Tips from a veteran Robot Inspector

[Wayne Doenges]

Per the FIRST manual. I hope this helps.
[R73]
Compressed air on the Robot must be provided by one and only one compressor. Compressor specifications may not exceed nominal 12V, 1.05 cfm flow rate, 120 psi maximum working pressure. Off-board compressors must be controlled and powered by the Robot.

If an alternative compressor is used, the team may be required to provide documentation to show compliance with the performance specifications.

The only difference between an on- and off-board compressor is that the off-board compressor is physically removed from the Robot. The intent of this rule is to permit teams to take advantage of the weight savings associated with keeping the compressor off-board. However, using the compressor off-board of the Robot does NOT permit non-compliance with any other applicable rules.The compressor may be mounted on the Robot, or it may be left off the Robot and used to pre-charge compressed air in the storage tanks prior to bringing the Robot onto the Court.

[Al Skierkiewicz]

Scott,
The pneumatic rules are very specific on what can be off board if you choose to place pneumatic items off board.
[R73]
Compressed air on the Robot must be provided by one and only one compressor. Compressor specifications may not
exceed nominal 12V, 1.05 cfm flow rate, 120 psi maximum working pressure. Off-board compressors must be
controlled and powered by the Robot.
Under R74
D. If the compressor is not included on the Robot (under the provisions of Rule [R73]), the regulator and high-pressure gauge may be located on-board or off-board, provided all other pneumatic rules are satisfied.
Note that if the regulator is kept off-board the Robot with the compressor, then only low-pressure (60 psi or less) “working” air can be stored on the Robot.
During Power On testing, you will need to show that the compressor indeed is controlled by the Crio, shuts off at ~120 psi, and meets all other pneumatic rules that apply.

[Abrakadabra]

Wayne and Al -

Thanks for the quick reply. I have just a few points needing clarification:

Assuming that I make a "compressor assembly" that holds the compressor and all the control components that I choose (and are allowed) to be kept off the robot:

- Compressor power will be provided through one Spike, which will remain on the Robot. Power will be provided to the compressor on the "downstream" end of the Spike via a suitable Anderson Powerpole connector.

- We will install one vent valve on the robot and one on the compressor assembly. The one on the compressor will be used to vent the supply line between the compressor and the robot before disconnecting. I assume this is the purpose of the "additional vent valve" specified on the Inspection Checklist, correct?

- We will keep the high pressure gauge and regulator on the robot in order to maximize on-board air supply. However, can I assume that it is okay to keep the mechanical compressor relief valve on the compressor assembly, because the only time we run the risk of overpressurizing the system is during filling? I.e. Can I ignore any overpressurization that might occur in my system due to ambient temperature changes after fillup? (In reality, I would assume the system would cool down, not heat up.)

- Likewise, can I leave the Compressor Control Pressure Switch on the compressor assembly if I make it obvious that the signal cable to the Digital Sidecar must also be plugged in when filling, thereby insuring full control by the cRio? After all, if the pressure switch circuit is left open, the cRio will not allow the compressor to run, correct?

I can see arguments for a "no" answer on either of the last two above, but I don't believe they are specifically covered in either the Rules or the Checklist. If the answer to all of the above is yes, then we would have three connections to make between the robot and compressor assembly:
1. air
2. compressor power (most likely a suitable Anderson powerpole product)
3. digital signal cable from the pressure switch to the sidecar

Sorry to be so detailed, and I realize the weight savings may be irrelevant in the overall scheme of things, but I would just like to do it right (and safe!).

Thanks!

[Kris Verdeyen]

Al et al,

I noticed a problem with the inspection checklist linked above, and I'm not sure how to report it, so I figured I'd kick it up to you and Wayne.

Under the custom circuits section of the electrical checklist, it says:

Custom Circuits, Sensors and Additional Electronics - may not connect to the cRIO’s serial or Ethernet 2 ports (except
in compliance with R53.B), cannot directly control speed controllers, relays, actuators or servos,.. <R47, R59-62, R65>

Rule R65 actually says:

All outputs from sensors, custom circuits and additional electronics shall connect to only the following:
...
E. the RS-232 DB-9 RS-232 port on the cRIO,
...

Probably something that will be fixed before week 1, but it does seem significant.

[Bill_B]

Abrakadabra,
The pneumatic system can also get pressurized if an actuator is moved by its mechanical linkage being thwacked during a collision, for instance. Since you're going with off-board compressor, I presume that your actuators are not very big, so this isn't necessarily a problem for you. But you know rule makers. Cover the whole spectrum of possibility, if possible. I would put the relief valve into the robot's circuit even if the rules didn't require it. See [R72]

[Al Skierkiewicz]

Kris,
I will check into this. The incongruity comes from the attempt to compress everything into one check item I believe. I thought I had everything cross checked. Thanks.

Scott,
The relief valve is intended to vent on the off chance of a control failure and the compressor runs continuously. The rule states it must be attached to the compressor through suitable brass fittings. The Thomas compressor can run up to 150psi before it's seals bypass.
The high side gauge may be located off board if you wish.
The pressure switch may not be located off board. This was allowed in the past but was changed for this year. The intent is that it accurately senses the stored pressure on the robot so it works in your favor to keep it on the robot.
The Spike must remain on the robot.
The thought behind this rule is that an equivalent loss in functionality is the consequence for the weight savings in removing the compressor.

[Al Skierkiewicz]

In honor of stop build day...
Today is the day to stop working on your competition robot. Midnight local time on Feb 21.
1. By midnight you should putt your robot into the bag and seal it, complete your robot lock form including the seal number(s).
2. Bumpers may be bagged separately if you choose.
3. Do not lose the form and be sure you have it handy when you arrive on site for your competition. You will need this form for every event you attend through the Championship.
4. For some teams who have been given permission to ship their robots by First, you will follow the instructions for crating and shipping from First in addition to bagging the robot prior to crating.
5. Do not lose the form. Your inspection team will sign off on your form and instruct you as to when you may cut the seal and open the bag.
6. If you lose the form, you will need to follow additional steps to complete a non-compliance form. This form requires three signatures in addition to the team's info and signature. Inspectors are very busy and it may take a while to receive all the required signatures on the form. You may not open the bag and begin work or practice on your robot until instructed to do so after the non-compliance form is complete.
7. Don't lose the form, don't leave it with someone who is not coming to the first day of the regional event, don't leave it on the bus or back at the hotel if you want to maximize the time you will have to work on the robot or practice.
8. All robots must be inspected before they are allowed to participate in matches. Those robots that are inspected early may enter the fill-in line during practice and get some needed extra practice time. You do not need to be inspected to practice but you may be prevented from taking the field if your robot has any safety issues that need to be addressed. Some events require at least a cursory safety inspection as you queue for practice.
9. As discussed above, inspectors will need a BOM to be displayed during inspection. You may show this on a laptop or by hard copy. Please make the print large enough for older people to see and read.
10. Please get some rest and relaxation. To those of you in Week One events, good luck. Your competition is only 9 days away.

Happy Punchki Day everyone. Don't eat too many.

[Squillo]

We have an exemption to crate/ship our 'bot. Can we put the lockup form (signed) into the crate (but outside the robot bag(s))? I guess what I'm asking is, will we need the form in our possession to claim or open the crate, or can we open the crate, take out the form and hand it to the inspector before opening the bag(s)?

Seems to me to be a good way to ensure that we don't forget to bring the form.

[artdutra04]

Originally Posted by Bill_B

Abrakadabra,
The pneumatic system can also get pressurized if an actuator is moved by its mechanical linkage being thwacked during a collision, for instance. Since you're going with off-board compressor, I presume that your actuators are not very big, so this isn't necessarily a problem for you. But you know rule makers. Cover the whole spectrum of possibility, if possible. I would put the relief valve into the robot's circuit even if the rules didn't require it. See [R72]

This should not happen if your pressure regulator is functioning properly. If a pneumatic cylinder is set to a working pressure of 45psi and it gets manually depressed by some impact or other impetus, the pressure regulator will vent anything over 45psi from the low pressure side out to atmosphere.

The 125psi relief valve is there in case the pressure switch fails and the compressor unknowingly keeps pumping air into the system.

[AngelBob]

Originally Posted by Wayne Doenges

2) Be sure Main Breaker is where anyone can reach/see it. If your robot starts to smoke, during a match, wouldn’t it be nice if someone can quickly shut down your robot without having to hunt for the OFF switch?

This is our problem. According to a veteran programmer, our plans never seem to include the position of the Main Breaker and it always winds up in some random place. This time it's definitely visible... but behind a sheet of lexan. Aaah!

[ratdude747]

Originally Posted by AngelBob

This is our problem. According to a veteran programmer, our plans never seem to include the position of the Main Breaker and it always winds up in some random place. This time it's definitely visible... but behind a sheet of lexan. Aaah!

cut a "mousehole" in the lexan, big enough to provide hand room.

[cgmv123]

Does a Xerox of the lockup form count or does it have to be the actual signed form? It would seem prudent to make copies in case it gets lost.

[Jaxom]

Originally Posted by ratdude747

cut a "mousehole" in the lexan, big enough to provide hand room.

And please remember that all hands are not the same size; small hands fit in large holes but not vice versa.

[Wayne Doenges]

1. By midnight you should putt your robot into the bag and seal it,

If I putt it more than twice do I get a bogey?

[Al Skierkiewicz]

I am going to answer a few questions in this post.

First, if you are shipping your robot in a crate, a reminder to everyone, it still must be sealed in a bag and the lockup form is still required. You can ship the lockup form in the crate if you wish. Be advised that when you remove the robot, the venue will take away the crate and you may not have access to it until the end of the event. You need the form in hand prior to a an inspector allowing you to open the seal and unbag your robot. In the absence of an original lockup form, a copy may accelerate the process but the non-compliance procedure may still be in effect. I will try and get an answer on that.

Breakers behind lexan while looking good make it harder for field people to protect your investment. A hole in the lexan needs to be big enough for my hand to go in. Ask anybody, it is pretty big, I can bridge almost an octave and a half on the piano. Much bigger than a mouse. If it isn't easy to turn off we will all just sit and watch it burn and toast marshmallows.