates. Traction wheels direct drive, larger mecanums raised and lowered. 1-CIM 1-775 per module.


Side loading is not a problem, as the traction wheels are mounted conventionally with a bearing on both sides of shaft, and the mecanums are braced with sideplates/slides. Obviously not all is shown in this rendering.

[JVN]

Originally Posted by JVN

After receiving a number of requests in response to this post, I decided to highlight some of the subtle parts of this year's design on my blog as part of an "Inside Raptor" series.

Another in this series:
http://blog.iamjvn.com/2011/02/insid...retainers.html

Want to retain a flanged bearing? Drill some holes and rivet a washer over the flange.

-John

[Alex Cormier]

Originally Posted by JVN

Another in this series:
http://blog.iamjvn.com/2011/02/insid...retainers.html

Want to retain a flanged bearing? Drill some holes and rivet a washer over the flange.

-John

Did you also replace the bolts in the AM omnis with rivets?

[Greg Needel]

Originally Posted by Alex Cormier

Did you also replace the bolts in the AM omnis with rivets?

Yes we did and they haven't failed us yet. Not sure how much weight we saved by doing this but anything we can do to save a little bit is worth the effort. Additionally by doing this it was and opportunity to check each roller to make sure it rolled freely.

[Madison]

Originally Posted by Manoel

Team 810 did the same thing in 2002, from what I remember.

810 used 9" Bead-lok wheels for its main drive and lowered two absurdly wide belts to the ground for pushing. I don't recall the overall ratios, but the difference between the wheels and belts was 3:1.

[Captaindan]

haha fusion answered the call for awsome funchional leds check it out at the bayou regional ladies and gentlemen

[lynca]

Originally Posted by Greg Needel

Yes we did and they haven't failed us yet. Not sure how much weight we saved by doing this but anything we can do to save a little bit is worth the effort. Additionally by doing this it was and opportunity to check each roller to make sure it rolled freely.

I've noticed that our omni rollers eventually stop spinning. We have tried loosening the screws but sometimes we have to change the rollers completely.

How often do you guys swap out rollers ?

Did you notice any difference between riveting omnis instead of screws ?

[Akash Rastogi]

On the topic of plate gears, I remembered that 1771 had plate gears integrated into their turreted shooter's hood. The entire thing was also turreted on a huge laser cut sprocket. Guess they should've published some documentation on their robots! What a dominant machine they had that year.

I'm hoping 1477 and 2415 also have some cool integrated components in the coming seasons.

For anyone interested, it was a simple but pretty cool application.

[Andrew Schreiber]

Originally Posted by Akash Rastogi

On the topic of plate gears, I remembered that 1771 had plate gears integrated into their turreted shooter's hood. The entire thing was also turreted on a huge laser cut sprocket. Guess they should've published some documentation on their robots! What a dominant machine they had that year.

I'm hoping 1477 and 2415 also have some cool integrated components in the coming seasons.

For anyone who is feeling left out on the laser-cutty-goodness you can achieve a similar effect by taking a length of timing belt and wrapping your circular surface in it with the teeth facing out. It isn't as effective as having the teeth laser cut but for low torque applications it does work. 2337 use this approach somewhere on their 2009 robot (I'll snap a pic next time I am down there).

[jwfoss]

The adjustable length four bar link is a really slick trick. I've had that sketched out in my engineering notebook since the first time I ever saw that done back in 2008 at FLR. They had an adjustable lower link to stay within the sizing rules and to tilt the gripper up, whereas you adjust your upperlink to actuate your wrist. Also I believe theirs may have been passive (gas shock) where your is pnuematically adjusted.

FRC67 - HOT from 2008
http://www.chiefdelphi.com/media/photos/30680

[pwnageNick]

This robot is awesome. My first year of FRC was last year, and I remember being very frightened after seeing your promo video last year. I can't wait to see how you guys do at Alamo this weekend. Good luck this season 148, 2949 can't wait to see you guys perform at Worlds!

[Redo91]

You guys always impress.

Are you not worried with getting pushed too easily from the side when your traction wheels are up?
How well does the robot turn when the traction wheels are down?

I wish I could see your robot in person.

[Adam Freeman]

Originally Posted by jwfoss

The adjustable length four bar link is a really slick trick. I've had that sketched out in my engineering notebook since the first time I ever saw that done back in 2008 at FLR. They had an adjustable lower link to stay within the sizing rules and to tilt the gripper up, whereas you adjust your upperlink to actuate your wrist. Also I believe theirs may have been passive (gas shock) where your is pnuematically adjusted.

FRC67 - HOT from 2008
http://www.chiefdelphi.com/media/photos/30680

Unfortunately our 2008 adjustable lower link design never made it passed our practice field. The mechanical implementation on that design (PVC and gas shocks) had a serious transition phase that caused our programmers fits. We ended up re-designing the lower arm and replacing it with a solid link as soon as it came out of the crate Thursday morning @ FLR.

Raptor's adjustable arm is much more elegant and functional than that HOT '08 adjustable arm ever dreamed of being.

[JVN]

Originally Posted by JVN

After receiving a number of requests in response to this post, I decided to highlight some of the subtle parts of this year's design on my blog as part of an "Inside Raptor" series.

Another post in this series, my last before we take her out of the bag tomorrow morning at the Alamo regional:
http://blog.iamjvn.com/2011/03/insid...ntiometer.html

Our programmers accuse me of having a mental block which keeps me from designing sensors into the robot. To them I say: "BAGH!"

Good Luck to everyone who competes in week 1!
Raptor has one more big surprise up her sleeve which is ready to go. See you on the field

-John

[JesseK]

Hmm. More compactness (potentially):

1. Fix 2 long VEX metal pieces to the dead axle of the arm such that one of the square holes is concentric with the axle. The hole will have to be enlarged of course. The two pieces of metal should be far enough apart that the slop is minimized, regardless of whether the potentiometer gear is cantilevered or dual-supported.
2. Attach the VEX gear to the arm, as shown.
3. Attach the potentiometer and the potentiometer gear to the VEX metal using appropriate spacing for the chosen gears. The spacing is built-in since it's VEX.
4. Profit.

We've always had issues with potentiometers since we can't seem to keep them from slipping in the shafts we directly mount them to (thus needing to recalibrate them). Or the rubber band / polycord belts we make slip. It results in a bad calibration. Maybe we can try VEX this off season. Right now we use limit switches with encoders -- not too bad coding-wise, but man that's a lot of little wires to run.