Discussions

Calibrating Sonar

Posted by Tissy on October 8, 2012 at 5:16pm

I have recently added Sonar (EZL0) to my HexaCopter which is a 3DR frame and the standard sonar mount.

 

However my Hexa also has skids fitted and the sonar is constantly measuring 20cm.

 

Although the sonar can see the ground, i'm guessing it could also be seeing the skids.

 

Can sonar be calibrated or the beam changed to ignore the skids.

 

Many thanks for any advice.

 

Steve

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Replies

  • MaxBotix Inc October 15, 2012 at 2:45pm

    Hello this is Scott from MaxBotix Inc.

    @Steven Tisseyre

    You stated that you have an EZL0 that is measuring a constant 20cm.   The MB1260 (XL-MaxSonar-EZL0) will measure the distance to the first detectable target.  In the case you have described this would be the skids.  To have the sensor ignore the skids on your Hexa-copter, the sensor will have to be moved away from the skids, or the angle of the sensor will have to be changed.  Both solutions will have to be tested.

     

    You may wish to try a sensor with a narrower beam pattern such as the MB1230 (XL-MaxSonar-EZ3).

    This is an exert from the XL-MaxSonar-EZL0 MB1260 datasheet about the sensors calibration

    "Each time before the XL-MaxSonar® takes a range reading it calibrates itself. The sensor then uses this data to range objects. If the temperature, humidity, or applied voltage changes during sensor operation, the sensor will continue to function normally. The sensor does not apply compensation for the speed of sound change verses temperature to any range readings."

     

    @Tobias Halldin

    Thanks for your help.  I want to point out one.   The datasheet that you refereed to is the MB1000, not the MB1260.  The LV-MaxSonar-EZ sensors will ignore targets if the target stays the in the same spot it was in when the sensor was powered up, and the target is closer then 6 inches away from the sensor.

     

    Best regards,

    Scott Wielenberg
    Technical Support & Sales
    of MaxBotix Inc.
    Phone: (218) 454-0766
    Fax: (218) 454-0768
    Email: scott@maxbotix.com

     

  • Tobias Halldin October 10, 2012 at 1:02pm

    I noticed this from the datasheet of EZL0:

    Each time after the LV-MaxSonar®-EZ0™ is powered up, it will calibrate during its first read cycle. The sensor uses this
    stored information to range a close object. It is important that objects not be close to the sensor during this calibration
    cycle. The best sensitivity is obtained when it is clear for fourteen inches, but good results are common when clear for at
    least seven inches. If an object is too close during the calibration cycle, the sensor may then ignore objects at that distance.

  • criro1999 October 8, 2012 at 6:28pm

    I would say sonar is checking objects which are not fix as distance. Your skids is fixed as reference to sonar and should not be considered. Maybe you need to do the sonar calibration.

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