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  1. #1

    Pablo, Land Art artist

    Pablo is a French autonomus rover using motors, sabertooth controller, GPS, odometer ... The goal is to draw large drawings on the French beaches.
    The mission is prepared before departure, the robot aims to trace the path on the sand with the help of a map, a GPS and sensors.

    General Specs
    Weight: 20 kg
    Dimension: width 50 cm x length 60 cm x height 60 cm
    Frame Material: Aluminium

    Hardware specs
    1 SaberTooth 2 x 32 Amps controler
    2 motors for the wheels
    1 12 volts battery
    2 odometres using arduino
    1 green pointer laser, rotating mirror and 1 webcam (work in progress)
    1 GPS
    1 compas HMC5883L

    Inside the robots
    arduino for odometers
    Laptop with batterie
    Joystick only for local moving

    Software
    Windows seven, C# Visual Studio

    I will describe the construction here.

    Last edited by Ulysse; 07-29-2016 at 02:58 PM.

  2. #2

    Re: Pablo, Land Art artist

    Oh, that's a neat idea!

  3. #3
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    Re: Pablo, Land Art artist

    Pretty sure I've heard of a bot doing this before, but still almost as cool as this little puffer fish.
    Please pardon the pedantry... and the profanity... and the convoluted speech pattern...
    "You have failed me, Brain!"
    bleh

  4. #4

    Re: Pablo, Land Art artist

    To prepare a plot, I first select the shape to draw in the sand. I chose the DXF format as it is wide spread and it contains vectors. later I can use another format.
    I then use an C# application to transform vectors in GPS coordinates. Just choose the scale, place the mouse on a map and just click.





    To be verified, coordinates are exported to a KML file that can be imported into Google maps. Pablo uses another file with more information to trace the shapes in the sand eg to raise and lower a tool like

    48,4450406781251 -2,08504594716869 False
    48,4450461265302 -2,08506101814332 True
    48,4450517909435 -2,08506631507817 True
    48,4450666555887 -2,08506418650572 True
    48,4451036193834 -2,08505440264829 True
    48,4451291246728 -2,08504492712652 True
    48,4451318136836 -2,08504202502935 True
    48,445129096546 -2,08503937794103 True
    48,4451265609555 -2,08503508080721 True
    48,4451263169431 -2,08502652944985 True
    ...

    Pablo can be brought close to the fields, he must continue alone. The serious work can begin !

    Last edited by Ulysse; 07-29-2016 at 03:00 PM.

  5. #5
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    Re: Pablo, Land Art artist

    This looks like lots of fun!

    I can't wait to see your first drawing
    01001001001000000100110001101111011101100110010100 10000001010010011011110110001001101111011101000111 0011

    My Instagram
    My YouTube

  6. #6

    Re: Pablo, Land Art artist

    Thank you for your support !

    Today we test odometry (video).
    The goal is to validate the measurement of distances with 2 odometrics sensors, one by wheel., the average of the two is calculated.
    Pablo has to travel a short distance of 8 meters in a straight line. At the same time the sensors give distance.
    At the end we compare the distance traveled and the value of the sensors.

    Click image for larger version. 

Name:	odo.png 
Views:	170 
Size:	208.4 KB 
ID:	6602

    Distance traveled : 8 meters
    Measured distance: 8.03 meters

    Approved !

    Now look at the results over a longer distance ...

    Last edited by Ulysse; 07-29-2016 at 03:02 PM.

  7. #7
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    Re: Pablo, Land Art artist

    Sand and grass are not pavement. It is quite likely that the wheels will slip frequently on sand, if those narrow wheels will even be able to support the bot without digging into the sand and getting bogged down. I suspect you will need to add a full AHRS/IMU like the Sparkfun LSM9DS1 breakout or the Adafruit BNO055 breakout to replace the plain compass module. There are several sensor fusion algorithms (the BNO055 has an on-chip ARM Cortex-M0 to do the sensor fusion for you) that would produce a rather accurate estimate of the orientation which can be combined with wheel encoder information and inertial measurements to produce much better odometry.
    Please pardon the pedantry... and the profanity... and the convoluted speech pattern...
    "You have failed me, Brain!"
    bleh

  8. #8

    Re: Pablo, Land Art artist

    Sand and grass are not pavement
    Thrue, crabs are at the beach and cow is in the field.
    Seriously, PABLO lost its battery (12 VDC ), so it is now connected to the mains by a power supply to continue to develop. The Adafruit BNO055 breakout is delivered this week.

  9. #9

    Re: Pablo, Land Art artist

    Et voilà
    Pablo is now equipped with an electronic compass.


  10. #10

    Re: Pablo, Land Art artist

    The chalenge of Pablo today : follow a programmed path and return to the starting point without using GPS.

    Not so bad. Small Errors are cumulative but nothing nasty, the final attitude will be different. Errors will be corrected in each segment by the real GPS coordinates.


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