2011 Minibot electronics [Archive]

ratdude747

09-01-2011, 01:45

I think you have to use the NXT brick or hardwired switches. see 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,
F. Polycarbonate,
G. Polycarbonate glue,
If an observation is made that aQRWKHUWHDP¶V52%27PD\EHLQYLRODWLRQRIWKHUR ERW
rules, please approach FIRST officials to review the matter in question. This is an
area where Gracious Professionalism is very important© FIRST 2011 FRC Game Manual, Section 3 ± The Robot, Rev- Page 31 of 32
H. Aluminum sheet, 90° angle, uchannel, tube, bar,
I. rivets,
J. non-metallic rope or cord,
K. wire nuts,
L. cable ties,
M. limit switches,
N. no more than two common
household light switches,
O. wire of appropriate gauge (see
Rule <R40>),
P. non-slip pad,
Q. PVC or CPVC pipe,
R. PVC cement or cleaner,
S. Mechanical hardware (i.e.
screws, bolts, etc) ,
T. Loctite or similar thread-locking
product,
U. Rubber bands,
V. Surgical tubing,
W. Electrical tape and shrink tubing,
X. PWM extension cables,
Y. Universal security clips to hold
the PWM connectors together,
Z. Hook and loop fastener (may not
be used as tape), and
AA.Magnets.

my vote would be for the nxt brick...

Duncan Macdonald

09-01-2011, 01:52

If I am understanding the manual correctly, I thought I could hook up a circuit consisting of a battery, light switch, and motor? Legal by R92 because there is no more than one controller.

Al Skierkiewicz

09-01-2011, 08:04

Please check sections
4.3.14 MINIBOT
4.3.15 MINIBOT Inspection
If you use a controller it must be an NXT controller.
<R92> The following items are the only permitted materials for use on the MINIBOTS:
A. TETRIX components,
E. No more than one NXT controller with the Bluetooth functionality disabled,

JohnHorton

09-01-2011, 12:26

It seems like one could build it without any "brains" at all. In fact, I think a KISS design with, say, a light switch turned on by the hostbot and turned off when impacting the target, rigged to a motor directly might be the best idea. They were very specific about having " exactly one 12V rechargeable NiMH battery pack...", so it would seem they want this to be electrically driven as opposed to something mechanically launched from the hostbot.
Unless you just stick a battery on your projectile minibot. That'd be legal.

Bruceb

09-01-2011, 13:57

I think the battery statement is vague. Do you read it as the mini bot MUST have a battery?
It seems we could build a recoil motor with the surgical tubing??
Hmm

Jester

09-01-2011, 14:30

where might I find these ftc parts?

JoesephWhite

09-01-2011, 16:19

where might I find these ftc parts?

http://shop.pitsco.com/store/default.aspx?CategoryID=62&by=9&c=1&page=1&s=32

peter1626

09-01-2011, 17:29

JohnHorton

09-01-2011, 17:46

I am a little confused by R92 it says that you are allowed 1 12v battery pack and 1 NXT controller, but the NXT requires 6 AA batteries thats 9 volts, so does this mean we are allowed to use both the NXT WITH its standard battery in addition to a 12V FTC Battery pack or do we have to somehow modify the NXT?

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.

Al Skierkiewicz

09-01-2011, 19:41

Since R92 is a list of the permitted parts and the NXT requires the AA battery pack, I would expect that those batteries would be legal. Since the only motors allowed are Tetrix motors that cannot be driven directly by the NXT, the NXT battery will not provide power to drive motors. (See above post of R92)

Jon236

09-01-2011, 19:46

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!))

ATannahill

09-01-2011, 19:52

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!))
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.

EricVanWyk

09-01-2011, 19:53

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.

My apologies if this has been discussed elsewhere, it is impossible to follow all these threads!

Jon236

09-01-2011, 19:53

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

09-01-2011, 19:56

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

09-01-2011, 19:59

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

09-01-2011, 20:01

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

09-01-2011, 20:03

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

09-01-2011, 20:33

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

09-01-2011, 21:02

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

09-01-2011, 21:24

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.
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! :eek: (Just kidding, of course. <G59> covers it).
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

10-01-2011, 00:06

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:eek:

Al Skierkiewicz

10-01-2011, 08:31

<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

10-01-2011, 11:16

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

10-01-2011, 11:18

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

10-01-2011, 11:27

JohnHorton

10-01-2011, 11:38

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

10-01-2011, 11:48

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 (http://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.

Al Skierkiewicz

10-01-2011, 13:57

It has also been pointed out (offline) that a tether would not fit in the 12" cube. Food for thought.

Nishant

11-01-2011, 22:21

For those of you interested in using NXT equipment:

FIRST now allows:
BB. NXT compatible sensors and related connectors/cables.
(Team Update 1)

bookman101

12-01-2011, 09:40

Your minibot has to be an electromechanical devises as stated in the logomotion summary, and your could possibly use a tether as long as you can assure that it will never touch the pole. The tether would be considered part of the hostbot by my understanding and would violate the rule of the host bot touching above the deployment line.

Alan Anderson

12-01-2011, 10:13

A tether between the HOSTBOT and the MINIBOT will mean that you won't be deploying the minibot, according to the clarified definition of DEPLOYMENT. The act of deployment ends the moment the HOSTBOT and MINIBOT are no longer in contact, and only then can the MINIBOT start upward.

MarcD79

12-01-2011, 10:36

I think the battery statement is vague. Do you read it as the mini bot MUST have a battery?
It seems we could build a recoil motor with the surgical tubing??
Hmm

Team update #1 yesterday saying it MUST be electrically powered climbing ability

Kdabr

12-01-2011, 11:09

What about deploying a minibot that has a base module (containing a battery and controller) that would be tethered to the actual climbing bit? I think this would be legal because a minibot would still be deployed, but only half of the minibot would climb...right? The base module would rest on the pole's circular platform while the upper part climbed.

GaryVoshol

12-01-2011, 11:10

What about deploying a minibot that has a base module (containing a battery and controller) that would be tethered to the actual climbing bit? I think this would be legal because a minibot would still be deployed, but only half of the minibot would climb...right?

The pole is more than 12" high ... just sayin'

::rtm:: (all of it)

blueyes2821

12-01-2011, 14:46

An earlier post on this page listed required materials. non metallic rope or cord is allowed, so that may be possible.

keyslammer

13-01-2011, 23:31

Team update #1 yesterday saying it MUST be electrically powered climbing ability

They've clarified that no "stored energy" other than what would be in a battery can be used. So you MUST use the electrical energy to move your minibot. Basically, you have to have the battery.

perry3018

14-01-2011, 20:23

well if the mini bots can't have the Samantha then how would we enable the automatous on it?

mikets

14-01-2011, 23:25

The minibot is always in autonomous mode waiting for a sensor to tell it to start climbing. Please refer to the other thread here.

http://chiefdelphi.com/forums/showthread.php?t=88644

DonRotolo

15-01-2011, 00:01

An earlier post on this page listed required materials. non metallic rope or cord is allowed, so that may be possible.Only if the minibot never exceeds 12" x 12" x 12". That doesn't allow for much in the way of rope dangling down.

We had thought of a small mechanical lever that, when the minibot hits the top, releases a cord we can pull after the match to retrieve the minibot, but this would have the minibot larger than 12", and so was ruled out. We decided to stick with the pole-mounted chainsaw. :ahh:

Al Skierkiewicz

17-01-2011, 07:28

well if the mini bots can't have the Samantha then how would we enable the automatous on it?

Deployment is initiated by the drivers. The only interaction with field control comes when all four posts have been triggered or the match clock runs out.

SciDKelly134

17-01-2011, 09:49

GDC
Re: Minibot Light switch

For the purposes of FRC 2011, a standard light switch is considered any standard switch which is normally installed in a wall box to control lights in a home.

We purchased a 4 pole (wall box) light switch from Home Depot and it works very nicely to reverse the DC polarity. On our prototype, we used a standard switch to turn the robot on and the 4 pole switch to bring the minibot back down the pole