We have only built 1 intake system, and it was not effective. Obviously we need an intake for this game, but aren’t sure where to start. We have watched several videos of other teams intakes and have a general idea of the wheels etc; however, we are unsure of the measurements we should go with. Understanding that the game changes each year, what are some general rules for intakes that you apply in the following areas:
Dimensions of the intake in relation to the floor and the height of the game piece.
Dimensions of the intake in relation to the frame and the game piece.
Wheeled intakes, vs roller?
Retractable or not? If so, what’s the most effective way to retract?
Material: What materials do you use? Polycarb seems to be pretty popular; however, we do not have any. What would be a good alternative to polycarb?
Motor/gearing: What motors/gearing do you use? Does that change depending on the game piece?
Where do you attach the motor? On the intake? Inside the frame?
How do you drive your rollers? Gears? Belts? Chain and Sprockets? Directly?
You want to build it in a way that you can actually build it…and in a way that will work, and survive. Looking at what other teams do is a great start. But…you need to figure out stuff on your own, by experimenting. Build something to prototype with, so you can adjust dimensions.
They sell relatively thin polycarb at building supply places, and more thickness at glass shops. And everything is available on the internet, if you have a way to purchase things that way (ie someone has a credit card, and can pay the bill). McMaster is great for speedy delivery and a wide variety of stuff in sizes that you can deal with, but also kind of expensive.
Aluminum sheet is even harder to find locally than polycarb. McMaster and Online Metals can do it over the internet, if you have means to get it that way. Larger cities have metal suppliers like IMS.
Motor speed…there’s a thread about that going on right now, generally you need the roller or wheel surface to be spinning faster than the robot drives, so it can pull in a ball as the robot is driving full speed chasing it.
Put the motor where ever it will fit and let you attach a belt, gearbox, chain, or whatever you are using to transmit motion. Which of these you use might depend on what you have available, what you’re familiar with, how well you can machine stuff, etc. Chains are a bit more forgiving of low resource machining capabilities.
I expect others will chime in with better answers on how to build a good robot, ours are a bit sketchy at times.
I don’t disagree with your assertion necessarily; however, simply copying an Everybot each year doesn’t really help us learn good practices for starting on our own. We are trying to find good advice for starting points to make intakes each year so we can have an idea of where to start. I understand the “just start prototyping” mentality that people have here; however, with limited resources and machining capabilities we quickly find ourselves spinning our wheels when we “just get something built.”
They set up a rig with a horizontal bar, spun it up with an impact driver, and just changed the wheels/roller type. A few things happened just after I snapped the photo… I had them back their rig up to a set of bumpers and moved them elsewhere to work on carpet. It is important that the testing happen on realistic surfaces.
Once we are back in our lab again, that intake shape will be assembled out of versaframe and polycarbonate and tested again. We like to power intakes with belts, with the motor placed as close to the intake pivot as possible. I think my team will want an intake that retracts into the robot, but we haven’t figured the geometry out just yet.
On wheels versus roller: I’d say wheels are great if you need to direct the game-piece somewhere (either to singulate or move into a frame/bumper opening) otherwise, rollers will do just fine. I think with retractable intakes, the best ones are usually pneumatic but I expect my team will use a motor because it’ll do the job and we don’t want the added weight/complexity. So we also make choices to minimize the weight of the system (roller, polycarb, belts, heavy stuff near pivot).
I’m also a fan of Everybot and would suggest you’re not doing your team a disservice by looking over build instructions and ideas from outside sources. My team spent lots of time examining climbers from 2013. And we’ll definitely look at the Everybot docs from 2022 (particularly intake) and 2020 (climber). We’ve built Everybot mechanisms both in-season and as off-season projects and it is a great way to improve mechanical skills.
Prototyping intakes is fairly easy. Grab a pair of 2x4’s, stick a hole in each on and run a shaft with wheels through them. Hook a drill up to the shaft and start playing! It’s best to do your testing against a frame with bumpers, so you can figure out any complications there - but once you do that, you’ll be able to figure out exactly where you want it. The rest is just figuring out how to get it out there!
If you are completely lost, I would consider looking at what some of our open alliance teams are doing. 1323 for example, has a pretty nice CAD going with their concept. You may be able to mock up something similar and test it out: 1339 Open Alliance Build Thread - #22 by mrnoble
You request is conflicting: Give us some advice on how to develop our own original ideas.
It is the end of week 2 of the build season. Have the students, if they are really stumped, build a quick version of Everybot-style intake and ask them how it could be better… how it could meet your needs better… etc. That way they’ve made something that works, AND they get to be critical.
EDIT: my students are also struggling with geometry of intakes! Simple is sort of sloppy, less sloppy gets complicated quickly.
Depends on how squishy the game piece is and the squishiness of your roller, you’re probably safe this year starting testing with an inch or so of compression and adjusting from there
When you need to take the game piece into your robot to do something with it, a lot of teams like to keep the full bumper wrap because this provides some structural benefits for the frame. This means an over-the-bumper intake. Obviously making it wide makes it easier to grab the game piece (to a point). The # of rollers required to get it over the bumper depends on game piece dimensions.
Both work, it’s really the wheel’s/roller’s reaction against the game piece that needs to be tested. A lot of teams use squishy wheels these days because they’re easy to implement (stick a wheel on a piece of hex shaft / churro / thunderhex)
Most games retractable, though there are some games where you may skip it. I’m preferential to pneumatics as the mechanism because it’s simple both mechanically and controls-wise.
Polycarb is great for the most external part because (to an extent) you can run it into things without getting damaged. You can buy a little bit from McMaster-Carr to test it out, or even the local hardware store (check the windows section). However, sometimes some elements of rigidity for the motor, power transmission, keeping the bearings for the rollers/wheels in their holes, etc. Teams will reinforce their intakes with things like sheet metal and long standoffs to get them to behave how they want them to.
A lot of teams try to run the intake with a faster surface speed than the robot can drive, that way you can pick up a game piece on the move. I’d start with 1.5X and adjust from there. With the motors available today, I would use one of these as a starter: 775Pro, Redline, NEO, Falcon 500. You’ll likely get the level of performance you need.
Either is ok, generally on the intake is easier to implement mechanically, but you want to put it in a position where it won’t get damaged
All of these are acceptable solutions depending on your intake geometry. I’m partial to chain and sprockets for most teams because you aren’t locked into a specific power transmission spacing and most teams need to fiddle with things like this on the final robot.
I would determine 1, 2, & 3 via prototype testing.
In most games the frame perimeter rules will likely drive you towards a retractable intake.
We used mostly 1/4" polycarb last year, but it did get broken pretty badly at one competition. So, this year, aluminum tube.
As others have said, you don’t need a particularly power motor, but you do want the surface speed of your intake > max forward speed of robot. Motors generally get attached wherever they can fit w/o interfering with something else.
We used chain and sprocket last year, it was kind of a hot mess, I think we will do belts and pulleys this year.
I think what you’re hearing several of us here say is that the Everybot is literally itself an excellent prototyping platform. It (and other successful designs) is a fantastic source of best practices and rules of thumb. In fact, my students almost always find that they learn much more about good engineering and new design by starting from existing robots themselves, rather than starting from generalized rules of thumb I provide them like your OP requests.
It’s not at all that the rules of thumb in this thread are wrong; it’s just that the act of iterating from an actual baseline design is often far more useful and educational (and a lot more like my day job) than asking others for the rules of thumb we’ve developed by doing exactly that ourselves. It’s not at all “simply copying”. It’s a cornerstone of professional engineering. And it makes it much easier and more useful so you really can in fact “just start prototyping” next year.
This statement is totally correct. This is why the people assembling the products I and my coworkers design generally don’t understand how we arrived at the design.
The proper way to learn from building an Everybot is to study the design as you build it. Studying the documentation explaining the thought processes behind the design decisions leading to the final design will teach you and your team how to think about the problems in the future.
As others have suggested, take the Everybot as a starting point and experiment to learn what does and does not improve it. You stated the one intake system you and your team build was not effective. There are many possible solutions. Many of them are bad. Some of them are really bad. A few of them are good. When a solution is really bad, it is difficult to learn from it because there are often so many different factors that make it bad and discovering and fixing just a few of them will not make that solution good. Starting from a solution that is already good, one can experiment with one factor at a time and learn from that experience.
Many (most) engineers and programmers start their careers by being assigned to add a feature or fix a flaw in an existing product. That requires studying the existing design to understand how the new feature can be integrated and/or to find and fix the flaw. The existing design serves as an example for the new engineer or programmer to learn what does work. I don’t know of any company that would assign a new engineer or programmer to design something totally from scratch. The young engineers or programmers who insist they can take on such a task are exhibiting hubris and I have never seen one succeed.
We prototyped an intake using some 2x4s and screws. When we did it we set our wheels at about 2" of compression on the ball. When the ball ran through, of course, the intake moved up. (Not really sure how much it moved, but my guess would be around 1.5-2"). We are planning to use pneumatics to raise and lower our lift, and are about to send our CAD to be CNCd, but I have some concerns about the amount of compression on the intake. If we use pneumatics I know it will allow some give, but probably not 2 inches worth. Should we move the mounting point of our intake higher (less compression) to account for the pneumatics or should we leave it as is with 2" of compression? What amount of compression are others running for the intake?
We’re using 1.5” of compression on the front roller of the intake, and 1” for the upper rollers, with ThriftyBot compliant wheels. Our prototypes still had some problems with the ball pushing the intake upwards, so we designed our linkage to mitigate that by pulling the roller back as it moves up. If that doesn’t quite make sense, feel free to check out our CAD for more details, as well as our Open Alliance build thread.
Our Google Photos Album also has several videos of the intake in action.
Hope this helps!