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  1. A remotely controlled mapping device

    During the Christmas holidays, I took the time to work on the Agayon. I hope that the mechanical parts are almost finished and I will be able to focus on the code in the following weeks/months.

    Do as you’re told

    A few years ago, I have been gifted with a PS4 controller to play on my Retropie Setup. These are quality controllers but Sony does not like makers. My model cannot be used with vanilla bluetooth drivers on my Pie. And for unknown reasons, the alternative driver ds4drv does not works for me. I purchased a 5m USB mini cable to not disappoint my lovely niece and nephew. They can plan with Supertuxkart for hours. But it's not the subject of this article. I plan to use the Agayon not only in my apartment but also to go on tour with it ! (let's dream a bit). Unfortunately, it is already quite heavy and it could be cool to drive it from my door to the car. I could dream again and imagine a system where it recognize me after a little bit of training like a dog or a case. It seems possible but why not use the controller at first. It should be easier and quick to implement. Moreover, the kids and friends seems to love the idea. So let's do it ! I will keep you updated when it is reliable and easy to use.

    Back to the future remote Photo credit: Back to the Future (1985)

    Re-verify our range to target... one ping only

    I have finally mounted the Lidar on the Agayon. The Raspberry Pi 2 was too slow to handle the data but the Pi 4 does well the job.

    Mounted lidar

    My living room

    The following animation has been made with the animate.py script from the RPLIDAR repository. lidar animation polar coordinates

    Streaming

    Last year I discovered the Raznot project and it inspired me. According to the readme, the RazTot is an easy DIY project which allows you to remotely control a roving security camera securely from your browser. After some tests, I decided to not use this project because the flask server and interface would not so nicely integrate with my R1D3 base code. I only use Janus Janus, a general purpose WebRTC server to stream from the robot in a generic web page for now. Unfortunately, my Microsoft LifeCam Studio does not produce a stream compatible with Janus. I need to transcode the MPEG-4 video stream to H264 with ffmpeg to see it in a browser. I hope to be able to release the code in the following weeks.

    More to come, stay tuned !

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  2. The rise of the machine

    Hurrah !

    After months of work on the Agayon, I can present some significant improvements ! This article is a little bit longer than the previous ones but it worth the read!

    Software updates !

    During the past few weeks, the code base of the Agayon has been updated. I forked my own project, r1d2 to update it. The new repository is named r1d3. I hesitated a long time before forking it. As the hardware base of the Agayon completely changed, I preferred to change the code name to maintain coherence between hardware and software.

    The update aims to provide

    • Python 3 support only
    • OpenCV 4 support for
      • Face recognition
      • Sign tracking
      • Face/hand detection and tracking
    • Better XMPP ad hoc support
    • I2C support
    • Hardware switches support.

    XMPP Ad hoc commands

    As I made tests with SLeekXMPP to control the bot, I observed some problems with Gajim. The Ad-Hoc extension allows one to send commands to an XMPP bot. R1D3 displays the following menus and submenus (in french):

    menu1 menu2 menu3

    When I try to use the "execute" button, SleekXMPP start a new session and Gajim complains that the session identifier has changed. I reported the problem to SleekXMPP and its fork SliXMPP. The XMPP community is great and Maxime Buquet responded quickly. To quote him, there are two problems (see the bug report for the whole explanations):

    • Slixmpp shouldn't assume execute is the start of a command
    • I don't see a place in the XEP that says that next or execute can be equivalent to complete. What to do?

    He sent an email on the "Standards" mailing list and some responses followed. It seems difficult to fix the protocol at the moment without breaking compatibility. Maxime proposed a patch to fix Slixmpp and it should work on SleekXMPP. For now, I just don't use the "Execute" button as "Forward" does the job. The depreciation of the "Execute action" is actually discussed.

    New hardware !

    The Agayon has now 8 LEDs and 6 switches. They are placed on a control panel.

    The LEDs aim to provide status information

    • 5V power (orange)
    • Pi powered up (green)
    • I2C on the Arduino (green)
    • I2C + serial on the Pi (green)
    • Serial communication (green, Arduino)
    • Video capture (red)
    • Internet connection (blue)
    • LIDAR mapping (red)

    The switches aim to provide

    • Power on (12V) (Ebay)
    • Start R1D3 (MCHobby)
    • On/Off Demo mode (Arduino) (Ebay)
    • On/Off Power down (Pi) (Ebay
    • Emergency stop (cut Arduino power) (Ebay)
    • Movie recording (Pi)

    In addition, the following hardware are also mounted to provide information and input/output. I2C addresses are displayed (0Xxx)

    The documentation of the SHT71 explains why the sensor has no I2C adress.

    The serial interface of the SHT7x is optimized for sensor readout and effective power consumption. The sensor cannot be addressed by I2C protocol, however, the sensor can be connected to an I2C bus without interference with other devices connected to the bus. Microcontroller must switch between protocols.

    One ground to rule them all

    I have been advised to use an epoxy base coated with a copper layer. The aim is to connect it to the negative pole of the battery. It is really useful because it decrease the wiring. The perfboards are fixed on metallics spacer bars to avoid shortcuts.

    plate1

    I2C Scans

    I²C is a bus communication that allows multiple device to communicate with each other.

    I2C devices are recognized by the Arduino (5V) and the Raspberry PI (3.3V) with the help of a level shifter.

    I've used the I2C scanner provided by the Arduino documentation.

    Arduino

    Scanning...
    I2C device found at address 0x1D  !
    I2C device found at address 0x20  !
    I2C device found at address 0x6B  !
    I2C device found at address 0x70  !
    done
    

    Raspberry PI

    user$ i2cdetect -y 1
         0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
    00:          -- -- -- -- -- -- -- -- -- -- -- -- --
    10: -- -- -- -- -- -- -- -- -- -- -- -- -- 1d -- --
    20: 20 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
    30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
    40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
    50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
    60: -- -- -- -- -- -- -- -- -- -- -- 6b -- -- -- --
    70: 70 -- -- -- -- -- -- --
    

    Gallery

    "Scaffolding" with hot glue

    During the past few months, my best friend has been my hot glue gun. I was skeptical at first but really much effective and fun. I used it to insulate some connectors. In Liège, we would say "mettre une noquette de colle" which translates to "put a knob of glue".

    glue1 glue3

    capot2 capot3

    Evolution of the frame

    full_base connection_base_capot

    complete_1

    complete_3 complete_4

    • A : Battery
    • B : Level shifter between Arduino (5V) and Raspberry Pi (3.3V)
    • C : Arduino Mega
    • D : Power lines and I2C (12V, 5 V, 3.3V, SDA 5V, SCL 5V, SDA 3.3V, SCL 3.3V)
    • E : Raspberry Pi (in his case)
    • F : Buttons and their pull down (3.3V or 5V depending on the GPIO)
    • G : LEDs

    New (old) Oscilloscope

    One of my colleague has been cleaning his lab, and he asked me if I was interested to have an old 20 MHz oscilloscope. I gladly accepted. It is a 34 years old Circuitmate 9020 (bought in 1985). I will use it for I2C debugging and visualization. oscillo

    Conclusion

    The hardware is almost done. I am happy to have a nice reliable base. I hope to be able to drive it with my smartphone soon. I will continue the programming to add the mapping functionality and a nice demo mode.

    Stay tuned !

    smile

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  3. Where is Charlie (part 3)

    Previously on agayon.be, I mentioned a new small project: a SLAM device.

    It was finished recently and this article presents its final form.

    After many trials, the chosen design includes an optical rotary encoder disk with 360 teeth in order to provide a theoretical resolution of one degree. The Arduino code sends the data through serial connection in a compatible way with the xvlidar library. Therefore, the lidar module can be used with the BreezySLAM module of Simon D. Levy. Moreover, the data are being sent through XMPP to another computer where the map can be plotted.

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