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Author Topic: Beginner Help  (Read 1428 times)

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Offline tyler555Topic starter

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Beginner Help
« on: December 07, 2011, 04:05:43 PM »
I am new to all of this....
My team is planning to compete in the lightweight division of the NRC sumo. The max weight is 50 lbs and it is remote controlled. So far we have a pyramid design. This is not a battle bot. It is strictly sumo, no weapons.

Parts list so far...
DX7 digital controller
Ar7000 Receiver
Two NPC-41250 Geared Brushed Motors, We plan on running them at 24v
Materials needed for construction
and that is about it

We need to get a speed controller/s, depending on if the speed controller is compatible with 2 motors at such high current. We also need to purchase batteries. And other various items that you guys think is necessary. I need help with the wiring also.

What I would like help with:
Purchasing/ using batteries-( I have no clue what the running time or voltage or amp hours for any of this so I have no clue what to buy)
Purchasing/ using speed controller/s- (what would be best for our set up and motors?)
Finally, The wiring, I don't know how to wire it so that I don't blow up my $90 receiver, or any other electronics)

If any of you could help me, It would be fantastic and much appreciated, plus I can teach the rest of my class what you guys have taught me, thank you.

Offline tyler555Topic starter

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Re: Beginner Help
« Reply #1 on: December 07, 2011, 04:08:54 PM »
ALSO I WOULD LIKE THE ABILITY TO BRAKE THE MOTORS, SINCE OUR SLOW AND STEADY HIGH TORQUE DESIGN.

Offline tyler555Topic starter

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Re: Beginner Help
« Reply #2 on: December 07, 2011, 04:32:37 PM »
Thinking about two of IFI VEX Pro Victor 883 speed controllers

Offline tyler555Topic starter

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Re: Beginner Help
« Reply #3 on: December 07, 2011, 04:40:32 PM »
or the Vantec RDFR22 dual Speed Controller

Offline Soeren

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Re: Beginner Help
« Reply #4 on: December 07, 2011, 07:26:41 PM »
ALSO I WOULD LIKE THE ABILITY TO BRAKE THE MOTORS, SINCE OUR SLOW AND STEADY HIGH TORQUE DESIGN.
No reason to shout (and in bold even)! If anything, it's a sure way to get no useful answers.

I hope you are a long way from the competition, as you seem to have no prior experience/knowledge of even the basics.
I'll recommend that you spend a couple of months on a basic 'bot like the $50 robot (tutorial for this can be found on this site), to make most of the beginners mistakes on something cheap and of the simplest possible structure - easier to keep an overview on things this way and then you may have a chance of actually finishing successfully with a larger 'bot, where mistakes will be more expensive (and demoralizing).
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

Offline billhowl

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Re: Beginner Help
« Reply #5 on: December 07, 2011, 10:04:56 PM »
National Robotics Challenge
April 12, 13 & 14, 2012
www.nationalroboticschallenge.org
http://www.nationalroboticschallenge.org/joomla/images/downloads/nrccontestrules2012.pdf
Quote
Sumo Robot
Remote-Controlled - Middle School, High School
Self-Controlled - Middle School, High School, Post-Secondary

Contest Description

The Sumo Robot Contest requires a student team to build a self-propelled, remote controlled or
sensing robot, designed to force another Sumo Robot outside a ring. The competition ring will be a
square painted flat black, measuring 15’ 2” across. This inside square is surrounded by a two-inch
(2”) wide, painted or taped, flat white ring. Another white one-inch (1”) wide, line will surround the
inner ring with 2 inches (2”) between them. When any part of the Sumo crosses completely over
the 1” white outer ring it will lose the heat.

Rules

1. The Sumo must be powered by electrical storage batteries. No other power sources will be
allowed. These batteries must be sealed and all possible precautions must be incorporated into
the design to prevent accidental spills. The judges may disqualify any design that is determined
to be unsafe.
2. The Sumo must use sensing devices to govern the motion of the Sumo and must use sensors
to either detect other Sumo and/or the edge of the white line. (The remote-controlled
lightweight robots do not require sensors.)

3. The Sumo Robot must fit inside a 24” x 24” x 24” space. Any robot entered that does not meet
the size requirement by the end of the device evaluation will be disqualified. Device evaluation
will take place at the time indicated on the Official Schedule
4. The Sumo drive wheels must be non-destructive to the playing surface.
5. All robots are subject to the final approval of the NRC staff and judges. Any robot that is
deemed too dangerous to other robots or competitors will be disqualified.
6. The contest has two sections: (1) Lightweight section in which the Sumo must be remote
controlled and cannot exceed 50 pounds and (2) Heavyweight section in which the Sumo must
be self controlled and cannot exceed 125 pounds. Each robot may only enter one section.
7. Weight may not be added after the Sumo has been weighed and evaluated by the judges.
8. Double elimination contests will decide the winner of each section.
9. At the beginning of each competition, with the robot deactivated, the Sumo handler(s) will
position their Sumo one foot apart as instructed by the judges. Four start configurations will be
possible:
At the command of the judge/facilitator, the handler(s) will activate their robot.
10. All robots must have a visible RED locking emergency stop button on top of the robot in case of
a malfunction.
(New for 2012)
11. All lightweight entries must have with the ability to change between at least 2 different
frequencies. We recommend that teams invest in 2.4 GHz radios and receivers such as
Futaba’s FASST system. (http://2.4gigahertz.com)
12. When any part of one Sumo completely crosses the outer white line, the other Sumo is
declared the winner of that engagement.
13. If both Sumos leave the ring at the same time, a "non-contest" is declared and the two Sumos
are repositioned and the contest begins anew.
14. If, after three minutes, no winner is declared, the two Sumos are repositioned and the contest
begins anew. If no winner is declared after this second encounter, the judges shall declare a
winner based on action observed within the ring and on the design of the selected Sumo.
15. A pit area, with access to 110-volt standard outlet, will be provided.
16. At the conclusion of each match the winning robot must be weighed to ensure that legal weight
has been maintained. (New for 2012)
17. Decisions of the judges are final and binding.


This is straightforward design using hobby RC Tx & Rx with ESC, but is good to have MCU and the sensors that detect the edge of the white line and turn off the forward motion of the motors.
The NPC-41250 Geared Brushed Motors can draw more then 82 Amps with 24V supply so use current sensors to detect and cut off the supply when current is over the ESC limit.
You have about 4 months to complete it.
« Last Edit: December 07, 2011, 10:07:48 PM by billhowl »

Offline tyler555Topic starter

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Re: Beginner Help
« Reply #6 on: December 09, 2011, 10:11:52 AM »
No reason to shout (and in bold even)! If anything, it's a sure way to get no useful answers.
[/quote]
Sorry, I was just trying to make the most important topics easily seen for ease of reading.

Offline tyler555Topic starter

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Re: Beginner Help
« Reply #7 on: December 09, 2011, 10:22:50 AM »
We are in the lightweight, therefore remote controlled division, so there is no need, thank god  ;), for sensors. And I already have some experience working with robots just not with DC motors, I am used to low current servos and nitro engines as the main driving force.
     One specific question, When connecting the batteries to the speed controller, do I need an extra interface between the speed controller and the receiver to protect the receiver from high current or should the speed controller already do that?

 


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