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location sensing robotic - any suggestions? — Parallax Forums

location sensing robotic - any suggestions?

grhodes29grhodes29 Posts: 1
edited 2005-08-29 12:52 in Robotics
I want to build a robot that uses one of the tranmitters/receivers sold by parallax. Either the IR or 433 Mhz radio so the robot can· detect it's relative location from a transmitter or transmitters and to be able to make decisions on movements based on its location.

How can I get a measurement of receivered power? I need a measurement ability to be able to get a relative distance from the tranmitter?


Any ideas?

Comments

  • allanlane5allanlane5 Posts: 3,815
    edited 2005-08-17 14:58
    I don't think you can. The radio transmitters are to send information from the BS2 to a 'base station'. Thus trying to use them to find a relative distance is not a purpose of the links.
  • BeanBean Posts: 8,129
    edited 2005-08-18 01:41
    I don't know if it's possible, but I know that invisible fence transmitters transmit at different signal strengths, and the receiver only has to determine the duty-cycle of the received signal to get a distance measurement.
    Bean.

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  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-08-18 15:13
    I ran across a used copy of "Robot Builder's Bonanza" while visiting Charlotte, NC over the weekend. I picked it up as a reference to help forum members. I remember there is a section discussing navigation using stationary towers to triangulate position. I haven't read it yet, but I'll see if any of the information is pertainent to your question.

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  • YanroyYanroy Posts: 96
    edited 2005-08-18 19:31
    In the recent past, the FIRST robotics competition has used IR beacons that enable you to triangulate your position on the field... you could see if there are any documents relating to these at www.usfirst.org.
  • bobledouxbobledoux Posts: 187
    edited 2005-08-19 13:10
    Try this:

    http://www.seattlerobotics.org/encoder/200109/lasernav.htm
  • bobledouxbobledoux Posts: 187
    edited 2005-08-19 13:16
    Another possibility is to build beacons that carry an RF transmitter and ultrasonic transducer. When the RF is pulsed the robot starts a timer that stops when it hears the transducer. RF travels at the speed of light and the transducer sends at the speed of sound.
  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-08-19 13:22
    Funny bobledoux, thats what the book said, though they specified IR instead of RF, either will work, IR will be cheaper if the parts have not been purchased yet. Also it is important to have a seperate code for each beacon so you don't get multiple responses.

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  • Steve JoblinSteve Joblin Posts: 784
    edited 2005-08-19 13:47
    Would this help?·· http://www.pololu.com/products/pololu/0001/

    The Pololu IR Beacon seems to be a relatively inexpensive solution.
  • HiTekGizmosHiTekGizmos Posts: 14
    edited 2005-08-29 02:05
    How about a couple of beacons AND a compass module? Knowing the angle between two beacons doesn't tell you much about your location, but knowing the bearings to two or more·can pinpoint your location... Mount your IR detector on a servo so you can scan for the beacons then using compass data you can figure the bearing to it...



    IR or (ultra)sonic ranging could also be used instead of the compass or to supplement it...
  • bobledouxbobledoux Posts: 187
    edited 2005-08-29 12:52
    Remember that RF is omnidirectional while IR and ultrasonic transducers are directional. This means a beacon and receiver may require multiple transducers to obtain the desired area of coverage.
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