How to get the mini bot down

[Joe Ross]

The GDC already ruled that a small step ladder violated <T25> http://forums.usfirst.org/showthread.php?t=16331

Originally Posted by JB987

Granted, I don't see what competitive advantage a pole to retrieve a robot provides

It keeps your minibot from being destroyed by Dean's chainsaw, which is a big competitive advantage in future matches.

[JesseK]

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.

[Mike Betts]

The real alternative is to design your minibot to come down autonomously as it's last action so that it is at the bottom when you go to retrieve it...

[JB987]

Originally Posted by Mike Betts

The real alternative is to design your minibot to come down autonomously as it's last action so that it is at the bottom when you go to retrieve it...

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...

[Jared Russell]

Our Victors have brake and coast modes. No reason you can't make a minibot have a "brake" mode too!

[Mike Betts]

Originally Posted by Jared341

Our Victors have brake and coast modes. No reason you can't make a minibot have a "brake" mode too!

Indeed...

[GaryVoshol]

<R11>, blue box:

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.

[Bob Steele]

I asked the question in Q and A today.

1. Is a pole legal to bring on the field to help retrieve the minibot.

2. If the pole is part of the robot and detached at the end of the match can it be used to retrieve the minibot?

3. If the pole is part of the drive console and is detached at the end of the match can it be used to retrieve the minibot.

I also mentioned that this is a safety issue and that this device would not give a competitive edge to any team.

It will be interesting to see what they say.
I personally don't know how they can no to either 2 or 3 and then it will be pretty silly to say no to 1...

We will see

B

[JB987]

Thanks, Bob! I look forward to seeing a common sense reply from the GDC soon...

[davidthefat]

Have the minibot have an ejection system with a parachute. Its safe and its cool to have the bot just float down by itself.

Originally Posted by JB987

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...

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?

[JB987]

Resistors would indeed reduce the flow of electrons...trouble is I don't see resistors listed in R92 that details what can be a part of the minibot.

[WizenedEE]

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?

[Jared Russell]

Even without a resistor, you can just shunt the + and - leads of the motors together to use the internal resistance of the motor itself as your brake.

Try spinning the shaft of a CIM with the leads disconnected from everything. Then connect the two leads together, and try again.