Ending The Round Loaded

[Willyspu]

Since many of teams are building catapults with fairly high powered and dangerous ball launchers with lots of surgical tubing etc. what safety precautions are your teams taking if your robot ends a round while your catapult is pulled back in the "cocked" or "loaded" position?

We are looking are making a safety device or clamp for our team to restrain the catapult if it ends loaded at the end of the round.

Is your team working on something to make it safe to move your robot if your robot ends a round with the launcher ready to fire?

[Joe G.]

Single acting pneumatic solenoids can be used to trigger safe settings as power is cut.

[IVAN]

if you are using the ratcheting gearbox concept the back side of a hammer does a good job of pulling out the shifter block on the andy's

[Nuttyman54]

In addition to the built-in safety features on the robot, we'll be clipping carabiners through parts of the shooter and the shooter frame to lock it out during transport and storage.

[Gregor]

Single acting pneumatic solenoids can be used to trigger safe settings as power is cut.

So your shooter fires every time you disable or cut power? That's hardly safe in the pits, or when testing.

[raptaconehs]

So your shooter fires every time you disable or cut power? That's hardly safe in the pits, or when testing.

Actually a single acting pneumatic piston will only fire on command. There is a spring that will force the piston back down to a resting position after each shot.

[Joe G.]

So your shooter fires every time you disable or cut power? That's hardly safe in the pits, or when testing.

No, should have clarified. It relieves the system of any built up tension when power is cut, rather than actually firing. Auto-fire on disable would be unsafe for a number of reasons.

[apalrd]

We have a few safety features, both in software and hardware. Most of these aren't unique to this year.

Software:

-We have incrementally (over the past few years) adding 'ok to actuate' (OKTA) signals in addition to the command signals for actuators. This year we've added them for all solenoids. Part of the output layer (in code) takes a boolean position for the solenoid and a boolean OKTA for the solenoid, and then the output layer takes care of dual vs single coil, safe states during OKTA, and polarity inversion.

-We also added OKTA signals for several control loops this year. A negative setpoint (since all of our setpoints are in the positive region) will trigger the control loop to hold the integrator in reset and hold the output to 0.

-We have a boolean signal in code called 'reinit' which is triggered every time we exit disabled mode, and it forces all the code into a 'safe' state. All of the state machines to go a 'default' or 'manual' state which sets all of the actuators to 'not OKTA'. The user must command another state for the actuators to go OKTA (usually all of them commanded by that system go OKTA at once, which is acceptable to us).
--For this year, we used several dual-coil solenoids vs single-coil solenoids for safety reasons as we did not want actuators moving when we disabled the robot. We also used a single-coil solenoid for similar reasons.

Hardware:

-We are planning on building a metal bar with features which latches between parts of the robot, preventing it from firing. This would be removed when the robot is set on the field

-We will release the stored energy between competitions and overnight.

[Willyspu]

In addition to the built-in safety features on the robot, we'll be clipping carabiners through parts of the shooter and the shooter frame to lock it out during transport and storage.

This sounds like a great idea especially for the team members that need to quickly (and) safely retrieve a loaded and ready to fire robot from the playing field!

Jim

[MrBasse]

We designed a catapult that can only fire when the robot is active. When disabled the stored energy (compressed air) simply vents to atmosphere. The same thin happens when we are active too. If we decide not to shoot, the system will vent and release all tension in the entire mechanism. The only time pressure is stored in the shooter is when the operator holds down the trigger.

[bowmanb]

We've also incorporated locking pins in our mechanism with big red "REMOVE BEFORE FLIGHT" streamers attached.