Re: Electrical Connectors
 

Copy/paste, he used the wrong HTML to create a link that made CD think it was an internal link... or, here ya go

http://www.digikey.com/product-detai...R15B-ND/825359

Re: Electrical Connectors
 

We did it for the 2013 season, in the form of a box. We won't be doing it again. Here's why...

The idea was that we could easily take out the box to service it, and everything was all connected together. (We didn't expect to use it for a different year) So everything was together, in one place, and you could take all the electronics out to run them independently if you wanted to. As we went through the competition cycles and design changes, problems arose.

Our design had literally all the electronics that could be in the box, in the box. Including the router. We had a total of 7 Victors and 2 Spikes inside, along with the small CRIO and Sidecar, a couple lights to make it look cool, and 2 fans for airflow. The signal light and power switch were mounted on top.

Problem 1: Where it goes.
We chose an area of the robot which ended up right under the shooter. We ended up having to cut a hole in the top of the box, as we snapped a few connector tabs on our shooter motor. And being under the shooter created another problem: we had to undo the shooter to take out the electronics. Kinda defeated the whole 'easy to remove' part. It also prevented us from having our shooter at the correct height to smoothly receive frisbees from a slot, as we had to drop them slowly from the 2nd slot instead of smoothly drop them in from the lowest.
The previous shooter to the one shown here's motor was closer to the top of the box. The motor was dipping into the hole you can see under the current shooter motors.

Problem 2: Wires on the outside
PowerPole connectors for motor wires weren't a problem. We were used to using them from previous years. Sensor PWMs were another story. The solution, 'David's Problem,' was incredibly tedious. (I swear they were working on it for nearly a whole 9-5 meeting) Using a cable similar to the one in the above post, we created slots for each and every DIO port, but nothing for solenoids, so we had to unplug/reconnect solenoids every time we removed the box.
'David's Problem,' connector mounted to robot end.

Problem 3: Wires on the Inside
Picture says it all

Problems with our design specifically:
-Main power switch was on top, and the wires were oriented so that you had to undo one of them to get into the electronics.
-The router being inside didn't seem to cause radio problems, *but* it wasn't happy with the inspectors. They want to be able to see the lights on the router. We had to cut out a part of our L bracket holding it together to make a window to appease them.
--In the revision for CalGames I moved the router on top and the power switch to the side.

The good (It's a small list):
-Built in cover for the electronics in the case of drilling.
-Occasionally, but very rarely, we could have one group use the electronics box and one use the powerless robot frame separately. Didn't really happen much though.

So my advice is not a box. For next year, I myself was hoping for something that might bottom out of the robot on our team; the box was pretty more trouble than it was worth, really.

Re: Electrical Connectors
 

Thanks for this...it is the kind of information I need to make sure our idea does not do the same thing.

Thus far, my vision was for more of a "plate" of sheet metal with the power board, sidecar, cRio, motor controllers, spikes, radio power converter, and radio. We planned to have all the pwm wires remain on this board so there would be no need to use any kind of data connector - only the power. I'll post an image of our first concept as soon as it's done - but I think it avoids most of the issues here. Oh - and we always have our electronics all together at the base of the robot, so the "where to put it question" is not really a question in our case. I picture having it slide out from either the bottom or between the wheels through the front or back.

Re: Electrical Connectors
 

control panel by Hotbotz 2640, on Flickr

The "donut shaped" pieces are rubber grommets so the wires can be fed through and run under the main board for neatness and ease of maintenance. The radio will, of course, be velcro attached, so it can be easily relocated in a more conspicuous spot if necessary. The battery and the main breaker will be elsewhere: we always position the battery somewhere to fine-tune the center of gravity, and the main breaker needs to be somewhere accessible. Our actual pneumatics will also be elsewhere (compressor and air tanks) so there will be one data cable running to the pressure regulator. All the solenoids will be positioned at their prospective cylinder to simplify the air lines. Thus, a two conductor APP for incoming power, a multi-conductor (28) PowerPole to power all the motors and other devices, and a pwm to the compressor high pressure shutoff.

Re: Electrical Connectors
 

Isn't this being a bit over-engineered? For what you're trying to do, you can make a simple teleop rig and cut out high-cost components like the cRIO altogether. This would allow you to affordably keep up a host of old FRC robots.

I've given some thought to trying to cut a cRIO out of the control system using the 2CAN. At that point, you'd be sending motor commands to each Jaguar wirelessly and emulating whatever drive code you have on an off-board laptop. There's a slew of bandwidth / control timing issues I won't get into here that I haven't fully puzzled out, but it's a relevant idea I've been playing with.

If you don't care about using FRC components, there's probably an easier / simpler off-the-shelf solution, but its an interesting problem nonetheless.

Things like pneumatics and Spikes are a little simpler, you can just use wireless relays.

Given that the FRC control system is changing next year anyway, I'd advise against putting too much effort into building a modular rig and modifying old robots when you could just get them all working for a similar or lesser effort using non-FRC parts.

Re: Electrical Connectors
 

Watch out for RF interference from the 12v-to-5v power converter. Having it so close to the Wi-Fi router is asking for trouble. I've seen a couple of teams fix serious communication problems by moving the router away from the converter.

Re: Electrical Connectors
 

Agreed, this is not a linear regulator as many have thought. One team had considerable trouble throughout the season when they had hot glued the regulator to the router case.

Re: Electrical Connectors
 

As several folks have mentioned Anderson Power Poles work great for motors and such. Our electronics mentor last year found some nice mounting fixtures for the andersons that let us mount them on a sheet metal connection plate on each side of the control board.

For sensor connections we used CAT-6 and RJ-45s.

Our board was modular and we were able to drop it out the bottom of the bot, repair it (had a digital side car go bad) and re-install/test in less than 20 minutes at a competition.

Making the motor/power connections usable year to year is straight forward. Signal and sensor data however is a bit harder unless you use 1 connector for each signal. I would like to come up with some almost breadboard style way to matrix/switch the wire pairs to specific digital side car inputs. Need to put some thought into that problem.

Someone mentioned in the thread not using the CRIO on past years robots. I really want to play around with the RobotOpenControlSheild (http://www.robotshop.com/en/robotope...d-arduino.html) and libraries.

But with a completely new control system in 2015 I think we will have plenty of cRIOs and digital side cars to keep out robots running.

Re: Electrical Connectors
 

I've had experience using it. I restored our ancient 2006 Aim High robot with it and after a few code tweaks we were able to get it to work properly. (These code tweaks may not be necessary with updated software, not sure) We had to re-calibrate our Victors (I'm not sure if it supports the different-width signals for Jaguars/Talons) but they worked fine afterwards. It's now our main outreach bot.

I also tried restoring our 2007 Rack n Roll robot. I was successful in getting the arm and wheels up and running. But the pneumatics don't work - we used Spike relays connected to 'double solenoids' (see bottom of this) and RobotOpen can't control the relay slots on the Digital Sidecar. Thus no shifter, and no claw. We were going to try and use some spliced up cables using DIO ports but preparation for offseason competition shifted my focus to that. I didn't bother trying to set up the pressure sensor for compressor, either.

So, if you have no pneumatics or relays, go for it! If you have a fast booting router, (aka not the dlinks...) you can be up and running in like 15 seconds from power switch on.

Re: Electrical Connectors
 

It can be done,
Just hook the red and white wires of the spike to DIO pins and drive them high to turn it on in that direction.