Al's Annual Inspection Thread
 

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.

Re: Al's Annual Inspection Thread
 

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?

Re: Al's Annual Inspection Thread
 

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.

Re: Al's Annual Inspection Thread
 

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?

Re: Al's Annual Inspection Thread
 

I'll chime in here with my biggest concern: R8, specifically the "cause unsafe conditions" part. This year many, many teams will utilize springs or tubing to create a mechanism that can fire with a lot of power. The last thing we want to see is a team picking up their robot and the thing firing without warning, injuring a student when it hits them on top of the head or under the jaw (given the speed and power of these shooters, I wouldn't be surprised if this caused a serious concussion or broke a jaw). Please, Please, Please design in some safety interlocks to make sure this doesn't happen! A locking pin, or a carabiner that can keep the shooter from hitting someone carrying the robot is really all that's needed.

Re: Al's Annual Inspection Thread
 

Max,
Should an inspector request a dry fire, it is because the mechanism looks unusual or appears to impart a large energy transfer. We are concerned about that "destructive dis-assembly" mentioned above. Many of our inspectors have seen these types of mechanisms over the years, and our concern is first and foremost the safety of all participants and audience. The last thing we want is a mechanism coming apart and launching it's kicker into the stands and injuring a grandmother or young child. We certainly feel a need to protect the field personnel. You don't want to hurt a ref or judge do you?

Re: Al's Annual Inspection Thread
 

Spontaneous Deconstruction can plague any type of shooter. Elastic or electric or pneumatic

Re: Al's Annual Inspection Thread
 

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

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.)

Re: Al's Annual Inspection Thread
 

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

Re: Al's Annual Inspection Thread
 

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.

Re: Al's Annual Inspection Thread
 

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...

Re: Al's Annual Inspection Thread
 

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...

Re: Al's Annual Inspection Thread
 

So what I think Al and Jon are saying is that you should (and RI's will) assume the worst case that your robot will dry fire at some point unexpectedly regardless of your mechanisms designed to prevent that, because mechanism fail, especially when interactive with other bots.

If it only fires 'safely' with a ball loaded, then that is not good enough, and the robot is considered to be too unsafe for FRC standards, and it probably shouldn't be good enough for your team's standards due to the risk of serious injury.

Make sense?

Re: Al's Annual Inspection Thread
 

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.

Re: Al's Annual Inspection Thread
 

I agree, there are no robots out there that are perfect.
You're saying that inspectors need to make sure that when the robot malfunctions, it's safe.

So, let's look at another malfunction. If my robot were to try to fire a ball as the intake was stowed, I'd break my intake. Does the inspector need to watch me break my robot that way too?

However, dry firing my shooter will break it, but pose no safety hazard.

This whole test is a bit stupid. It's kind of like asking teams to drop their robots from the top of the pyramid to make sure that when it falls, it isn't dangerous.

Re: Al's Annual Inspection Thread
 

Next thing you'll be asking me to demonstrate that my gearbox properly constrains parts if I break my gears...

We'll have a system in place to bypass any safety systems we end up with.


I'd hoped to clarify under what circumstances dry firing will be needed. I just don't like being told "oh, it depends on how your inspector feels" because I'd like to think that all robots are inspected equally and fairly and an inspector can't cause undue wear and tear on a mechanism/stress on a team merely because they feel like it.

Re: Al's Annual Inspection Thread
 

The difference is that a robot on the pyramid has a large amount of potential energy that could end up directed as kinetic energy towards the ground (or maybe onto another robot), where a spring or winch on the robot stores a lot of potential energy that is many times directed upwards and at an angle, which could potentially go towards any number of volunteers, human players, or audience members.

Re: Al's Annual Inspection Thread
 

No, not really. When my shooter dry fires, the lexan arms shatter in an enclosed area at the bottom of the robot. When we break the shooter, it's safer than if it took an actual shot. Standing near an arm smashing itself into the bottom of our robot is way safer than having a 2 lb ball be thrown at you from a foot in front of the robot, and getting the shooter arm to hit you on your head.

Re: Al's Annual Inspection Thread
 

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.

Re: Al's Annual Inspection Thread
 

If a sensor goes out and my default is to not allow firing how is that failure? If we determine that the potential risks of not being in a known good state are not worth the cost of losing a match I would say that is both OUR call to make and the proper call.

This isn't my first rodeo, when designing a system that has potentially dangerous states I prefer to know exactly where things are and be sure that the system protects itself from damage and keeps itself from getting into states that could be dangerous. Dry firing the system is potentially dangerous due to the fact that it bypasses the regular firing procedure meaning any of a handful of other systems could be in the wrong configuration and could be damaged, destroyed, or cause other problems. There is a firing procedure for a reason. If the forks were to hit the intake neither system would likely be destroyed but it would present an unsafe condition for the humans that have to sort that crap out.

Asking for clarification isn't "crying about it" it's making sure we are adequately prepared for any known contingencies. It's something engineers try to do. I will comply with any and all procedures that the LRI's deem necessary to ensure safe operation of robots, I just want to know what they are and what the expectations on my team are.

I would assume you wouldn't talk to one of your mentors as you have just done to me, I will ask you nicely once to change your tone. After that I will be contacting your team leaders to have a discussion about how your team is representing itself online.

Re: Al's Annual Inspection Thread
 

If it is obvious that when your shooter self destructs that all shrapnel will be contained safely inside the robot, then it would not be necessary to dry-fire the mechanism. The safety concern is with a robot where the mechanism is not contained in such a manner and the possibility exists that it could throw parts outside the field border into an area where people are present. Or throw parts into an adjacent pit. I would consider a robot that was designed to contain all parts in the event of a failure to be consistent with the desired intent, and would commend the team on the design.

Unfortunately, however, not all robots fall into that category yet. I eagerly look forward to that day.

Re: Al's Annual Inspection Thread
 

Here's my thoughts and response, but I suspect Al will chime in as well...

There are some safety issues that can only be minimized to a point based on the game design requirements. Exposed spinning shooter wheels at output orifice (2012,2013), launched frisbees, etc. This year's game piece is harmful when launched at close range to a person also (though probably likely to cause less injury than from a frisbee.)

So the fact that live firing is unsafe has no bearing on issues associated with the safety of dry firing. The point is to maximize safety to the extent that it can be reasonably maximized. And the threshold FRC has chosen is that dry firing should not result in parts breaking off at high speed. If dry firing is shattering lexan parts, that may not be safe enough, since projectiles and parts flailing at high speed in directions they are not designed to go is the concern here.

Re: Al's Annual Inspection Thread
 

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?

Re: Al's Annual Inspection Thread
 

Thanks for the response. I do understand the point of the rule, as some systems may fail more catastrophically than others.

EDIT: Just to clarify, when we dry fire, the shooter arm goes > 180 degrees into the bottom of the robot where the lexan on the arms shatters. None of the lexan leaves the robot.

Re: Al's Annual Inspection Thread
 

And if that's the case, I would fully expect you could explain it to the inspector (and possibly go through a low-energy/slow motion demo to show where the stress will occur without actually breaking your arm) and get agreement that dry firing is safe without requiring full test. I'm not saying we'll require every robot to dry fire... It's a judgement call on safety when a dry fire does happen. If I think the results of a dry fire will be bad (like launching the head of a 30lb sledge hammer into the crowd), then I'm going to arrange for a safe dry fire to see how the system holds up, even if there's a sensor the team swears won't let it dry fire. If a dry fire will result in a situation that's safe for those in the stands and next to the field, then I won't have a need to ask for a dry fire test.

Re: Al's Annual Inspection Thread
 

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

Re: Al's Annual Inspection Thread
 

And would be illegal per R53:
Note that R64 mentions the solenoid breakout as part of the control system.

Re: Al's Annual Inspection Thread
 

Custom circuits (which your switches are considered) can't alter solenoid pathways, so your system is illegal on non safety grounds.

Re: Al's Annual Inspection Thread
 

It would probably be an effective system, but it would violate the robot rules. Custom circuits may not affect the power pathways to robot actuators. The only "hardware interlocks" permitted on an FRC robot are limit switches connected to the Jaguar switch inputs.

Re: Al's Annual Inspection Thread
 

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.

Re: Al's Annual Inspection Thread
 

I personally do not trust any sort of "aircraft cable" to prevent explosive disassembly in a robot mechanism. We all know that mechanical engineers are allowed to tinker with the robot after inspection, and there is no sort of control in place to prevent the removal of aircraft cable, either intentionally or accidentally.

One characteristic of a "robot" is that it's a system where, if the software fails, hardware will break.

Of course, if the software works, it'll probably break then too, we just won't know who to blame.

Re: Al's Annual Inspection Thread
 

The mechanism for this is reinspections. Any time a team makes changes (which incldues removing components), they are supposed to ask for reinspection, and reinspections can happen at any point in time. I know that I always have my inspectors watching the field and chatting with teams in the queue after we're doing with inspections Thursday morning... this is to give inspectors a chance to notice something dangerous on the robots and then perform an inspector-initiated reinspection.

Re: Al's Annual Inspection Thread
 

Am I missing something here? Our catapult is applying 150lbs over 1/4 sec or so. I assume many people are doing something similar. It does NOT matter all that much whether the 2.75 pound ball is there or not - I think. Why is a "dry fire" all that different from a "wet fire"? The mechanism that stops the motion has to work all the time.

So why not demo a dry fire for the inspector to let him/her see the robot does not fly apart? Ours has a ratchet to prevent back drive and if the motors are disabled it would be difficult to accidentally fire. I don't even get the necessity for a "ball present" sensor - the driver can see it well enough.

Re: Al's Annual Inspection Thread
 

Al,

Thanks again for this annual thread.
I just passed the VIMS RI "test" this morning as I will be a Inspector this year at Davis.

This is the first time I have filled this roll. Reading through this thread always helps a team, as well as Inspectors, prepare for competition.

Re: Al's Annual Inspection Thread
 

Most shooters are going to need the ball to be settled in a specific spot, if that ball is not settle before they try to shoot its not going to go where they want.

Re: Al's Annual Inspection Thread
 

That is for shooters that store energy in some sort of spring. our uses 6 cims in a similar manner to the way Team Boom Done's shooter worked. we fired ours into our hard stop and it did stop it-- it also bent the shooter shaft and took a chunk out of our stop. that is where I have a problem with this. It does not say in the rules your shooter has to be capable of dry firing either.

Re: Al's Annual Inspection Thread
 

Agreed - but that is not a safety issue. And it is hard to understand how it would be visibly "unsettled".

Re: Al's Annual Inspection Thread
 

Many catapult systems will fire a lot slower with the load of the ball at the end of the lever. Thus 'dry' firing will be a lot faster.

Since F=M*V(squared) if you double the speed of the catapult, you get 4X the forces on it. Some catapults will triple (9x forces) or even quadruple (16x forces) their speed when 'dry' fired vs. the standard 'live' fire.

Re: Al's Annual Inspection Thread
 

Wow - something is not right about the design, sounds scary. Perhaps you could add a spring-loaded bumper or something to keep the shooter from destroying the stop. Or maybe a spring that engages just after the soft stop?

Good luck!

Re: Al's Annual Inspection Thread
 

OK,
This will be brief as I am already very late. Dry firing a shooter mechanism that is suspect has been part of FRC inspections as far back as I can remember, perhaps 1998. I know and you should know that students make mistakes driving and shooting. I know that just at the wrong time, the ball comes out and bang, a shooter dry fires. I have seen hundreds of wiring errors, software glitches and damaged latches fail in competition. I know that regardless of your software or hardware, an unsafe mechanism is still unsafe. I and all other inspectors, field volunteers, Safety Advisors and Refs are tasked with keeping the participants safe. I am not going to take your word that your shooter won't harm anyone, I want/need to prove it to myself. You only have to see one near miss to know you never want to relive that experience again.
So here is the only answer I can give you. If an inspector believes your shooter or anything on your robot violates...
R8
ROBOT parts shall not be made from hazardous materials, be unsafe, cause an unsafe condition, or interfere with the operation of other ROBOTS.
and you disagree, then you will be asked to prove it. It is the third item in the Inspection Checklist under the mechanical section.

Re: Al's Annual Inspection Thread
 

Are code safeties enough to pass a dry fire inspection? Our shooter has issues dry firing, but we do have a reliable safety mechanism to guarantee no shots without a ball in place.

Re: Al's Annual Inspection Thread
 

I believe the request for a "Dry Fire" has less to do with software or mechanical safeties, but has wholly to do with mechanical robustness.
In other words, and as Al has stated, will the shooter catastrophically self destruct, endangering ..... you name it.

Re: Al's Annual Inspection Thread
 

I can remember being asked to dry-fire more than once over the years. We account for that in the design to avoid self-destruction.

As a RI, I'd only ask for a dry-fire if it looked like something could be flung from the robot and off the field.

It is feasible to add some mechanism to help mitigate the destructiveness of a dry fire in your system?

Re: Al's Annual Inspection Thread
 

Al,

On our robot we currently have a end of a piston protruding 0.2 in outside of the frame perimeter in it's default position and are wondering if this counts as an minor protrusion?

This is less than the 0.25 in shaft collars that we have that are deemed acceptable.

Re: Al's Annual Inspection Thread
 

After 3 pages of "Dry firing" discussion, I'd like to underline the excellent point Jon made earlier. In my visits with a few teams I can see this being very relevant and I'm going to be asking teams to show me some type of mechanical interlock if they intent to load up their mechanism prior to placing it on the field and demonstrate a safe way to unload it or lock it up prior to removal from the field. Hopefully most have already thought of this but it reminds me of the wheel guards we had everyone add last year. I don't want teams to be caught by surprise by such an obvious safety precaution.

Good luck!

Without seeing the mechanism that sticks out of the frame perimeter it seems that it isn't a bolt that is used to mount something on the frame or hold it together. It also doesn't sound like it is in the bumper zone. As such it would violate the vertical projection of the frame perimeter in the starting configuration.

Re: Al's Annual Inspection Thread
 

Al,
Thanks so much for your insight. I have a question regarding bumpers....

We've come up with a possible bumper mount system, and I'm not quite sure of the legality of it. I'll do the best I can to describe it here. It uses a sort of keyhole shaped hole where the wide end drops over a bolt/screw head and then slides over so that the skinny end is under the bolt/screw head. (Like the holes for hanging things on a wall, see this picture) This allows for a quick drop down and slide over motion for attaching bumpers. Our bumpers are in two halves, both of which would slide in towards the center of the robot if using this idea. To prevent them from sliding back out we thought of using a draw latch similar to the style of the one in this picture. The latch would be mounted on the two halves of the bumpers, to draw them together and hold them firmly in place.

While the latches would be a critical part of the mounting system, they aren't directly mounted onto the robot itself, but rather the wood of the bumpers. I'm not sure if this would comply with the Vertical Cross Section in Figure 4-8 of the manual. I realize that my explanation may not be entirely clear, please ask me to clarify anything you may not understand.

Thank you very much!

Note, I'm sure we can make the system strong and rigid. I'm only worried about the legality of the latches.

Re: Al's Annual Inspection Thread
 

I presented my hypothetical example primarily as a counter-argument, but, since the issue was raised...

I maintain that I can have a CUSTOM CIRCUIT, consisting of a Pneumatic Solenoid Valve and two limit switches.

Per
, this can be attached to either a solenoid breakout or a spike (as well as a motor controller, but that isn't useful in this case.)

Some additional observations...

* R51 includes solenoid breakouts, but it isn't included in the list of power regulating devices in R50.

* I suspect that the intent of Table 4-4 in R51 is that "Solenoid Breakout" should read "Each Solenoid Breakout Output". This would be consistent with the answer to Q352.
-Karlis (learning more than my share today, especially if I work through the stress analysis of our shooter.)

Re: Al's Annual Inspection Thread
 

Since solenoid valves are defined in the pneumatic rules, I don't think you can clump them with other elements & call them a custom circuit. If they are a custom circuit they are not on the allowed list for pneumatic items. The limit switches by themselves cannot connect to a solenoid since solenoid are not on the allowed connections for custom circuit outputs. But then I am not the one inspecting your robot.

I have seen all kinds of strange things from a finger fumble in software. At least on the mechanical side when you disconnect a safety item, you can see it.

Re: Al's Annual Inspection Thread
 

In that case, such a CUSTOM CIRCUIT is not an allowed pneumatic component, per R74. It doesn't matter how you want to define the example, it's not a legal configuration.

Re: Al's Annual Inspection Thread
 

In that case, aren't all pneumatic solenoid valves illegal? Electrically, the Glossary and R40 both define a pneumatic solenoid as a CUSTOM CIRCUIT.

Re: Al's Annual Inspection Thread
 

Pneumatic solenoid valves are custom circuits, yes.

Limit switches are custom circuits, yes.

Putting a pneumatic solenoid valve and a limit switch or two in series may be counted as a custom circuit, I suppose--but if you do that, you do need to be very consistent about "this is one custom circuit".

So... let's take a look at what custom circuits can and can't do. OK, they can connect their outputs to other custom circuits, or to the control system via various means. They can't affect power pathways between elements of the robot control system--but the rule referenced does not include solenoid valves as a control system element.

Electrically, I'd say that that looks good--but only by the letter. Something smells near the spirit--my opinion, not backed up by any rule--yet.

However, pneumatic solenoid valves are also pneumatic components. Limit switches are not. So we've gotta look at the pneumatics rules.

R76 allows wiring of solenoids and other pneumatic devices to be modified to interface with the control system. Note that the control system, as defined elsewhere, does NOT include custom circuits--and we've already established that limit switches are a custom circuit. End applicable pneumatics rules.

So, from an electrical point of view, we're good. From a pneumatics point of view, not so much--again, note that custom circuits are not considered part of the control system, and you're not to modify pneumatic wiring except to interface with the control system.

So where does that leave us?

As one custom circuit, you're introducing a disallowed pneumatics part--it's not COTS, and it's pneumatic, so R75 rules it illegal. That's what you were initially claiming to be able to do. Under R77, pneumatic solenoid valves are legal provided they meet certain constraints--but custom circuits that happen to include pneumatic solenoid valves are not!

As 2-3 separate custom circuits, a particularly picky inspector would probably use R76 to rule it illegal. Pneumatics with wires can be modified to interface with the control system, but it can be argued that a pneumatic is a custom circuit, where the rules are wide open. Personally, I prefer to take the safest route, and figure on the former route. At which point, I note that I've got two custom circuits connected to something that may or may not be a custom circuit, and thus may or may not be legal under the electrical system rules, as well as a pneumatic item with modified wires that aren't connecting to the control system (custom circuits are not part of the control system), which may or may not be illegal, depending somewhat on how lenient the inspectors are.


In short: I can think of one way it's legal, and at least two it could be ruled illegal. Might be a really good question for Q&A to answer (unless Al wants to weigh in first).

Re: Al's Annual Inspection Thread
 

Joel,
In looking back at your question I wanted to be sure that my response is based on your description, it is up to the RI to make that determination once you are inspected. I making an educated guess based on your description.

Karlis,
As to the use of limit switches in series with solenoids. The defining rule in my mind is...
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).

Switches used in this fashion are considered as Custom Circuits as there is no other general electrical rule that governs them other than as sensors. If considered as a sensor, by definition they are data input only devices. In either case (sensor or Custom Circuit), neither can be used between the control system and any driven component. If you think about the actions of the robot, it is the intent that when the robot is disabled, all further action is prevented other than that which results from gravity or the natural movement of robot parts when power is removed. Solenoids are considered electrical loads under R51.

Calvin,
The bumper mounting you describe sounds like it could work but an inspector will need to make that decision when working with you. It actually sounds like a unique and desirable solution. What we are concerned with is the reaction of your mounting when physical interaction with other robots and with the field elements occurs. If you ask any inspector, they will almost 100% tell you that they want to see nice, clean bumpers that don't fall off and don't sag out of the bumper zone. You may ask why. It is because we have such respect for the beautiful machines that you have made, it seems counter productive to add a bumper system that doesn't fit the rest of your design.

Re: Al's Annual Inspection Thread
 

Solenoid valves are explicitly allowed per R74 and R77. Other custom circuits are not.

Re: Al's Annual Inspection Thread
 

Day 2 Installment Electricals
1. Motors. While there are wide variety of motors available to teams this year, there are still some limits. Be sure to stay within the limits, 6 of the larger CIMs, a total of 4 Banebots in different models, 4 AM motors, etc. The list is split between tow pages but you only have 2 window, door, windshield wiper or seat motors. Not two of each. Electric solenoid actuators (Not solenoid valves) are limited to 1" stroke and 12 volt, 10 watt total. I hope to see some of these for shooters. For some of these you may need to provide documentation. Please attach that to your BOM or B&T forms so they are all together. Please choose wisely, the battery and main breaker can only pass so much current to your electrical system.
2. Custom Circuits. We expect more of these this year as teams investigate vision processing and passing/throwing. Custom Circuits must satisfy the electrical rules. In particular, they may not "alter the power pathways" and they need to have sufficient insulation to prevent electrical problems and shorts to frame.
3. On the subject of Frame Faults, the cRio and certain cameras have the case tied to the negative lead of the power cable. For this reason, they need to be insulated from the frame. Lexan sheet, non-conductive hardware, etc. are all effective methods. The reason for this, is the possibility of robot to robot contact or electrical issues on the robot that will pass current through frame parts, interrupting power supplies or resetting control components. We want every robot to play every match for the full match.
4. Cameras. These are components we see more of each year. There are rules in other parts of the manual covering cameras, so be sure to read the entire manual. Even if you are only using the camera for collecting demo video, robot rules still apply. The camera must be included in robot weight, and be securely mounted on the robot. Duct tape is not a fastener.
5. Wireless Bridge. Please mount this critical component where it can "see" the field antennas. The inspectors and FTA needs to see the lights especially if you are having issues connecting. This radio has two antennas near the left and right side of the radio. Both are needed for maximum bandwidth in both directions. Metal interferes with the RF signals so try to keep the area near the radio clear of metal and moving parts.

Re: Al's Annual Inspection Thread
 

Would it be a fair statement to say that "Custom Circuits" are used as inputs to the cRio, and not as outputs to anything, such as: motor controller, motor, servo, pneumatic component or mechanism?

The one exception I see is where the CC is used for display or decoration purposes. As an example, an Arduino used to drive a display or LED strip.

Re: Al's Annual Inspection Thread
 

Bill,
In the case of processor controlled custom lighting, the whole system is a Custom Circuit. In that case, the system is a stand alone or it may take input from cRio status or a DIO on the DSC. Custom Circuits make take input from another sensor or even camera. Any command that is generated by a Custom Circuit for robot control must pass through the cRio so that it can be managed by FMS. There are a variety of ways to accomplish this and there is documentation on the FRC website.

Re: Al's Annual Inspection Thread
 

Got it.
The description "Any command that is generated by a Custom Circuit for robot control must pass through the cRio so that it can be managed by FMS." is the decision point. Granted, all CC's must adhere to the rest of the electrical and safety rules as well.

It looks like the RI's really need to be talking with the teams as they pass through the inspection process.

Re: Al's Annual Inspection Thread
 

That's what we do. The first question will be "do you have a custom circuit?" What follows depends on the answer.

Re: Al's Annual Inspection Thread
 

I don't think any safety inspection & discussion, dry-firing or otherwise, is unreasonable. With the amount of stresses place onto relatively small areas a misfire into someone's face can be just as bad as getting a finger stuck in a live #35 sprocket.

Here's an additional thought for winch-style systems:
As the guy who has put my teams' robots on the field for 10 seasons I can say this is the only year where robot transport to a field would make me really nervous if there wasn't a mechanical safety somewhere in the system. I'm a programmer/integrator by trade and losing a finger (even temporarily) would really hurt my career given the stage it's at. If the pneumatic cylinder accidentally fires, the "dog gear" (loosely-termed) breaks, pneumatics looses pressure and the "dog gear" engagement cylinder rail slips, the anti-backdrive wrench eats itself, or the nylon strap attachment breaks then the launcher will definitely fire with many pounds of force.

The build team very easily implemented a hard-pin lock system. The pins are quick-release (McMaster #90293A313) and will have massive ribbons (similar to this) so they're easily the last thing removed before we go behind the driver's station. When the system is under tension yet not in a live-fire environment (i.e. a field), these pins will be in place. This means that no matter what software wants to experiment with or how bumpy that ride from the pits is, our robot will not fire in my or my student's face. It also gives the pit team peace of mind as they remove any energy from the system post-match.

Re: Al's Annual Inspection Thread
 

This sounds like a robot the Green shirts will love.

Re: Al's Annual Inspection Thread
 

We where initially going with the pressure loaded catapult in the disabled state. We have switched to disabled vents the cylinders. For us, the safety benefits out weighs the pressure on when disabled benefits. Obviously you don't have that choice with springs. Having a secondary locking system is a really good idea for those cases.

Re: Al's Annual Inspection Thread
 

I understand the intent.

My issue is that when they changed the wording from previous years (this is last year's)
, that they removed the power pathway restriction for elements beyond those explicitly listed.

<rhetorical>
Doesn't this also then exclude an amplifier for a [legal] pressure transducer?
</rhetorical>

What I'm really asking is "How do I get the GDC to clarify the distinction between the mechanical and the electrical aspects of pneumatics in section 4.10?", since it, with the exception of R76-B and R88-B, appears to focus on the mechanical side.

-Karlis

Re: Al's Annual Inspection Thread
 

Ask on the Q&A.

Re: Al's Annual Inspection Thread
 

Al, for some clarification: does a custom circuit have to be controlled by the cRio, if it's controlled at all?

That is, if we have an LED ring on our camera, and LED lights elsewhere for blinging-up purposes, can they just be powered by the PD board (which jives with the 2014 wiring diagram), or must they have some kind of active control?

Re: Al's Annual Inspection Thread
 

Karlis,
The wording has remained relatively unchanged for many years re: power pathway and custom circuit. I spot checked the 2008 rules and the only difference there is reference to hardware that was used in that year. What you are asking (in my mind and Jon's as well I suspect) is that limit switches in series with pneumatic valves alter the power pathway between "elements of the robot control system". The intent has been, and will remain to be, to prevent any robot action after the FMS has issued a stop command other than that which results from the action of gravity on robot parts. Potentially, limit switches could be satisfied by this condition resulting in the moving of robot parts under pressure after a stop has been issued.
As to the amp for the pressure transducer, it is the transducer that is pneumatic and the amp as Custom Circuit. They have to satisfy that part of the rules to which each is identified.
Pat,
There is no rule that states that a Custom Circuit has to be controlled by the cRio or send data to it unless that data is used for robot control. In the case of an LED Ring, it may be connected directly to the PD and turned on with the robot. If it is extremely bright and other participants complain that it is obstructing vision during most of the match, we can ask that it be wired to a control device and only illuminated during the period you really need it. We want you to play but not at the detriment of other participants. The same rule applies to power supplies that are part of a Custom Circuit, they may be powered when the robot is turned on directly from the PD. As always, they must meet all other electrical rules that apply. (breaker size, wire, insulation, etc.)

Re: Al's Annual Inspection Thread
 

Right on, thanks. Last year we took some flack from an inspector and had to put a spike relay in place to control our LED. I'll come armed with the wiring diagram this year. :)

Re: Al's Annual Inspection Thread
 

Pat and everyone,
Please, please, please, if an inspector tells you to do something and it sounds weird, ask for clarification to be sure. The rules allow you to ask for the LRI to make a decision if you suspect some decision is in error. Every LRI has my email, cell phone and other contact info. I try to be available during the event season for questions. Again, this decision may be different once an onsite inspector sees your robot, your implementation and the effect on other teams. I see teams every year, all the way to the Champs, that have to make a change because something was missed at previous events or decisions were made based on specific circumstances at that previous event. Illumination has been an issue many times in the past, including a specific complaint on a robot aiming system last year at Champs. Yes it was bright, but it was not blinding unless you were right on the robot looking into it. It was aimed at the sky.

Re: Al's Annual Inspection Thread
 

Well to get back on track sort of...
Team Update posted yesterday:
As we approach competition season, we wanted to remind Teams to prioritize safety when transporting their ROBOT on and off the FIELD, to include transporting the ROBOT in its lowest potential energy state and/or including lockouts to help mitigate unexpected release of stored energy. Inspectors will ensure ROBOTS comply with R8 and do not create unsafe conditions. If inspectors feel your ROBOT is unsafe to be transported while storing energy, they will work with you to add lockouts to help mitigate the unexpected release of stored energy. If you are unsure as to whether or not you need lockouts, it’s best to be on the safe side and assume you do. Per T12, the Team should be able to safely release stored energy and be able to demonstrate this during Inspection. If the ROBOT creates an unsafe condition for people to be around it, on-FIELD troubleshooting prior to the MATCH will be limited to that which can be achieved safely.

I do not expect this to be a great issue for inspections or teams. The majority of teams have already designed their robot to be safe, release energy in a controlled way and transport in a zero or near zero state of stored energy. Many of you have experience watching matches from the stands or seeing robots in the pit, but only the drive team and coaches have that intimate knowledge of what it is like in a crowded queue waiting to get on the field with a programmer who is making last minute changes with a powered robot. Anyone who has been around for a while can relate something scary that has happened in the queue.
While safety is a high priority, we inspectors also want everyone to have a great event. That means we want to help make the match fun for everyone and watch for things that could ruin a team's day. While we are looking at your robot, we are thinking about your alliance partners as well. Getting all teams inspected is our goal to insure that everyone has a full alliance in every match. So this post should be a request to teams to get inspected early and help us get everyone inspected.

At the top of the list of items teams need to complete inspections is bumpers that meet the rules and the BOM. No BOM, no sticker. Please don't leave it in your hotel room, don't let the dog eat it, don't give it to your teacher who won't be there until later in the day, don't leave it on the workbench at your build space. Make several copies, put it on a couple of thumb drives and on your driver station computer. I only have to be able to read it and compare the list with what I see on your robot. You don't have to include the candy you bought for the pit crew but you do have to list the no cost items that are KOP or First Choice. There is a template on the FRC site, this is preferred.

Re: Al's Annual Inspection Thread
 

Al, I know this is really a Q&A type question, but... Are voucher items considered KOP in terms of cost accounting?

Bimba Cylinders?
Bane bot vouchers?
So on.
Does this leave open the barn door?

Re: Al's Annual Inspection Thread
 

From the Glossary:

Kit of Parts (KOP): the collection of items listed on any Kit of Parts Checklist, has been distributed via FIRST® Choice, or obtained via a Product Donation Voucher (PDV)

Re: Al's Annual Inspection Thread
 

Thanks. I should have looked there. I guess my confusion is anything that was available on first choice or KOP checklist can be used with $0 cost without regard to how it was actually purchased. A cash value PDV or the Bimba cylinder list would open up the entire website.

I guess the key word is obtained by the PDV as opposed listed or distributed for first choice or KOP checklist. Sort of q fine distinction.

Re: Al's Annual Inspection Thread
 

What about the candy you bought for your LRI? :D

Re: Al's Annual Inspection Thread
 

Shhhhh! It will be there, I promise. I know people.

Re: Al's Annual Inspection Thread
 

What about the RI? We are people too and like candy :(

Re: Al's Annual Inspection Thread
 

At the Long Island Regional our LRI brings ME candy (and for all the RIs too).

Re: Al's Annual Inspection Thread
 

Wayne,
You know where the candy is coming from...

Re: Al's Annual Inspection Thread
 

Third Installment...
Well I hope everyone finally got their robot bagged. For those of you attending district events, you have the ability to open your bag, under certain specific conditions, to perform additional work. Please check under Robot Transportation in Section 5 of the manual. Be sure to document your bag open on your Robot Lockup Form.
Electrical Continued...
1. Visibility of components. This is really an important one. The robot rules require that electrical components be visible for inspectors to see values and wire types as well legal motors etc. We will make every effort to check these items but if you make them invisible it will be difficult to get through inspection. We must be able to compare breakers to wires and check wiring of the radio, cRio, etc. I just read a team post this morning about electrical students wiring with undersized wire that smoked and melted due to being the wrong gauge.
2. Wire color code must be followed. I get the complaint every year that the automotive industry uses different colors than those specified. Yes, but the robot rules are very specific. The Q&A also answered this question earlier in the season. You must use the color code supplied in the Robot Rules.
3. Motors. Only the legal motors please, those listed in R29 of the Robot Manual. Fisher Price and Globe motors are no longer legal motors.
4. Servos. You may use servos but they are limited by power output to 4 watts@6 volts based on the industry standard, Stall Torque x No Load Speed.
5. Main breaker accessibility. This is an important one. Please do not put your main breaker behind your signage or inside a hole that my hand cannot fit through. Marking it's location is a huge plus. When your robot sets itself on fire, we want to shut it off. If we can't get to the main breaker to turn off your robot, it may self destruct. We may also suggest that you move your breaker to a more secure location if we think it may actually be in a position that it will get bumped off by another robot or the ball.

Re: Al's Annual Inspection Thread
 

Some comments from the LRI at FiM Southfield for this year"

This can be a violent game. Robust bumper mounts is a must. Mounts that have been OK in the past only made it 6-7 matches before becoming quite loose or falling off.

This can be quite a violent game. Make sure your PD board and CRIO are very secure as well as strong electrical connections. We had a lot of 6 gauge power leads getting loose around the 4-8th round of matches. Around the same time we saw an up-tick in radio power plugs coming loose as well as CRIO power leads and CRIOs getting thrown around.

Cog belts can cut the ball and pop it. While many of use are used to looking for chains and sharp edges around collectors, we had a cog belt saw a hole in a ball this weekend in about 2 seconds in one of our early matches.

While FIRST Robotics Competition is not battle bots, the wide open field this year allows teams to build up a lot of momentum. The 2011 game would often start matches with 1 big hit, but this year teams are experiencing hit after hit after hit... Strain relief on electronics and proper length cables is helpful. Having guards, shields, and covers helps a lot. Contact inside the frame perimeter happens a lot. While you might earn 50 foul points, a dead bot has difficulty earning any additional points.

Re: Al's Annual Inspection Thread
 

Well, We have week one under our belts. So here are some reminders based on what appeared over the weekend.
1. Bumpers. Please remember that bumpers must be between two and ten inches above the floor when you compete. This is a violent game thus far and teams with lack of substantial fastening systems risk having their bumpers knocked out of position, torn off or fail in a hard collision. The bumpers need to be backed by structural robot frame. I saw one robot frame bent this weekend following a hard hit with another robot.
2. Springs. As I listed earlier, the use of springs brings with them special problems. Not only do we need to consider safety in the event during firing, please consider what you sue to fasten the spring ends to your robot. Ty-wraps are NOT a spring fastener. These items need substantial connections to your robot frame. Should one of these let go during a loaded condition, the result is the same as a dry fire or worse. You wouldn't design your company's product like this, don't use them on your robot.
3. BOM. Everyone needs one, it needs to be accurate and it needs to list everything used on the robot. That means, you need to account for all the parts you made or used, all the motors, electronics, even the KOP items. You can use any form you like, but FRC provides a really nice form that comes from a spreadsheet first designed by Raul Oliviera. If you use this simple entry form, your RI will get through inspections much faster. This and bumper issues are the at the top of the list of items preventing the final inspection from occurring.
4. Battery chargers continue to be a problem. The Safety Manual addresses this issue. Show up with a 50 amp charger and you will be asked to remove it under the Safety Manual, Battery Charging, on page 8.
5. Since this is turning into a very physical game, I can only suggest that teams protect certain parts of their robots from damage. In particular, you might want to mount air tanks inside the frame, add additional fastening to your cRio and battery.
6. While the Main Breaker should be protected as well, please don't bury it within the robot or put it under the moving parts of your shooter. It needs to be accessible for you and us. It should be marked as well. What I often tell teams is this...
"We may need to reach your breaker to prevent further damage on the field. If we can't, then everyone will just point while watching your robot self destruct."
7. I have talked about this before, but it is still an issue. When you bring your robot to your event and drop it off, you need to leave the B&T form attached to the robot. If you don't bring it with you, it will delay your bag open. Most teams use a simple binder envelope that protects the forms and anything else that goes with the robot. Do not put it in the bag before you seal it. We will not open the bag to retrieve it and sign off the bag open. The B&T instructions are very clear and can be found in the Robot Transportation section of the manuals.
8. Bumpers. Yes I know I listed them already, but this needs to be repeated. Bumpers need to be securely fastened to the robot frame and be backed up with robot structural frame. The KOP chassis when assembled per the instructions satisfies the bumper rules for mounting on the frame.
Congratulations to all the teams that made it through week one, and see you after week two.

Re: Al's Annual Inspection Thread
 

Just curious.
Has any team been asked to dry fire their shooting mechanism in the past regionals?

Re: Al's Annual Inspection Thread
 

It was discussed at our inspector at Palmetto. Disable vents the cylinders so we don't load our catapult when it is disabled. We were not asked to dry fire it.

Re: Al's Annual Inspection Thread
 

I did ask one team to dry fire their mechanism at Lake Superior, and it really didn't seem to be a problem. We then had a different robot that got into a continuous dry-fire exercise on the field that started disassembling their mechanism. Things held together enough that parts didn't go more than a foot or two, though.

Re: Al's Annual Inspection Thread
 

Al, do you think you could get the powers-that-be to put a link to the safety manual on the homepage of the FRC Manual? It took a minute to find it because I rarely actually go through usfirst.org to get to the manual.
http://frc-manual.usfirst.org/

Re: Al's Annual Inspection Thread
 

Jesse, I will see what I can do.

I am going to take a departure from my normal listing to make some recommendations based on observations over the weekend.

Bumpers. I don't know why bumper construction is so difficult for teams. This year is proving to be a violent game and bumpers are taking a beating. Teams, please modify your design to stand up to the hard hits. I watched as a team was disabled when their bumper was ripped from their frame. If you do not use substantial fasteners, you will risk the same fate. The bumper system is designed to absorb the shock of massive robots hitting each other at high speed, exactly what we are experiencing this season. While many teams use a different cloth color to mount over a permanent color (skirts, flip over covers, etc.) few are considering the effect of a hard hit has on this method. You should use some positive attachment to prevent the fabric from coming off in a collision or from slipping and allowing loose fabric from dragging on the floor. You have spent a great deal of time making a nice looking robot. Invest equal effort in building your bumpers. While bumpers in the corners are legal, this might not be the game that best utilizes that design. It seems that teams with full bumpers are surviving the best.
You have a choice of fabric available to you, but even the 1000 dernier Cordura is getting damaged. Don't skimp on the fabric, get the "good stuff". Two colors that closely match the FIRST Logo colors are needed. You need to add your team number to the fabric. There are several methods that you can employ for that, including number kits available from several locations. Expect that the numbers will pull off and have spares ready to apply.
Remember that they must be fully in the 2" to 10" zone above the floor when sitting on a flat floor. If you have allowed some slack in your fabric, expect the pool noodles to sag. When they go out of the bumper zone, you are in violation. A quick check is a boot toe should fit under the bumpers. If you have checked yours with a tape measure than calibrate to your own shoe and insure that every match you are within the bumper zone.
And lastly, if you use a method for attachment that takes your team 30 minutes to remove or to remount, you really need to think about a better method to attach them. The rule of thumb of one person and ten minutes should be your starting point for attachment design.
Good luck everyone.

Re: Al's Annual Inspection Thread
 

This is a different discussion, but teams really need to remember that they have an e-stop button and that there is no real penalty for using it.

This particular team could have cut the damage to their shooting mechanism in half if they had e-stopped before the field staff got to their driver's station and gave them a hand with pressing the button.

I saw similar incidents more than once at Lake Superior. If your robot is damaging itself, the electronics fall out, your battery starts dancing, or your robot is no longer vertical, hit the button!

Re: Al's Annual Inspection Thread
 

I requested one (motor-powered), just to verify safe operation when empty.

The result did no damage other than to shake a battery loose that I'd already suggested be further secured.

Re: Al's Annual Inspection Thread
 

Today's installment will be referencing the Team Updates.
1. Teams should regularly check the team updates, keep a copy handy with their other manuals and check them against their own robot designs.
2. Inspectors will use any Team Update that is current for that week of competition.
3. Any update that is a change in robot rules will be reflected in a revision of the Inspection checklist. We are currently at Rev B, reflecting changes in the stored energy warnings and lockouts and for the change in Pressure Relief Valve mounting.
4. Team Update are planned for Tuesdays but other immediate items may cause an update at any time. Watch here on CD for alerts and check the FIRST website often.
5. The Team Update for Tuesday, 3/11/14 has repeated a blog post from last year highlighting safe practices for using pneumatics and in particular the white storage tanks.
6. Yesterday's Team Update also added some language to clarify the withholding. "This static set of items may only be brought into the Pits when the Team initially loads in at the Event. Items made at an Event do not count towards this weight limit." Teams have thought that they could continue to bring items to an event throughout the course of the event as long as the total weight for all items did not exceed 45 lbs. This has never been the case so this added language is just making that clearer. You may bring items in at team load in.

As a reminder (since this has been an issue the past two weekends) you are allowed one and only one robot at competition per R1. If you feel a need to bring a second robot for some special reason (demo, sponsor display, etc), you must receive prior authorization from FIRST HQ to do so. You may not bring a second robot to scavenge for repair parts. Remove the items you wish to use for repairs prior to the event.

Re: Al's Annual Inspection Thread
 

Am I correct that this means zips ties cannot be used to structurally secure surgical tubing? What would be considered appropriate? (I'm remembering this thread, that was principally centered around zip ties.)

Re: Al's Annual Inspection Thread
 

Siri,
You can secure the surgical tubing to itself (after you have wrapped the tubing around a structural part of your robot) using ty-wraps as there is very little load on the ty-wrap when the tubing is in motion. You don't want to use them in place of hardware (as a tie bar or link) to secure one end to a stationary part of your robot. The dynamic loads could cause them to fail.

Re: Al's Annual Inspection Thread
 

Thanks, Al. Understood; this is the way we use them.

Re: Al's Annual Inspection Thread
 

I prefer Rapid Unplanned Disassembly.

Re: Al's Annual Inspection Thread
 

We just finished the Dallas Regional and the robot on robot contact was pretty rough. We are thinking of adding some strength in the bumpers. Can the CD community help us understand on the limits and intentions of R21? We know we need to query the GDC but I'm not sure how to phrase the query (yet).

So the angle to hold the cloth must be aluminum, correct? No steel? But we could use 7071 or 7075?

Can we interconnect the top and bottom angle pieces? We know many top tier teams do this. But is it contrary to the rules? I'm thinking a solid 5"x1"x<length> u-channel is problematic for an inspector. But perhaps if there are just some small finite number of inter-connections between the top and bottom angle that might be OK. So my last query is how much structure can there be between the top and bottom angles before it causes inspection problems.

TIA

Re: Al's Annual Inspection Thread
 

Most of what you see behind the bumper is consider part of the mounting system for teams. Texas Torque and my team both used sheetmetal parts as part of our bumper assemblies this year that become part of the mounting system for the bumpers. Torque's are an entire c channel like you describe. We use a z- bend on our top rail and normal 1" angle on the bottom.

Re: Al's Annual Inspection Thread
 

Per the rules, "structure" between the top and bottom angle isn't allowed. HOWEVER, you can do pretty much whatever you want in terms of mounting (within all other applicable rules). If your bumper mount included a 5"x1" U channel that covered the entire back of the bumper, I don't think I would have a problem with it, provided it met all the other rules (specifically weight, 1" limit on hard parts and backing requirements come to mind).

Re: Al's Annual Inspection Thread
 

Jon,
As I understand the description, this is a legal implementation. The angles are optional but the ruling has been that as long as the "hard parts" definition is not violated and the bumper system remains under 20 lbs., sheet metal is acceptable. I expect to see more of this type of design as the season progresses due to the intense contact inflicted in this game.

Teams, please remember...

3.2.6.2 G28
Deliberate or damaging contact with an opponent ROBOT on or inside its FRAME PERIMETER is not allowed.
Violation: TECHNICAL FOUL
High speed accidental collisions may occur during the MATCH and are expected.
ROBOTS extend elements outside of the FRAME PERIMETER at their own risk; no
penalties will be assigned for contact between two such extended elements.
A ROBOT with an element outside its FRAME PERIMETER may be penalized under this
rule if it appears they are using that element to purposefully contact another ROBOT
inside its FRAME PERIMETER. Regardless of intent, a ROBOT with an element outside
its FRAME PERIMETER that causes damage to another ROBOT inside of its FRAME
PERIMETER will be penalized.

Re: Al's Annual Inspection Thread
 

My previous post has triggered my reminder for today.
If your robot design has elements that extend outside the frame perimeter, (i.e. hammers, kickers, leg lamps, etc.) your inspector should remind you that you are responsible for that element coming in contact with or inside another robot Frame Perimeter. If you are using a hammer or kicker, you have to be careful as to when to deploy the mechanism. A robot standing behind your robot may be contacted in such a manner.
Anyone who has watched any match videos has seen that bumpers are taking a beating. Many teams are finding they are receiving a disable when their bumper(s) get torn off in the hard hits that come with this game. When your inspector points out to you that your bumpers may meet the intent of the bumper rules but will not likely survive the game, please take their advice. A few screws will not meet the "robust connection to the main structure/frame" in this game. Remember that "lift" test mentioned earlier? Even passing that test may not be enough to determine the survivability of your bumper system. My team has added additional structure behind the bumpers.

Re: Al's Annual Inspection Thread
 

Where does this appear in the rules? I have looked in the Game Manual, the Team Updates and the Q&A.


We were using hinges at each corner to connect the various bumper sections together (front, sides, back) but they got pretty mangled due to repeated heavy impacts. Would it be acceptable replace the hinges with aluminum sheet formed into L-shaped corner brackets that extends 6-8 inches (or more) along each side/front/back? Multiple screws would be used to attach each bumper section to each corner bracket. The corner brackets would be sandwiched between the bumpers and the chassis. The bumpers would be attached to the chassis using aluminum angles screwed into the bumpers (and sheet metal brackets) and 1/4-20 bolts into the chassis. Some of our bumper sections are too short to have more than one point of attachment to the chassis. The corner brackets would transfer a lot of the forces to the neighboring bumper sections.

Re: Al's Annual Inspection Thread
 

philso,
I obviously cannot make an interpretation based on a description, that would be for your inspector to decide and of course for the Q&A to answer if it is something that hasn't been seen in the past. In general, bumpers using an angle to secure the corners has been allowed in the past. This is provided all other bumper rules are in compliance (the 1/4" gap rule and support in the corners for instance). As always, bumper construction is examined for weight, specifically for the maximum, and for any weight that should be correctly attributed to the robot weight.
Please remember that even if you have reversible bumper covers, the removal by one person in fifteen minute guideline still applies. We don't want you to miss a match because we need to accurately weigh your robot for some reason, only to find out it takes 30 minutes to get the bumpers off. I have seen one robot this season already that riveted their bumper system on to the robot frame thinking they would never have to remove them. That became very evident when the bumper fabric got ripped off in their second practice match.

Re: Al's Annual Inspection Thread
 

we were at Superior a couple weeks ago and I can tell you that there were NO penalties called for inside the frame perimeter contact. We have a lot of damage on parts that are well inside the frame perimeter so build them strong folks!!!!