Robust Electrical and Wiring Practices

I’m sure this has been discussed in past years, but with all of the talk this year about high speed/energy collisions from a combination of the field layout, the swerve revolution, and power-dense brushless motors I wanted to start a new conversation about best practices around electrical and controls to mitigate unexpected power losses, especially to critical components such as the radio and RoboRIO.

We experienced some difficult to diagnose electrical problems after a collision with a field element, which caused several electrical and control related failures which had plagued us for the rest of the competition, so we’d like to look for ways to improve our wiring practices to mitigate these problems in the future.

So… what are some things your team has done to improve the robustness of the electrical and control systems on your robot.

Specific areas of interest:

  • Mounting and protecting the RoboRIO
  • Maintaining solid connections to Radio
  • Mounting/isolating electrical components
  • Recommended connectors (CAN/Power) and wire
  • Strain relief solutions beyond sticky-back ziptie mounts
  • Wire routing and electrical layout
  • Anything other creative solutions that you’re willing to share

Hopefully, we can collect some good information to keep teams mobile on the field as much as possible.

Thanks!

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I’m still hoping that the Holy Cows post videos of their wiring workshop.

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three letters: vhb

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One of the things that we do is redundancy. Example: power the radio through both POE and the barrel jack because of this our robot has never lost radio connection with the field. Another thing is isolating failures. Example: Running each of the Cancoders on the swerve of off separate breakers on a mini-power module. The last suggestion is to use lots of hot glue to hold things in place.

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We’re having the same issue this season, mostly the encoders and Sparkmaxes and we already had hot glue. Thinking of redoing the connection with more robust connector and isolating components better for easy swap.

Following

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Adding a grounding wire to the robot, releases built up static from the floor both on field and n the pits. Bonus if it’s added to the cart too!

Protecting the Rio is mostly down to buring it somehow in the robot, although it barely needs it, we have found that a piece of polycarbonate and some distance protect it well enough. Hot glue if you really are concerned about connectors.

Velcro tape for mounting provides shock absorption and good solid mounting.

We like molex and Wago for CAN, and Anderson powerpole 15 to 45 for power.

Tape for extra strain relief?

Open and with many grooves for wires and routing, make sure you can see everything. Having disconnects in blocks to remove an entire component or wire is great!

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Very Hard Bash?

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Ferrules are your friend. We have no wagos, weidmullers, or lever locks that have bare wire in them. All wires get ferruled to prevent whiskers.

All weidmullers, duponts, and barrel connectors (radio) get a blob of hot-melt glue on them to prevent vibration and movement from unplugging them.

All andersons get the red retention clip inserted upon final inspection (by someone other than who terminated them). We confirm the terminals are seated properly and a tug test to validate the crimps before putting a retention clip in.

All wires get ziptied to something stationary within a couple inches of where they plug in to something, this is to reduce movement from the intertia/weight of the wire itself.

We had exactly zero electrical related failures this season.

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I know there is enough wiring visible to make the delorean from back to the future look simple, but here is our robot as the wiring was in progress this season…



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This is a great idea if you’re using a VRM to power your radio, but it is not possible if you’re using a RPM.

Also a good idea, but also consider not having friction connectors (radio barrel connector, micro-USB) on the bottom (gravity is not your friend) and use appropriate strain relief.

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Reviewing the new radio wiring diagrams, as well as all the other diagrams and power specifications in the manual, no need for smoking wires for using too small a gauge.

That’s a nice setup and good labelling, but where is your radio powered from? (R617-B)

My views on wiring from 11 years of mentor and being a CSA

  • Mount it so you can remove it easily and so that it’s protected from metal shavings.
  • Use a 3d print or tape around the RSL housing to help hold it in, the right amount of good hot glue helps too.
  • Use tape to cover up all of the pin connector you don’t use and think REALLY hard of why you need to use any you do use.
  • Don’t use the IC2 slot
  • If you have a roboRIO 1 and your code works on it, use that.
  • Mount it so that the main wire connection to your Rio is upwards or sideways, don’t fight gravity
  • Keep the radio as high as possible and as far away from motors as possible.
  • Use CAT6 wire cut to length with high end RJ45s
  • VHB Tape or Dual Lock Tape with supporting zip ties.
  • 3D printed mounts general make things bulkier use them sparingly
  • Use good crimpers, a bad/cheap crimper will make the best connectors not work.
  • Use bonded wire and only bonded wire.
  • Don’t leave excess wire on your bot.
  • Connectors - 12AWG Andersons power poles(use small zipties to lock them shut), less than 12AWG in line lever nuts (unless you have the SL Molex crimper then the locking box connectors), Ferule for connecting wires to wagos/wiedmullers/etc…
  • Use sticky-back ziptie mounts
  • Design your electrical system DURING mechanical design, not before or after.
  • Keep wires as short as you can.
  • Use energy chain or wire wrap on wires that go anywhere near a belt, chain or gear.
  • Label each end of each wire where it’s going.
  • 3D print, in a bright color, a cover for your main breaker to protect it and make it clear where it is.
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  • Only use TP-link or Netgear ethernet switches, and power them from the VRM 5V ports.

  • Make sure to prepare your laptop and firewalls before comp

  • Use a USB to ethernet, built in ports fail often.

  • In this era of highly complicated robots, you need to use a CANivore to ensure your motors don’t randomly lose inversion on the field bc of missed CAN frames.

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Looks very clean.

One q - why introduce another connector so close to the PDH outputs? We have done this when accessibility was limited, but it doesn’t look like this is driven by a serviceability issue.

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There is an RPM powering the radio, it is powered from the PDH fused channel. It is not pictured in these photos.

This is done to ease replacements. We have another power center prepared with the same breakers and pigtails, so that in the event of a PDH failure, we can simply swap the entire works out.

This also facilitates wiring simplicity from year to year, not having to re-terminate wires into the PDH/PDP once it is in a position that is difficult to reach. This is mostly a hold-over from the PDP where using a screwdriver or wago tool was very difficult once tucked into the robot.

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OK. From the label, I see that channel 20 is connected to the roborio with a 10A fuse, but none of the other fused channels have a 10A fuse so they can’t be connected to the RPM.

Got it, thanks! Yes, the PDH is much nicer to re-install wires into than PDP, so that’s coloring my view a bit.

Ahh, yeah, its the next channel. When I took this picture, I hadn’t swapped the fuse yet, because I originally populated them based on an outdated diagram showing a 15A fuse for the RPM.

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