Rules Change I Would Like to See - Batteries
 

Under the current rules, all systems must be powered from the single 12 volt battery, with the exception of sensor/computing systems that have their own built in battery.

I would like to have the "built in battery" portion removed, allowing separate batteries for coprocessors such as the Raspberry Pi.

The reasoning behind it is that there are sensors and processor boards that are meant to run on USB power, and may not be easy to hook up with anything else. The USB port of the RoboRio can't supply enough power for these systems. It would make it easier for teams to make use of more advanced sensing and control strategies for which the RoboRio is not well suited.

The exact wording could be problematic. I'm not sure I could come up with a perfect wording of the rule, but if someone could, then it could work. I would want a rule that allows "portable phone charger" type power supplies to be used to power those auxiliary boards that are designed to run vision coprocessors or similar algorithms.

Arguments for:

We are trying to encourage young people to use cutting edge technology. This makes it easier.


Since it is only used for computing, there are no safety issues with supplying power to motors and actuators.

The current rules encourage the use of tools with built in power devices, which might not be the best for the job.

Arguments against:

It makes the inspection process more complicated. An inspector might miss some sort of "sneak circuit" that could allow an actuator to be activated when the robot is supposed to be disabled.

Although it allows use by students of cutting edge technology, it also makes it easier for mentors to put in systems that are far beyond student capabilities, allowing an even greater advantage to "mentor built" bots.

"Making things easier" is not always a worthy goal for a First program. Working within constraints might be more important, so the current constraint is simply an engineering challenge that teams have to work within.

Although the intent is straightforward, the actual wording of the rules might be extremely complicated. If the rule is too simple, it might be easy to exploit loopholes for unintended capability. If it is too complicated, it might result in accidental violations due to misunderstanding the rule, or misinterpretations by inspectors resulting in confusion and controversy at competitions.



And now, fill in your own advantages and disadvantages. This is just something I have in mind. I am not adamant that we need to do this right away. I simply find myself wanting to do some Raspberry Pi work with some students, and I find that I will have to do some rather odd things to power the board, that might not be the safest for the equipment. (There's no human safety issue that I can see.) It would be easier if I could just velcro on one of those battery power packs and power the Pi directly. It may be that there is an obvious problem with this idea that I haven't thought about, that might turn it into a very bad idea.

An alternative would simply be to modify the next generation RoboRio or control system boards to provide more USB power. I don't know how far in advance these things are designed, but my guess is that there are already modifications in the works. I just don't know if we are likely to get new or modified control systems in 2, 3, or 4 years.

Re: Rules Change I Would Like to See - Batteries
 

Why not use a 12V to 5V adapter? Wouldn't that count as a custom circuit (and already be legal)?

Re: Rules Change I Would Like to See - Batteries
 

It is already possible to power a Raspberry Pi off of a robot. You just need to wire the power cable to the 5V/2A port on the VRM. My team used it this year for our vision system and it worked just fine.

+1

Re: Rules Change I Would Like to See - Batteries
 

Allowing 12v to 5v regulators would be a lot more useful in my opinion. There's not need to have a separate battery when you can just step down the PDP voltage.
Sometimes the VRM doesn't have enough power to give. Even the 5v 2a slot isn't enough for some applications, and I dislike the extra loose wires that it requires. Ultimately though, there's not enough need for more 5v power to make it worthwhile imo.

Re: Rules Change I Would Like to See - Batteries
 

DC-DC converters are legal.

Re: Rules Change I Would Like to See - Batteries
 

We have also used automotive USB power converters to power USB and other 5V devices on both our competition and non-competition robots (e.g. t-shirt cannon); you can get these at almost any local convenience store. (Example). It is usually a simple matter to remove the power port connectors and expose the wires to provide the 12V input. There are also units with wire pigtails or spade connectors for inputs, designed for installing in a dash board; a bit more effort to locate, but neater-looking.

Re: Rules Change I Would Like to See - Batteries
 

I would suggest against a USB converter because you're really only guaranteed 500 mA. Odds are it can actually do more than that, but something to watch out for, especially if you're doing anything computationally intensive on the Pi. I'd also watch out for some of the cheaper automotive USB converters. The power is often really ugly (lot of switching noise), which is generally fine for charging your phone, but for a Pi, it may be a little more sensitive to switching noise.

Re: Rules Change I Would Like to See - Batteries
 

Thanks for illustrating the issue very well.

Yes, there are ways to do it, and lots of teams do them. However, there are issues with them. Gotchas. Things to look out for.

If the students were just allowed to use devices that were actually designed specifically for providing power to a device that was specifically designed to use that power, those gotchas wouldn't exist.

Again, some people might look at that as a good thing. Providing an easy solution is not necessarily the best thing for a FIRST team. The question that the rule makers have to ask themselves is whether they want to encourage people to make use of the fancier processing available through the use of coprocessor boards. If so, do they want to make a little bit of electrical engineering a prerequisite, or do they want to let them cut straight to the processing part, assuming they are willing to pay a small weight penalty. (I would assume that, unlike the main battery, any batteries used to power auxiliary computers or sensors would count against the robot weight allowance.)

I don't think there's a "right" answer to the question. I have an opinion on the subject, obviously, but I won't say that there is an obvious answer.

So far, though, the people providing information haven't really discussed advantages and disadvantages, just that the rule change isn't necessary because there are engineering solutions available for teams under the current rules. I suppose the disadvantage is that it introduces an unnecessary change to solve a problem that, in many people's opinion, already has an adequate solution.

Re: Rules Change I Would Like to See - Batteries
 

What would you define as a dedicated USB power source? The powerbanks for phones are one example, but those have a non-negligible power storage compared to the robot battery itself. One can simply use a larger DC-DC regulator to get bigger 5v power.

Re: Rules Change I Would Like to See - Batteries
 

What I have in mind is the powerbanks for phones. The exact wording is something I would leave for the rule makers.

Sure. You could use a DC-DC regulator. It's not that hard, but it requires either a student or mentor who understands the requirements, and a little bit or rewiring and cable cutting to hook the output of that to whatever the coprocessor board requires.

It just means that a programmer who wants to do some cool programming has to team up with someone who understands how to get an adequate amount of 5 volt current out of the available power sources. A student whose focus is programming, and who knows nothing about electricity and power supplies now depends on having someone else on his team that can take him past the "easy" step of finding the appropriate regulator.

Not that that's a huge deal, but on smaller teams that might be the thing that prevents the budding programmer from making it happen during competition season.

One thing that I have seen, both in my professional career and in FIRST robotics is programs stalled because the person assigned to the task knew how to do the "hard part", but not the "easy part". Just last week at the office, I had to coach an expert Java programmer through the arduous task of reading a voltage from a device. We have been working on automotive diagnostics via Canbus. She knew everything possible about networks, communications protocols, and data structures, but we had a new task to mix in voltage data read from a data acquisition device. She knew everything about how to write the program, but she was utterly perplexed about where to connect the wires, or even what to connect them to.

I've seen it happen in FIRST as well. The electrical people can't do anything because they can't write a two line program. The software people can't do anything because they can read the sensor, but they can't connect it to a power supply. This proposal just makes it easy to get over that hurdle.

Whether or not that is a good thing is a matter of opinion.

Re: Rules Change I Would Like to See - Batteries
 

I would guess that $5 noname chinese usb battery packs off of Amazon are exactly the type of thing the GDC has created so many electrical rules to ban. Unless they only approved a few specific models, regulating something like this would be a nightmare. Not to mention the 5V/2A isn't even enough for many computers. Odroids (5V/4A) and Jetsons (12 or 19V ??) come to mind.

Re: Rules Change I Would Like to See - Batteries
 

I think a lot of what you're describing is just the reality of FRC, and robotics in general. The mechanical people need somebody to program PID for them, the electrical people need the programmers to make the lights blink, and the programmers need the other two to do everything they need to.
I agree that finding people who know electronics is hard (of the entire "Electrical" division on our team, maybe 2 of them know electronics; the rest are programmers only). But the knowledge that it takes to wire a 5v circuit shouldn't be something beyond the capabilities of a few mentors to tackle.
Personally, I've found my knowledge both of electronics and of programming to be very useful, especially when it comes to using microcontrollers. Also in helping the programmers figure out electrical problems. :P

Re: Rules Change I Would Like to See - Batteries
 

Exactly. There are safety concerns as well given the prevalence of lithium ion chemistry batteries. You do NOT want a large one of those punctured or shorted. Cell phones and Kangaroos have pretty small batteries, and laptops are typically above the $400 cost limit (or considered too heavy). Punctures in even small LiPo batteries can be quite destructive, and a large lithium ion battery on a FRC robot sounds like a really bad idea when DC to DC converters (or doing vision processing on the driver station) are perfectly viable alternatives.

Re: Rules Change I Would Like to See - Batteries
 

While we're at it, I think it's worth a mention that you are allowed up to 3 Additional VRM units on your robot according to R48 of the 2016 Manual. If you do have a processing unit on your robot that requires more than 2A (but less than 20 due to the fuse on the PDP), that is a possible option. As many others have mentioned, DC/DC converters may also be of interest.

Honestly, if you have a processing unit on your robot that is constantly drawing more than 2A, it might be a good idea to ask yourself "is this worth the trouble?". Something to keep in mind that electrical engineering, especially on a mobile robot, usually has the challenge of working with the power you're given. FRC Robots have a pretty big supply of power going to them as is, do we really need more?

Re: Rules Change I Would Like to See - Batteries
 

Many of the 12V converters feature a 2.1A port and a 1.0A port, which is enough for a pi. You can always add a couple of capacitors (it's a custom circuit) to clean it of if necessary. Our preferred method is still the VRM or other robust, regulated DC-to-DC converter. Jaci's bottom line is right on the money:

Remember, in addition to the battery, we can (in most recent years, anyway) have pre-charged pneumatics tanks, pre-wound springs, and gravitational potential energy. (R35 A, C, and B respectively in 2016.)

Finally, If you really want that separate USB battery-power, charge up an old laptop, and power your pi off its USB port. There's no rule that says you have to turn the laptop on, much less do any processing on it. If you can use a classmate from a KoP, you won't even have to list any dollar cost in the BoM.

Re: Rules Change I Would Like to See - Batteries
 

As I see it. The problem the second battery solves is not losing your sensors and CPU from brown outs. The old (pre 2009) control system had a battery for this purpose because a brown out would cause a loss of control without disabling the robot. A second control power battery Powering the Rio and radio along with other custom circuits would solve a lot of issues. It would also add cost and complexity to the robot.

Would another possibility for the auxiliary processing be the android system used in FTC? The come with batteries and meet the COTs definition.

Re: Rules Change I Would Like to See - Batteries
 

A cool idea, but I think the VRM (or a second or third VRM as needed) would do the trick.

We powered a Pi and an IP camera (and its LED ring light) off the VRM on our competition robot. On our practice bot, where we were a little less, uh, picky, we plugged the Pi into the USB port on the RoboRio.

Re: Rules Change I Would Like to See - Batteries
 

Well, that's a pretty compelling argument against my proposal. If there's a genuine safety concern, that pretty much trumps everything else.

The DC-DC converter plan seems like a better idea.

Re: Rules Change I Would Like to See - Batteries
 

The safety aspect can be dealt with fairly easily. Cost and complexity still remain. The battery powered tool industry has pretty much gone to Li ion for everything except the bottom line tools. They get badly abused and have a low risk of fire/explosions. First could pick one or two commercial solutions and restrict maximum current draw and require specific chargers.

Another option for Arduino and PIs is somebody to package it with a battery and case. As long a it a company and they make it available for sale, it becomes a legal COTs device. (insert the usual future rules disclaimer here). Make it nice enough and maybe AndyMark would stock it for you.

Re: Rules Change I Would Like to See - Batteries
 

Having a separate battery isn't without its own concerns. Assuming this became legal, you just know there will end up being a team somewhere, sometime that will be kicking themselves for losing a key match because they forgot to charge the battery pack powering their vision processing system.

Re: Rules Change I Would Like to See - Batteries
 

Hey look! It's a raspberry pi with a battery: https://www.sparkfun.com/products/13896

Ok, seriously, I agree with OP that this is a topic that needs to be dealt with.

My suggested rule change is simple though. Just enable teams to use all batteries outside of the standard robot battery provided they do not interfere with the control pathways for any motors, they can be removed and disconnected quickly/easily, and they do not appear to be unsafe to a reasonably astute observer (no exposed wires, held securely, can't be easily punctured, well protected, etc).

I don't think my suggestion will do either personally and it *might* just help a lot of teams who are struggling to deal with power-hungry games that demand power-hungry drivetrains and power-hungry mechanisms and power-hungry co-processor vision systems. I dare say, it might even inspire some students.

For one, enabling the use of all batteries means the inspectors don't have to look at an approved list or deal with the currently ambiguous ruling of only allowing non-standard batteries that are "integral to" a COTS computing device.... which by the way, I'd like to know if this flashlight (http://www.lightmalls.com/nextorch-p...4aAvW 98P8HAQ) counts as a COTS computing device since it is programmable.

Let's talk safety with alternative battery sources. If the concern is that something is going to catch fire then coin cell batteries and USB power supplies aren't likely to do it. I'm not saying they can't but they are common components (Sorry FRC fans but those crappy Chinese USB power supplies are a lot more common than FRC batteries) and I suspect the likelyhood of a fire is about the same as the chances of one from the standard robot battery we all know and love so can we ignore this facet of safety and move on? Not to mention that the same crappy Chinese batteries are legal provided they are "integral to" a COTS computing device.

The real issue/fear is that a robot or robot mechanism will remain powered up and running. I believe that if the team can demonstrate to an inspector that the power source does not interface with the power for a motorized mechanism or drivetrain then it should be legal. I believe teams already have to do this if they have an "integral" power supply for a COTS computing device on board... and if they don't then they should.

Also, I want a ruling about super capacitors while we're at it. They are circuit components and not batteries so they are legal for keeping a raspberry pi powered right? :yikes:

While I disagree with the way the OP worded his initial post, this issue is a sore spot for me as well and I do think FRC should address it in a manner similar to the "allow but educate" style that they have adopted in the recent years. Come on KOP team, Frank, and LRIs... how about showing some love for additional power sources for computing devices?

Re: Rules Change I Would Like to See - Batteries
 

That's not what that rule means. It gives you permission to break the one wago one load rule with up to 3 VRMs. It doesn't limit you to 3 additional VRMs, you could have as many as you want limited by the number of 20amp breaker slots there are * 3 VRMs.

Re: Rules Change I Would Like to See - Batteries
 

Coin cells aren't a concern as much as the others. If we allow even small USB li-ion packs, then what's to stop somebody from manufacturing a 60c lipo pack that can output 10 amps through the USB port? And that's not even including the inherent risk of cheapo battery packs that do catch on fir sometimes due to internal shorts. It's a lot safer just to use the existing battery which has proven to be extremely robust and safe IMO than to risk unknown, possibly dangerous components. The safest solution to avoiding sensor issues and brownout is just good power management. Unfortunately, that's definitely limiting, but safety is #1.
If FIRST partnered with Samsung or another reliable company to supply teams with a FIRST legal battery pack, that would be a good solution to the problem without allowing weird loopholes or dangers.

Re: Rules Change I Would Like to See - Batteries
 

I don't think powering your 10W raspberry pi off a separate battery is really going to noticeably reduce the power consumption of your 6-CIM drive robot. While I am aware that there are much more power hungry co-processors out there and that is probably what you are referring to, none of them come close to 337W. Either way, the GDC has changed a lot of rules over the past few seasons encouraging teams to understand the power limitations of their robot and to design accordingly (less motor count limits, getting rid of max servo power (kind of)). Just like you shouldn't power your drive train off of 6 CIMs and 10 miniCIMs even though you can (at least based on motor limits and PDP slots), if that vision system really wrecks your power consumption, maybe you should select something that is less power-hungry or reduce your power consumption elsewhere on your robot.

Re: Rules Change I Would Like to See - Batteries
 

Hey, that's profiling - and OBTW, my beard isn't gray, it's almost white, except when I dye it green ;->.

More seriously, inspection is already a challenge for many inspectors; there should be a better reason than this to make it more difficult. If FRC can find a standard 5V power source for which they can provide a concise list or (even better) get something donated as part of the KoP, wonderful! Otherwise, this is (IMHO) a pound of solution for an ounce of problem.

Re: Rules Change I Would Like to See - Batteries
 

It removes the hassle of a brown out by enabling two different and disconnected power systems so one does not interfere with the other. It's pretty similar to the way some vehicle power systems are designed.

They are a problem though because they are currently illegal based on the rules. And why aren't they a concern? I've seen them go boom the same way I've seen LiPos go boom.

Nothing other than the USB spec but you can dodge the spec. USB C is rated for 5 amps continuous and I'm not sure about surge but something tells me it could handle it. What's wrong with pulling 10 amps from another power source though? Is there something inherently dangerous about 10 amps? Doesn't the existing battery allow me to pull 10 amps?

Again, the safety concerns come from something going boom or something moving when it shouldn't be. Or maybe you are worried about someone being shocked? Either way, all of these can happen and have happened with the existing battery.

There is no inherent risk that is not already present with existing batteries and as I've already pointed out, these cheap battery packs are WAYYY more common than FRC batteries and many people seem to be using them everyday without issue to charge their cell phones.

While safety might be #1, making it easier on teams to do cool stuff should be #2 or maybe #3. Enabling teams to run co-processors without worry of brownouts and similar makes it easier on the teams to do cool stuff.

[sarcasm]Yes, because partnering with another company to deliver parts is just that simple and that has never produced supply problems for FRC teams in the past...[/sarcasm] It also does allow weird loopholes and dangers... the part could become obsolete or it could have a manufacturing defect (*cough* white exploding tanks *cough*). Just because you think a company is reputable doesn't mean they are impervious to turning out a malfunctioning product.

Inspection is a challenge and I'm very cognizant of that. So, instead of training the inspectors on a particular part, train them to look at the control system and power pathways for the motors to ensure they are not being interfered with from a USB power source... I'm not saying it will be as simple as asking the team to point out any onboard power sources other than the big robot battery but you could and then verify they aren't plugged into any motors or motor controllers.

You guys need to get real about this though. If you actually want to see this rule changed then suggesting that FIRST partner with another supplier for it and make rules about requiring specific part numbers just makes it more difficult, not easier. It puts the burden on the FRC folks to track down parts, get them donated, include them in the kit, write specific rules about them, etc. That's a lot of work for some already overworked people.

An alternative, as I have suggested, is to change the existing rule to fall in line with the example that is already allowed under the batteries integral to COTS computing devices. No one is checking those specific devices or batteries but they are typically checked to make sure they aren't powering any moving assemblies on the robot.

Also none of you addressed the existing loop holes that I already pointed out including a flashlight that could be considered a COTS computing device and using super capacitors, which I'm more worried about other teams trying to use than I am a cheap LiPo pack (I'm not actually worried, I encourage it, go use them because they are legal under the existing rules!). It is possible to make all of these items secure and safe though.

And with that I'm done with this thread. I could argue with you guys all day about this. I've offered up a solution that makes sense and should make it easy. Stop arguing and actually think about the problem for a while. What I've said isn't crazy talk and is a good way to solve this.

Re: Rules Change I Would Like to See - Batteries
 

Ok, I do agree a separate power source will limit the impact a brownout will have on your robot, but I am still of the belief that designing to avoid brownouts is just part of the game and that FRC should solve the actual problem by better educating teams on power consumption, rather than just helping one of the symptoms.

Re: Rules Change I Would Like to See - Batteries
 

While it is certainly part of the current rules and you have to allow for it...
My opinion is it would be a better game if you didn't have to deal with controls brown out as it is now. As a complete tangent, an industrial design that had these issues would either separate control & power energy or make the energy source big enough so that is wasn't a issue.

With the current rules, a super capacitor would likely make the robot fail the power off test on the robot inspection check list.

Re: Rules Change I Would Like to See - Batteries
 

If you make a COTS device that consists of the battery, charger and device you can work this rules set without major changes. I've brought this up before elsewhere on ChiefDelphi and passed that concept around with FIRST engineering a few times. (I reread this topic and note that FrankJ brought this up previously).

So it's possible to make a bundled Raspberry Pi based device with a battery and sell it as a unit COTS. You must sell it to the general public essentially engineered with safety in mind. So the battery boards for the Raspberry Pi do not really cover this because they are not bundled with the system or even enclosed.

The risk of *any* lithium based battery is already present because FIRST allows laptops with batteries on the robots, again they could always change that next year, but FRC11 has used a laptop with battery several times.

Once the risk exists already it's really hard to argue we can't regulate the hole.

Re: Rules Change I Would Like to See - Batteries
 

If a supplier is thinking of doing this, please do not make this. 3 times the price for a cable and a sticker.

Re: Rules Change I Would Like to See - Batteries
 

Acrylic in laser cutter.
Glue.
Proper design.

I believe this could be done as a simple business but I don't want to start a business with returns this low myself. Might be willing to help someone else start it. There are a lot of good Linux systems that one could make cases with batteries for and provide simple assembly before delivery to the customer. Such as the ODroid XU4 and NVidia Tegras.

See the ODroid XU4 CloudShell as an example:
http://www.hardkernel.com/main/produ...=G143599699669

Re: Rules Change I Would Like to See - Batteries
 

See bolded text above.

Re: Rules Change I Would Like to See - Batteries
 

What about this? Does that not qualify as both COTS and having a battery? I know its not in stock, but I don't see why it would be illegal.

Re: Rules Change I Would Like to See - Batteries
 

Nope because again no enclosure and not delivered assembled together. The whole idea is the laptop/phone maker took steps to deal with puncture. The SparkFun Pi-Top laptop Marshall linked earlier may have the same issue, but because it looks like a laptop the inspectors might not catch it.

Basically FIRST wants to know that a company is backing up the safety of the device with their own liability using that power source. Using an assembly like you linked leaves the FRC team risk of liability if their package is inadequate. It is dubiously legal FIRST can argue that a laptop/phone maker intended their device for FRC use but they figure at least, as a package, a professional was involved with design.

Also supercapacitors are able to be used as part of a COTS device but as others have pointed out: the presence of power does not mean field safety is overridden. So the COTS device can not power robot motors directly. Therefore no USB rocket launchers from said COTS device even though you can buy said toy COTS. Technically I suspect USB powered fans would be denied as well, but internal cooling fans to the COTS device are okay. I have no idea how FIRST would react to a USB connected laptop cooler, that would be worth asking in the official Q&A. Point being: you should not be moving robot parts directly with the COTS device (my laptop cooler rarely tries to spin around and kill me...rarely ;)).

We've had the on board laptop and a Kangaroo die before like this. However we've also had a whole robot get unplugged because the Anderson connectors were not all the way together. It's much easier to insert process to fix this issue than to insert process to fix unusual brownouts caused on a field you usually don't have access to with other robots that you don't have to test with.

Actually, I'd also like to see FIRST extend a power source for the radio. Beyond all the 3d party COTS devices we loose radio power with devastating consequences most often. Worse the power to the radio is not something FRC teams are really allowed to regulate or adjust themselves. So if the co-processor issue is annoying the radio power issues is a magnitude worse because right now we can't change anything as an FRC team to address it except check the wires, replace hardware or find the power draw (which may be from being stalled by a pushing match).

Re: Rules Change I Would Like to See - Batteries
 

Thanks to everyone who posted suggestions.

I think the real takeaway from this and related discussions is that as time goes by, coprocessors that require more and more power will become more and more common. If FIRST wants teams to be able to use these things, they'll probably have to have some sort of dedicated power solution for computing/vision/sensing devices, and will have to be sure that they can somehow make sure those dedicated power solutions aren't powering motors or other actuators, and otherwise won't kill anyone or start any fires.

For the meantime, I have a couple of different solutions in the works that I don't think break any rules.