Not my usual Al's annual inspection thread

So, I have been pretty busy this season and didn’t get around to my annual inspection thread. I have seeing a lot of teams and robots in the past few years and would like to talk about issues that are part of inspections but are not subjects called out directly on the inspection sheet.

I would like to start out talking about the “do not modify” portions of the robot rules. I don’t like “do not” messages but these cannot be avoided.

  1. You may not modify parts at your hotel. Teams can work on anything that is part of the robot in the pits during normal pit hours. Software is not included in this rule.
  2. R34 allows certain modifications to be done to motors, in general you may trim wires as you wish and cut the output shaft. Please note that the wire on the CIM motors is a special, high temperature #14 wire and is designed to withstand the high stall current of this motor. any extension to these wires should be done with wire sized appropriately for the breaker you choose (i.e. #12 wire for 40 amp breaker). You may modify legal servos if the mod is specified by the manufacturer.
  3. Electrical control parts, in general, are also “do not modify”. That means RoboRio, radio, motor controllers, PDP, VRM and PCM. You may make repairs as listed in the robot rules. You may not paint these items or drill holes in the case of any of these items. Use the mounting holes provided or if needed, velcro or dual lock for attachment.
  4. Do not modify batteries other than to add wires as specified in the robot rules. Do not add tape, in particular to the top of the battery. You disturb the vents designed to release internal pressure in the battery. This may lead to failure in the battery case. If you need to label, please use a Sharpie to write on the battery. We need to read battery type, specifications and model numbers.
  5. Do not glue, drill or use other methods to secure items like handles, connectors and clamps to the battery.
  6. Virtually all pneumatic parts are on the “do not modify” list. This means do not paint or use abrasives to modify the part(s) in any way. There is a list of what you may do under R82.
  7. Do not bend the springs on the SB50 Anderson Connectors to make them easier to mate/unmate. This reduces the maximum current specification and will cause heating and possible damage of the contact and connector body.
  8. Do not try to modify COTS parts that are not meant to be modified. i.e. electrical connectors, certain springs, support brackets on COTS parts, etc.
  9. Do not try to make unsafe parts safe by modifying. Yes, I have had teams try to use circular saw blades on their robot and tried to grind the saw blade teeth down.
  10. Please read the robot rules and Q&A. One of the biggest errors is for a team to read a paragraph at the bottom of a page in the manual and fail to look at the next page. Often rules will spill over to the next page for additional info or a “blue box” for further explanation.

Thanks, AL

Was the circular saw blade connected to a motor ?

A dulled circular saw blade would make a great mounting plate for a turret. Bore a 1.125" hole in the middle to put a hub of some sorts, rotate the shaft that goes through the hub (SLOWLY), and boom, you have a turret.

It probably isn’t THAT easy but still doable :stuck_out_tongue:

Our Ultimate Ascent robot had a circular saw blade on the shooter as a flywheel.

Yes, the teeth were ground off. It was still scary as heck.

I had a question about R54. I asked my LRIs before each event I inspected at and got slightly different answers.

Are teams allowed to connect other loads to the VRM with the wireless bridge?

R54. The VRM supplying power to the Wireless Bridge per R53 must be connected to the designated supply terminals at the end of the PDP, and not the main WAGO connectors along the sides of the PDP as shown in Figure 8-12. With the exception of a single CTR Electronics Pneumatics Control Module (PCM, P/N: am-2858), no other electrical load shall be connected to these PDP terminals.


Why not? The restriction is that the PDP terminals may not be used for anything other than the VRM powering the radio or a PCM.

Further, R53 specifies

The Wireless Bridge (Radio) power must be supplied directly by the 12V 2A output of a CTR Electronics Voltage Regulator Module (VRM) (P/N: am-2857, 217-4245) and must be the only load connected to those terminals.
and the blue diagram outlines the four 12V 2A terminals. In the absence of contradiction, this implies that things MAY be connected to the other terminals of that VRM.

Allowed, yes. But not the 12V 2A terminals, per R53. However, it’s not a good idea. Any issues with the VRM will kill the radio. For example, my team had a low load LED ring light that shorted out the VRM, and we sat dead for a match last year.

Overall this season has been really good for inspections. Here are some things I’ve noticed, or recommendations for the future. I’m sure most of these things are pretty obvious, but I feel like it helps to share them.

  • Take a picture of your lock-up form every time you bag the robot. Inspectors are not required to physically hold or sign the form, only verify that your team followed procedures and that everything is properly documented. Having a digital copy of the form is the easiest way to ensure that you don’t lose valuable time when/if the form is lost, misplaced, mysteriously placed inside the bag even though it was completely filled out, or accidentally destroyed through no fault of your own.
  • The biggest source of failure I encountered last year was radios losing connectivity due to the barrel connectors slipping out. The PoE connector from the KoP dramatically reduces the likelihood of this happening. You can use both the barrel and the PoE connector simultaneously for redundancy.
  • Avoid using any kind of clamping action to secure your radio; this can cause the radio to have intermittent connectivity due to how the antenna is located inside the casing. One solution that seems to work well is to use sticky-backed hook/loop tape such as 3M Dual Lock.
  • Spend the time to pull on every wire in the robot and make sure nothing pops out of your connectors. This includes loose connectors on the batteries, loose leads on the circuit breaker, and loose or exposed wires around the PDP. Properly crimped wires (I recommend investing in a hydraulic crimper) are the first part.
  • Batteries that aren’t secured can pose a risk to your robot and the field. Put in the time to ensure that your battery doesn’t move, and make sure that whatever method you use is applied consistently. It’s easy to forget about tightening your battery strap, especially in the playoffs, and that could be the difference between victory and being disabled.
  • Take care when securing your pneumatics. If you choose to use something like cable ties (personally I am not a fan but they are legal) then check them occasionally to ensure that they don’t stretch over time. Something that was secure at the beginning of the event could become loose after several matches of wear and tear. Consider using the Clippard brackets if using Clippard tanks, or if you’re storing a significant amount of compressed air there are other options. A 1 gallon aluminum air tank holds the same amount of air as 6.6 Clippard tanks, weighs the same as 6.6 Clippard tanks (when you include the mounting brackets) and takes up 36% less volume. Tape is not a fastener and may not be used to secure pneumatic components.
  • Examine the location of your circuit breaker and think about what is the potential risk of a field element (or another robot) accidentally turning your robot off. If the risk seems significant consider adding some kind of protection.
  • Make sure your pressure relief valve is set to the correct pressure and hasn’t moved during the course competition (which is what the jam nut is for). If accessing your PRV is difficult, or if you just want things to be easier, consider the McMaster-Carr pressure relief valve (48435K714) which does not need to be adjusted.
  • Check your storage and working pressures during the course of an event. You may discover that something bumped your regulator.


Taking a picture of your lock up form when you bag it is an excellent idea. However, R21 sure looks like inspectors have to sign the form; it’s going to be tough to verify that an inspector “…checked and approved…” your form unless an inspector actually signs it. And that’s standard practice at every event at which I’ve inspected since bags were introduced; if we didn’t sign it the LRI isn’t going to let you unbag the robot.

I’d also recommend taking a picture of your form after it’s been unbagged. We had 2 teams lose their forms at Heartland this year, which is potentially going to (or already has) caused them problems at their next event.

Having a picture of it makes the whole Non-compliance process a lot easier. As an LRI, I can get a new form started for you at the event, going off the picture of the old form to verify that the bag and tag rules were followed.

There is no requirement that an inspector has to sign a form in order for things to be “checked and approved” per R21. The only requirement is that it be signed by an adult who is not a student on the team. It’s a standard practice for inspectors to fill out the form out of convenience, but it is not required.

I read (R21-I) as the RI needing to sign your form as approved to unbag. That as been the case at events where we competed since we have been required to bag the robot. Filling out the form where the RI signs is common sense.

It needs to be checked by an inspector, and approved by an inspector. Does not need to be filled out by an inspector!

That being said, the fastest way to verify approval is for the inspector to fill out the next line on the form.

Losing forms isn’t uncommon, but if you lose it while the robot is out of the bag isn’t not terribly hard to generate a new one and fill out starting at the event, with a note that the previous form was lost. Generally there’d be an assumption that you were legal during the event, or already served your penalty if any…

I will start by answering some questions from above.

  1. *R53. The Wireless Bridge (Radio) power must be supplied directly by the 12V2A output of a CTRElectronics Voltage Regulator Module (VRM) (P/N:am-2857, 217-4245) and must be the only load connected to those terminals. *However, I really recommend no other loads be used on the VRM feeding the radio. Intermittent loads can upset the output and you don’t want to wait the 50 seconds for the radio to reboot.

  2. Inspectors sign the form to allow you to unbag. If the form is inside the bag, the RI can’t sign the form until everyone is allowed to unbag. The team can remove the tag in the presence of an RI to get it signed and begin work. We do that all the time but it will lose you time for working on your robot.

  3. Teams lose forms all the time, don’t be one of them. Keep the form with your registration forms and team forms. Make sure it goes with the load in crew. It takes a finite amount of time to find, fill out, obtain all the signatures and get the Non-Compliance form ready for you to open your robot bag. There is no fixed time and the process can take more than an hour in many cases. The non-compliance form must be attached to your B&T form to help explain the delay in opening shown on the form.

Some pneumatics discussion…

  1. I recommend the PCM be wired to a PDP standard output with a 20 amp breaker. If the compressor tries to pull high current, the 20 fuse on the PDP feeding the terminals marked “PCM” will blow leaving you without pneumatics. The fuse, in my opinion, is guaranteed to blow at some point.

  2. Off board compressors have some very clear and distinct rules. These rules are intended to give you the advantage of weight reduction by putting the compressor and other items off board. The compressor must be under the control and power of the robot battery and RoboRio through a PCM module or other legal control as if it was on the robot. That is all. See R86 and R91-R92 and referenced drawings. Pretty simple really. Most teams are using pneumatics this year so we are seeing a variety of pneumatic system issues.

  3. The pressure relief valve is the only device required to be attached to the compressor by ‘rigid’ parts. When mounting this critical component, make sure it is positioned so that you will not hit it with your battery when changing the battery. Make sure it is calibrated for ~125-130 psi relief under R93. This fitting is not precision and will vary in the range ~125-130 psi. This is easy to do, however it is not calibrated before you perform the calibration. The hex fitting at the top is not the installation device, it is the locking fitting for calibration. The hex shape nearest the threaded part of the valve is the place to use to tighten the valve. The alternative valve listed in R83 from McMaster is precalibrated if you buy the correct version.

  4. The Viair compressors come with a silver check valve attached to the compressor. These may not be removed, they are considered to be part of the ‘do not modify’ compressor. You may only use the one output port of the old Thomas compressor that is open. Do not remove the plug and do not rotate the compressor head to make it easier for your robot design. The larger Viair compressor comes with a stainless steel woven hose with the check valve. That is also part of the compressor and may not be removed as specified by Viair.

  5. If your regulator is not regulating the way you think it should and if it is leaking air around the adjustment knob, it is in backward. Please correct.

  6. The pressure switch needs to have the terminals insulated except when calibrating the pressure relief valve. You will need to short the terminals to make the compressor run continuously to calibrate the pressure relief valve.

  7. Only one pressure vent valve must used to vent all stored air on the robot. You may not design your pneumatics so that it will require two vent plug valves to relieve all stored pressure.

This is special electrical entry. Read this carefully if you want to play every match.

  1. Tighten all electrical threaded terminals. The main breaker and battery are essential. Loose terminals drop voltage and cause brownouts. You heard it here first folks.

  2. While there is locking hardware on the main breaker, the nuts needs to tightened until the wire terminals do not move. 50 in-lbs (5.6N•m) max is the torque specification for the hardware.

  3. Battery terminals also need to be tight and not move. It is very simple to add a #10 external tooth lock washer between the battery terminal and the wire terminal before tightening. The lock washer will prevent the terminals from moving.

  4. Tug test every crimped terminal and all wire entering into the push to terminate terminals on the VRM, PCM, and RoboRio. Don’t be gentle when pulling. Reterminate all wire connections that does not survive. Wire needs to be stripped 5/8" for the PDP main outputs. All push terminals should be stripped 3/8" and neither should have any whiskers or frayed wires that could touch adjacent wire. Do not tin any wires for these connectors. You mat use ferrules if they are the correct type for your termination. The main outputs of the PDP require a ferrule that is crimped in a square shape. Round ferrules are the same as solid wire. The manufacturer states that round wires derate the terminal by two wire sizes when used with solid wire due to the reduced contact area.

  5. Use a known good method for powering the radio. If you use the barrel, tie the wire somewhere close to the connector to be sure it doesn’t move with the robot. A very simple method is to attach a wire tie mount like Digikey 298-1116-NDto the top of the radio. Fold the power wire over the mount and secure with a wire tie. It will not fall out and it will not vibrate. I do not recommend hot glue for a variety of reasons. POE also works well.

  6. Batteries need to be firmly mounted to the robot. Small bungie cords will not keep the battery from moving around. A small velcro strap also won’t keep the battery in place. We want to see straps that are at least 3/4" wide or wider with significant overlap if velcro is used. Dragging a battery around the competition floor during a match, is not looked at favorably by potential alliance pickers. Having a battery box or at least some structure to prevent the battery from moving inside the robot is a must. Don’t let you $50 battery take out your RoboRio, radio, or other expensive assembly.