Re: Ball eject
 

Well, hypothetically, if you have 2 robots that can throw, none of the robots left available to pick can catch, and one of your robots has a multi-ball autonomous, the safest pick is a box (or ramp if you want to get fancy with loading) with a good drive-train under it.

Re: Ball eject
 

This isn't possible.

The Driver's Station (and FMS) are responsible for telling the robot if it is in teleop, in autonomous, or if it has been disabled. If there is no communication with the DS/FMS, the robot cannot move. Allowing the robot to move at all (electronically) in this situation would be a huge safety issue.

I think the point of the question also goes beyond communication issues. What if the robot loses power (due to a loose wire, a battery that fell out, or something else)? What if a hit from another robot resets your cRIO?

There are a number of problems that could cause your robot to become inoperable with a ball in its grasp.

Re: Ball eject
 

This is what it should be like:
If the driver thinks the robot is jammed, either the robot is disabled by FMS, or that ball is invalidated if it ever exits the robot. That way, even if the robot is stuck, it can perform something else, like defense or if they add an endgame!

So you could try to build your robot so that it has the ability to retrieve balls from disabled robots with an arm of some kind.

Re: Ball eject
 

There is no secret endgame. End of discussion.

Re: Ball eject
 

The solution is, unfortunately, completely mechanical. The electrical and software rules and libraries expressly prohibit a disabled robot from taking any action.

What teams will have to do, one way or another, is design their collection systems such that when disabled they either release the ball or weaken their grip such that a hit from an alliance partner will dislodge it. Congratulations, you've found the difficult design challenge in this year's game. No, don't design your launchers to immediately fire if they lose power, as that's a clear violation of safety.

Re: Ball eject
 

On our vex robot our pistons default to retracted so we start in a legal configuration, but can you have a solenoid that defaults to push a piston into where you store your ball when it has no signal, and possibly have it on its own pneumatic circuit in case the first one fails? This way if you have a ball and you become disabled/battery dies/act-of-god, the ball will be ejected, or is this not allowed?

EDIT: I does not need to be very forceful, just enough to make your ball holder a shape that the ball will roll out of.

Re: Ball eject
 

Are you saying that it is illegal to have a robot with a pneumatic cylinder that, when working properly with bot powered on, gets air via a normally closed solenoid valve and extends, stretching some surgical tubing to move an element which keeps the ball from falling out of the robot.

Then when emergency stopped, the normally closed air valve closes, and a 2nd normally open valve opens to bleed air from the cylinder, allowing the the piston to retract by the surgical tubing tension, releasing the hold ball element and dropping the ball.

If this kind of ball eject scheme would be illegal by the current rules, then there should be an exception rule written to allow such a scheme, or to just have another fresh ball cycle be started from the pedestal, when robots carrying calls are disabled

-Dick Ledford

Re: Ball eject
 

In theory nothing (much) can move if the communications are down. The FIRST libraries on the robot fire a watchdog that disables all control outputs.

If a robot on my alliance went brain dead I would want them to hit the big red button - maybe the refs would put the ball back into play?

Re: Ball eject
 

A very BIG test of gracious professionalism

I'm not sure where to go with this aspect of the game.

I'm asking myself very seriously, if a robot can't automatically eject a ball when disabled, should it be allowed to intake it?

Autonomous is also very tricky - if your robot requires the ball to be inside your robot at the start of the match, and can't be easily freed by another robot, your alliance partners might ask you not to run it.

How would you feel if your alliance partners ask you never to pick up a ball? Or to not run your autonomous?

Would you ask your alliance partners not to do those things?

Because right now, this seems like the prudent thing to do.

Re: Ball eject
 

The issue is the state "Estop" is really the same as disabled. So you load the ball in the disabled state (Robot is disabled until the match starts) Nothing will happen until the robot is enabled. The coders that can make the robot magically eject the ball on system failure aren't going to be the ones with these kinds of issues.

Scouting is going to be important this year (as if it was never unimportant) because a non functioning robot in the seeding matches can really skew the scores.

This might be the year that a good defense is a good offense.

Re: Ball eject
 

It's a terrible enough feeling at a regional telling a team "Hey we need you to put this giant net on and sit there and not do what your robot was designed to do because of the nature of the game." I cannot imagine telling someone they cannot play the game in its proper form because "We don't trust your robot's design".

Heck, there are times when a team will just refuse and try it anyways and when the ball gets stuck then what do you do? The rules pertaining to this are not fair for any member of an alliance.

An E-Stopped robot with a ball most definitely should not have its ball counted. That way there's at least a way to keep playing the game for the other 2.

Re: Ball eject
 

Why wouldn't the referees consider a ball in an EStopped robot "out of play"? It's a good idea to raise this question in the Q&A, but software solutions aren't what you want when a simple human decision can solve your problem. That's what referees are for.

/Randy

Re: Ball eject
 

I would think a robot capable of taking action while disabled would be a safety hazard, violating R8.

Re: Ball eject
 

What about the robots in 2012 with the after-the-buzzer pneumatic bridge balancers?