Electrical Board or Distributed System?

[michchinn]

Team 5404 had a single electrical board with almost all of our electrical components attached to it this year. We ran power wires to the motors and actuators distributed throughout the robot and signal wires to our various sensors.

We are considering switching to a more distributed system, with a primary electrical board with the PDB, roboRio, VRM, and PCM attached. All of the other electrical components (motor controllers, spikes, etc.) would be distributed throughout the robot to be close to the actuators they are powering.

We think that a distributed system would be a lot more modular, though possibly more difficult to make, as the electrical board couldn't be fully made off the robot and then attached.

Which method does your team use? Why do you use it?
Thank you for any guidance you can offer.

[GeeTwo]

We have used a centralized control board each year so far. Every year we re-consider whether the board will be centralized or distributed. The greater ability to program and trouble shoot a removable board has so far trumped the modularity aspect. After our first two years, not only do we keep the board centralized, we have it oriented so that we can see all (or at least most) of it at one time.

We did move our pneumatics control module to the back with the compressor and other pneumatics components.

We also considered moving individual Talon SRXs to be near their motors and encoders to shorten the encoder cable lengths.

* That is, easier to see all the lights at once, and easier to trace the shorter signal runs.

[parry1126]

Our team has always used panels. One thing we used for many years was something we referred to as a "smart door". The panels were hinged and able to fold out of the robot to allow it to be easier to work on.
This past year we used an electrical box that 1405 came up with. RoboRio, PDP, VRM, Talon SRXs, Gyro, Radio, main breaker, and RSL were all inside. The idea behind this was to have everything well protected and compact and allow for easy swap outs in case of electrical failures.

[InFlight]

There's a good argument to keeping sensor wires as short as possible. We use the TALON SRX almost exclusively, and try to locate those near the motor/encoder to reduce noise pickup. The CAN bus is quite reliable, and not as subject to noise pickup.

[Alan Anderson]

We've done both ways. Having things spread out always seemed to be more prone to damaging wires in robot mechanisms, but that can be addressed. Having things centralized is good for plan-in-advance neatness, but it can end up being harder to work on and might make it more difficult to see all the important status lights.

I prefer to have the electrical system as a single module, with sufficient space allocated for it from the beginning of the robot design. That space is in three dimensions, and needs to be accessible and kept from getting buried under other mechanisms.

[Foster]

Having everything in one place is really cool, but the ability to put things in other parts of the robot shouldn't be discounted. I've done both and as long as you can get to the connections / devices for repair & replacement it's all good.

I think having an electrical person on the mechanical design team is your best bet. I always harken back to my first car, an AMC Rambler. It was a clear case of the mechanical team and the electrical team never met. Since on that car to replace the starter you needed to pull the engine.

[timytamy]

For our team, we've found a nice balance between the two.

Firstly, we try to have a traditional spider layout w/ banked motor controllers for the drive train eg

The key thing is that the path from battery to all the drive motors is as short as possible. This means we usually end up with a layout similar to the above, except with only four-to-six motor controllers in the banks.

The rest of the electronics is more loose. We quasi centralise all the "intelligence", namely the roboRIO, radio, camera-processor etc. mainly for convenience. However when using the SRXs, we prefer to place them as close as possible to the mechanisms, keeping sensor cables short.

This allows us build mechanisms complete with most of their electronics, so that we only have to connect/wire power and CAN to the rest of the robot. It also has the secondary advantage of not needing to deal with all the SRX CAN wires when they are right next to each other.