2011 Minibot electronics

[Jon236]

Originally Posted by rtfgnow

You can have your one way trip, I don't want the field reset team to pull out a shotgun to get our minibot down.

I meant one-way powered......after contact with the sensor, the 1/2 bridge is turned 'off' and the mini coasts downward.

[Jon236]

Originally Posted by EricVanWyk

Is it legal to have a tether wire between the robot and the minibot? Wires are allowed in R92X, but I'm not clear whether or not the sizing box in R91 precludes them.

While only the GDC can say for sure, I am assuming that tethers would be illegal because of the 12x12x12 sizing box requirement and by the usual no-entanglement rules.

[Al Skierkiewicz]

Erik,
From Section 1
MINIBOT – an autonomous vehicle designed and built to perform specific tasks when competing in the 2011 competition LogoMotion. The MINIBOT must obviously follow a design approach intended to play the 2011 FRC END GAME and must be compliant with all MINIBOT rules defined in Section 3.4.14.

And from Section 1.5
The match ends with robots deploying minibots, small electro-mechanical assemblies that are independent of the host robot, onto vertical poles.

I read those two references as not tethered. The Q&A will be the only place to get an official answer on this question.

[EricVanWyk]

Originally Posted by Al Skierkiewicz

Eric,
...
I read those two references as not tethered. The Q&A will be the only place to get an official answer on this question.

Thanks Al

After reading those sections, I agree with your interpretation.

[Tom Line]

Originally Posted by JohnHorton

Well, a 9v regulator would work, but that isn't listed on the components allowed.I find it kind of odd they don't allow basic electronics (resistors, caps, etc.) for the minibot. Correct me if I'm wrong.

I think a simple DC loop of Battery - Lightswitch - motor(s) - back again might be the best, as far as electronics go.

I believe their assumption was that if you are using the NXT, it drives a PWM signal out (at least, I believe that's how it drives the servo motors used in FLL). You would use that to send the duty cycle to a motor controller which in turn would actually use the 12V battery to power the motors.

[ptan]

Originally Posted by Tom Line

I believe their assumption was that if you are using the NXT, it drives a PWM signal out (at least, I believe that's how it drives the servo motors used in FLL). You would use that to send the duty cycle to a motor controller which in turn would actually use the 12V battery to power the motors.

The allowed Tetrix motors are ordinary DC motors. You can power them directly from the 12V battery through a light switch if you wanted.

In FTC, the NXT connects to the HiTechnic motor controller which converts the I2C from the NXT brick to control an HBridge powering the DC Tetrix motors.

[JohnHorton]

Originally Posted by Jon236

Maybe it's time to teach the students how to make a speed controller (1/2 H-bridge....since all we want is a one-way trip (powered, at least!))

That begs the question, can we fab our own parts? I'd love to skip the NXT controller and just build an H bridge run by a flip-flop. State 0 on it would be triggered by the "launch" command from the hostbot, sending the motor forward and State 1 would be triggered by a switch on top, when the minibot hits the target, reversing the motor so that Dean Kamen won't go after my bot with a pole saw.

However, they don't list discrete components on the list. I guess that's something for the Q&A.

[DonRotolo]

Originally Posted by JohnHorton

However, they don't list discrete components on the list. I guess that's something for the Q&A.

My interpretation is, if it is not on the list, it is not allowed.

Originally Posted by JohnHorton

so that Dean Kamen won't go after my bot with a pole saw.

Well, since you can bring any number of minibots to competition, just bring one per match and let THEM figure out where to apply the pole saw! (Just kidding, of course. <G59> covers it).

Originally Posted by Al Skierkiewicz

I read those two references as not tethered.

<G22> HOSTBOTS may not contact their ALLIANCE’S MINIBOT once it has climbed above the DEPLOYMENT LINE.

I read <G22> as not tethered as well.

[PAR_WIG1350]

Originally Posted by Jon236

While only the GDC can say for sure, I am assuming that tethers would be illegal because of the 12x12x12 sizing box requirement and by the usual no-entanglement rules.

Oh dear, tape measures

[Al Skierkiewicz]

<R92> The following items are the only permitted materials for use on the MINIBOTS:
A. TETRIX components,
B. no more than two motors (PN W739083),
C. exactly one 12V rechargeable NiMH battery pack identical to those supplied in the FTC kit of parts (PN W739057)
D. No more than one HiTechnic DC motor controllers,
E. No more than one NXT controller with the Bluetooth functionality disabled,

The motor controllers are driven from the NXT outputs.

[Bruceb]

Again what do you all think. R92 d sayes exactly 1 battery pack. Do you think that means we HAVE TO HAVE a battery??
Bruce

[Jon236]

Originally Posted by Bruceb

Again what do you all think. R92 d sayes exactly 1 battery pack. Do you think that means we HAVE TO HAVE a battery??
Bruce

Without specifying a required wiring schematic, I think that IF we want a battery, it has to be the battery they specify. But I don't read anywhere that we HAVE to have a battery.

GDC just want to make our brains hurt!

[Just a Mom]

Does anyone else find it frustrating that we must use the FTC kit to build the mini robot? There are no FTC teams near us that I know of so the only way we can do this is to buy a kit and they are already on back order.

[JohnHorton]

Originally Posted by Just a Mom

Does anyone else find it frustrating that we must use the FTC kit to build the mini robot? There are no FTC teams near us that I know of so the only way we can do this is to buy a kit and they are already on back order.

As per my understanding, you don't have to use the FTC kit, it just helps. Making the whole thing out of polycarb. or aluminium, using the 12v NiCd, and the lightswitches is possible, and a lot simpler than using the NXT and co.

[Travis Hoffman]

Originally Posted by Just a Mom

Does anyone else find it frustrating that we must use the FTC kit to build the mini robot? There are no FTC teams near us that I know of so the only way we can do this is to buy a kit and they are already on back order.

You can obtain a free FTC kit as part of the FIRST Choice program (ala carte kit of parts items that were not handed out to all teams) on www.andymark.com.

There are 1265 sets left as of 11:45 AM this morning, 1/10/11.

Be proactive - order now.

Please see http://www.andymark.com/SearchResults.asp?Cat=245 for instructions on how to login to FIRST Choice.