Ball eject

[Woolly]

Originally Posted by redneckrobot

that is the programmers job

I for one think that robots moving without connection to the driver station constitutes a safety issue, as does FIRST. This is why the base robot project shipped with your choice of programming language tends to make the robot refuse to do anything without connection to the driver station, and a signal that it is in teleop or autonomous mode.

[wireties]

Originally Posted by Woolly

I for one think that robots moving without connection to the driver station constitutes a safety issue, as does FIRST. This is why the base robot project shipped with your choice of programming language tends to make the robot refuse to do anything without connection to the driver station, and a signal that it is in teleop or autonomous mode.

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?

[Bryan Herbst]

Originally Posted by redneckrobot

that is the programmers job

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.

[yash101]

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!

[atucker4072]

Originally Posted by yash101

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!

There is no secret endgame. End of discussion.

[Dalrik]

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.

[RRLedford]

Originally Posted by Dalrik

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.

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

[Kevin Selavko]

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.

[yash101]

I really think that this is something not clearly written in the manual. Either the ball will be freed, a new ball will be entered or the alliance will only be able to defend the rest of the match!

[Libby K]

Originally Posted by yash101

I really think that this is something not clearly written in the manual. Either the ball will be freed, a new ball will be entered or the alliance will only be able to defend the rest of the match!

Or, teams will just have to make sure that being able to eject the ball is a priority. If you can't get rid of the ball, then you're going to seriously mess up the match.

There are some thoughts on that (especially for Team Copioli's posts) on the Build Blitz blog here:http://www.buildblitz.com/blog/

[atucker4072]

Originally Posted by Libby K

Or, teams will just have to make sure that being able to eject the ball is a priority. If you can't get rid of the ball, then you're going to seriously mess up the match.

There are some thoughts on that (especially for Team Copioli's posts) on the Build Blitz blog here:http://www.buildblitz.com/blog/

Thanks for the link!

[AllyMeeg]

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.