How to power Mini-PC on robot?

[team-4480]

Originally Posted by Kevin Sevcik

EDITx2: Since it looks like you need that ID pin, you're back to first or third party laptop chargers. this might work if the OD of that connector is right. I'm afraid this is going to be a little hit or miss to get this working, though. Can you post the model number of the stock AC-DC adapter? If it can be matched up to a corresponding laptop, then you just have to find a car charger that's compatible with that laptop.

Yes, there is a center pin for the charger.

I will post a picture tomorrow of the official charger brick. Hopefully, we can figure something out. Thanks for the help thus far!

EDIT: Now that I think of it, I believe there was a third white wire when we stripped of the connector to test with our DC-DC adapter. Maybe we just have to apply a certain voltage on that wire and it will work?

[Kevin Sevcik]

Originally Posted by team-4480

Yes, there is a center pin for the charger.

I will post a picture tomorrow of the official charger brick. Hopefully, we can figure something out. Thanks for the help thus far!

Yeah, that's a "smart" charger. Hopefully a pic of the label on the charger will let us cross reference a laptop it works with and then a third part car charger you can power from the PDP.

[rich2202]

IMHO, you should really be thinking laptop with a built in battery.

[marshall]

Originally Posted by rich2202

IMHO, you should really be thinking laptop with a built in battery.

Actually, I'd say this device should be able to run off batteries since most PCs aren't designed to have power yanked from them or drop down randomly so running them from the ROBOT's battery isn't going to work. I'd say that independent battery power is "essential to completeness" to pretty much all COTS computing devices.

However, it is up to all of the LRIs with how they interpret the ambiguously worded rule about COTS device batteries. I know how I'm interpreting it until I'm told otherwise at an event by an LRI.

And based on Al's comments in a prior thread, as long as the COTS computing device's batteries don't interface with the control or drive systems for the robot, you should be following the intent of the rule in his eyes.

EDIT: Or don't test the rules and just use one of these after adjusting the output voltage: http://a.co/gd9yFkM

[rich2202]

Originally Posted by marshall

I'd say that independent battery power is "essential to completeness" to pretty much all COTS computing devices.

"Essential to completeness" is not the standard. Everything on the robot needs something else in order to work.

R37 says: "batteries integral to and part of a COTS computing device". There have been many discussions about batteries and the Raspberry Pi. Until someone sells a Pi COTS with battery, the Pi cannot have its own battery. Team 4480's computer is no different. Hence a laptop (notebook, chromebook, pad, etc.) with a built in battery is the preferred solution.

Just because you have an Operating System on your COTS computing device that does not like a random shutdown is not an excuse. If you had a more fault tolerant OS (and a fast booting one), you would not "need" the second battery.

[marshall]

Originally Posted by rich2202

"Essential to completeness" is not the standard. Everything on the robot needs something else in order to work.

R37 says: "batteries integral to and part of a COTS computing device". There have been many discussions about batteries and the Raspberry Pi. Until someone sells a Pi COTS with battery, the Pi cannot have its own battery. Team 4480's computer is no different. Hence a laptop (notebook, chromebook, pad, etc.) with a built in battery is the preferred solution.

Just because you have an Operating System on your COTS computing device that does not like a random shutdown is not an excuse. If you had a more fault tolerant OS (and a fast booting one), you would not "need" the second battery.

I call shenanigans. Your logic is broken. Laptops do not require a battery to function and can run off of a voltage regulator just like mini PCs and raspberry pis. If we're forced to deal with corrupt operating systems and files then why does a laptop not have to deal with it?

Q&A was asked a direct question about allowing replacement batteries for COTS devices and they chose to answer by explaining that integral means "essential to completeness". You are picking and choosing what that means (Just like I am... see the problem YET?!?!)... and if you're an LRI then you are entitled but no one else is.

[Bkeeneykid]

Originally Posted by marshall

I call shenanigans. Your logic is broken. Laptops do not require a battery to function and can run off of a voltage regulator just like mini PCs and raspberry pis. If we're forced to deal with corrupt operating systems and files then why does a laptop not have to deal with it?

Q&A was asked a direct question about allowing replacement batteries for COTS devices and they chose to answer by explaining that integral means "essential to completeness". You are picking and choosing what that means (Just like I am... see the problem YET?!?!)... and if you're an LRI then you are entitled but no one else is.

Well it seems the Q&A explicitly disagrees: https://frc-qa.firstinspires.org/qa/284

[marshall]

Originally Posted by Bkeeneykid

Well it seems the Q&A explicitly disagrees: https://frc-qa.firstinspires.org/qa/284

So I truly do not understand what FIRST is after here. If they don't want external batteries then specify that.

If they are going to allow batteries for laptops then I truly do not understand why they think laptop batteries are integral. They are not required for a laptop to function. They are not essential to completeness yet that is how they defined it so I'm left to think that a battery must be required for a laptop because if it loses power then it will potentially corrupt the OS or files. Any 1st year EE undergrad can tell you that a power source is a power source yet FIRST doesn't seem to think that. Maybe a cell phone has a battery that is literally required for completeness but that's not strictly true either. All of these devices can be run from an alternative power source like the robot battery.

Now they've said that USB power packs shouldn't be considered integral. Well, ok... what about this: https://www.sparkfun.com/products/13896

IT USES A USB BATTERY PACK!!!

Not to mention the custom circuit rules which allows for other things like this:
Ebay link for a supercap based system that should be able to charge from the robot battery

USB batteries aren't legal but yet this thing seems perfectly legal provided it charges from the robot battery and doesn't power anything on the robot's control system or motors. IT MAKES NO SENSE! It's not a battery after all, it's just a bunch of capacitors in a custom circuit. Bonus, it has a built-in USB port.

I'm committed to kicking and screaming about this for as long as it is ambiguous and believe me, we'll push boundaries on trying stuff.

I really implore FIRST to stop and think about what this rule is trying to accomplish and then explain the intent. At this point they are just being silly.

[techhelpbb]

Originally Posted by marshall

So I truly do not understand what FIRST is after here. If they don't want external batteries then specify that.

If they are going to allow batteries for laptops then I truly do not understand why they think laptop batteries are integral. They are not required for a laptop to function. They are not essential to completeness yet that is how they defined it so I'm left to think that a battery must be required for a laptop because if it loses power then it will potentially corrupt the OS or files. Any 1st year EE undergrad can tell you that a power source is a power source yet FIRST doesn't seem to think that. Maybe a cell phone has a battery that is literally required for completeness but that's not strictly true either. All of these devices can be run from an alternative power source like the robot battery.

Now they've said that USB power packs shouldn't be considered integral. Well, ok... what about this: https://www.sparkfun.com/products/13896

IT USES A USB BATTERY PACK!!!

Not to mention the custom circuit rules which allows for other things like this:
Ebay link for a supercap based system that should be able to charge from the robot battery

USB batteries aren't legal but yet this thing seems perfectly legal provided it charges from the robot battery and doesn't power anything on the robot's control system or motors. IT MAKES NO SENSE! It's not a battery after all, it's just a bunch of capacitors in a custom circuit. Bonus, it has a built-in USB port.

I'm committed to kicking and screaming about this for as long as it is ambiguous and believe me, we'll push boundaries on trying stuff.

I really implore FIRST to stop and think about what this rule is trying to accomplish and then explain the intent. At this point they are just being silly.

I would like to third that an external battery properly engineered - should be just as safe as a in integral battery. Considering that certain products known to smoke have integral batteries that were not properly engineered either.

I believe I understand the spirit of the goal with this rule - but I disagree that integral batteries insure proper engineering and external batteries are more risky.

If it's down the bare legal issue of having someone to sue - consider that most companies DO NOT recommend mounting their systems on a mobile robot so in a Court of Law they'll pull that out as a defense.

Unrelated to the quote above:

I disagree that a small PC that is not a laptop will fair poorly on a robot. I know of several HP Pavilion models (550 for example) that are miniITX motherboards in unusually large cases and take 19VDC power in. With the addition of a cheap SSD these would be no more likely to fail than a laptop and that style board is often mounted in large full size motor vehicles. Granted a full size motor vehicle has a suspension. Years ago someone told me on Chief Delphi that a laptop on a robot would fail if it wasn't as robust as a Panasonic ToughBook so I put a Dell Mini 9 (SSD) and a Gateway netbook (with a HDD replaced with an SSD) on a robot in a box merely padded with foam and drove it over the 6" bumps in the field that year hundreds of times without a single failure of any sort. Could it fail - sure. Did it fail - no. I have watched people drop average HP and Dell laptops down stairs in a padded case in hibernation and they come out in one piece and still work.

As far as how to produce reliable power for such a setup - I strongly recommend that someone boost their input voltage from the battery as high as they are legally allowed then buck it down to whatever voltages they require (use switching power supplies). If 24VDC is the maximum (likely because of the history of the cRIO) then go as high as that. If you don't do this you'll always have risk that the battery will absorb a heavy load and drop output voltage just enough to force a reboot.

If would be better if your PC could run off 16V or less because at 19VDC you only have room for the input voltage to dive about 5-6VDC before the only safety you have to insure a correct output voltage will be the temporary charge of the internal switching power supply capacitors.

Finally I am still game to produce a 3D printed or laser cut case with a Raspberry Pi and battery in it but the requirements for this are more about FIRST rules than some huge business opportunity. If someone wants to put the work in I am will to provide assistance if asked. I figure the goal should be to provide such platforms for a bunch of common FIRST coprocessors because frankly - many times the coprocessors in FIRST are each powerful enough to run a mobile robot outside of FIRST and there could be some opportunity there if that business later provides expanded I/O solutions for those platforms as well. If someone designs the case I have access to many 3D printers and the large format laser cutters at NextFAB in Philadelphia. I can also provide free web services and domain registration to reduce the operation costs. I can finally provide testing and prototyping for the electonic elements. As I have effectively made this offer for this 5 times now on Chief Delphi alone - please be aware that you'd be working on something for next year because this year is cutting it very darn close and if FIRST (understandably) asks for something to examine themselves you are leaving them far too little time to complete that evaluation.

[Jon Stratis]

Marshall, I think you're reading too much into the Q&A ruling. It specifically says that "laptops are designed to have a battery" - even if the battery is swapable, that doesn't mean you're constrained to the one that originally shipped with the laptop, so long as you use a battery intended for use with that laptop by the manufacturer.

But I can't see a way to interpret that ruling to allowing batteries to be added to a computing device that is designed to be run off wall power. Before you try that route, ask a direct question on the Q&A, otherwise you're likely to be disappointed at competition.

[marshall]

Originally Posted by Jon Stratis

Before you try that route, ask a direct question on the Q&A, otherwise you're likely to be disappointed at competition.

I did ask a direct question and got a "go read the dictionary" response. They were being cute with that response and they know it.

I'm already disappointed... nowhere to go but up from here.

[Jon Stratis]

Q138 was intentionally worded to be extremely broad, don't deny it. Any attempt to give a detailed response by the GDC would have likely opened up loopholes for teams to exploit. Instead, they gave a simple response that most people can conceptually understand.

Q284, on the other hand, was an extremely straightforward and narrow question, and as such got a straightforward and direct response. Be more like Q284.

[marshall]

Originally Posted by Jon Stratis

Q138 was intentionally worded to be extremely broad, don't deny it. Any attempt to give a detailed response by the GDC would have likely opened up loopholes for teams to exploit. Instead, they gave a simple response that most people can conceptually understand.

Q284, on the other hand, was an extremely straightforward and narrow question, and as such got a straightforward and direct response. Be more like Q284.

Asking them to explain the meaning and intent of a rule is broad? I think not. I wasn't being cute. I was being sincere and trying to get a response.

I'd like to see one of two things:
A) Say that teams can use batteries for computing devices provided it is done safely and doesn't interface with the control or motors for the robot. This can be demonstrated by having the team turn off the robot and see what is still running.

or

B) Make the only legal source of power on the robot to be the ROBOT battery.

[Bkeeneykid]

Originally Posted by marshall

Asking them to explain the meaning and intent of a rule is broad? I think not. I wasn't being cute. I was being sincere and trying to get a response.

I'd like to see one of two things:
A) Say that teams can use batteries for computing devices provided it is done safely and doesn't interface with the control or motors for the robot. This can be demonstrated by having the team turn off the robot and see what is still running.

or

B) Make the only legal source of power on the robot to be the ROBOT battery.

Both of those options bring up a lot of concerns that I don't think FIRST will agree with. With option A, you have the potential of teams connecting batteries to things that really shouldn't have batteries on them. You'd of course need much more changes in the rules to define what is "safely and doesn't interfere with control or motors for the robot". Option B means a lot of devices are now back out of the reach of teams, which kinda negates the original purpose of R37's lower info box. It's much too late in the season to implement that choice, as many teams are already designing in Phones ala 254 last year, GoPros and other small devices. I'd be ok with that first option, just as long as there's an explicit regulation on what it can and cannot power. Honestly, a single thread on CD and a few Q&A posts are unlikely to change these rules, so I'm not seeing that this could be implemented easily this year.

[marshall]

Originally Posted by Bkeeneykid

Both of those options bring up a lot of concerns that I don't think FIRST will agree with. With option A, you have the potential of teams connecting batteries to things that really shouldn't have batteries on them.

You really don't. Limit it to cameras and COTS computing devices and you have what we have now.

Also, S03 already covers unsafe robots.