Team 319 - Single Mechanism Collect and Throw

Any thoughts?

This is pretty clever.

I don’t know how simple it is if it needs a 5 minute video to explain and involves concentric shafts and more than one ratchet. :slight_smile:

Thanks for the videos, I really hopes this works well for you, as this is definitely a unique mechanism.

It’s an interesting idea, the one thing that I would be worried about would be the springs. They are legal, but we purposely avoided them because we knew safety inspectors wouldn’t really like them.

This is an awesome idea. I can’t believe I didn’t come up this idea when designing. It’s so simple yet so effective!

could you explain that please?

Neat idea. I remember a similar concept used by 1276 back in 2008.

One thing I remember from watching that robot was how is the shooter was influenced by movements of the drivebase. Throw your prototype on a robot and see what happens when you shoot while driving. You may not want to shoot while driving but what will happen when you shoot and someone hits you?

Just some ideas to consider.

This is at least what my mentors told me. Using a spring is fine by the standards of the rules, but they’re not necessarily liked by safety inspectors, depending on the size. Small ones are fine, but when you get large and strong springs it becomes questionable.

We used them back in 2010 and had no problems.

How large and strong were they?

You’re right insofar as more stored energy invites a more detailed inspection. However, the burden of proof is always on your team to demonstrate to your inspectors that your design is safe. If you can design within this constraint, you can use any size spring you want.

Exactly, I agree. We just do our best to stay away from springs because we know that it will bring on a more detailed inspection, like you said.

This is the best photo I could find showing the size of springs we used. They were pretty huge. At full stroke, we could kick the ball the length of the field and hit the mid-point of the alliance station back in 2010.

https://scontent-a-atl.xx.fbcdn.net/hphotos-ash2/736957_190304664449042_2063546056_o.jpg

Like Nate said, design your robot to be safe. Inspectors will not allow unsafe robots to pass inspection when it comes to those robot mechanisms that require the inspectors opinion to pass. If you can demonstrate the system is safe, reliable, and will not dry fire when bumped/touched you should be just fine. Make sure you can release the stored energy when you need to and when your robot is chilling in your pit, que line, or really anywhere you don’t need to launch a ball don’t keep energy in the system.

We intend that our shooter can have the energy released quickly, safely from the system, and could even start the match without stored energy/tensioned springs.

I think we are planning on using the Surgical Tubing that was supplied in the KOP.
Interesting thought about shooting while robot is moving. I am looking forward to putting it on a bot and testing it.

The discussion in this thread has me slightly worried, not about our design, but about the standard of “safe” varying between inspectors and between events. We’ve seen this in the past with things like chain guards or spinning wheel guards.

Is there a universal standard that can be set for the burden of proof that a mechanism is safe? Is it simply “make sure a positive action is needed to fire, and there is no chance of misfire” ? That’s good enough for me.

What I would not want to happen is for a mechanism to be deemed illegal when an inspector’s opinion is that it is not safe. That’s not a good way to go about this. Thoughts?

Well when we had springs on our robot all we had to prove was that it was securely fashioned to the robot and that we had a steel wire running through it so that if it did unhook it wouldnt go flinging anywhere.

Have you not run into this in any prior year? I’ve put extra shields on mechanisms to have an inspector call the robot safe multiple times. The worst is when a different inspector comes over to do the final check off and says, “That really wasn’t necessary, why’d you waste an hour doing that?”

With our single mechanism collect and throw, we had lots of problems with throwing chain and having a closed loop control law to hold the arm up. I’d be curious to know how you’re going about collection, especially since the ratchet will only let you go one way. Our control law had a “home” collect position, and the driver could control the position from there with joystick inputs.

We’ve passed at our regional with no problems, ever. Our robots were safe, and we weren’t really questioned about safety stuff by our inspector. Then, while we were in St. Louis, the inspector failed to pass our ball kicker because he thought “the engineering behind it wasn’t good” and that it would “fail after the first kick” due to “extremely poor design” and that our team could “seriously injure somebody with our ignorance”. So, we waited, got inspected by somebody else, and passed. When we told the ref that the kicker had been used in >40 matches already, he refused to believe us.

We’ve seen teams get passed with a motor at least twice the diameter of a CIM, and we’ve seen teams fail because their battery is too close the the air tank (??).

tl;dr Inspectors are usually great, but sometimes, you can get screwed.

They key take away should be… pay attention to safety while building the robot! If I inspect two nearly identical robots, I’ll be more likely to pass the one that has shielding and safety locks on their high-energy mechanisms than the one that doesn’t.

With this particular game and the robot designs we’ve seen, I’ll be looking for a couple of things from teams regarding safety. First, think about how things are when you pick up the robot. I want to see some protection so a spring or tubing doesn’t break when your face is a half inch away. I want to see some assurance that the catapult/kicker/other launching device isn’t going to spontaneously trigger and bash someone holding the robot over the head.

And please everyone remember… if you feel an inspector is being too rough on you, politely ask them for a second opinion from the LRI. I can guarantee you that the LRI’s are only concerned about three things, listed in priority order: That everyone plays, that they do so safely, and that they do so in compliance with the rules. We try really hard to make sure that everyone passes inspection and has their robot in the best shape possible before they reach their first match. But we need your help to do so - both at the competition and now, during the build season!