pre-charged Pneumatics
 

when we go to mesure the perimeter of the robot can we have a pneumatic piston charged (ie pulling somthing back) or does it have to be empty. thanks for the help guys

Re: pre-charged Pneumatics
 

no, i believe everything has to be uncharged and powered down during inspection, but i'd ask the GDC/ consult the rules first

Re: pre-charged Pneumatics
 

thanks... the rules arent very specific on that topic

Re: pre-charged Pneumatics
 

I disagree. I believe this is perfectly legal for wieghing and sizing.

In the past teams have had srping loaded protrusions and expansions that activated at the start of the match but allowed them to meet size requirements and I see this as no different.

A good portion of this year's ball manipulation devices will be required to be pressurized to size during inspection. Explaining this to the inspectors as a precaution makes sense. Also remember every time you place your robot on the field this devisce will need to be charged fot the same reason.

IMHO you can go through inspection and place your robot on the field with charged pneumatics.

Re: pre-charged Pneumatics
 

Peter and Howie,
This is the rule that applies...

<R90> The ROBOT will be inspected for compliance with the dimension constraints specified in Rule <R10> while in its NORMAL CONFIGURATION, by being placed within a FIRST Sizing Device that has inside surface dimensions consistent with the rule. Other than resting on the floor of the Sizing Device, no part of the ROBOT can break the plane of the sides or top of the Sizing Device during size inspection. The ROBOT must be self-supporting while in the Sizing Device.

Inspections are carried out with all systems unpressurized and unpowered for obvious safety reasons. Robot size and weight are tested with the bumpers off and the battery out. Please refer to Rule <10> and <11> as both are referenced in robot size.

The rules for stored energy govern the condition that a robot can be in at the start of a match including air stored in the Clippards. This rule allows teams to pressurize their robot with an off robot compressor but speaks to the start of a match, not to inspection. Please ask the question as we have no guidance to the contrary from the GDC. I expect the pressure vent valve to be open until the "power on" portion of the inspection takes place.

Re: pre-charged Pneumatics
 

Missed that one Al.
It looks like a manual "safety" lock is how everyone will have to skirt this issue for inspection.

Re: pre-charged Pneumatics
 

Or have your robot kick the ball without any parts extending past the frame perimeter. It's possible.

http://www.youtube.com/watch?v=Mb0_i3hbVNY

Re: pre-charged Pneumatics
 

Everyone really should have a safety lock available anyways. If you are going to be carrying the robot on or off the field with any mechanism "charged" and ready to fire, it needs a secure lock in place to ensure that any jostling doesn't result in someone getting kicked in the gut and dropping the robot on their foot. That is a simple safety practice that every team should have (I would even go so far as to suggest that inspectors should fail teams without it) that can easily prevent real injuries.

Which leads to a question for Al... If a team had such a safety lock that was removed from their robot after placing it on the field, could they use it during the sizing part of inspection, but remove it when weighing the robot? If the safety lock is a few pounds for something real sturdy, it could make a real difference when being weighed.

Re: pre-charged Pneumatics
 

I've always told my team to release the air pressure before lifting the robot off the field. It makes the robot that much safer and doesn't take that much time.

Re: pre-charged Pneumatics
 

Ahh, but not all mechanisms are "charged" with air pressure. Teams that utilize springs or surgical tubing with a motor to charge their kicker may, depending on design, leave the kicker in a charged position when the robot is off, while having no pneumatics at all! And other teams will pressurize their robot from the cart in order to save weight (not have a compressor on their robot) - in such a case, you would have to carry it onto the field charged.

Re: pre-charged Pneumatics
 

FIRST provided some good safety guidelines for precharged devices (and this forum came up with some more) a couple years ago for the trackball launchers.

Mind you... if your ball kicker has as much energy stored up as a trackball launcher, you ought to be able to kick balls up into the stands.

My estimate so far is that we are using about 1/4 the force and about 1/2 the stroke on our pneumatic kicker that we did on our pneumatic launcher.

Jason

Re: pre-charged Pneumatics
 

one of the big reasons they put the weight restriction on is because team members are going to be carrying the robot, it's a safety issue.

Re: pre-charged Pneumatics
 

Eagle,
The answer would be yes and no. A safety lock could be used but under the rules for start orientation, the robot (not humans) has to be able to remove the lock after the match starts. The robot must be able to hold itself in the same size it did when in the sizing box at the start of the match.

During previous games where mechanisms used considerable stored energy, the team had to demonstrate during inspection, that the stored energy could be released (safely and easily) prior to moving the robot on or off the field. One of the most impressive devices I have seen was on the Baxter robot during Overdrive. It used surgical tubing and a cam type charging device. To move the robot, a team member just needed to back the cam to the point where the tubing was no longer stretched. Those that played against Team 16 that year knows the effectiveness of that ball launcher.

Re: pre-charged Pneumatics
 

Al,

I have to disagree with you (at least partially) on this one.

If the safety lock, when removed, will cause deployment of a mechanism, I agree.

If we are talking about making a trigger mechanism for a stored energy device absolutely foolproof safe but it's removal does not cause deployment, I not only think it legal but almost mandatory.

We do not want accidental deployment of a mechanism when putting a robot onto or off of the field.

Let's use a theoretical kicker for an example. It has a deflected spring and/or pre-charged pneumatic piston and a trigger that makes it fire. A pin in the trigger, removed after the robot is placed on the field, will prevent accidental firing while the robot is handled.

The pin is never part of the robot during a match. It is in a team member's pocket.

I would call this legal and almost mandatory.

JMHO,

Mike

Re: pre-charged Pneumatics
 

Mike,
I would agree on this example provided the robot was able to fit in the box and start the match without said locking device in place.

Re: pre-charged Pneumatics
 

Aircraft usually have a collection of locking pins with attached flags saying "remove before flight". They extend into visibility so that the ground crew can prepare the plane for use.

Re: pre-charged Pneumatics
 

This is exactly the approach we will be using for our shooter's safety pin. We will also try a similar approach for anything else that might save time and embarrassment, like forgetting to turning the main breaker on. :rolleyes: (Not that we have ever forgotten to turn the breaker on........more than twice a day during competition.:ahh:)

Mind you, anyone that has done this little boo-boo is immediately demoted to "Freshman" for the day, regardless of how long they have been on the team, in school, or beyond. This even extends to our Mentors..... of which I am one,... and have worn this label. :yikes:

Re: pre-charged Pneumatics
 

yeah, I've even seen them on robots!

Re: pre-charged Pneumatics
 

Al, I think I also need to disagree a little here. As the rules currently stand, normal configuration definitely implies a powered-on, disabled state ("the state of the ROBOT immediately before being enabled by the Field Management System, before the ROBOT takes any actions, deploys any mechanisms, or moves away from the starting location"). Although for reasons of practicality and safety it would seem valid to inspect robots in their least-energy state, if doing so would inaccurately simulate the normal configuration during sizing, the rules would seem to demand that it be tested in the normal configuration (per <R88> and <R90>).

Of course, there are not many mechanisms for which this is a valid concern, because with control system outputs disabled, control of most actuators and other devices is not practical. One possibility that comes to mind is an electromagnet that receives power directly from the PDB, through a mechanical switch, and which holds down some component until that switch is triggered, cutting power. (This is a custom circuit, and by using a non-relay switch, avoids being controlled by the cRIO.)

Now, it is certainly within an inspector's authority—and indeed, responsibility—to take steps to minimize the risk to themself and others during inspection. In the above case, if the team were to argue that they needed that component to be held back, but the inspector was uncomfortable with the presence of an armed mechanism in the sizing box, perhaps a compromise could be reached where the mechanism is fixed in the appropriate position, but in a locked-out state.

But in other cases, if the inspector considers the hazard relatively minor, I don't think that the rules would prevent a team from asking to be sized in a powered-on, disabled state.

Re: pre-charged Pneumatics
 

Tristan,
As I have pointed out in a different thread, we have received no direction from the GDC on any changes to the method of inspection. I cannot agree, based on past safety discussions and procedures, that transporting a robot with a charged mechanism, pneumatic or mechanical, is appropriate. If that is the case, then inspecting under different conditions is also inappropriate. Teams for many years have figured out ways to move robot objects into playing position that did not require charged systems to do so.
I think that the majority of this discussion likely is directed at kicking mechanisms. If the kicking device would fall outside of the robot frame perimeter without being in the charged state, it seems to me that the team needs to design their mechanism to keep the kicker inside the frame perimeter when at rest.

Re: pre-charged Pneumatics
 

That's not exactly the point I was making; basically, there's a balance to be struck between a team's possible expectation (following directly from the rulebook) that the robot will be inspected in the normal configuration (powered, disabled), and the inspectors' need to perform a safe inspection.

If some aspect of a robot is designed to comply with the size limits only when powered (i.e. in normal configuration), and it can be inspected safely while in this state, then there's no need to categorically insist that this particular robot be unpowered during inspection. But by the same token, if the inspector cannot safely perform an inspection while this particular robot is powered, then there's no question that he has the right to instruct the team to make their robot safe while still accurately simulating the normal configuration. (For many robots, an accurate simulation of normal configuration could be achieved with power off, pneumatics discharged, and springs at rest position—they're not the ones I'm concerned about.)

The exact steps necessary to achieve this will vary from robot to robot, but might, for example, include disconnecting the cRIO and all nonessential circuit breakers, while still allowing the custom circuit to remain powered. That's totally reasonable for something like a lifting hook that is retained electromagnetically, but which doesn't pose much of a risk. That's not necessarily sufficient for something like an electromagnetically-retained ball kicker, because of significant amounts of energy stored in the system.

In principle, I think the safety lock system envisioned by eagle33199 would be another reasonable way to address this (obviously provided that the lockout method was adequate). The lockout doesn't have to be elaborate, just effective: for low-energy systems, it might be a zip tie in place of an electromagnet, for higher-energy systems, it might be a well-placed two-by-four physically stopping the kicker from reaching its outermost limit.

Re: pre-charged Pneumatics
 

Tristan,
Weight and size is performed with the bumpers off and the battery out. Inspection continues with no power until such time as the inspector reaches the "power on tests" at the end of the inspection.
As Mike has pointed out in example above, there will be mechanisms that require locking pins to transport the robot safely onto the field. I agree with his assessment. If removal of the lock cannot keep the robot within the sizing box, then it doesn't pass the test of "self-supporting" in <R90>. If the robot is prepared for a match by storing energy in one of the allowed methods in <R01> and the locking device makes handling and transport safe then as Mike has put it, it's use should be mandatory.
Again, until the GDC releases a rule governing this situation or the inspection checklist is released, this is my opinion and no one else. In training inspectors, I cannot advise them to inspect a robot powered, precharged, or predeflected until such time as there is a need to demonstrate the power on tests or the energy and travel of a moving robot mechanism as part of that inspection.

Re: pre-charged Pneumatics
 

Tristan,

Concerning electromagnets, the GDC has been slow to make a definitive, clear ruling. As Al put it, what follows is my personal viewpoint...

A very popular electric solenoid actuator is a hinged clapper design. This is a ferrous core electromagnet with a spring loaded ferrous plate hinged at one end. Applying power to the electromagnet causes the plate to clap to the magnet and deflects the spring. When the EM is de-energized, the spring moves the clapper away from the EM.

Electric solenoid actuators are not allowed as per <R53>.

Many of the designs I have read about sound like the team has made their own ESA and are calling it a magnetic lock. This would not be allowed under this year's rules.

Concerning powered up robots. Al is 100% correct. The beginning of the inspection process is done with the battery removed...

My last point is safety. The idea that unpowering a robot, intentionally or unintentionally that causes a mechanism to deploy is just not safe.

Bottom line: While EMs are being allowed by the GDC, I can not envision an non-trivial, EM system that could be legally used on this year's robot.

IMHO, the GDC has dug a hole and will have to enlighten us further...

Regards,

Mike

Re: pre-charged Pneumatics
 

Let me put this another way—the issue is with this year's rules:
It is explicitly stated that size inspection takes place while in normal configuration. The most straightforward reading of "immediately before being enabled by the [FMS]" leads me to believe that they are defining normal configuration in terms of the instant before a match begins—the robot is powered, and disabled. Therefore, despite usual practice (of which I am certainly aware), and perhaps our better judgment, the 2010 rules do not specify size inspection with "the battery out".

If a team reads <R90> and constructs a mechanism that is self-supporting in normal configuration, but either non-self-supporting or outside the size limits when unpowered, and then presents it for inspection, the inspectors need to formulate an appropriate way to measure its size, while avoiding the imposition of ad hoc constraints and simultaneously maintaining a safe process.

If we leave that particular robot unpowered and unrestrained, it will fail—but these conditions are inconsistent with normal configuration. This is therefore an unacceptable basis upon which to evaluate rules compliance for that robot. (For other robots, where the unpowered configuration is clearly equivalent to the normal configuration, this is moot.)

On the other hand, if we power it and leave it unrestrained, there may be unnecessary hazards to the inspectors and bystanders. Only if the risk is minimal would this be appropriate.

If the risk of harm is too high in the previous scenario, then we must consider restraining it. If we're willing to interpret the self-supporting requirement in <R90> as a constraint on design (in other words, the robot must be able to be self-supporting in the box), rather than as a constraint on the precise process used by the inspectors, then it would be sufficient for the team to independently demonstrate self-containment, and then put it in the box with a restraint to permit it to fit and to preserve safety. (For example, a robot's kicker is known to be self-contained when in normal configuration, but requires power. However, the robot will not fit with the kicker extended. Partially retract the kicker and restrain it securely, so that it fits in the box. Check for size.)

Alternatively, if the shape of the sizing box permits it, and the robot had already demonstrated the capability to self-constrain when powered, you could simply insert the unpowered, unrestrained robot and ignore the protrusion.


Now, with regard to electromagnets: I presented that as an example of a mechanism that would require power to stay within size limits, but which did not depend on the controls being enabled. If that's indeed ruled illegal, then for the purposes of my example, we can imagine another mechanism that behaves similarly.

As an aside, I'm not convinced that that clapper mechanism is a solenoid actuator—it seems to fail the usual definition of a solenoid (an electromagnetic coil surrounding a cavity, within which there is a uniform magnetic field) or a solenoid actuator (which moves an armature linearly within the cavity). It is definitely an electromagnetic actuator—but if there was no intent to distinguish a solenoid from any other electromagnet, why use the specific term?

Similarly, with the electromagnetic locks, their geometry is totally different from a solenoid—they rely on the field outside of the coil, and do not directly drive an armature.

Re: pre-charged Pneumatics
 

You know, I think that our first Lead Inspector conference call is going to be very interesting... :rolleyes:

Re: pre-charged Pneumatics
 

When is the first Lead Inspector conference call scheduled to take place?

I'm new to FRC this year; do you usually publish notes from this conference call? Does GDC participate?

Thanks.


~

Re: pre-charged Pneumatics
 

Still waiting to hear myself...

In the past, recordings have been made and posted (albeit infrequently).

They are always welcome but, no, they have never participated in the past.

Regards,

Mike

Re: pre-charged Pneumatics
 

Let's try some real world examples and maybe that will help. I think we are all discussing kickers as being the one thing that can, will and likely must extend outside the frame perimeter. As kickers would pertain to the two second rule, teams should design their mechanisms such that if all else fails (power and air pressure), the kicker while at rest does not extend beyond the FRAME PERIMETER. The game rules have set a penalty and YELLOW CARD as the result of such a violation. As that is a risk most, if not all, teams would choose not to take, I do not foresee a reason that a robot will need to be inspected in a powered condition.

As to solenoids, even the Wiki definition includes this...
"solenoid refers to a loop of wire, often wrapped around a metallic core, which produces a magnetic field when an electric current is passed through it." This is the definition I have been taught and used for many years. In what way a designer chooses to use the magnetic field does not keep it from being a solenoid. Although the most powerful solenoids use a moving core/plunger/armature surrounded by a coil, not all implementations do. I, like you are waiting for a definition from the GDC for which we can test whether a mechanism is a solenoid or not. I would prefer to use the "moving" test as we have in the past. i.e. If in the presence or the removal of the magnetic field something (plate, plunger, rod, arm) moves then it is a solenoid. This is a simple test and easy for both inspectors and teams to recognize.
The GDC responses on the Q&A muddy the waters in my mind on their responses to electromagnets. Essentially, the relays we use and those that might be part of custom circuits are allowed under the rules but are in the strict definition, solenoids. Electromagnets are also solenoids but the GDC has excepted some if they do not violate other rules.

For those who are wondering about the Lead Inspector Phone calls... Lead Inspectors have available to them a phone conference every Monday night starting usually the week before the first week of competition and extending through each week of competition. It is during these calls that LRI's are given up to date information on things like parts availability, problems with field interaction, latest software updates and other changes that pertain to the coming week of competition. In addition, LRIs are asked to report on the competitions of the previous week so that we may all become aware of particular robot designs, software issues, and parts implementations. This is all in an effort to keep inspections as uniform as possible so that teams are judged uniformly. Please know that all inspectors at your competitions will not have all the info or be as well trained and informed as your LRI. If you question a decision by an inspector or are asked to make a major change in your robot, you have the right to ask the LRI to review the decision of that inspector. LRIs who will have up to date knowledge also work closely with the FTA's, head refs and FIRST reps at your event and together should be able to render a decision. If that fails, they also have access to FIRST staffers via phone for answers.

Re: pre-charged Pneumatics
 

That is not correct. One or more GDC members have been on almost every inspector telecon of which I am aware for the past several years. They may not loudly proclaim their presence, because it is an Inspectors Telecon not a GDC call. But they have been there.

Re: pre-charged Pneumatics
 

According to that definition transformers, inductors, loop antennas, resolvers, servo motors, and even any wire that has a loop in it anywhere on the robot would be a "solenoid".

So that can't be the definition that GDC is using.


~

Re: pre-charged Pneumatics
 

Ether,
Any transformers on the robot would be LAN isolation devices and allowed as part of the supplied control system, there are no loop antennas as the Wireless bridge has two dipole antennas and is also part of the supplied control system. Inductors and other large coils of wire as well as servos fit into the allowed motors section of the rules or are part of the supplied control system boost/buck power supplies. While loops in wire are effectively solenoids, straightening the loop will not result in a change of function nor is the magnetic field useful so these have been ignored in the past as cosmetic.

Re: pre-charged Pneumatics
 

Dave,
As you are lurking here, I would hope that the GDC is at least discussing this inspection process as it applies to sizing, "self supporting" and charged/powered/deflected inspections. I am always available for discussion.

Re: pre-charged Pneumatics
 

The prohibition is not against solenoids, but against ELECTRIC SOLENOID ACTUATORS. Solenoids might just be a coiled wire carrying current, but adding the word "actuator" makes the intent clear to me. If powering your electromagnet results in a piece of the robot moving, it breaks the rule.

Re: pre-charged Pneumatics
 

Thanks Alan, that's exactly what I though, but I could not find the words.

Re: pre-charged Pneumatics
 

I agree with the above. The GDC use of the word "solenoid" does not include any of these devices.



~

Re: pre-charged Pneumatics
 

That's probably the clearest way to state it, and seems consistent with all posts by GDC to date (as updated this morning).


~

Re: pre-charged Pneumatics
 

Another real-world example to put to the test. A team is using surgical tubing to provide all the force for their kicker - thus, when "charged", there is a lot of stored energy in the tubing. To "charge" the kicker, they use a cam driven by a motor. The assumption here is the cam is set up such that it can stop in a "fully charged" state, and by turning as little as a few degrees provide a rather explosive discharge of energy through the kicker - requiring another full revolution to become fully charged again. Note that for the kicker to be "fully charged", the robot does not need to be powered on, assuming the cam is difficult/impossible to back drive.

During play, the expectation would be that a kick would simply be a full revolution of the cam - go from fully charged, to kicking, to fully charged again. In the "default state", the code would always return it to fully charged, and within the frame perimeter, to avoid penalties and the yellow card mentioned for the 2-second rule. This is a relatively stable system - the kicker can return inside the frame quickly, and while not in use will remain there should power be lost on the robot. (of course, if power is lost the the half second immediately following a discharge, the kicker may remain outside the frame, but this would be a rather exceptional circumstance)

To be in compliance with the rules, such a robot would have to arrive on the field "fully charged" - carrying it as such would not be safe without redundant safety measures to ensure it couldn't fire if the cam was jostled too much, and hopefully EVERY team with such a system would have safety devices in place.

For inspection, the sizing portion would have to be done in this "fully charged" configuration. During such an inspection, would the inspectors permit (or hopefully require) the safety mechanisms to be in place during sizing? Would they allow them to be removed after the robot was placed on the scale (but before the weight reading was taken)? Depending on robot design, such safety mechanisms may have to be fairly significant (fairly large weight) if, for example, a simple pin (fairly lightweight) can't be used due to access restrictions from other parts. The addition of a single pound of safety equipment on the robot may be enough to put teams over the limit.

Please note - the concern here isn't over safety (the assumption is all proper actions have been taken to ensure the device is safe when being handled), it's not over penalties or the 2-second rule, and it's not over the actual operation of the robot on the field. It is simply in ensure that teams can be safely inspected while having a consistent understanding of what can and cannot be done while weighing and sizing the robot.

Re: pre-charged Pneumatics
 

Eagle,

Unless you want to post your question to the GDC, we inspectors will not have a definitive answer for quite a while.

Let me suggest this: Volunteer to be an inspector at your regional (they always need more volunteers).

Furthermore, volunteer to work the sizing box and scale.

You need to process 60 robots in just a couple of hours (everyone waits until the last minute) and 30 to 40% will require multiple trips to your station...

Keep in mind it's not just you. it's 60 teams of students that are putting the robot into the box and onto the scale. One of them might include your son or daughter...

Now, what would you feel comfortable with?

Regards,

Mike

Re: pre-charged Pneumatics
 

Eagle,
It would seem that a simple application of surgical tubing in front of the kicker in your example would prevent it from extending beyond the FRAME PERIMETER and still allow sizing with the kicker in the fired (non-deflected) state. This is the requirement we used in your first year although only one or two robots used a system like this in Minnesota that year. As I remember it was one of the Cat teams who had discussed this with me prior to the regional and had it corrected by the time they were inspected. This is also an excellent example of Mike's previous post about needing a locking pin to hold the mechanism in place while moving the robot to the field. Although for the life of me, I cannot see a good reason that a team would need to pre charge this device before a match begins unless it takes many seconds to charge. The safety to students and field personnel in the event of an accidental discharge staggers the imagination.

Re: pre-charged Pneumatics
 

Robots hanging from the tower at the end of a match may have their undersides exposed. Safety must extend inside the frame perimeter as well.

Just my 2cents.


~

Re: pre-charged Pneumatics
 

The surgical tubing would simple be holding the kicker inside the frame, it should not need any unsafe deflection to do so.

Re: pre-charged Pneumatics
 

I believe the point was that the danger of an accidentally fired kicker is not restricted to whether or not it leaves the frame perimeter. During removal of the robot from the tower hands may be placed inside the frame perimeter and within danger of a moving kicker device.

I believe this example helps prove the superior safety of a rigid restraint as suggested by eagle33199.

I also fail to see how surgical tubing can restrain a kicker within the frame perimeter without compromising the energy being imparted in the portion of the kick taking place between the edge of the frame perimeter and the edge of the bumper perimeter.

If a rigid restraint system (locking pin, harness, etc.) is recommended when transporting the robot, it would seem to me that it would also be prudent to keep this safety system in place for as much of the inspection process as possible, including during the jostling as the robot is inserted into, and removed from, the sizing box. As long as the device can be shown to remain inside the frame perimeter with the device removed (while not being jostled and while everyone is clear of the kicker) there should be no rules issues here.

Removing such a device for weighing should also fall well within the rules as it is not part of the robot when the robot is in the NORMAL CONFIGURATION on the field.

Re: pre-charged Pneumatics
 

Kevin,
I was addressing the fear that a kicker that is not in firing position would fall outside the frame perimeter during inspection. A small piece of tubing would suffice for that purpose.

Re: pre-charged Pneumatics
 

<<A small piece of tubing would suffice for that purpose>>


Many teams are using surgical tubing for kicking. After kicking, they require substantial force to retract.



~

Re: pre-charged Pneumatics
 

We don't know that yet.

Re: pre-charged Pneumatics
 

Yeah, we do know that. We've seen the videos. Our own design is probably going to work this way. We are going to try our best to keep it inside the frame perimeter at all times, for various reasons. We'll see if we can get the distance we want from it that way....

Re: pre-charged Pneumatics
 

Our design will likely work this way as well. We will also be testing the "inside the Frame Perimeter" version, but we expect we will be going with a version that does utilize the 2 second exception. It will need to be in a partially retracted position for inspection and the start of each match.

A piece of surgical tubing strong enough to restrain the device inside the frame perimeter would slow the kicker down as soon as it reached the frame perimeter, negating the purpose of the extra 3" of travel (as soon as the kicker slows due to a force not part of the collision the ball will be traveling faster and lose contact).

We are making every effort to make this partially retracted state safe, including using a robust latch, but barring circumstances where we are forced to do otherwise we will have a separate safety device restraining the kicker when it is in this position and the robot is anywhere but it's starting position on the field.

It would be preferable to have this safety device in place when sizing the robot, but if that is not we will do what we can to make sure the process is as safe as possible.

Re: pre-charged Pneumatics
 

Ok Jim,
Using your robot as an example, what happens to the kicker when your tubing is not stretched? Does gravity affect it's position? Is it firmly held outside of the frame perimeter even though the tubing is not stretched? If all systems fail on your robot (a hard hit causes your battery to become dislodged and it breaks off a pneumatic fitting), what happens to the kicker? Same scenario but the kicker was not yet in a position to fire?

Re: pre-charged Pneumatics
 

The tubing is always stretched, in the "just fired" position there is a lot of tension on the tubing, pulling the kicker forward.

No.

The current designs have the kicker firmly prevented from moving outside the frame perimeter, because it hits the frame and stops.

That is a good question, we can't answer it because we dont' have the firing system all designed and built. A good answer might be to design it so that it can't fire accidently under circumstances like this, and that is what we're trying to do.

Re: pre-charged Pneumatics
 

I would like to propose another hypothetical: A team's kicking mechanism uses a winch to pull back an arm connected to a torsion spring. To fire, the winch motor is mechanically disconnected (with a dog gear or the like), and the wire allowed to unwind freely. A mechanical stopping device prevents the arm from extending past bumper perimeter. The winch motor does not allow for backdrive.

In this case, the winch must be at least partially winded to fit in the box, but it may do so without power, and it is thus self-supporting. Would this be considered safe for inspection if it was only winded enough to fit in the box? What kind of safety devices should be used with this design, if the intention is to pre-load it before a match?

Re: pre-charged Pneumatics
 

Nadav,
I don't have any direction from the GDC to answer your question at this point. I would have to examine it before I would make a decision to put my hands inside while inspecting.
Jim,
I have considered that some teams would have a design likes yours as well. However, the tension supplied by the tubing at rest, holds the kicker in position against a mechanical stop and it can't be fired from that point. (No threat to human safety should something fail except the damage that would occur if the tubing let go.) If the end of the kicker is inside the FRAME PERIMETER then effectively the robot fits the parameters we have been discussing. If you had answered that the kicker had to be in the firing position to fit inside the box, then Mike Betts and I are in agreement I think, that the robot doesn't fit the criteria of unsupported sizing. I expect that teams are considering the same design criteria as you and coming to the same crossroads. Your answers are encouraging, thank you.

Re: pre-charged Pneumatics
 

hey all
Just have some questions about a latex tube + 1.5" bore cylinder kicker...
we have protoyped it and it seems like a nice and easy mechanism. However it only gets about 10' @ 50psi. we are using a peice of angle alum. to hit the ball, and its doesnt look promising. we found the falcon guys demo video, and it looks very similar, but no where near there results. what can we do to precharge or help a fast release. we have a gate latch, fresh latex tubing, bearing mounts... doesnt seem very active.
any thoughts are appreciated.

Re: pre-charged Pneumatics
 

If you are concerned then it seems to me that you can bring velcro straps with you to the sizing so the robot will be in the "box" as it will be when you are on the field and charged. The difference is that you will not be charged. These can be on the robot for weighing as they weigh nothing.

I have seen too many teams not do something because they were afraid. I say read the rules, have a good argumnet why it is allowed but push the envelope.

Re: pre-charged Pneumatics
 

If you could post a close-up video or series of pictures of your prototype it might expedite the process of understanding what you're doing and result in more focused responses.

~

Re: pre-charged Pneumatics
 

As requested by Mike, we posted the question t the GDC and, i believe, inspired part of update 7 :)

I believe this is exactly the type of guidance the inspectors (and teams!) were asking for in this thread. Inspection takes placed powered down, however if your design requires power to conform to the volume rules, and you have sufficient safety mechanisms in place, then you can be sized in a powered on state, or with significant amounts of stored energy.

This makes designs that have been discussed here legal (where in a powered down state a mechanism would extend past the FRAME PERIMETER) for th purposes of inspection.

However, i would beg ALL TEAMS to show up at inspection fully prepared and ready. If your robot requires power for sizing, tell the inspectors about it first, and demonstrate your safety mechanism before heading over to the sizing box. We all know how crazy it can get when an understaffed inspection team is trying to get all the teams signed off to play - It's up to us to make their job as easy as possible, especially when rule conditions like those discussed here pose potential issues that will slow the process down.