Competitive Intakes

I think building a competitive roller intake was one of the hardest challenges this year. Our team for example trashed our intake design midseason, after spending many, many hours prototyping. However many teams still built fast intakes, despite our team’s troubles. What were the challenges that your team faced in building an intake? What designs overcame these issues? What designs led to the fastest, most consistent roller intakes?

How about not using rollers at all?

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Really, we decided to just leave space for the intake and save it to design last. And, well, someone had the idea that we have an intake like a carwash, so we prototyped this design. With a few tweaks, it worked really well.

Sometimes you just need to think outside the box.

Edit: we have the mechanical capability to do a 7-disk autonomous easily (at least in terms of picking up), but we never got to program it during the season.

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We built a pretty darn fast pickup. It is capable of a 5-shot auton. Picking up the two frisbees side-by-side was probably our biggest challenge. We fixed this by racking the outside roller at an angle- the left side is .25" lower than the right side.

As you can see from the picture, we have two pivoting arms with rollers on them that run off one RS-775 motor. I’m not sure of our gearing (I can check it tonight if you want) but it is plenty to pick up frisbees no matter how fast the robot is moving. The first, outside roller hits the frisbee up onto the ramp. The inside roller (it’s hidden by the frame in the picture, but it’s there) pushes it into our hopper.

In the picture, the shooter is up. In order to pick up frisbees, it has to be down. The edge of the cylindrical canister lines up with the ramp under the rollers.

http://www.chiefdelphi.com/media/img/ce9/ce9b9c47e1950d19609328ab9236795e_l.jpg

I was responsible for the design and fabrication for the intake mechanism (we called it Disc Acquisition Device, or DAD for short). We worked on a few prototypes but the best one was a top roller with a bottom “scoop” (essentially just a slide that would drop down when we were gathering disks, so as not to pick up excess) this design worked nicely and reliably for bot right-side up and upside down disks, though it never made it to the robot.

The team responsible for transportation of the acquired disks to the hopper was a bit behind schedule. If you would like to see video of the DAD in action, I am sure I could get that posted for you.

Ours used a roller for the intake, and a scoop. It’s a little slow, and we also have trouble with jamming when picking up two side by side frisbees. We tried the trick of angling the intake roller so when encountering two disks one gets sucked in first. This ended up making the single disk pickup less reliable.

We are currently designing and rebuilding a new arm as a summer project.

Could I request that people link to video of their working arms?

Prototype testing:


Integration testing:

Final testing:

Match footage:

I should note that we designed the arm to be easily replaceable if damaged, which was necessary in Richmond. This was cited as one of the reasons we won the Quality Award at that event.

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You probably would have had to compensate by leading with the side where the roller was lower.

Honestly, I never considered picking up two discs at a time. I made the opening 16.5 inches (quite wide for the purpose) to accommodate a disk coming in from any number of given angles. I was just assuming that our elevator (or disk transport) would be build fast enough to process one after another. I will try to get some video up soon.

We had a ground intake that worked but never made it to competition. It was the classic flat flexy bottom plate with rollers and belts on top.

Our problem lay in moving the discs into our hopper. We had planned on a magazine that indexed upward (bottom loading). Once we realized that the indexer was too complex to fit in the area we had slated for it, we moved to a simplified top loader and that eliminated picking up under the bot.

Our floor collector this year was a great success. I was in charge of designing and prototyping the collector mechanism, which our bot solely relied on. After much prototyping, we made the decision at the beginning of week 2 that we would only collect discs from the floor. While this was a risky decision, it allowed us to cut down significantly on the complexity of our design. Instead of using a hopper, discs were stored in a linear path to the shooter. Our 2013 bot was one of the simplest and most competitive in our history.

Our design consisted of a bottom scoop that dragged on the ground, and an articulating intake roller that compensated for the change in angle as discs were collected. The collector was only slightly larger than the width of a disc, but we believed that by adding a camera facing the collector, we could still ground load from across the field effectively during a match. The system worked extremely well throughout competition, and functioned properly for each of our 44 official matches. It’s robustness and reliability helped us win two Motorola Quality awards this season, and go undefeated at the Connecticut regional. We were able to use the collector to run feeder station cycles as well. We realized that loading from the floor of the feeder station was actually a lot faster than most human loaded teams. Another cool feature that we discovered was our ability to flip upside down discs. By running the intake roller in reverse, and driving into a disc, we were could reliably flip discs, although we never used this on the field.

We did however, encounter a few problems. At first, we tried using poly-cord to drive the discs. This produced very mediocre results. We experimented with using VEX wheels on the discs, driven by poly-cord, which produced much better results. In the end, we went with Banebots 2 7/8" soft compound hex wheels. These produced an incredible amount of friction on the discs, and worked phenomenally well on the robot. Another challenge was placing the roller wheels in the right locations so that it would maintain contact with the disc as it traveled up the scoop. This was done with prototyping, and we transferred the measurements to our production collector. Finally, maintenance became a big concern. On our practice bot, our collector assembly wore down several times, affecting it’s performance tremendously. The wheels, while great on the field, lasted for one competition at maximum.

Match Video:


We only fired 3/4 in auto, so there was still one in it when we went for the center line in teleop. Since our bot is capable of carrying a maximum 4 discs, it appears as though the last one wouldn’t collect, since it was full.

This is our bot before WPI. We extended the outer shaft and added extra wheels for Connecticut.

http://www.team20.com/wp-content/uploads/2013/02/2013-robot.jpg

Our team decided day one we would need as much time as possible to get a “competitive” intake prototyped, put into cad and fabricated. We set a small group of students who wanted to work on the intake aside from the beginning of the build season and gave them the task. We also realized our resources were already going to be spread thin so we had the mentality of if we can get it done then we will use it but we focused more on shooting and climbing. Our week one regional came around (Hub City) and we had lots of trouble getting our machine debugged mechanically and with software. We were playing a match against 1986 Titanium and when they hail a deadly fire storm of 7 disc above your head during autonomous within the first 15 seconds we soon realized how demoralizing it was and how it gave them a psychological advantage let alone a big point difference. When we came back home we definitely wanted to get the intake done. We got it working well and worked out some kinks before the Dallas regional. Our biggest problem was getting the intake to not “chatter” while driving and picking up two frisbees side by side and funneling them in without getting jammed. Got a centerline 5 disc working from both sides of the pyramid, a 7 disc auto from middle and a 5 disc middle working. (Enough of my story)

Our intake is lowered while our "shooter"is lowering also. We use pneumatics to get the robot to lower the intake by retracting the piston. It was really reliable and didn’t have much trouble with it. We use a banebot motor (Don’t know what specific model) to drive one of the rollers and the other roller is driven my the polyurethane belting connecting the two rollers.

Picture of the robot/intake:

Here is video of the testing phases before worlds:


Here it is in action:

How did you guys do a double wide intake? My team is working on an intake mechanism for a summer project and we want to be able to do a 7 disc auto but cannot figure out what the most reliable way to do a double wide intake is. The main problem we have run into is figuring out how to get one disc to enter before the other.

We were thinking about doing it like Miss Daisy did where they have a spring-loaded intake with one side in the front having larger rollers than the other side.

Anyways please let me know what you guys did to solve this problem, thanks.

33’s primary design objectives for our intake were:

  1. Had to be two disks wide for the 7 disk auto.
  2. Had to be extremely fast (469 in 2012 was our benchmark)
  3. Had to be able to properly function over wrinkles/tape on the carpet.

We had a very successful prototype using an overhead roller and spatula. However, this didn’t meet our 3rd functional objective.

Recognizing that the key to intaking was getting the leading edge of the disk off the floor we began prototyping a counter rotating bottom roller. This resulted in a second very successful prototype using a 3/8” fiberglass rod sleeved with surgical tubing. However, the very tight dimensional restrictions (54” cylinder) meant that this design was almost impossible to package.

Because of packaging constraints we began prototyping large diameter bottom rollers. These evolved to have “fingers” and we ended up with AndyMark stars cut down slightly.

The final intake pretty much met all of our objectives. We consistently averaged 6 disks in auto throughout the season, and the collector functioned properly up to about 1/2” off the ground and wasn’t affected by tape or carpet wrinkles. It didn’t quite meet the 469 in 2012 requirement but it was still good enough that we never had to wait around for disks to enter the robot.


Photo by Dan Ernst

The way we solved this problem is to have a varying diameter roller which can articulate on an axis. When it touched 2 disks at the same time, the disk on the larger diameter portion would get sucked in and lift the roller up so the other disk isn’t getting engaged. When the first disk is in our system, the roller falls back down due to the weight of it and picks up the second disk. We had to play with the height of the roller off of the floor, the proportion of larger BB wheels to smaller BB wheels etc.

These pictures show the mechanism:
http://www.flickr.com/photos/team341/8529147069/in/set-72157632915395077/
http://www.flickr.com/photos/team341/8537323737/in/set-72157632545513277

We actually solved this problem by attempting different variations on how the tread was mounted (the direction of the tread when the rollers rolled) and we used a hex standoff to kinda hold the frisbee so the other one can come in before the next one comes in. The different combinations of tread configuration allowed the frisbee to be pulled to the side where the first frisbee came in. So the frisbees come in side by side, the right frisbee goes straight in and the left frisbee kinda rotates to the right side then entering the robot right behind the first frisbee. I’ll add a picture when I get home from school.

Find someone on 846, they had the quickest one that I saw in person this season. They used a roller and a piece of plastic to lift the disc into a pulley system which then dropped it into their hopper. I can’t give you all the specs but it was by far the fastest I saw in person.

While ours wasn’t double-wide (in retrospect, it should have been…) it still worked very well. It was as simple as a pivoting front roller with a piece of lexan on the bottom. Flat polybelt drove it off of our conveyor system. The entire pivoting assembly was also tensioned down with some surgical tubing. At first we had trouble gripping the frisbee, but we wrapped a short piece of solid core surgical tubing in the center in a helix and we never had any issues since. Heres some cad and a video:

http://team2495.com/images/intake.png

Videos:

Before the surgical tubing grip

With the grip

I find it funny that your third design objective ended up being our biggest problem. I think we broke our intake almost ten times just on tape. It was something we completely overlooked and didn’t think of as a problem.

Why not just do a 1986 pancake flipper feeder? Sounds like you will only use it for auton anyway? Just a thought.

Got a shoutout from 3173, had to respond! I designed our floor collector this year, and it seems to be the system that people remember when they see our robot. There are features that I would never replicate on that collector if I could do it over . . . there are also great features, and I’ve tried to detail them below.

Mooretep had an awesome video (0:30 has a really nice shot): http://www.youtube.com/watch?v=GqfuRlymtSQ

Official Reveal (showcases initial testing): http://www.youtube.com/watch?v=jmdET56tukM
Official Recap: http://www.youtube.com/watch?v=w79l4VhjrD0

Ironically, the floor collector wasn’t really our top priority (we didn’t have priorities due to the fact that we tried to do everything; don’t do that!), so features such as being able to funnel really well and take two discs at the same time didn’t make it into the final design. If we had properly valued the collector, we would have thought differently and implemented those features.

Cool Attributes:
At the mouth of the collector, there are actually two rollers, one on the bottom and one on the top. We arrived at the same conclusion as 33, that the bottom roller for kicking the disc up was crucial. The coolest part was really that we did not drive it using anything nearly as complicated as a gearbox; it was just a twisted belt run from the top roller. I can get a picture later, but it was something like this: http://www.chiefdelphi.com/forums/showthread.php?t=102889&highlight=2826+teaser

That bottom roller kicked the disc into contact with the upper roller, and that powered the frisbee through the rest of the system (geared at 18 ft/sec roller surface speed) and out into our storage subsystem.

To prevent our collector from getting caught on the carpet and irregular surfaces we installed wheels for the collector to ride on. This was another pretty cool feature, we machined two delrin rounds with holes for bearings, turned down the ends of two 3/8" bolts to 1/4" diameter and the bearings rode on that makeshift shaft.

What I would have liked to do:
Here’s a really easy way to make your collector take two frisbees side by side. Make your collector funnel to the side, kind of like 233’s or 973’s collectors. One straight edge, one slanted edge. Our prototypes indicated that this worked really really well, and we only didn’t implement it because our robot design forced that compromise.

Alternatively, do something like 971’s collector (I would note that both their 2012 and 2013 robots are absolutely phenomenal in handling game pieces throughout their system) . . . http://www.youtube.com/watch?v=6bsWRIMV9CY It would be really cool if they posted on this thread :slight_smile:

Hope this helps! Collectors this year were really challenging, and it’s really interesting to see how other teams approached that problem. Keep the responses going, I’m having a blast reading this thread :stuck_out_tongue:

We had a very long, arduous journey over the course of the season to prototype and perfect our intake. Our original intake design was like many others with a single double wide roller in the front and a “scooper” plate underneath. Here’s two pictures of our original intake design, the pool noodle on the front was just a bumper to protect the roller underneath. The entire roller was on a hinged arm that allowed the roller to actuate vertically

https://fbcdn-sphotos-c-a.akamaihd.net/hphotos-ak-prn1/45194_530669790308132_1265201574_n.jpg

In this picture the black rollers were made of a low durometer urethane called sorbothane, it was by far the most frisbee-adhesive material we could find. If you just laid the sheet of sorbothane on a frisbee you could pull the frisbee across the carpet with only the weight of the sorbothane holding itself down.

https://fbcdn-sphotos-b-a.akamaihd.net/hphotos-ak-snc6/10067_530670010308110_72841928_n.jpg

This intake design was fairly successful, it picked up almost every frisbee we touched, however like other teams we occasionally had some jamming problems when feeding 2 discs next to each other and the scooper plate getting stuck on the carpet lip around the pyramid. The other problem was that it would push the frisbees a short distance before picking them up which was a problem in autonomous. We went back to the drawing board using 254’s intake as inspiration. Our final intake design worked better than we ever could have dreamed.

https://fbcdn-sphotos-b-a.akamaihd.net/hphotos-ak-prn1/65685_543068262401618_2110431654_n.jpg

Our final design used a thin front roller with a polyurethane sheet wrapped around it that had similar traction properties to the sorbothane. The entire intake was wide enough to pull in two frisbees next to each other. Only having the traction on the center of the front roller allowed us to pull in one frisbee at a time without them fighting each other while being pulled in.

Behind the front roller we had a counter rotating roller with the same polyurethane traction material on it that lifted the edge of the frisbee and pulled it into our hopper. We also had another roller directly above it with a large brush on it, rolling in the same direction as the front roller, to assist the frisbees getting pulled in after the bottom roller had lifted the edge. This intake design worked flawlessly, it instantly picked up any frisbee touching the front roller, never had jamming issues, and had an additional, accidentally built in feature, if you picked up an upside down frisbee then lifted the intake it would flip the frisbee out right side up to be picked up again:D

Our final intake also had no bottom scooper plate and the entire intake rolled on two steel track balls which kept the front roller at a consistent height and allowed easy transitions over the carpet lip. Our intake also took a much heavier beating than it should have including a full speed hit against the pyramid and several pushing matches with other robots. We did end up bending the side plates that make up most of the intake however we reinforced them with a set of back-up plates that we had brought along in case that happened.

I’m sure most of you saw this live but here’s a match with our intake after it had been “Frankensteined” back together.

Thanks to 973 for the great quality video of the einstein matches.

Very interesting about the different materials you used on your rollers. I wonder what other materials people used for their rollers.