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Help for School Project

Discussion in 'General Electronics Discussion' started by ozgunoral, Dec 7, 2012.

  1. ozgunoral

    ozgunoral

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    Dec 7, 2012
    Hello, I have a group of five people responsible for this project:

    http://www.eee.metu.edu.tr/~design/Projects_2012_2013/kpr3.html

    We are also responsible for building the track and gates. I need design ideas from the experienced people like "Use an ultrasonic sensor." or "Use a brushed dc motor powerful enough for the robot, this model would be sufficient.".

    Your help is appreciated. Thank you.
     
  2. BobK

    BobK

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    Jan 5, 2010
    It is kind of hard for anyone to give that kind of advice without knowing if the "robot" is 100g or 100Kg.

    Perhaps you could give a few more details.

    Bob
     
  3. ozgunoral

    ozgunoral

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    Dec 7, 2012
    Thank you for your reply.

    All requirements are specified and the robot's weight depends on the solution. If a robot that has a sensor, motor, power supply, processor, body and wheels weighs 5 kgs, then it is 5 kgs.
     
  4. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Nov 28, 2011
    That's a very vague specification.

    Does the robot have to be able to steer? The specification doesn't say whether the gates can all be in a line or not. You mentioned a "track" but this isn't part of the specification.

    Do the gates open like hinged doors or like sliding doors? Do you have a choice?

    If the gate's period can be set down to one second, and it's open for half the time and closed for half the time, that only allows half a second for the vehicle to go through the gate, assuming that the gate can open and close instantaneously. The vehicle would need to be very short and/or move quickly (and brake quickly to avoid hitting the next gate).

    There are many other questions that you should be asking yourselves. I hope you can talk to the person who created the specification to get it rewritten with some clarity!
     
  5. ozgunoral

    ozgunoral

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    Dec 7, 2012
    Actually what is not specified is optional. We can build a track that guides the robot or may not build a track at all. If it meets the requirements it is ok. Gates can be anything if it allows the robot to pass in half of its cycle and stops it in the other half. For we are the ones building the gates, size of the robot is not important. If the robot is 10 cm high then we can simply build a 20 cm door with a constant speed motion.

    So if it is not specified we are free to use our imagination. Actually building different types of doors or giving robot extra abilities gain extra points.
     
  6. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    So do you think you'll be able to get the robot through the gate in less than half a second?
     
  7. ozgunoral

    ozgunoral

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    Dec 7, 2012
    What makes you think I wont?
     
  8. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Nov 28, 2011
    I probably shouldn't have said anything.
    I can't help with any component recommendations.
    Sorry for wasting your time.
     
  9. ozgunoral

    ozgunoral

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    Dec 7, 2012
    I was trying to send you the following private message but the website won't let me since I am a new member now, here enjoy it publicly:

    "Hi, thanks for your concern about my project

    I think I couldn't get what you meant by your question about whether we'll be able to do it. If what you meant what this is really hard, well we have to do it since it is our graduation project. The project is assigned with the joint-decision of 8 professors from my school and that gives the idea that it should be possible to build such a robot. I know it is going to be hard and need lots of optimization and calibrating. However like I said we are free to alter lots of things and I think if we build little gates, a light robot can be powerful enough to obtain such speeds.

    I am expecting more input from you. Thank you again."
     
  10. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Nov 28, 2011
    Actually, I doubt I'll be able to help you much. I have no experience with robotics.
    I really just replied to try to point out how vague that specification was, because if there IS anyone here with robotics experience, I assume they would expect a much better specification than that.

    Now that you ask though, I have a few ideas. As I said, I have no experience in this area, so these are just suggestions.

    The specification doesn't say anything about the surface that the robot runs on, does it? In that case, it might be a good idea to use toothed wheels running on a surface that consists of wide teeth that mesh with the wheels. This will ensure that your robot always faces straight forwards. If you make the teeth square instead of triangular, you should be able to get a lot of acceleration and deceleration without any slipping.

    You would need a reasonably long robot - I'm thinking around 6~8 cm from front axle to back axle, for stability. Presumably it would have four wheels, and a chassis that sits as low as possible - definitely below the wheel axles. The wheels should probably be smallish, say 1 cm diameter or somewhat less. This is all based on gut feelings and may be wrong!

    All four wheels will turn identically. I don't know whether two wheel drive will be enough. Perhaps drive on the front axle and braking on the rear axle. But the braking needs to be controlled, just like the acceleration. So perhaps the front and rear axles should be coupled together.

    A stepper motor should be good for wheel drive, but it needs to be small and light. Floppy disk drives use a very small stepper motor to seek the head inwards and outwards.

    You would probably want a small microcontroller to control the movement, though it might be possible to do it with discrete components. I should be able to help with the design here.

    As for batteries, you can probably get a few minutes' run time from a stack of 3V lithium button cells, which are small and light and easy to stack. Probably an operating voltage of 6V would be good, and you could parallel up several stacks to get the required current.

    You need to figure out how to control the robot. It needs to be able to detect the presence of a doorway, so it knows when to stop, and it needs to be able to tell whether the door is open or not. Probably some very light whisker-style wires would do this. You would want at least one on the front, to detect the presence of the door, and probably one on each side, to detect the doorway. They would have to be light enough that they would just bend and spring back as the robot goes through the doorway.

    Other options would be ultrasonic sound or infra-red light, but these would complicate everything, and shouldn't be needed. You could perhaps use magnets on the floor to signal the robot that it's approaching a doorway, but attaching it to the doorway so the examiner can move it around might be impossible.

    As for the doors, I would definitely go for a sliding door rather than a hinged door, because they're probably easier to actuate, and the robot won't have to stand clear of them. But does it slide left/right or up/down? At least up/down means you only need to move it in one direction; gravity will do the other direction.

    I would be happy to discuss ideas with you if you want, but remember that I don't have any experience with the mechanical stuff, and you'll probably need to do a lot of work yourself.
     
  11. stevee2002

    stevee2002

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    Dec 5, 2012
    I have never dealt with robotics projects, but you could look into using Lego's for the track and gate contruction, as these are widely available and cheap. The patterned bumps can also serve as a guide for the wheels.
    For the robot itself, you can also look into Lego K'nex, or Lego Mindstorm.. there are alot of ideas out there, as well as robotic parts and programmable controllers.
    Have fun with the project!
     
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