Al's Annual Inspection Thread

[Al Skierkiewicz]

OK,
Another year and another list. As we wind down to stop build in a few days, teams should be thinking about inspections coming up and should be performing a pre-bag inspection of their own.
1. The inspection checklist and the BOM template are both located here...
http://frc-manual.usfirst.org/
2. As Q&A or Team Updates modify robot rules, the Checklist may also change to reflect the rules change.
3. Stored Energy. Just about every robot will have some form of stored energy this year. To keep safety in mind at all times, springs will get an extra look by your inspectors. You may be asked to "dry fire" a shooting mechanism to check for the possibility of "destructive disassembly". If you are using COTS springs, please think about adding some type of cable (aircraft cable preferred) to keep the parts together should the spring crack or fracture. If you are using surgical tubing or some other form of latex or rubber, please be sure to have the ends secure. Inspectors may ask Safety Advisers for assistance in determining the safety of these mechanisms.
4. Bumpers. These are an issue every year and I am only mentioning them here so you can think about them. Bumpers do not need to be included in your bag with the robot. You do need them at competition and they will be required for practice rounds on the field. There has been a recent Team Update that allows you to use tape or other fasteners to affix the pool noodles to the "robust wood" to aid you in making pretty bumpers while you secure the fabric covering. Whatever method you choose, the intent is not to change the overall cross section of the pool noodle or compress it nor to add hard parts beyond the 1" dimension from the frame. Please refer to Fig. 4-8 for guidance.
5. Pneumatics. As last year, you are allowed to use any 12 volt DC compressor that does not exceed 1.05 cfm. If your compressor is not a common type, please be ready to provide documentation to show it meets spec. A new compressor that has become available requires a stainless steel, woven hose ( provided and as stated in the manufacturer's spec sheet) for operation. That has been ruled by the Q&A as part of the compressor and must be included. Reminder that pneumatics parts must be unmodified COTS devices rated for 125 psi working pressure.
More to follow, good luck everyone.

[eddie12390]

Originally Posted by Al Skierkiewicz

3. -snip- You may be asked to "dry fire" a shooting mechanism to check for the possibility of "destructive disassembly". If you are using COTS springs, please think about adding some type of cable (aircraft cable preferred) to keep the parts together should the spring crack or fracture. If you are using surgical tubing or some other form of latex or rubber, please be sure to have the ends secure. Inspectors may ask Safety Advisers for assistance in determining the safety of these mechanisms.

Does this affect pneumatic-based catapults? If so, will we be required to run it through the Driver Station/program or would the manual overrides provided on the Solenoids be acceptable for showing a test fire?

[Al Skierkiewicz]

Yes and we will ask you to dry fire using an powered and enabled robot in a protected area of the venue or a corner of the practice area if safe for others.

[Max Boord]

Originally Posted by Al Skierkiewicz

You may be asked to "dry fire" a shooting mechanism to check for the possibility of "destructive disassembly".

How does that work for all electric shooters? We have several shooter presets and a slow manual mode. Will/ could inspectors ask for us to dry fire all of them? Its powered by 6 cims so dry firing it could cause a problem.

Also if we instal a sensor to prevent dry firing (right now it just takes a button sequence) then will we be asked to bypass that sensor or will that exempt us from that test?

[kmusa]

Originally Posted by Max Boord

... Also if we instal a sensor to prevent dry firing (right now it just takes a button sequence) then will we be asked to bypass that sensor or will that exempt us from that test?

Al:

This is our situation as well. Pneumatic shooter, ball sensing interlock (eg shooter doesn't fire if the ball isn't present.) If we need to disable the interlock, we would rather do this in a way that is consistent with the interlock being as fail-safe as possible.

We'll certainly comply, but the ball (between it's weight, as well as it's air resistance) has a significant impact on the loads and speeds that the shooter sees when fired.

-Karlis

Originally Posted by Al Skierkiewicz

Why does this year's game remind me of Violet in Willie Wonka? Hmmmm?

So true. There are now two clips that I will forever look at differently. (The other is the image of the Poofs singing "Call Me Maybe" to Karthik - always brings a smile whenever I hear that song being played.)

[Al Skierkiewicz]

Karlis,
Your RI will figure it out when you are inspected.

[Andrew Schreiber]

Originally Posted by Al Skierkiewicz

Karlis,
Your RI will figure it out when you are inspected.

I'm sorry, that's unacceptable.

If there is a system in place to prevent dry firing is an inspector asking a team to bypass it a reasonable request? Should we anticipate it? Could you provide guidance under what circumstances this request may be made? (Being more specific than 'at the discretion of your RI' would be greatly appreciated) I am merely trying to understand the circumstances under which an inspector should ask a team to disable a safety mechanism which the team has deemed necessary given the behavior of their system.


I do not recall any such behavior in 2008 when more energy was stored.

[Jon Stratis]

Have you ever seen a fool-proof mechanism or sensor on a FIRST robot? I know I haven't... It would take quite a bit for a team to convince me that whatever system they have in place to prevent a dry fire isn't going to break at some point during the competition and allow the system to dry fire anyways. We've all seen some crazy stuff happen to a robot that no one expected...

[geomapguy]

If you don't the ability to do stuff manually in your code, then you are setting yourself up for failure. What happens if a sensor goes out during a match....you still want to be able to function without the sensor.

So honestly, just figure it out and stop crying about it...

[notmattlythgoe]

Originally Posted by geomapguy

If you don't the ability to do stuff manually in your code, then you are setting yourself up for failure. What happens if a sensor goes out during a match....you still want to be able to function without the sensor.

So honestly, just figure it out and stop crying about it...

That is not always the case. There are many times I'd prefer to not do something if a sensor goes out during a match than have manual control over it. I don't want a motor over driving through a hard stop because an encoder went out and the motor was manually over driven. Better to lose one match than break something on the robot.

Also, no need to be rude about it.

[Jeff Pahl]

I personally do not trust any sort of "software interlock" to prevent a dry fire of a robot mechanism. We all know that programmers are allowed to tinker with the code after inspection, and there is no sort of control in place to prevent the removal of a software interlock, either intentionally or accidentally.

I realize that the ball being present changes the physics of many shooters. However, it is my opinion that stored energy mechanisms should be designed to withstand the additional stresses of potentially being fired without the ball being present.

These are my opinions. You may not agree with them. However, be aware that I am the individual that presented this section of the rules during LRI training, and these are the opinions regarding this subject that were given during that presentation. There was discussion, but no disagreement on the subject. And I know all the Championship division LRI's are in agreement on the subject.

[Andrew Schreiber]

Originally Posted by Jeff Pahl

I personally do not trust any sort of "software interlock" to prevent a dry fire of a robot mechanism. We all know that programmers are allowed to tinker with the code after inspection, and there is no sort of control in place to prevent the removal of a software interlock, either intentionally or accidentally.

I realize that the ball being present changes the physics of many shooters. However, it is my opinion that stored energy mechanisms should be designed to withstand the additional stresses of potentially being fired without the ball being present.

These are my opinions. You may not agree with them. However, be aware that I am the individual that presented this section of the rules during LRI training, and these are the opinions regarding this subject that were given during that presentation. There was discussion, but no disagreement on the subject. And I know all the Championship division LRI's are in agreement on the subject.

Thus, can we expect all stored energy launchers will be expected to demonstrate a dry fire as part of the initial inspection and any subsequent re-inspections?

[Jeff Pahl]

Originally Posted by Andrew Schreiber

Thus, can we expect all stored energy launchers will be expected to demonstrate a dry fire as part of the initial inspection and any subsequent re-inspections?

No. You can expect any stored energy launcher that, upon review by the LRI, appears to present a risk of catastrophic failure resulting in parts leaving the robot, to probably be dry fired in a safe area. If the robot design is such so that risk does not appear to be present (mechanism is contained, mechanism is significantly robust) then it is reasonable to expect that a dry fire will not be necessary. If a shooter is modified and the modifications appear to possibly affect the structural integrity of the mechanism, then a possible demonstration during a re-inspection is possible. If you worked on some other part of the robot we are not going to re-inspect the shooter each time.

Rule R8 requires that robots not "be unsafe" or "cause an unsafe condition". The burden is on teams to be able to show compliance with the rule. I would welcome teams to provide written analysis that shows that the energy present in the mechanism is not sufficient to cause the materials used to exceed their yield strength, with sufficient margin, in lieu of physical demonstration of the mechanism.

Please keep in mind that if something goes wrong with a robot that we did not verify was safe, and parts go flying into the crowd, that in today's litigious environment, the lawyer's are going to sue everyone they can, including the robot inspectors that said it was safe.

The inspectors are not "out to break your robot". We want everyone to play with a fully functioning robot. But we are also responsible for making sure everyone goes home in the same condition they came in.

[kmusa]

Originally Posted by Jeff Pahl

I personally do not trust any sort of "software interlock" to prevent a dry fire of a robot mechanism. We all know that programmers are allowed to tinker with the code after inspection, and there is no sort of control in place to prevent the removal of a software interlock, either intentionally or accidentally.

I don't believe anyone restricted this to only software interlocks.

For instance, two limit switches in series (which require contact from the ball to close), and connected in series with one of the leads for the solenoid would be robust, and not open to software override.

-Karlis

[Jon Stratis]

Originally Posted by kmusa

I don't believe anyone restricted this to only software interlocks.

For instance, two limit switches in series (which require contact from the ball to close), and connected in series with one of the leads for the solenoid would be robust, and not open to software override.

-Karlis

And would be illegal per R53:

CUSTOM CIRCUITS shall not directly alter the power pathways between the ROBOT battery, PD Board, motor controllers, relays, motors, or other elements of the ROBOT control system (items explicitly mentioned in R64). Custom high impedance voltage monitoring or low impedance current monitoring circuitry connected to the ROBOT’S electrical system is acceptable, if the effect on the ROBOT outputs is inconsequential.

Note that R64 mentions the solenoid breakout as part of the control system.