How to get teh closest Metal object

  1. Hello,
    I'm a junior engineer, and I'm facing a physics/maths problem, for my new project.
    I dont know all the technologies at the moment, and don't know all the tools available. I would like to calculate/get the closest Metal object from an other object (called x).
    x could store a sensor or a microcontroller to proceed in the calculation, but what do i need, to get the distance(dont need the distance in cm or m but more the closest object).What will be the easiest method to use? Ulstrasound? the laser meter is not an option as I'm in a 3D environment.
    Hope I was clear in my explanation you help will be greatfull.
  2. jcsd
  3. Drakkith

    Staff: Mentor

    If you don't get any answers here, try the Engineering forums.
  4. ZapperZ

    ZapperZ 30,450
    Staff Emeritus
    Science Advisor
    Education Advisor


  5. Are you trying to discern a metal object from a group of objects? That would make a difference in terms of the sensors you want to use.
  6. No one as any ideas ???
  7. yes I'm trying to dicern the closest metal object (I forgot to mention) all the objects will be metal.
  8. One thing, are all the metal parts the same, that is to say, all ferromagnetic like iron or most steels, or will some be non-magnetic like aluminum? Will the sensor sweep by the metal or would the sensor be stationary and the metal sweep by the sensor? That complicates the wiring issues if the sensor has to move, for instance.
  9. all the object around can move , they will al be made out of stell , and wont be bigger then 10cm of diameter, and smaller then 6 cm of diameter.
    If you wont a concret exemple if we throws then (for exemple 5 object toward the sensor) when they stop the sensor should be able to find to closet one.
    Hope I was clear enough :) and thanks for your help
    Last edited: May 24, 2011
  10. You will probably want to mix visual processing with a magnetic sensor (although you haven't specified whether or not they are ferromagnetic)
  11. thanks for your feedback but a magnetic sensor will make the object move??
  12. I'm not an expert but steel object are ferromognetic??
    Last edited: May 25, 2011
  13. Steel is ferromagnetic, most steels anyway. Some stainless steels are non magnetic but to see if the steel in you app is magnetic, just take a magnet and see if it attracts your steel.
    Is this app for a moving robot, like a college robotics contest? Sensors don't HAVE to be magnetic.
  14. No its not for a Robot, but more for a game when I will have finish every single part ;). One thing is that the object musn't be moved that is to be taken into account
  15. In that case, you should not use a simple magnet with a reed switch which depends on a magnetic field to detect the metal and close a tiny switch. You need a more elaborate detector, either an optical detector which puts out an IR beam with a small LED and a light detector, where the beam goes out at an angle, like too headlights not pointing out straight but like crosseyed where the two beams would cross at a short distance away from the body of the detector, but the other 'beam' is just the IR light receiver, the detector. When the light beam goes out it runs into a piece of metal and it has to be at a small distance to reflect some of the IR light back into the detector, at other distances, it does not detect.

    Or you can use the same idea but it sends out ultrasonic audio beam and an audio pickup, same idea.

    The magnetic way would be a sensor that uses a low power RF field, maybe 200 Khz or so, and if it gets close to a piece of metal, there is a receiver coil that gets a change in impedance and that is sensed, that is like a miniature metal detector people use to scan for rings and such on a beach.
  16. I think the IR beam seems the most suitable solution, but could you explain in more details have to admit got lost a bit ;)
  17. If you put an Infra red emitter (IR LED or laser) next to an IR detector, and they are in parallel, the IR beam would go straight out and the return could be a long ways away. If they are aimed inwards, like a triangle, where if they were both emitters, the beams would meet at some point, but instead one of the devices is an optical detector, then the most likely detection would be where the lines of the triangle would meet. You take the output of the IR detector and put it to the input of a schmitt Trigger. Here is a Wiki about this circuit:

    The output of the schmitt trigger can be used to activate a relay or an LED or whatever. You use the signal however you wish. Could be an audio beep, whatever.
  18. Hi Litup! :-)
    are you still looking for ideas?
    I suggest ultrasonic 'radar'. You could pulse a burst of 40kHz sound, time the received signals, and locate the nearest item using Arduino.
    I hear that the Arduino platform is very good for this kind of work, and is very cheap. There will be a fair bit of work in programming though.
  19. thks that could be a really good idea I ll dig in to it :)

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