Ultrasonic sensor help please

Discussion in 'The Projects Forum' started by BriefcaseW, Nov 21, 2012.

  1. BriefcaseW

    Thread Starter New Member

    Nov 21, 2012
    2
    0
    Hi there,

    I am currently undertaking a project to mount an ultrasionic ring on an autonomous machine for working outside, I have narrowed the sensors down to these:
    http://www.rapidonline.com/pdf/35-1805.pdf

    They will be used for objet detection which will stop the vehicle if something enters it's pereimeter. My question for you is what interface device do I need between the control board and the sensors as some I have seen have a board like these:

    http://www.rapidonline.com/Electron...rformance-ultrasonic-range-finder-SRF08-60296

    I think i need the five outputs like shown above as it will be controlled by a picaxe microcontroller circuit then sent onto usb for the main control.

    Thanks in advance.
     
  2. tshuck

    Well-Known Member

    Oct 18, 2012
    3,531
    675
    Since you are using a PICAXE, you will spend a of of your processing time simply trying to read teh sensors. Not to mention you are going to be doing DSP on a PICAXE.... or, rather, attempting to do DSP on a PICAXE....
    In order to use there devices, you'll need to modulate your signal, transmit that signal, recieve the signal, and understand that it is, indeed, your signal(as opposed to a bat flying around), all while timing the whole thing, something I don't think a PICAXE is suited for...

    Unless you have a huge monetary advantage to using these sensors, I'd say they aren't worth it. When I built my robots, I usually go with a Maxbotix sensors: here. Their sensors are great and offer many different methods of reading the data from the sensors.

    Since these sensors take care of the DSP portion, all you are concerned with for the PICAXE is packaging, though, I'd still recommend not using a PICAXE, but that's just me...the PICAXE will work....
     
  3. BriefcaseW

    Thread Starter New Member

    Nov 21, 2012
    2
    0
    They look good, thanks, from your experience what sort of area do the cover (in terms of degrees) as these are purely safety features rather than guidance round the rear and side machine, that will be done via GPS and LIDAR
     
  4. tshuck

    Well-Known Member

    Oct 18, 2012
    3,531
    675
    It depends on the sensors, each one has it's advantages and drawbacks....beamshape, resolution, durability, distance, etc... you'll just have to peruse the site for information. It is important to note that ultrasonic sensors do not have a linear beamshape, it is conical radiating from the emitter...
    Basically, they will have an ability to measure x degrees at a distance of y with a resolution of z...
    i.e.:You can design for the ability to to detect a 2" diameter pole at 15m with a window of 30°, or a 0.5" diameter pole at 5m with a window of 50°... each of these are sensor specific...

    Note: The beamshapes will begin to level out after a certain point.... it will be conical out to a point, then appear as a beam...

    Your LiDAR can easily do what you are wanting the ultrasonics to do. Unless you are using some form of sensor fusion, forget the ultrasonics...;)
     
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