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How to find width of the object? — Parallax Forums

How to find width of the object?

rohitbr1rohitbr1 Posts: 3
edited 2010-03-28 17:59 in Accessories
I am new to these things. I & my friends want to prepare a robot for some competition for which we want to use sonar sensors that can measure the distance and the width of the object.

So please guide me in this.

Got little idea for finding distance but i have NO idea for finding the width of the object using SONAR!!!!

Comments

  • kwinnkwinn Posts: 8,697
    edited 2010-03-27 20:56
    The distance to an object can be calculated from the transit time of the sound pulse, but width (or height) is another matter. The amplitude of the return signal provides some indication of the size, but the amplitude is also affected by the angle, shape, and material of the object so it is not a very accurate indicator.
  • Mike GreenMike Green Posts: 23,101
    edited 2010-03-27 21:29
    Please delete your other duplicate message. You can do that by using the X icon in the upper righthand corner of the message box.

    Usually width is measured by scanning the space in front of the robot. Once you determine that an object is in front of the robot, you move the sensor to either side and see where the object appears to disappear. That gives you the angular width of the object once you account for the width of the sensor beam. If you know the distance to the object, you can calculate the object's width. Obviously, the accuracy of this scheme depends on the distance to the object and the sharpness of the edge of the sensor's beam.

    Note: It is very much against forum rules to post duplicate messages. Please delete them and do not do it again.

    Post Edited (Mike Green) : 3/27/2010 9:36:43 PM GMT
  • LeonLeon Posts: 7,620
    edited 2010-03-27 21:33
    Electro-optical methods are usually used for width and length measurement.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Leon Heller
    Amateur radio callsign: G1HSM
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2010-03-28 00:43
    If the object you want to measure is well-lit and has good optical contrast with its background, you could use the Ping))) to measure the distance, and the TSL1401-DB to determine an apparent width. Then you can multiply the apparent width by the distance to get the actual width.

    -Phil
  • rohitbr1rohitbr1 Posts: 3
    edited 2010-03-28 17:59
    thanks kwinn,Mike Green&Phil Pilgrim (PhiPi) for your support
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