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-   -   pic: Spectrum 3847 - 2017 CAD Model: Gamma Ray (http://www.chiefdelphi.com/forums/showthread.php?t=154584)

nick4130 03-02-2017 09:57

Re: pic: Spectrum 3847 - 2017 CAD Model: Gamma Ray
 
This CAD looks beautiful, cant wait to see this robot on the field.

Chris is me 03-02-2017 10:03

Re: pic: Spectrum 3847 - 2017 CAD Model: Gamma Ray
 
Quote:

Originally Posted by Ty Tremblay (Post 1639746)
I'm not 100% sure I follow. If you're extending your hopper with your collector, you negate the effects of making your frame smaller while still gaining the advantages of an over-the-bumper collector.

The primary advantage of an over-the-bumper collector, other than width (which is significant), is that the leading edge of your robot is your collector instead of your frame and/or bumper. If you move your "frame" (hopper) out just as far forward as your collector, you remove that advantage - your frame could contact a wall before your collector contacts a ball along that wall, etc. If your roller still protrudes out farther than your hopper, then you have to at least some extent compromised your hopper space.

Considering even a full length robot can actuate their front roller so that it occupies the space between the frame and the edge of the bumper, this advantage starts to seem limited to making the collector wider. Again, this is a sizeable advantage, but at the same time, the field will have hundreds of balls on it, and I'm not sure the complexity of this solution is justified for this benefit.

It's not zero benefit, and it's certainly worth exploring for many teams, I just wonder if the tradeoff in complexity and / or ball storage will end up being clearly worth it or not. This isn't the path my team took and it certainly simplified a lot of the robot once we decided not to do this, plus we still have the option to switch to a drop-down "in-the-bumper" intake if we really need that little bit of roller to grab balls against walls.

Ty Tremblay 03-02-2017 10:09

Re: pic: Spectrum 3847 - 2017 CAD Model: Gamma Ray
 
Quote:

Originally Posted by Chris is me (Post 1639819)
The primary advantage of an over-the-bumper collector, other than width (which is significant), is that the leading edge of your robot is your collector instead of your frame and/or bumper. If you move your "frame" (hopper) out just as far forward as your collector, you remove that advantage - your frame could contact a wall before your collector contacts a ball along that wall, etc. If your roller still protrudes out farther than your hopper, then you have to at least some extent compromised your hopper space.

Considering even a full length robot can actuate their front roller so that it occupies the space between the frame and the edge of the bumper, this advantage starts to seem limited to making the collector wider. Again, this is a sizeable advantage, but at the same time, the field will have hundreds of balls on it, and I'm not sure the complexity of this solution is justified for this benefit.

It's not zero benefit, and it's certainly worth exploring for many teams, I just wonder if the tradeoff in complexity and / or ball storage will end up being clearly worth it or not. This isn't the path my team took and it certainly simplified a lot of the robot once we decided not to do this, plus we still have the option to switch to a drop-down "in-the-bumper" intake if we really need that little bit of roller to grab balls against walls.

The balls are 5" in diameter. This means you can have a 4" collector wheel/drum, bring your hopper out to the outside edge of those wheels, and still have your collector touch the ball before your hopper touches the wall. If you make your collector smaller in radius, your hopper well be even further away from the wall when the ball gets collected.

Chris is me 03-02-2017 10:26

Re: pic: Spectrum 3847 - 2017 CAD Model: Gamma Ray
 
Quote:

Originally Posted by Ty Tremblay (Post 1639822)
The balls are 5" in diameter. This means you can have a 4" collector wheel/drum, bring your hopper out to the outside edge of those wheels, and still have your collector touch the ball before your hopper touches the wall. If you make your collector smaller in radius, your hopper well be even further away from the wall when the ball gets collected.

I guess it depends on how much you can compress the ball with your intake. We have been using a rigid collector and found that it works best with surprisingly little compression, so we are mostly "on top" of the ball. This made it a bit trickier. You still touch the ball before the wall but it's a bit closer than I'd like for my team's particular design choice.

I'm sure you guys have done your research and totally know what you're doing here, and I don't mean to doubt that. Just trying to share a data point.

Robomarfa 03-02-2017 12:33

Re: pic: Spectrum 3847 - 2017 CAD Model: Gamma Ray
 
Nice work 3847. SJCP has come a long way since I left in 77.

Keefe2471 03-02-2017 14:36

Re: pic: Spectrum 3847 - 2017 CAD Model: Gamma Ray
 
Another benefit of an over the bumper intake being the full width of your front bumper (minus the 3.5 inches of side bumbler on each side) is that it minimizes the ability of balls to space you off the wall by 5 inches. Even with the maximum size gap in your front frame perimeter you still have 19 inches (6*2 + 3.5*2) of bumper without a way to move balls out of the way Scoring gears, picking up gears, inbounding fuel from both the hopper and human player station, and catching HE fuel rebounds are all potentially compromised when your robot can't get flush to the wall. With some spinning and approach angle practice maybe you can knock those balls flying with some consistancy, but critical seconds could be wasted each time you perform one of those operations.

Lil' Lavery 03-02-2017 18:42

Re: pic: Spectrum 3847 - 2017 CAD Model: Gamma Ray
 
Are you using a PTO for your climber? Or will it be linked to one side of your drive at all times? If so, are you concerned about any additional drag generated for that drive side? Are you going to steering correct with sensors/software?

fresh_prince 03-02-2017 20:10

Re: pic: Spectrum 3847 - 2017 CAD Model: Gamma Ray
 
Quote:

Originally Posted by Lil' Lavery (Post 1640090)
Are you using a PTO for your climber? Or will it be linked to one side of your drive at all times? If so, are you concerned about any additional drag generated for that drive side? Are you going to steering correct with sensors/software?

The current plan for the climber is for it to be linked to the right side of our drive at all times. We have, however, included VersaPlanetary mounting holes on our side panels in case we want to power it from a dedicated motor. As for the drag, we haven't really decided whether or not we will implement drive-straight code. If, after some driver practice with our practice bot, we realize that the robot is pulling hard, we will likely attempt to account for drift or just decouple from the drive train if the sensor integration proves too finicky.

fresh_prince 05-02-2017 00:07

Re: pic: Spectrum 3847 - 2017 CAD Model: Gamma Ray
 
Quote:

Originally Posted by Brian Selle (Post 1639207)
Nice job 3847! What are the servo motors on the front/back of the shooter for?

I finally have a visual answer to your question! Just hashed out CAD for the lane blocker this evening. It is a .25 in thick piece of ABS driven by a rack on the blocker and a pinion mounted to the aforementioned servos. Each will ride on two .25x.25 in shoulder screws with 10-24 threads (McMaster 91259A533).

The process has been detailed in our most recent blog post, which includes a download link to the calculator we used to design the rack teeth.

Spectrum Blog




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