Although I think that the compressor will be run in a closed loop without any way of code affecting it, you are certainly right. We had 6 cims on our drive train this year and we often browned out the cRIO with about 20 seconds left in the match. Having the ability to see the current being pulled would let us stop that from ever happening again.
Although this is partly true, current draw isn’t the whole story to tripping the 120amp main breaker. The main breaker, which is a thermal breaker, will heat up and become more susceptible to tripping as it gets hotter.
Thus, tripping the main breaker is a function of both current draw and temperature. We have set up our practice bot with a thermocouple on the main breaker and inductive current sensors on the ground pole of the PDB. We have been logging current and temperature values in an attempt to isolate tripping conditions, but even then it can be difficult to really narrow down exactly what is happening the moment the main breaker trips.
I only have a limited knowledge on this subject, I’m hoping the students on our electrical team will post a whitepaper on the subject soon.
Regardless, excited to see current sensing integrated into the PDB.
-Mike
Currently, the ‘access point’ is a USB Dongle with drivers on the rRIO. It’s a huge improvement in size and weight, and is easy to place anywhere on the robot now.
I understand that it’s a near integration of current draw, but this now very easily lets programmers sense when they get into a pushing match. From that point, they can now decide to shift automatically or to cut off a CIM on each side. When in a pushing match, 6 CIMS easily draw about 450 Amps. The main breaker can only sustain that for a fairly short period of time before tripping (couple of seconds). However, if you drop down to 4 CIMs while in a pushing match, they’ll stall out at about 350 Amps. The main breaker can sustain that for a much longer period of time.
The submission date in the blog post has been updated to May 30, which matches the flyer that was handed out at the championship.
The roborio is only $435. That’s really nice, but is this a once per year deal like the cRIO is?
At championships they said that the Roborio will be sold through AndyMark with no limits on the number ordered. I suppose they might decide to limit initial purchases to just make sure they don’t run out before everyone gets one or two but that’s not the plan going forward.
There have been Alpha test teams working on this since September of last year, and per the last post from FIRST they plan on starting a wide-ranging Beta test this year 2 months early and getting stuff to folks in July.
The Alpha test teams working on the system (and let’s exclude mine for a moment) include some absolutely top level programmers from World Champion teams - folks who have had working relationships with NI and FIRST, and many of whom have done Beta testing every year it’s been offered.
Hardware details are quite literally, released as soon as they have them. In many cases they are still ironing things out and making changes. In fact, we were given Rev C roboRios at Champs that we are now shipping back from some improvements.
Alpha Teams are traveling back to New Hampshire with our robots in a little less than a month after just having finished champs. New software updates were just release a short time ago. We’ll be spending every weekend between now and then testing all the new changes. It would be pointless to release a WPILIB to the community that isn’t even completed yet and still has bugs.
I don’t mean to be snarky, but there are a whole lot of people working with this stuff since last September non-stop, including setting up demos, bringing it to competitions, and holding a seminar with NI folks who took their personal time to fly up to Michigan and put it on, etc.
FIRST, NI, and CTRE and the other Alpha testers are doing a phenomenal job testing a product and getting information out to testers as fast as possible. They won’t stick up for themselves out of professionalism, but I’ve got no problem saying flat out that they’re doing a great job.
For anyone who wants to get involved and see the stuff ‘before December’, by all means sign up for the Beta testing and be part of the solution. The more experienced teams who test, the better. Keep in mind though that part of being a Beta team means holding a seminar for other teams, so none of the information comes as a shock to anyone.
I don’t work for NI, but my understanding is: no. You will be able to buy as many as you want.
It’s $11 more and it has data logging as well as current sensing.
I’m not sure if you’ll be able to do this. Teams currently have to charge the pneumatics using the control system, even if the compressor isn’t on the robot. I’m not sure if the current compressor object in WPILib will survive the upgrade, although you could always program your own with a relay and digital input.
I’m not sure how it’s “way more complicated than it needs to be”. It has power, pressure switch, and CAN bus inputs. And compressor and solenoid outputs. It’s as dead simple as it can be.
And, you’re talking about using $140 in spikes to avoid buying a $90 board that can power twice as many solenoids.
You’ll not be shocked by the updates to either of these items. If you know what you are doing now, you’ll know what you’re doing with the new parts. If you have specific questions about anything, there are a lot of people on this board who have a spent some time Alpha testing. Feel free to ask.
I charge my pneumatics with a relay that is many years old. I buy a single $34.95 relay for shifting. I would not like to purchase $180 worth of pneumatics boards, instead, I would like to purchase 1 new spike relay for use on the competition robot, and use an older relay for our practice robot. That is spending 5 times as much money to accomplish the same task. In my personal opinion, providing CAN functionality to the pneumatics board is too complicated.
Then use a spike relay off one of the relay ports. If you feel you need more than 4 spikes, some of the general purpose digital i/o can be set up to run relays (probably).
I was told at St. Louis that we would not be able to use the normal I/O for the relays. They did say that the setup they had there was not the final one, so the new one might be able to do that.
Is there a any particular reason you’re using spikes instead of Victors/Talons for the motors? The only time I think we’ve used a spike over a motor controller was when we temporarily maxed out our PWMs outputs. Given that the new RIO allows for 20 PWMs, I don’t see this being an issue.
Yes. The spike costs half as much as the victor.
Ah. I see what you are saying.
I’d say you are in the minority in using pneumatics, not wanting to use a PCM, and using more than 2 relays. NI / CTRE built the system for the majority of users and yours seems like a pretty signicant edge case.
CAN on the PCM is 2 wires using reliable connectors and the programmer is blind to its application. Not really complicated.
Without reading the 2015 rules, you will not know if you can run the compressor with a spike or if you will have to use the compressor port.
I dug around a bit trying to find the Beta Signup Page. No Joy. Can someone please point me to it?
Thanks,
Joe J.
I just wanted to highlight the words “get involved” as in actually investing time in testing and having more activity in the beta forums etc. We’ll need to step it up more than ever… For example, I’m still somewhat frustrated about the SmartDashboard lockup bug that was never found during beta testing… grant it… it was hard to reproduce, but that’s where the beta program comes in… testing over and over again… to increase chances of finding the intermittent bugs.
This in going to be a lot of fun 
Can’t wait to see what the USB radio will entail and also those USB camera’s (Hint Hint: Kinect on robot)
Can anyone provide information on the USB Radio? What manufacture or model number? I am not familiar with this interface.