Wiring in general help

I am from team 2906 and we have just finished our season. During the off-season we are hoping to train the newbies. Anyway, our wiring is horrible. We always say ‘oh this year it will be clean’ but it always seems that either we dont have enough time, space or tolerance to make it streamline, like it should be. I was hoping to get pointers, any clever ideas that may help us out and any pictures of others layouts for this year that are clean. If it helps I can include a picture of the layout on our bot now.

Anything helps…
~Walker Ward
Team President~

Some things I would do:

  • Make sure you have at least 1-2 people that are dedicated to the electrical system. They’ll help push the entire team on all of the following points.

  • Design for the electrical system from the beginning. Figure out where things will go so you aren’t cramming them in at the last minute.

  • If at all possible, design the electrical system to be on a single board. Your electrical students can spend their time working on that board off the robot, and attach it later. This can lead to very clean, well wired boards! I highly recommend putting the electrical system in your robots bottom pan, it helps with CG management, and you can usually make room for it there if you plan for it ahead of time.

  • Utilize connectors, like the Anderson PowerPole series. These allow you to separate on-robot work and off-robot work, connecting the two after the fact!

  • Use zip ties and tie downs liberally. The difference between a neatly wired robot and a hot mess is constraining your wires to sit where they’re supposed to!

If you can, plan the layout of your electronics while you’re planning the rest of the robot. It’s easier to wire neatly if you’re able to put the components in a nice row on a single plane, with a space in between to channel the wires, as opposed to cramming each component wherever it will fit.

We also kept a consistent naming/numbering convention and labelled all the wires accordingly. Our robot has four drivetrain motors and two intake/mechanism motors. When looking at the robot from a top view we declared that the motors would be numbered in order from top to bottom, left to right. 1-2-3, 4-5-6. Left side: intake motor is 1, forward drive motor is 2, rear drive motor is 3. Right side: intake motor is 4, then drive motors 5 and 6. We stuck with this convention for everything. The PWM ports for these motors are 1,2,3, and 4,5,6. The encoders for the drive motors are on DIO’s 2 and 3, and 5 and 6. On the PDP, they’re wired in that same order on the left and right side 40A channels. Very predictable.

Making time for good wiring is something you need to enforce if you want it to happen. Even I was pushing for “let’s just get it done” as we approached crunch time. The electrical mentor insisted that we do it right. We did, and the wiring (a) looks amazing, (b) is easy to figure out and troubleshoot, and © never once failed us during two rigorous regionals.

Interesting…I highly recommend putting the electrical system anywhere EXCEPT the bottom pan. We do best when we put it in a vertical box on the rear or side of the robot, so the tops of the components are facing away from the rest of the robot. When we do put it on the bottom pan, we can’t get to anything, and there ends up being a spaghetti mess of wires over all the components.

For access, we always make the bottom board hinged. This lets us tip the robot up, remove two bolts, and drop out the pan for easy access and work. Then we just need to worry about the service loop in the wiring, which can easily be managed with zip ties!

Of course, you do need to worry about metal shavings when everything is on the bottom. That’s why the electrical board is one of the very last things to go in to the robot. during construction :slight_smile:

Our wiring has definitely improved over the years. While we still won’t win any awards for neatness, we have improved year-over-year (except rookie to 2nd year) in terms of shorts, loose connections, accessibility, and labeling. [Edit: After suffering from TRS (Twitchy Robot Syndrome, that is partial or complete robot paralysis in at least half of our matches) in 2013 Ultimate Ascent, we had [b]zero electrical faults during competition in both the relatively benign 2015 Recycle Rush and the thoroughly brutal 2016 FIRST Stronghold.] These are our big lessons learned over the years:

  • **Have **
    a wiring sub-team. Our first two years, the programming team did the wiring. The first year it was not too bad (partially because the robot was monstrously tall), but the second year it was jammed into way too small a space with even less access, because wiring was an afterthought. If you have a team member who is gifted at organization and documentation, or who is a “whole picture” person, try to get him/her on wiring. Because the wiring group literally connects the programmers to the mechanical team, this is a perfect position to coordinate, document, and communicate the overall robot design. OBTW, we have had better schematics than mechanical design drawings, and I’m in no hurry to change that --I’d like mechanical to catch up, but I don’t want electrical to fall back to achieve it.

  • Plan the board as though you will remove it and replace it regularly, even though you probably never will. Thinking through connectors as though the board is replaceable makes it much easier to replace any single component. Our third (Aerial Assist) robot was supposed to have a removable control board, but once we put it in place (in the belly pan, which I agree with MrForbes is a bad idea), we never actually removed it. It was still much easier to manage when we made changes, so we continue the fiction that the board is removable.

  • Because the board will not actually be removed, make it accessible, and make it easy to shield from swarf when the build team decides to add on that super-whamo-dyne manipulator at the last minute. The last two years, our control board has been at the top of the robot, roughly facing the ceiling, covered by a polycarbonate cowling. (The battery has been low both years.)

  • Thoroughly qualify crimping and soldering students, and inspect connections just as thoroughly. One of our control team catch phrases (borrowed from an IBEW phrase, I believe), is “LCKR (pronounced locker): Loose Connections Kill Robots”.

  • Whenever you have a choice, select a polarized connector. Anderson Power Poles are our favorites for wires carrying more than 5A, and Molex for smaller wires.

  • Label, label, label. We have successfully used general Dymo labels, number labels, and the “resistor color code tapes” from 3M. We’ve found that the value of the labeling has far more to do with how well and consistently you use it than what labels you select (unless, of course, they fall off, in which case they’re worthless!). Caveat: If you have a color blind member on your wiring or pit team, don’t depend on color labels.

  • Hinged panels don’t really work out. This was the first year our control board was mounted on hinges. Despite repeated explanations that all wires must pass through **this **
    gap, only half of them actually did. We had to re-run a few connections to allow us to change the battery, but we wound up not re-doing a lot of others that really should have been torn out and replaced.

  • Use the correct length of wire. Except for wires left at their COTS length to comply with those rules, measure all wires to be long enough to reach from one end of their path, along a well-defined (mostly rectilinear rather than hypotenuse layout) track, to the other end of their path, with little excess. While panduit looks neat when installed, it tends to promote over-long wires and is not such a good idea in the final analysis.

Second Edit: We do not have any special software for schematics; we make do with MS Power Point and similar drawing tools.

Look into using Solidworks Electric tied into the Solidworks routing plugin.

In short, here’s what you end up with:

  1. A harness diagram for making the entire robot’s harness OFF the robot.
  2. Ensuring that everything fits, and all spaces clear the # of wires required.
  3. Wires can be accounted for in weight during your robot design.
  4. Good experience in proper electromechanical design.

There’s tons of youtube tutorials out there that will teach you everything you need to know about SW electrical.

If you want to try something cool, you can put the majority of your electronic and pneumatic components on a “control panel”. My team has done this for the past two years, and it’s worked out well for us. Last year we had one control panel with electronic and pneumatic components, and this year we have two panels roughly dividing the systems into separate electronics and pneumatics panels due to limited space on the robot. These panels are removable in case we need to do any work with the control system separately. They are a byproduct of our modular design process which involves a team of a few designers CADing subsystems that can be modularly integrated with each other.

The basic idea behind our approach is to have two .125" lexan plates separated by 1"-2" standoffs with control system components mounted on both sides with the wires running through the middle. The wiring process is a bit tedious, and I promise you’ll be unscrewing the panel plenty of times when it’s first getting wired up, but the end product is nice and elegant.

Check out this Google Doc if you want to learn how we make our panels: https://docs.google.com/document/d/1dYFZ_sQpsQfBHANWClhqpnIHUAS3fDf9OELv7-Rv-1s/edit?usp=sharing We base our CAD models off of the actual CAD files of the control system components we are using, to make sure that all of our holes align and everything is spaced correctly.

How do I know that this actually makes your wiring noticeably better and more attractive? Well, not to brag or anything , but we are constantly getting people from other teams commenting on our wiring at events and taking pictures. Also, the judges’ comments for the five design awards that we’ve received in the past two years have all mentioned the quality of our wiring. Now, I’ll admit that our wiring does get a little bit crazier as the season goes on, especially as we add new sensors and whatnots (all of those ugly pwm wires in the last url), but having a nice clean start is good.

https://scontent-dfw1-1.xx.fbcdn.net/hphotos-xpl1/t31.0-8/10988274_10203868044558401_2898672782872616124_o.jpg
http://i.imgur.com/sI13plw.jpg
https://scontent-dfw1-1.xx.fbcdn.net/t31.0-8/12888615_1303371016346182_6685089353445235607_o.jpg

I agree with what everyone else was saying. IMO, the most important parts for cleaner wiring are having an electrical sub-team,planning out where everything goes ahead of time, and most importantly leaving time for wiring, if possible. This past year, once we had the basic dimensions of the drivebase, a few people on the electrical sub-team CADed out an electrical pan and did placement of where all the components would be. It ended up helping greatly. As this was my first year on the electrical team, the thing that helped me the most was doing wiring during off-season. We had to rebuild our 2013 robot and I ended up getting practice by doing the pwm crimps for the old bot. If there are things needing to be wired during off-season, maybe let your newer students practice. Just some thoughts…

Here’s a article I found about some wiring for robotics that might help. https://frcdesigns.com/2015/07/22/frc-electrical-form-versus-function/

And also don’t be afraid to use a plethora of zipties, fasteners, etc. :smiley:

For my team, we didn’t do much before the season started, but we learned when we made the test bench for software. We also had people looking up the parts. This year was my first year and what really helped was researching because it made sure that I understood what they did. We put everything on the bottom pan, and attached it with velcro in case it ever needed to be removed. Some things, such as the PDP and RoboRio were on plexiglass mounts. I would recommend using zipties to keep the wires from going all over the place. Planning the layout before hand definitely helps. We just took measurements of everything, scaled it down, and tried to arrange it on paper before we worked on putting it on the robot.

Let me emphasize an aspect of electronics placement that 1726 does very well.

Make every status light easily visible from some distance away from the robot!

Both you and field personnel can instantly tell what’s gone wrong on a robot by being able to effortlessly see what the status lights are there to tell you.

I can’t count the number of trivial problems that have killed robots and were harder to diagnose than they had to be just because the simple status lights were buried in the bowels of the robot.

P.S.
Almost as bad is quickly diagnosing a problem, only to have the drive team unable to reach the malfunctioning part to fix it before a match has to start.
Don’t bolt covers on or require the disassembly of the robot just to be able to plug a camera back in and stop the robot code from crashing due to an unhandled exception.

Keep the FTA happy…he is here to help you!

We usually wire as we’re building and fabricating the rest of the robot–i.e. as soon as the chassis is built, it gets wired immediately. This helps testing get done quicker. Components are mixed in wherever there is space, and sensors are designed in during the CAD process.

To help keep it clean, we run some wire in tube structure, use a variety of colors for both labels and wires, and keep it retained with zip ties and wire sheaths.

For us, there is no dedicated electrical team–wiring is done by basically everybody. The wire map is pretty clear and consistent from year-to-year, so it’s usually a “just get it done” task as opposed to something that is incredibly planned.

The Electrical Sub-Team should be reviewing the CAD to ensure that the design allows sufficient space for the electrical (and pneumatic) components AND sufficient space to install and service those components. They need to speak up and veto designs that do not allow easy access to critical components. I have seen many beautiful CAD designs that cannot be built and/or cannot be repaired easily so they are essentially worthless.

Time spent planning your electrical (and pneumatic) system and time spent doing a good quality construction job is an investment that will pay you back in the form of fewer failures, easier and faster repairs during your competition season.

Here is a link to the “Electrical Layout & Construction” presentation I gave at the local Mock Kickoff last fall. It is based on many years of professional experience in mass manufacturing of electrical equipment. It may give you some good ideas on how to lay out your electrical system.

http://www.chiefdelphi.com/media/papers/3177?

Probably the two biggest problems I have found in our robots and the robots of teams we help at competitions are bad crimps and loose (screw) connections. Both can leave you dead on the field or cause intermittent problems like radio or RoboRio resets that will drive you crazy and cause you to lose matches. A pull test should be done immediately after each and every crimp. Screw-type terminals such as those on the batteries, the breaker and SPARK motor controllers should be tight and should not move when you push on the lugs with your fingers.

I would discourage hinged panels unless absolutely necessary. Routing the wires across the gap so that the do not impede the motion of the panel and do not get damaged by the motion of the panel is tricky. We avoid such practices at work for this reason. Often some time spent thinking will result in alternatives.

Do you happen to have the files for the 3D printed PWM thing?

One of our students printed us a few this year – I believe he got them off GrabCAD, but I don’t have the links. (It may have been sourced from a CD thread, I’m not sure.)

Here you go:

https://grabcad.com/library/roborio-10x3-retention-clip-1

Thank you so much!

Our system focuses on being able to “read ones work.” Even if something is routed underneath the panel for cleanliness, the wires are all color coded and if someone that didn’t wire the panel isn’t able to at least read where the wires go to, then it needs to be redone. We also have the luxury of being able to build two bots, so more experienced students wire the first panel and rookies gain experience by having ownership of wiring the entire second panel themselves.

Zipties are king.

If you have any other questions feel free to PM me, I was Electrical Lead for 2 years on my team before I was VP of Build, and cleanliness is one of my huge things.