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-   -   pic: Seen at Fall Classic: Side (http://www.chiefdelphi.com/forums/showthread.php?t=138714)

EricH 24-10-2015 12:52

pic: Seen at Fall Classic: Side
 

cbale2000 24-10-2015 12:53

Re: pic: Seen at Fall Classic: Side
 
Wouldn't there be balance issues with a drive configuration like this?
Certainly an interesting concept regardless; at the very least in certainly makes good use of space.

EricH 24-10-2015 13:04

Re: pic: Seen at Fall Classic: Side
 
Quote:

Originally Posted by cbale2000 (Post 1501584)
Wouldn't there be balance issues with a drive configuration like this?
Certainly an interesting concept regardless; at the very least in certainly makes good use of space.

I didn't see any issues. At least not in terms of tipping.

asid61 24-10-2015 13:24

Re: pic: Seen at Fall Classic: Side
 
Wait, can it strafe? How do the wheels look while driving?

EricH 24-10-2015 13:35

Re: pic: Seen at Fall Classic: Side
 
Quote:

Originally Posted by asid61 (Post 1501591)
Wait, can it strafe? How do the wheels look while driving?

It can strafe. Can't say I was paying attention to the wheels. Talking to the team, they started with mecanum code.

Jamie Kalb 24-10-2015 13:52

Re: pic: Seen at Fall Classic: Side
 
What’s the main body piece made of? It’s not fiberglass, is it?

EricH 24-10-2015 14:02

Re: pic: Seen at Fall Classic: Side
 
Quote:

Originally Posted by Jamie Kalb (Post 1501596)
What’s the main body piece made of? It’s not fiberglass, is it?

Right the first time. You should see their regular-season robot.

Travis Schuh 24-10-2015 15:51

Re: pic: Seen at Fall Classic: Side
 
Is that back omni wheel powered? It is hard to tell from the picture, but would make most sense if it was powered.

EricH 24-10-2015 16:15

Re: pic: Seen at Fall Classic: Side
 
Quote:

Originally Posted by Travis Schuh (Post 1501603)
Is that back omni wheel powered? It is hard to tell from the picture, but would make most sense if it was powered.

All wheels are powered.

Some of the chain runs actually drive the lift.

GeeTwo 24-10-2015 19:05

Re: pic: Seen at Fall Classic: Side
 
I LIKE IT!

Seems like the U-drive concept is popping up all over this off-season (third I've seen posted, including my own), but this one definitely takes it to a new level, especially when it comes to controlling unintended torque, and also in wrapping around the game piece.

Are those chains or belts running to the back? Are the motors all the way back with the strafe wheel? That looks like too much slack.

seg9585 24-10-2015 23:27

Re: pic: Seen at Fall Classic: Side
 
I'm trying to understand the overall benefit of this configuration vs a standard mecanum setup or even front mecanum back 2 omni. Surely this config is not favorable in traction with only minimal benefit to powered rotation. Weight reduction (3 gearboxes vs 4)?

AdamHeard 24-10-2015 23:53

Re: pic: Seen at Fall Classic: Side
 
Quote:

Originally Posted by seg9585 (Post 1501645)
I'm trying to understand the overall benefit of this configuration vs a standard mecanum setup or even front mecanum back 2 omni. Surely this config is not favorable in traction with only minimal benefit to powered rotation. Weight reduction (3 gearboxes vs 4)?

Three points of contact is deterministic at least and makes a suspension not needed to handle ramps such as this year properly.

EricH 25-10-2015 01:09

Re: pic: Seen at Fall Classic: Side
 
Quote:

Originally Posted by GeeTwo (Post 1501624)
Are those chains or belts running to the back? Are the motors all the way back with the strafe wheel? That looks like too much slack.

Chains. Not all of them are for drive. I forget exactly where the team put their other drive motors--the outer ones look like the lift chains. (Of note: the midships gearboxes change chain direction to operate a lift, and are not part of the drivetrain. Unfortunately, they didn't quite have the time to get that fully operational.)


Edit: Just for the record, I'm not affiliated with the team. But after seeing that... Well, here's the result. I'll have to see if I can signal one or two of the 585 folks to describe it in more detail. As I said in the description, I've never seen a drive like this before.

GeeTwo 25-10-2015 14:39

Re: pic: Seen at Fall Classic: Side
 
Quote:

Originally Posted by seg9585 (Post 1501645)
I'm trying to understand the overall benefit of this configuration vs a standard mecanum setup or even front mecanum back 2 omni. Surely this config is not favorable in traction with only minimal benefit to powered rotation. Weight reduction (3 gearboxes vs 4)?

Quote:

Originally Posted by AdamHeard (Post 1501646)
Three points of contact is deterministic at least and makes a suspension not needed to handle ramps such as this year properly.

Yes, that's part of it. It also reduces the amount of width and machining that would be needed to mount rotated omni wheels to produce a kiwi. The angles between the forces of adjacent wheels here are 90- 135-135 as opposed to 120-120-120 for kiwi, but it should be close enough to work after some tweaks to the inverse kinematics.

A peculiar thing I just noticed after mentioning kinematics is that the robot can deliver more drive force in the direction transverse to the direction it picks up totes than in the direction parallel to the totes, by a factor of about 1.7 for equal loading on each wheel, more or less as the CoG moves. This means that when you want to cover ground, you'll want to think of the long edges as the front/back, and the open and closed short edges as the sides.

Edit: If this drive style does not yet have a name, I dub it Meckiwi.

Connor McBride 25-10-2015 14:50

Re: pic: Seen at Fall Classic: Side
 
I noticed that there are manipulators on the robot. How did it perform at the event? were there any break downs and if so, what were they?


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