It seems like every time I meet with someone or talk with someone about the mini bot they have 3 stock questions/comments.
Everyone on CD says they can do it in 1.5 seconds, how are we supposed to compete with that?
2.How do we deploy it?
and this threads topic
3.How do we get it down?
I’ve been wondering this and the way we designed our mini bot, and the common theme I see with many, it would not be good to just reverse the motors, seeing it would just shoot down at over 32.2ft/s^2. While pondering this I was thinking
-Well why don’t I just climb the pole and get it, well cause a few hundred people would yell at me for not being safe and wouldn’t let me do it again.
-How about shaking the pole, same reason as not reversing the motors except this time it won’t have such a predictable landing spot.
-Next was the giant pool skimmer idea, why not get a long pole with a net on the end, cause there’s got to be a better way (although still plausible)
My final thought and question to you now is, why not just tip the tower over. Looking at the design of the tower it is connected to the field with just velcro, so are we allowed to just tip the pole over?
You don’t just tip something that’s attached to carpet with industrial strength velcro. Trust me on this–I’ve done a little too much field setup/teardown. If you’re lucky it’s not on a base plate that is covered with carpet too–and that’s just the setup I’d suspect.
Besides risks of damage and all that.
What if the motors could simply be stopped and allowed to be backdriven? Maybe with a slight loosening of pole clamps. This would allow gravity to take over, but in a (mostly) controlled manner.
How about a long pole with a fork on the end that fits around the pole? Put it above the minibot and pull down until it’s within range of your tallest drive team member.
Eric,
Doesn’t look like T25 allows us to bring “special equipment” to retrieve our minibots from the pole:
<T25> The only equipment that may be brought on to the ARENA is the OPERATOR CONSOLE,
reasonable decorative items, and special clothing and/or equipment required due to a
disability. Other items, particularly those intended to provide a competitive advantage for
the TEAM, are prohibited.
Granted, I don’t see what competitive advantage a pole to retrieve a robot provides:confused:
There is a way to get around it: make the device part of the robot or the operator console. (Obviously the robot isn’t “equipment”, because if it were, you couldn’t bring it on the field; the console is equipment, but exempt.)
The part can be detachable, if you like. What’s more, you arguably don’t even have to have it attached to the rest of the robot during the match—its a modular component that you chose not to install during gameplay. (Just make sure to get it inspected as necessary; it would count toward weight.)
(Making it part of the robot is a standard solution to having an alignment device. In that case, it’s a bit of a grey area whether those can be non-installed parts of the robot at the time of use. In this case, given the relative lack of ways to penalize you for it—because use occurs after the match—it’s pretty much moot. Note that “moot” is distinct from “strictly legal”…)
An alternative is to ask the Q&A; they’ll probably end up amending the rules to allow unpowered retrieval devices anyway.
Our team and many others last year used special “tools” to get our robots down once they hung. We had two fairly large “U” shaped hooks that we would slide into our hooks to release our robot. This was never questioned by anyone, and we actually receieved many compliments for thinking ahead and creating the tools.
Obviously the standard disclaimer of “last year’s rules don’t apply to this year” also fits here, but that is just an anecdote of a similar situation from previous games.
Personally, I think having a team bring some kind of device to get it down that the mini bot and device are both designed to do together is a lot easier to deal with than having to rip down minibots with whatever device FIRST is going to use. Even with an extremely well designed minibot and retrieval method, things can go wrong that may cause your minibot to be stuck.
Sounds to me like the GDC should be asked about this to get some clarification.
Technically, by that wording of <T25>, tools to discharge a pneumatic mechanism and/or pick up a robot are illegal as well; yet I haven’t seen a single judge or referee ever say anything about them. Particularly, Curved T-handle hooks are used by a few teams to pick the robot up. Usually these items are in the best interest of safety, and the only ‘competitive’ advantage they provide are allowing the drivers to safely retrieve game pieces and/or lift the robot without straining their back, in order to stay healthy for future matches.
It will be interesting to see the implications of enforcing <T25> as worded.
But the challenge is how do you get it to come down at a reasonable speed if you are not using the NXT to reverse and lower the motor speed used to climb the tower because you are using the lightest, bare bones design for the climb and if you are geared such that you aren’t going to backdrive with gravity’s help? Assuming you have found that such ratios that allow backdrive increase likelihoold of stall conditions for the climb…
Note that the total weight of the ROBOT, MINIBOT, BUMPERS, and battery may approach 165 pounds. Please think carefully about lifting the weight safely. Teams are encouraged to use their forth TEAM member (typically in charge of the ROBOT cart) to carry the MINIBOT on to the FIELD separately. Teams are also encouraged to think about handles or lifting bars to aid in lifting and carrying the ROBOT.
Now it doesn’t say, one way or another, whether those are removable lifting bars or handles. But as has been noted, separate carrying devices have been used in the past.
<G07> Items other than the ROBOTS and the GAME PIECES shall not be placed on the FIELD prior to or during the MATCH. Violation: PENALTY and YELLOW CARD
… says nothing about after the match.
I’m not sure how this works with <T25> - someone will have to ask.
If there is one thing I have learned in my seven years of FRC, is that what works with one robot on the practice field rarely works as smoothly when you have six robots crammed on to a playing field.
As for getting it back down, the easiest would seem to be to either have the motors turn off (a switch or a fuse, perhaps) and then let it backdrive down.
Have the minibot have an ejection system with a parachute. Its safe and its cool to have the bot just float down by itself.
Now I am not an EE major or anything; but can’t you use resistors to restrict the flow of electrons to the robot? So less electrons flow through, the slower it goes. Isn’t that how it works?
What about a diode that would connect the two poles of the motor together when it’s moving backward and not do anything when it’s forward?
Like… put the anode on the end where the 12V is applied and the cathode on the end where the GND is. That would reverse the diode when power was applied, but when the power was shut off and the motor started generating power, it would go through the diode and act as a brake.
Now if we build our own diodes out of some sort of electromagnet, is it legal?
