pic: Roborio mounting and protective case
 

Re: pic: Roborio mounting and protective case
 

I am not expert in CAD, but I am really interested to see a stress analysis of this case. I do not have CAD on this laptop because it is not powerful enough to run the software at a manageable level.

If you're going to post a CAD file of a case, the least you can do is strength test it in software ;)

Re: pic: Roborio mounting and protective case
 

Hold on let me just support my entire robot with this roborio case so that it has a stress I can analyze for you.

In the event you really do not understand the most basic concept of a case, let me explain it to you:

-The Roborio sits comfortably inside the case
-The case sits bolted to your electronics pan
-Nothing else happens

I hope this has been helpful to you, and if there is anything else I can do, please don't hesitate to ask. :)

Re: pic: Roborio mounting and protective case
 

There are quite a few definitions of "strength" in the engineering world (sorry not bored enough to list them...). Which one(s) do you have in mind?

Re: pic: Roborio mounting and protective case
 

I don't know about him, but I'd sure like to see a stress analysis.

Call Andrew Pizza Hut, because he better deliver.

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I am mostly just interested in the amount of force required to break the polycarbonate sheet, as that is the most probable place of impact.

The case seems like it'd serve its purpose, to protect the roboRIO, I was just wondering how good of a job it really does. The worst case scenario the past few years would be either the 2014 game ball landing directly on it, or a Frisbee deflected into it. The latter has the potential to have a lot of force. FRC games are tough. You have to design durable parts.

Re: pic: Roborio mounting and protective case
 

I'm a programmer, but I'm willing to bet money on if you design something for industry, you have to extensively stress test it in software before implementation is ever thought of. It's kind of like with code, only it's called unit testing then. Bill Gates got so much free programming time because someone who wrote the login info to computers back then they didn't unit test their code. When prompted to put time, he simply put a letter, and the software couldn't make sense of it so he got to use the computer for free.

NASA wouldn't have gotten to where they are today if it weren't for extensive stress testing, in software and in the lab.

I think it would be a good habit to get into the ensure what you design can serve its purpose in the worst case scenario. What if brakes of a new car failed after 10,000 miles? What if pacemakers fail after 4 years?

It may seem silly for a little case, but it pays off. It gets you experience, and isn't what this is all about?

This is a bit off topic, but I had an interview today for an internship for developing software. One of the questions was how I unit test (stress test) my code. It is important to do, and it could be the difference between getting a job or not. You never know.

And if you really don't want to do it, I'm sure there exists some program online that allows you to upload a cad file (I don't even know what extension they have....) and it will do it for you, or you could figure out how to do it in whatever software you designed it in.

I could easily see the quality award going to a team that has documentation about their robot's durability (and of course a good robot) How much the frame will deflect during a collision, stuff like that. It shows good engineering practice.

Re: pic: Roborio mounting and protective case
 

Good engineering practice is to not over engineer or overanalyze things. If this case was protecting components for manned space exploration, on which lives depend, and was something never-before-done, then yes, extensive stress testing would definitely be in order.

This is not going into space. It is a simple protective cover for a relatively replaceable component in a robot designed to play games, for a robot whose operational lifespan will be measured in hours, using materials the designer has almost certainty used in similar applications dozens of times, in an application that is highly weight sensitive. Given these constraints, stress analysis is a waste of the designer's time, and overbuilding the case to withstand any freak accident imaginable in FRC is poor use of resources.

Nice case! Have you considered implementing cable retention into the base piece?

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I hope you don't mount your electronics where a big 2lbs ball or a supersonic (exaggerating here) frisbee could hit it!

I bet that it would protect it from most things, especially if you 3d print it properly. I don't think stress testing is necessary, and if this case goes through more than a little stress, shame on you

Re: pic: Roborio mounting and protective case
 

I for one think this is a very good idea. Although this is akin to the sidecar, which is typically mounted deep within the structure. If your design necessitates mounting to an exposed surface, this thing will shrug off a bouncing rebound rumble ball.

It is made out of ABS and a 6.25" square of 1/16" polycarb. Anyone who has touched either of these materials could attest to their properties.

Will it survive a frisbee or a yoga ball? Ask yourself this: would a naked rRIO survive better?

You guys are really being harsh. My count is near nil for CAD files posted on CD that get berated for lack of stress testing. What about that thing that jammed into the 8-slot cRIO to hold a sidecar, or the Tower of Talons thing.

Yeah it won't survive a worst case scenario. It wont even stop a freight train. Perhaps consider casting it from pure Adamantium.

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For example, designing it to withstand a combination of hits that sheared a 1/4-20 bolt. That's a LOT of OUCH! And, yes, I have seen that happen. It also happened to be a bolt that was holding a battery holder on. The battery was plainly visible shortly afterwards, and the robot wasn't moving.

A more reasonable test would be bouncing a Frisbee or a ball off of a robot's side panel that was made of similar material, several times, as hard as thought to be reasonable (grab a freshman and tell him to break it using X, but stop after half an hour, for example). If it breaks early, redesign. If it doesn't break (probably won't), you should be OK.


There's a time and a place to do analysis. A case to try to keep FOD out of the controller, you pretty much need enough strength to hold it together. A robot frame, you need a bit more for some reason...

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A 1/16" sheet of polycarbonate will not shatter no matter what you do to it.

Are the standoffs 3D printed, or are they aluminum or steel? Even with the 10/32s running through them, that would be the only part I'd have any concern about. It looks great and my team would totally use something like it. We've already printed a mock up of the roboRio for our off season bot, so we're right there with you.

Re: pic: Roborio mounting and protective case
 

Could you modify the 3d printed base to include something like this?

Re: pic: Roborio mounting and protective case
 

Wasay, I'm feeling more like Digiorno right now. ;)

Thank you! It wasn't in my original design, but as Electronica1 mentioned below, it's definitely possible to.

The standoffs are printed as well (they are a part of the base - they don't come off), but with a decent enough wall thickness to hold their own (it's an odd number due to the wall thicknesses driving the overall dimensions of the case, I forget the exact number). I'm sure aluminum standoffs could be used just as well.

It definitely can include something like that. There's plenty of room.

Re: pic: Roborio mounting and protective case
 

That is a cool idea. It looks like it should be able to sustain an impact from pretty much any game piece. A robot arm would be a different story but it would not be considered debris either.

From your description, it seems that you intend that the #10 screws used to attach the polycarb cover also holds the case onto the electronics panel. If so, removing the cover would detach the case from the bellypan. You will likely need more than 2 inches of space between the top of the Roborio and the cover in order to insert the various wires and cables. This design also requires screws that are longer than 2 inches, which will be harder to find. Four #10's in a more common length would be perfect for holding the case onto the bellypan. Four more short #10's could then be screwed into the pillars to hold the cover on.

Is each Roborio meant to be permanently attached to a case? It may be difficult to remove the Roborio if a lot of Velcro is used. Some holes in the bottom of the case would allow the Roborio to be pushed out of the case.
Alternatively, use the case to clamp the Roborio to the bellypan and dispense with the Velcro.

Please consider adding some strain relief features to the case to allow the various wires and cables to be secured to the case with zip-ties. Pairs of ridges on the vertical cylindrical parts would be just one way of doing this. Allowing the wires to be tied down would, hopefully, encourage the people installing the wiring to do a neater job overall.

Please also consider a version of the cover with a flap on each of the 4 sides of the cover may help keep debris out of the Roborio. Is it as prone to getting debris in it as the old Jaguars? The flaps can leave holes near the pillars for the wires to exit or the flaps can be custom trimmed for each application.

With this concept, it would be possible to "bury" the Roborio in the robot and gain access through the removable cover. The case would be mounted upside down so the top of the pillars would be touching the bellypan. You may have to make a larger version so that there is room to work on the connections.


Yes, please consider adding features like the one Electronica1 linked.

Re: pic: Roborio mounting and protective case
 

You know, some people might take that as a challenge...

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Agreed, if you are going to all the trouble to print what amounts to something that could be made out of plywood and wood glue you might as well take advantage of the 3D printers abilities, like some sort of cable management on all sides.

Also, the 2+ in long steel bolts and nuts could be removed if you made the holes in the standoffs a bit smaller and tapped them from both ends (or tapped from just the top and just velcro the entire thing to the robot)

Re: pic: Roborio mounting and protective case
 

That's a very good suggestion. I'll try to remember it when it comes time to design the electrical layout for our 2015 robot.

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Well, if you're going to enclose the Roborio somewhat anyway, what about getting some rubber/flexible 3d printing filament and making somewhat of an otter-box for the Roborio?

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FYI, from someone in the industry... 4 years isn't an unusual failure rate, although most do last longer. For example, check out the SABA study (Disclaimer: I currently work for Boston Scientific): http://www.bostonscientific.com/en-U...ABA-Study.html

Anyways, my point with that is... know the expectations for the part you are designing, and do your due diligence accordingly. An electrical enclosure like this is designed to shield the part from debris like metal shavings, not from robot-robot impacts. If your roboRio is exposed to impacts from other robots, this enclosure won't protect it.

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A lot of good ideas in this thread. I was thinking about something similar last night as we are working on a project with the Sasquatch controller that is extremely exposed in comparison to the roboRIO.

We'll probably design a case soon but something that does concern me a little with this iteration is the ease of removing the RIO and a little more coverage.

For the base I would tap the bottom of the standoffs and connect that directly to the robot frame and either velcro the RIO in or use zipties but make them easily accessible. The cover I would us velcro to attach it to the base for easy removal without tools/hardware and make it a 5 sided cover that extends down to provide more coverage around the perimeter which is where you need it most. If your cover is easy to take on and off you don't need to worry about providing clearance to get your fingers in to connect wires.

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Have at it. I'm sure you can freeze it to -30C and have something weird happen.

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Screw the water game, how about a liquid nitrogen game!?

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This isn't NASA, where robots must work in outer space for decades without maintenance. We also don't have unlimited budgets and time.

Ask any great team (1114, 254, 118, 111...) if they've done "stress analysis" on every single part in their robot. I'd be willing to be that they've only done this sort of work for maybe one or two parts on their robot.

From a mechanical point of view, this is not a simple analysis to conduct, nor would the results be very useful.

If you're so sure, please send me a link to this program. If a solution that lets you throw in a CAD file and tells you where weak points exist, then thousands of people would be out of jobs.

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Unit Testing is GREAT. But it's not the end of your tests. You need to do full integration testing as well as user acceptance testing. Furthermore, writing tests is an art in of itself. I've seen lots of situations where overconfidence in our test suite let a bug slip in. Or where the tests, while exercising the code in the proper ways, weren't quite testing every data point. (This was a tool for generating QRDA CAT 1 documents from a data warehouse for patients, testing every single data element wasn't required, just the ones we needed at the time). You've also got to worry about ACTUALLY stress testing your system as well as doing security audits and tests.



I can safely say that there is NOT a tool like that. FEA is a topic entire courses are dedicated to because, not only is it hard, it's complicated to set up your simulations. Even IF there were a tool like you described I feel it would cause more harm than good because of aforementioned terrible simulations. This is a situation where your ego is going to take a bit of a bruising - the CS world is easy compared to the ME world. I say that as a programmer. We control inputs, can filter bad ones, and testing all our edge cases is fast/easy. The real world? Not so much. Testing a design is often much more difficult than testing some code.



I highly suggest reading the criteria for the Quality Award in the manual. I'd also suggest reading the sections on Industrial Design Award. While your gut feeling is mostly correct there's a fair bit more that goes into deciding those awards than what team can show the most pretty pictures of contrived scenarios.

Re: pic: Roborio mounting and protective case
 

Or drop a little loc-tite on the polycarb.... not a pretty sight

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Let's see: Which would possibly result in more damage from the impact of a softball:

• A roboRIO with a cover

or

• A roboRIO without a cover

?????

Any speculation out there?

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Hey Andrew when you are done stress testing beating the covered vs uncovered roboRIO with a lead pipe can you set fire to my car so we can see how the glove-box handles hold up?

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Well, if said cover is made of, say, water balloons... :rolleyes:

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If something were to magically impact this in the middle of your robot, or you were to place this on some mechanism that extends outside your frame for some strange reason, the last thing I would be worried about breaking would be the polycarbonate. The 3d printed legs would go way, way before that.

Andrew, this could actually be really neat and useful if cable management is included. If you decide to do it please update us!

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Could you make a case for the main breaker, victor, talon, and even pdb? I feel those components could benefit greatly from the added security. I would like to test these ASAP on our old bot. If you could upload all the stl files to thingiverse that would be great.

Chow out

Re: pic: Roborio mounting and protective case
 

All of those components are completely fine without a protective case (as they have been for the past few years) because they have strong outer cases themselves and no open wire electronic ports.

Unrelated - I didn't know that there was an FRC team in Chowchilla. I'm new to the Central Valley area and working with Team 1323 - if you or your team ever needs any help with anything, feel free to contact us - we'll always be more than happy to help you. I'm also on facebook, so look me up if you ever have any FRC or design related questions.