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Problem Solving Help — Parallax Forums

Problem Solving Help

The Crazed InventorThe Crazed Inventor Posts: 4
edited 2005-09-27 19:18 in BASIC Stamp
I am working on a device that will be able to track a student around a room. I do not want it to follow them but just keep the student in the sight of the device. I am having a problem getting this accomplished. I though about using a ultrasonic device, but I am stuck. I would appreciate all help and please get back with me if you are confused or need more information. Thanks!

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Comments

  • NewzedNewzed Posts: 2,503
    edited 2005-09-26 17:03
    Think about it as a line follower.· If the student goes left of center, then you would use a servo to get the student back in the center of the sensing device.· I would consider an IR device since they will work up to about 35 feet.· And what about interference from other students in the room?

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    Sid Weaver
    Do you have a Stamp Tester yet?
    http://hometown.aol.com/newzed/index.html

    ·
  • The Crazed InventorThe Crazed Inventor Posts: 4
    edited 2005-09-26 17:54
    I would like to not have any interference in the line of sight.· I would like to use IR light but I am afraid that sense I will be using this outside, the IR light will have some difficulty with the sun light.· Are there IR light emitters that are extremely powerful so that no other light should effect them within so many feet?· Thanks again.

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  • The Crazed InventorThe Crazed Inventor Posts: 4
    edited 2005-09-27 02:57
    does anyone else have any thoughts on this?
  • Bruce BatesBruce Bates Posts: 3,045
    edited 2005-09-27 04:14
    Crazed Inventor -

    Originally you wanted "to track a student around a room", and now the target/subject is outside. It sounds like you'd better define your parameters and environment better before anyone will be able to help. The first step in any problem solving venture is defining the problem clearly. I'm afraid that hasn't been done yet.

    I/R light can easily be modulated so that ambient light, indoors or out, is minimized. So too optics can be used to focus the beam. Once you get beyond the capabilities of ordinary I/R emitters (transmitters), you then enter the realm of laser I/R but there will probably be health and safety concerns therein, particularly in a school environment. If you choose to investigate this further, look up "LIDAR" on the Internet using Google or your favorite search engine.

    If you notch it up one more level, you end up getting into microwaves, which isn't a bad idea, except for the exponential increase in cost, the need for additional technical expertise, and much higher levels of sophistication, not to mention the FCC regulations, and other such matters. This enters the area of radar "guns" and detectors used by law enforcement, and at sporting events for timing. Similar things are done with automatic opening supermarket doors as well.

    What is the point or purpose of this "targetting", since perhpas there is a different direction to investigate, if we knew more about the purpose? What is the maximum distance involved? What is the budget for this project, just in general terms?

    Regards,

    Bruce Bates
  • metron9metron9 Posts: 1,100
    edited 2005-09-27 10:14
    Off the top of my head i would say radio signals and I would look at how for example an invisable fence for keeping a dog in your back yard works, The dog wears a collar that shocks him if he gets too close, yours would siimply work in reverse, the student would have to remain in range of the master signal to keep his alarm from going off.
    So yout transmitter could be inside the room, each student has a small receiver that polls for the signal sent out by the transmitter, if it can't find the signal it outputs either an alarm, shocks the student with 50,000 volts (low current of course), or sends out a pulsed RF signal that yout transmitter/receiver box can sense. Each student could have a different frequency transmitter.

    Very cheep AM receivers can be made with a few components.
  • allanlane5allanlane5 Posts: 3,815
    edited 2005-09-27 14:29
    The CMU-Cam has the ability to track a ball, or object, of a particular color. You might try that approach. I've read a paper, where a college student used a CMU-Cam to track people in an office space. Each one got a colored badge, which the unit then tracked, using a Servo to steer the camera.
  • steve_bsteve_b Posts: 1,563
    edited 2005-09-27 15:04
    Be wary of purchasing surplus police radar guns....the guns they use today are much safer than older ones.
    A coworker was leaving a radar site (weather radar) and noticed a cop sitting by the side of the road with his radar gun.

    He stopped and chatted the cop about his radar gun. Turned out (I think the guy tested the gun) that the gun was always radiating and that all the "trigger" did was turn on the electronics for the readout (turned on the receiver).
    So while this guy was waiting for the next car...he set the gun in his lap, and was working on some free Neutering! haha
    So just a note of caution; there are exposure limits based on wattage/m^2/minute. Well, I think any exposure to RF for a long period of time (even if it is WAY below thresholds) isn't all that good for you....(don't mean to open up a can of worms with that comment).

    Anyhow, do you want the students/people to be passive targets? You could put IR beacons on them and track them that way! Or, have an IR scanning radar checking the room, and have your "pointing device" respond to the closest target (or a moving target).

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    ·

    Steve

    "Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
  • kelvin jameskelvin james Posts: 531
    edited 2005-09-27 16:55
    Check out the radar board on this site, now that is nice! Probably costs an arm and leg.
    www.neobotix.de/en/products/Components.html

    kelvin
  • steve_bsteve_b Posts: 1,563
    edited 2005-09-27 19:18
    Crazed,
    I'll post public so as to have the information here for those that might look for something similar in the future....

    To build a poor mans IR radar, get a stepper/servo and an IR ranger...mount the range finder on top of the stepper and you have something that can sweep back in forth over ~355degrees and give you readings.
    I build one to play with and it seems to work alright....didn't have my loop 'tight' enough to get it going really fast.

    If you wanted to scan continuously in one direction, then you'd have to modify your stepper (or buy one for continuous rotation) and also allow for some sort of device to replace the wires (3 typically) going to your IR ranger....sliprings of some sort.

    Basically, move position...take an IR reading....move position...take an IR reading....
    What you do with the readings is up to you! You can compare to previous readings or previous batches of readings and look for the peak value (closest to you or furthest away) then act on what you see.

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    ·

    Steve

    "Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
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