pre-charged Pneumatics

[Ether]

Originally Posted by Al Skierkiewicz

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...

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.


~

[Al Skierkiewicz]

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

[Vikesrock]

Originally Posted by Al Skierkiewicz

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

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.

[Al Skierkiewicz]

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.

[Ether]

Originally Posted by Al Skierkiewicz

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.

<<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.



~

[Al Skierkiewicz]

Originally Posted by Ether

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

We don't know that yet.

[MrForbes]

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....

[Vikesrock]

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.

[Al Skierkiewicz]

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?

[MrForbes]

Originally Posted by Al Skierkiewicz

Ok Jim,
Using your robot as an example, what happens to the kicker when your tubing is not stretched?

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

Does gravity affect it's position?

No.

Is it firmly held outside of the frame perimeter even though the tubing is not stretched?

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

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?

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.

[Nadav Zingerman]

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?

[Al Skierkiewicz]

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.

[infocus]

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.

[pafwl]

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.