BOB4 - another autonomous indoor flight

Here is another autonomous flight. The UAV just tries to hold a fixed position.

Remember that this UAV is 100% autonomous with its own sensors (sonars + IMU + magneto).

The autonomous part of the flight begins at 0'09" and ends at 2'20".

I plan to take part to the IMAV2011 competition with it.

Do not hesitate to ask me question about it. 

Leon - French Hobbyist.

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  • On the AR Drone (another french drone! cocorico!) there is only 1 ultrasonic sensor. But this sensor is made with 2 ultrasonic tranducers: 1 for emission, and the other for reception. It is like the SRF04. The advantage of this configuration is that the sensor can measure very short distances (several cm).

    In my drone, I use SRF02 sensors, with just 1 transducers, because of the weight. Such sensor must wait that the transducer ends its forced oscillation (emission) before begining the reception of the echo. Therefore, it cannot measure short distances.


    Leon - French Hobbyist.

  • Moderator
    On my AR.Drone there are 2 ultrasonics, so I wonder why there are 2 right next to each other.
  • Wow, you have done a real good job with that long delay!


    I tried .net framework and I did not like it! I believe with more update, you will have almost completely stable!

  • @Patrice : It's one of the improvement that I plan to make.

    I already tried to measure several sonars at the same time, but I faced an issue: The ".Net Micro Framework" has a stupid limitation. You cannot use 2 I2C devices at the same time, and using 1 I2C device monopolize the I2C bus during more than 1ms. Therefore, 2 sonars cannot trigger exactly at the same time. If there is a delay of more than 2ms between 2 sonars, this can induce erroneous measures. 

    If the 4 sonars are triggered within less than 1ms, it works fine. I tried this with another microcontroler.


    I have got several ideas to solve this issue, but I have a lot of work to do on other subjects. I have a long "TO DO" list...


    Leon - French Hobbyist.

  • Sure you tried, but, all 4 in the same time or 2 opposite at the same time was not working?
  • There are 4 sonars on my UAV. All the sonars are not triggered at the same time. They are triggered one after another. I wait 50ms between 2 measures. Therefore, a single sonar is only triggered every 200ms.


    Leon - French Hobbyist.

  • Developer
    I didn't think that multiple sonar on a single quad/heli/whatever would work.  I thought they would interfere with each other.  Presumably you've had no problems like this?
  • wow, impressive, really impressive!
  • You can find a brief description of my UAV here:


    I use a custom Electronics based on an "Emedded Master" module + Sparkfun IMU.

    The UAV is based on a LAMA V3 (Esky) helicopter.

    Yes, it uses the walls to determine its position with the sonars.



  • What computing module & IMU does it use?

    Is it scratch-built or based on a coax heli kit?


    Is it using the wall for stability, or is it just lucky? :)

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