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Spectrum 3847 - 2017 CAD Model: Gamma Ray

AllenGregoryIV

By: AllenGregoryIV
New: 01-02-2017 13:36
Updated: 01-02-2017 13:36
Views: 3355 times


Spectrum 3847 - 2017 CAD Model: Gamma Ray

Spectrum 3847 Blog
The Blue Alliance Blog Post

Blog posts with links to download the full CAD model either as Solidworks files from our GrabCAD partner space or a STEP file.

Spectrum 3847 on Episode 4 of check_in
With a discussion about some of the design decisions that went in to this robot.

Discussion

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01-02-2017 14:14

flemdogmillion


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

That arm on the front stays inside the maximum robot volume, right? It looks like you're going with the tall dimension set, and it also looks like lowering that arm is against the rules.



01-02-2017 14:19

notmattlythgoe


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

Quote:
Originally Posted by flemdogmillion View Post
That arm on the front stays inside the maximum robot volume, right? It looks like you're going with the tall dimension set, and it also looks like lowering that arm is against the rules.
That looks like the short dimension set to me.



01-02-2017 14:22

lukekaiser


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

Quote:
Originally Posted by flemdogmillion View Post
lowering that arm is against the rules.
Agreed

Teams need to make sure they read all rules pertaining to robot size carefully. I would hate to see a robot this well designed get to a competition and then not pass inspection.



01-02-2017 14:23

Chris is me


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

Quote:
Originally Posted by flemdogmillion View Post
That arm on the front stays inside the maximum robot volume, right? It looks like you're going with the tall dimension set, and it also looks like lowering that arm is against the rules.
I'm sure they know what they're doing and have read the rules - they're a long standing veteran team who's built high-quality robots for years, who publicly posted a full cad of their robot in week 4.

You don't think it's more likely that you have an inaccurate perception of the robot's dimensions?

It's not against the rules to lower the arm as long as the robot still fits within the volume with the arm lowered (i.e. their chassis is shorter to compensate). This is clearly the case here. If the arm doesn't go past the bumpers then it's legal for it to be lowered even at max dimensions.



01-02-2017 14:23

Ryan Dognaux


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

Quote:
Originally Posted by flemdogmillion View Post
That arm on the front stays inside the maximum robot volume, right? It looks like you're going with the tall dimension set, and it also looks like lowering that arm is against the rules.
It's Spectrum, I'm sure they're in the volume. These guys do their due diligence. You can lower an arm outside of your bumpers as long as it all stays within the appropriate robot volume.

Looking slick Allen!



01-02-2017 14:28

fresh_prince


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

Quote:
Originally Posted by flemdogmillion View Post
That arm on the front stays inside the maximum robot volume, right? It looks like you're going with the tall dimension set, and it also looks like lowering that arm is against the rules.
notmattlythgoe is correct, we are using the short configuration. We are 29x29 so we have room for a 4" extension off either side. The gear collector also fits within our bumper cutout.

See these photos for reference. The pic with the grey gear is current, the pic with the yellow gear is from an older revision, but demonstrates how the intake fits inside our front cutout.



01-02-2017 14:31

AllenGregoryIV


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

The robot frame is a ~29in square making our dimensions with bumpers about 36" square. That gives us 4 inchs of room to extend past the bumpers. The mecanum intake and the gear intake both come close to the full extension limit but can't possibly break it.

And of course we are short. Top of the robot is 23.8in I believe but the student that's doing most of the shooter CAD can tell you for sure that we are under.



01-02-2017 14:34

fresh_prince


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

Quote:
Originally Posted by AllenGregoryIV View Post
Top of the robot is 23.8in I believe but the student that's doing most of the shooter CAD can tell you for sure that we are under.
By my best memory we are ~23.97. I will update this post later in the evening if I'm way off.



01-02-2017 14:38

AllenGregoryIV


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



01-02-2017 14:42

Michael Corsetto


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

Allen,

Really cool bot, love what your team is doing with the open build/blog. Seems like a great learning experience for your team.

Whats the process for scoring the gear once in the gear holder?

Great work as always,

-Mike



01-02-2017 14:42

lukekaiser


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

Very nice. What is the upper appendage intended for?



01-02-2017 14:45

notmattlythgoe


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

Quote:
Originally Posted by Michael Corsetto View Post
Allen,

Really cool bot, love what your team is doing with the open build/blog. Seems like a great learning experience for your team.

Whats the process for scoring the gear once in the gear holder?

Great work as always,

-Mike
They talk about some really good details of the gear intake here in the video.



01-02-2017 14:46

JesseK


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

This makes me wonder how they'll inspect boundaries this year. Our arm is 1" within the boundary with fully-down, but comes to within 0.25" of the boundary during articulation up/down.



01-02-2017 14:48

dodar


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

Quote:
Originally Posted by JesseK View Post
This makes me wonder how they'll test things this year. Our arm is 1" within the boundary with fully-down, but comes to within 0.25" of the boundary during articulation up/down.
In previous years where they had appendage requirements they made the teams extend out to their furthest point and then measured them.



01-02-2017 14:50

fresh_prince


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

Quote:
Originally Posted by lukekaiser View Post
Very nice. What is the upper appendage intended for?
The roller with the mecanum wheel is our full-width fuel intake.



01-02-2017 14:52

RoboChair


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

Quote:
Originally Posted by fresh_prince View Post
The roller with the Vectored Intake wheels is our full-width fuel intake.
Vectored intake wheels are the best.



01-02-2017 14:55

D_Price


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

Great looking robot there! Awesome cad work as always.



01-02-2017 14:56

AllenGregoryIV


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

Quote:
Originally Posted by Michael Corsetto View Post
Allen,

Really cool bot, love what your team is doing with the open build/blog. Seems like a great learning experience for your team.

Whats the process for scoring the gear once in the gear holder?

Great work as always,

-Mike
In our testing it hasn't been difficult to deliver the gear out of the intake by just reversing the roller, lowering the arm, and driving backwards once the spring has pierced the gear. We were hoping for a cleaner release but couldn't get the gemotry of our first system to a point we thought it would be robust enough for the whole season. We haven't tested this geometry on a rolling chassis yet and that will be one of the first things we do when parts come in next week.

I'd assume we will be iterating on the drop off portion all season to make it as fast as possible without compromising it's pickup speed and ability to securely hold the gear during high speed collisions.



01-02-2017 14:57

Cothron Theiss


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

Quote:
Originally Posted by RoboChair View Post
Vectored intake wheels are the best.
So if "vectored intake wheels" are now a thing, does that mean we can add mecanum to the list of misspellings of mecanum-err-vectored intake wheels?



01-02-2017 14:59

EricLeifermann


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

What is your shooter drum made out of?

This is awesome, just wish my computer would load the step file so I could get into the model more.



01-02-2017 15:09

fresh_prince


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

Quote:
Originally Posted by EricLeifermann View Post
What is your shooter drum made out of?

This is awesome, just wish my computer would load the step file so I could get into the model more.
The current version is 45A high-temperature silicone rubber tubing from McMaster, I believe 1" ID 1.25" OD, stretched around 1.25" aluminum tubing. We hope to Smith to some white 35A though to keep with our colour scheme (and maybe get some better grip on the ball).



01-02-2017 15:11

EricLeifermann


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

Quote:
Originally Posted by fresh_prince View Post
The current version is 45A high-temperature silicone rubber tubing from McMaster, I believe 1" ID 1.25" OD, stretched around 1.25" aluminum tubing. We hope to Smith to some white 35A though to keep with our colour scheme (and maybe get some better grip on the ball).
We used that in our testing but it expanded too much. It looks like your're using a belted 2:1 reduction from a 775pro, have you not seen this expansion as well?



01-02-2017 15:17

fresh_prince


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

Quote:
Originally Posted by EricLeifermann View Post
We used that in our testing but it expanded too much. It looks like your're using a belted 2:1 reduction from a 775pro, have you not seen this expansion as well?
What speeds were you testing at? We were testing primarily at 6000 rpm and didn't notice any separation from the aluminum or excessive expansion.

Granted, we did used solid 4" conveyor wheels [I know them as fairline (Fairlane?) Wheels, but maybe Allen can reply with their proper name] to shoot in 2016, and those loved to expand so maybe we're just used to shooter wheel expansion.



01-02-2017 15:21

EricLeifermann


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

Quote:
Originally Posted by fresh_prince View Post
What speeds were you testing at? We were testing primarily at 6000 rpm and didn't notice any separation from the aluminum or excessive expenses.

Granted, we did used solid 4" conveyor wheels [I know them as fairline (Fairlane?) Wheels, but maybe Allen can reply with their proper name] to shoot in 2016, and those loved to expand so maybe we're just used to shooter wheel expansion.
I don't know what we were spinning them at accurately but it was faster than 6000. The problem wasn't that the expansion was affecting the shots, its that I wasn't comfortable safety wise with the expansion. We were also using 2in roller over a 1.5 aluminum tube, so maybe the smaller diameter doesn't expand as much was we saw with the large.



01-02-2017 15:29

fresh_prince


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

Quote:
Originally Posted by EricLeifermann View Post
I don't know what we were spinning them at accurately but it was faster than 6000. The problem wasn't that the expansion was affecting the shots, its that I wasn't comfortable safety wise with the expansion. We were also using 2in roller over a 1.5 aluminum tube, so maybe the smaller diameter doesn't expand as much was we saw with the large.
Ah, that's fair. 1.5/2 does just have a lot more material to expand, so I wouldn't be surprised if our were also expanding but it's subtle enough to miss. Our shooter wheels are also boxed up so uncontrolled expansion should be relatively contained.



01-02-2017 15:34

jkelleyrtp


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

How many balls can you guys hold? Doesn't look like the traditional hopper to me, are you planning on intaking only?



01-02-2017 15:37

fresh_prince


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

Quote:
Originally Posted by jkelleyrtp View Post
How many balls can you guys hold? Doesn't look like the traditional hopper to me, are you planning on intaking only?
Our current estimates sit around 50 balls or so. We will have a hopper, the lexan sheets that it is made of have yet to be fully modeled though. There will be one panel on either side and an angled panel out over the fuel intake that will spring out when the intake is down, but be forced back into frame when the intake is pulled back up.



01-02-2017 15:42

Mecanum Wheel


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

Quote:
Originally Posted by Cothron Theiss View Post
So if "vectored intake wheels" are now a thing, does that mean we can add mecanum to the list of misspellings of mecanum-err-vectored intake wheels?
NO.



01-02-2017 15:54

holygrail


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

Great bot as always! I really like the built-in handles.

Nice work!



01-02-2017 16:11

Kevin Sevcik


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

Quote:
Originally Posted by EricLeifermann View Post
I don't know what we were spinning them at accurately but it was faster than 6000. The problem wasn't that the expansion was affecting the shots, its that I wasn't comfortable safety wise with the expansion. We were also using 2in roller over a 1.5 aluminum tube, so maybe the smaller diameter doesn't expand as much was we saw with the large.
Centrifugal acceleration* = w^2 * r. More RPMs and more radius = more force expanding your tube. Since this acceleration applies to all of the tube, thickness won't matter, aside from the smaller force on the ID of the tube. The only material property that matters is some sort of ratio of density and elastic modulus, but that'd be the same since ou said it was the same stuff.

So all in all, not surprising your tube wanted to expand more than Spectrum's. Are you guys going for a longer shot to need that much more surface speed?

*Yes centrifugal. Pedants are welcome to spend 15 minutes drawing a FBD with a tangential velocity, required change in velocity to create a circular path, implied acceleration, unbalanced force to create that acceleration, etc, etc. I'm going to pretend it's a real force and get on with my life.



01-02-2017 16:14

EricLeifermann


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

Quote:
Originally Posted by Kevin Sevcik View Post
Centrifugal acceleration* = w^2 * r. More RPMs and more radius = more force expanding your tube. Since this acceleration applies to all of the tube, thickness won't matter, aside from the smaller force on the ID of the tube. The only material property that matters is some sort of ratio of density and elastic modulus, but that'd be the same since ou said it was the same stuff.

So all in all, not surprising your tube wanted to expand more than Spectrum's. Are you guys going for a longer shot to need that much more surface speed?
No just limiting the contact time and wheel size, as well as bad prototypes and the mentality that we will be able to spin slower with a properly built robot that has less friction deficiencies.



01-02-2017 17:16

Brian Selle


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

Nice job 3847! What are the servo motors on the front/back of the shooter for?



01-02-2017 17:21

fresh_prince


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

Quote:
Originally Posted by Brian Selle View Post
Nice job 3847! What are the servo motors on the front/back of the shooter for?
Thanks! We'll only be using one of the two sets of three, but they're intended to be lane blockers. If we line up to the boiler and one of our side streams isn't on target, we want to be able to disable that stream instead of realigning our entire robot. We have one in the middle so that we can theoretically make a shot while our side is lined up with either the driver station or the front wall of the field.



02-02-2017 01:32

Joy4201


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

This is so amazing!
My team and I just had a few questions:
What is your shooter compression and how did you settle upon this number?
What is your intake height and how did you find this number?



02-02-2017 03:34

AllenGregoryIV


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

Quote:
Originally Posted by Joy4201 View Post
This is so amazing!
My team and I just had a few questions:
What is your shooter compression and how did you settle upon this number?
At the moment I believe it's around 4 5/8" between the drums but the tower includes two plates that can be changed to allow us to increase compression if we need too.

Quote:
What is your intake height and how did you find this number?
The height of the fixed intake roller is about 4.75" from the floor but that could also be changed by going to larger wheels. We currently have 1 5/8 compliant wheels from WCP but we could use 2" wheels if needed.

We wanted to design to the smallest amount of compression we could get to work and increase if needed. That way we start with the least load on the motors and add load as needed.



02-02-2017 14:19

GeeTwo


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

Great design! Ironically, just looking at your rather complex robot, I was inspired of a way to make our gear pickup MUCH simpler (replace two motors with one belt). Thanks!



02-02-2017 15:11

Bob Steele


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

Beautiful looking robot... and the CAD is nicely done.
I am looking forward to seeing how this plays on the field.

Well done!!



02-02-2017 15:50

Joe G.


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

Quote:
Originally Posted by lukekaiser View Post
Agreed

Teams need to make sure they read all rules pertaining to robot size carefully. I would hate to see a robot this well designed get to a competition and then not pass inspection.
I'm equally worried about teams building drive base/bumper assemblies to the maximum allowed dimension, and then regretting this decision when they realize all the cool things they could have achieved with a smaller base that enabled over-the-bumper dropdowns. In past years, iterating in new systems was just a matter of finding the space and weight, this year there are going to be a lot of teams boxed out of improving their robots and adding features like Spectrum has because they assumed bigger=better early in the process.



02-02-2017 16:11

Chris is me


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

Quote:
Originally Posted by Joe G. View Post
I'm equally worried about teams building drive base/bumper assemblies to the maximum allowed dimension, and then regretting this decision when they realize all the cool things they could have achieved with a smaller base that enabled over-the-bumper dropdowns. In past years, iterating in new systems was just a matter of finding the space and weight, this year there are going to be a lot of teams boxed out of improving their robots and adding features like Spectrum has because they assumed bigger=better early in the process.
I honestly expect the opposite to happen - teams built chasses that were too small so they could do over-the-bumper stuff, expecting a huge advantage, then realizing it was more trouble than its worth and are now sad about the substantial decrease in ball capacity they traded for that decision.

3847's robot is a good example of leaving a conservative amount of space (just an inch or three) for OTB stuff, but I bet others left way more than they should have.



02-02-2017 17:13

Ty Tremblay


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

Quote:
Originally Posted by Chris is me View Post
I honestly expect the opposite to happen - teams built chasses that were too small so they could do over-the-bumper stuff, expecting a huge advantage, then realizing it was more trouble than its worth and are now sad about the substantial decrease in ball capacity they traded for that decision.

3847's robot is a good example of leaving a conservative amount of space (just an inch or three) for OTB stuff, but I bet others left way more than they should have.
Why does a smaller frame necessarily mean a reduction in ball capacity?



02-02-2017 17:37

ngreen


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

Quote:
Originally Posted by Ty Tremblay View Post
Why does a smaller frame necessarily mean a reduction in ball capacity?
Unless you are expanding your hopper too, which they are.

I really like the design of this robot. I wish we'd have considered a gear pickup on the same side as the fuel intake because I think fuel on the floor will make it difficult to reach gears in some cases.



02-02-2017 23:00

Chris is me


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

Quote:
Originally Posted by Ty Tremblay View Post
Why does a smaller frame necessarily mean a reduction in ball capacity?
I mean, if you grow your hopper out over the top of your intake, sure. But if you grow your hopper out in that direction, isn't that just going to stick out the same distance as your over-the-bumper intake? Which then isn't sticking out farther than your robot's frame anymore? Isn't that kind of defeating the purpose then?



02-02-2017 23:32

Ty Tremblay


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

Quote:
Originally Posted by Chris is me View Post
I mean, if you grow your hopper out over the top of your intake, sure. But if you grow your hopper out in that direction, isn't that just going to stick out the same distance as your over-the-bumper intake? Which then isn't sticking out farther than your robot's frame anymore? Isn't that kind of defeating the purpose then?
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.



02-02-2017 23:44

cadandcookies


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

Quote:
Originally Posted by Chris is me View Post
I mean, if you grow your hopper out over the top of your intake, sure. But if you grow your hopper out in that direction, isn't that just going to stick out the same distance as your over-the-bumper intake? Which then isn't sticking out farther than your robot's frame anymore? Isn't that kind of defeating the purpose then?
I'm not sure I follow you now. If you expand your hopper when your intake goes over the bumper, then your hopper is not constrained by your frame perimeter anymore. Thus you're minimizing the effects of lost storage space and still getting your full width over the bumper intake, at the cost of now having to designing the whole expanding hopper thing.



03-02-2017 09:57

nick4130


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

This CAD looks beautiful, cant wait to see this robot on the field.



03-02-2017 10:03

Chris is me


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

Quote:
Originally Posted by Ty Tremblay View Post
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.



03-02-2017 10:09

Ty Tremblay


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

Quote:
Originally Posted by Chris is me View Post
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.



03-02-2017 10:26

Chris is me


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

Quote:
Originally Posted by Ty Tremblay View Post
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.



03-02-2017 12:33

Robomarfa


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

Nice work 3847. SJCP has come a long way since I left in 77.



03-02-2017 14:36

Keefe2471


Unread 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.



03-02-2017 18:42

Lil' Lavery


Unread 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?



03-02-2017 20:10

fresh_prince


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

Quote:
Originally Posted by Lil' Lavery View Post
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.



05-02-2017 00:07

fresh_prince


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

Quote:
Originally Posted by Brian Selle View Post
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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