Stored Energy Devices?

[K.Porter]

Since the Q&As aren't open yet, I'm turning to you all for an opinion here.

My team has been contemplating building a slingshot or other projectile device to hurdle the track balls, using springs or bungees, or similar. I know that the FIRST rules don't specifically prohibit this, and in regards to stored energy devices FIRST states simply that teams "must be very careful" when installing springs, etc.
Since the track balls are very heavy, it would take a rather large slingshot to get them moving at any real speed, and while I'm confident that we could design such a device, I'm not so sure how the FIRST judges would react.
For teams that have used stored energy in springs or similar previously, has anyone had trouble with the judging? And I suppose for those of you who have been at this longer than I have, do you think such a large slingshot idea should be cause for concern?

Thanks.

[DonRotolo]

This is an opinion.

Any stored energy device is OK, as long as the team has clearly understood the risks inherent with it and taken actions to reduce that risk to an acceptable level.

For example, let's say you decided to use a car's suspension spring (very powerful, somewhat dangerous). But, the spring itself was enclosed by some structure that kept people away from it, there was a safety wire (in case the spring fractured, the pieces would be contained), there was little chance for people to get anywhere near it when it was 'loaded', and the release catch was very secure (no accidental firings), then it would probably pass OK.

The key phrase here is "Is it safe?". That's what they mean by close inspection, and what they'll be looking at.

Don

[Laaba 80]

One of our mentors said that the stored energy may not be released faster than it is created. I'm not sure if this is a FIRST rule, or a team rule. That may be something to look into.
Joey

[David Brinza]

As an inspector, beside evaluating the intended function of the the mechanism, I would carefully consider whether unintentional release of this energy could pose a risk to members of the team, others in the pits and on the field. "Arming" mechanisms, mechanical inhibits will need to be demonstrated to prove that someone not familiar with the robot couldn't accidentally trigger the release of energy and cause harm.

[ebarker]

Originally Posted by Laaba 80

One of our mentors said that the stored energy may not be released faster than it is created. I'm not sure if this is a FIRST rule, or a team rule. That may be something to look into.
Joey

You are guaranteed to use electricity way faster than it got stored in the battery. So therefore this 'rule' can't be true.

[Darunada]

If you're using a spring or such, I would run a cable through the middle if possible to prevent it from going flying. If pulling it back, I would have a ratcheting safety device to prevent it from firing prematurely...

A pin to prevent it from shooting (and perhaps locking the ratchet) if for whatever reason you have it compressed while it shouldn't be is a good idea, too. ;D

[Al Skierkiewicz]

The overriding rule in this case lies in the robot section as follows...
<R01> Energy used by FIRST Robotics Competition ROBOTS, (i.e., stored at the start of a
MATCH), shall come only from the following sources:
• Electrical energy derived from the onboard 12V and 7.2V batteries
• Compressed air stored in the pneumatic system, stored at a maximum pressure of 120 PSI
in no more than four Clippard Instruments tanks. Extraneous lengths of pneumatic tubing
shall not be used to increase the storage capacity of the air storage system.
• A change in the altitude of the ROBOT center of gravity.
• Storage achieved by deformation of ROBOT parts. Teams must be very careful when
incorporating springs or other items to store energy on their ROBOT by means of part or
material deformation. A ROBOT may be rejected at inspection if, in the judgment of the
inspector, such items are unsafe.

This must first be asked on the Q&A for a correct interpretation and will likely be addressed by each inspector that evaluates your robot. At this point in the build, you may very well find an alternative method in the next few days. Prototype like mad and build with experience.