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Robot metal detector — Parallax Forums

Robot metal detector

JonPattonJonPatton Posts: 3
edited 2006-08-01 20:18 in BASIC Stamp
A little ideal I had many years ago. A steady plateform to mount a rotating metal detector to build up a picture of whats in the ground. The original ideal was to run the device at night and place a light under the coil. As it ran, a photo would be taken form above with the shutter open and a high F-stop. The result would be photo of the area with the detected areas shown lit up more. With the boom 4 feet or so would get a nice path.
It was never built. Now I've got a Boe bot the ideal has surfaced again. Since the compass for the Boe Bot is nearly useless to drive in a straight line. I bought a gyro and added to one servo. The servo stopped working when gyro is connected. Arrgh. I haven't dug up my RC reciver to test the gyro to see if it is working or not. I looked at the wiring to see if Boe Bots servos are that differant and they look the same other than the stop tab is gone to allow continuous rotation.
After I get the Bot to going in a straight line, then I can work on sending the signal back to the chassis via Ir link and stored in memory for post processing and display. No sense in using a photogragh these days. Althought the original ideal was pretty cool.
I just thought that you guys might be interested.


JonPatton

Comments

  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2005-05-08 02:20
    Jon,

    Here is an old post of mine that you might be interested in...

    sensitive Stamp based Metal Detector

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    Beau Schwabe - Mask Designer III

    National Semiconductor Corporation
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  • JonPattonJonPatton Posts: 3
    edited 2005-05-08 03:22
    That's a cool little design. Simplicty. Can be made to be very light, I like it. I just picked up a herd of 3904's for a Lightning detector. I'll have to think about how to send the signal down to the Stamp. Maybe a PWM(like a 555) IR led to a phototransistor at the motor shaft. Mmm. I would hate to use a wiper on a commutator. Noisy things. (:> And using RF coupling is right out. Possible feedback.

    Thank's for the plan,

    JonPatton
  • Philip GamblinPhilip Gamblin Posts: 202
    edited 2005-05-11 01:26
    Is your detector code in the archives? It could be a edge detector for my robo mower dream.
  • Erik ArendallErik Arendall Posts: 21
    edited 2005-05-11 01:51
    Phil,
    I remember coming across someone that built a robot lawn mower. They used a radio fence for animals to define the boundary.
    You should be able to get these off of E-bay or take the idea and create one.
  • JonPattonJonPatton Posts: 3
    edited 2005-05-11 06:31
    I ran a mow-bot for years until she was stolen from the shed. I really miss my Moo-bot. http://web2.airmail.net/jcpatton/pics/mower1.jpg

    I still have the transmitter for the fence. The bot had a flux gate compass (I guess) and was tied to the fence signal some how. I never took it apart so I don't know for sure. I might build one from scratch sometime. If I do I'll post the plans. I'm more apt the hotter it gets outside.(:>

    JonPatton
  • Billericay-BoyBillericay-Boy Posts: 28
    edited 2006-08-01 13:19
    Hi, i see that you had a MowBot but still have the perimiter cable and sender unit. have you taken the sender unit apart to see what is in there ? if so did you take any photos or worked out what circuits it uses so we can try to emulate it ?

    Thanks
  • Bruce BatesBruce Bates Posts: 3,045
    edited 2006-08-01 15:08
    Billerica Boy -

    With most of the perimeter controlled robotic mowers which use a buried wire system, the "sender" is nothing but a low-power RF transmitter, which is picked up by a directionally sensitive RF receiver on the mower robot. Not much to the simpler systems.

    Regards,

    Bruce Bates

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  • Billericay-BoyBillericay-Boy Posts: 28
    edited 2006-08-01 19:16
    Thanks Bruce

    i dont understand the components that have to be used to make these devices as i am only just starting out on the robot / electronics path. i can do 240 wiring no problem but the little stuff is a bit ofa mystery. are there any simple to construct low-power transmiters and detectors which you could recomend for me to try and make so i can add it to my bot.

    many thanks
  • Bruce BatesBruce Bates Posts: 3,045
    edited 2006-08-01 20:18
    Billerica Boy -

    As much as I usually recommend Parallax products, the following link will take you to the "Remote Control Section" of the Rentron web site. Here you will find numerous projects and worked examples of simple I/R, and RF systems using inexpensive transmitters and receivers.
    http://www.rentron.com/remote.htm

    Bruce Reynolds (owner of the web site) is always happy to help any hobbiest who wants to learn more about how remote control systems operate. After you have developed a remote control system you like with inexpensive parts, you may want to purchase the more sophisticated and hardier RF equipment from Parallax. Feel free to tell him I sent you, as we've been friends for ages.

    Have fun, as it's one of the more enjoyable parts of the hobby once you get the basic principles down, IMHO.

    Regards,

    Bruce Bates

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