Follow algorithm implementation for a UAV (PX4 firmware)

Posted by Anjum Shariff on November 12, 2016 at 12:48pm


I am pretty new to UAV's and everything related to it. I am working on a project where I have  to implement a follow algorithm for the UAV using PX4 firmware to follow a car(both the car and the UAV will have a GPS module). The communication between the UAV and the car is through a C2X module. MAVLink is used for the communication between GCs(qGround Control) and UAV. It would be really helpful if you could give any pointers on how to go about this.

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Tags: control, fmu, mavlink, px4, sitl, qground, simulation
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  • Anjum Shariff November 14, 2016 at 12:22am

    I apologise for not being clear with my question. I edited it. I hope it makes better sense now.

    For now, what I understand is that the follow algorithm can be implemented onboard on the Pixhawk. I haven't really understood about how the communication happens via MAVLink. Should I implement my module as a MAVLink message or does it need to be put somewhere else in the PX4 firmware?



    Clifton Hipsher said:

    So what we need to find out is the OP's definition of "car."  Is he talking about a full sized passenger automobile, or is he talking about a model and a "flight controller" that is running ArduRover firmware.

    As for his qGroundcontrol question, I don't have a clue.  I took a look at qGC, and found it did not suit my needs (I use an APM and a Pixhawk)...

  • Anjum Shariff November 14, 2016 at 12:17am

    Thank you for the reply.

    I am still a little unclear about the simulation part though. As of now, I do not use any hardware for the simulation. Does that mean I cannot test the follow-me mode this way.

    Just to give you a better understanding, I run the following command in the PX4 firmware

    make posix_sitl_default jmavsim

    I, then start the qGround Control. I am able to test most of the other modes this way.

    I am unsure if this isn't correct.

    Bill Bonney said:

    The 'follow me' functions in Mission Planner and Tower are GCS based. i.e. the Tower/MP calculate the next point for the drone based on the users GPS reported location and instruct the drone to move to a new location. You can implement the same feature onboard the vehicle. so the GPS only needs to report its location to the drone and the vehicle plans how it shall move and where. 

    There are advantages and disadvantages to both approaches ArduPilot is only working with GCS follow me at the moment.

    PX4 has an onboard implementation 

    Testing this in SITL requires you to feed control point from your GCS to the drone, and feed simulated user movements (GPX data point) to the GCS you are using.

  • Clifton Hipsher November 13, 2016 at 9:33am

    So what we need to find out is the OP's definition of "car."  Is he talking about a full sized passenger automobile, or is he talking about a model and a "flight controller" that is running ArduRover firmware.

    As for his qGroundcontrol question, I don't have a clue.  I took a look at qGC, and found it did not suit my needs (I use an APM and a Pixhawk)...

  • Developer
    Bill Bonney November 13, 2016 at 8:53am

    The 'follow me' functions in Mission Planner and Tower are GCS based. i.e. the Tower/MP calculate the next point for the drone based on the users GPS reported location and instruct the drone to move to a new location. You can implement the same feature onboard the vehicle. so the GPS only needs to report its location to the drone and the vehicle plans how it shall move and where. 

    There are advantages and disadvantages to both approaches ArduPilot is only working with GCS follow me at the moment.

    PX4 has an onboard implementation 

    Testing this in SITL requires you to feed control point from your GCS to the drone, and feed simulated user movements (GPX data point) to the GCS you are using.

  • Anjum Shariff November 13, 2016 at 5:25am

    Thank you for the reply. I tried to simulate the code using SITL. I am not able to use the 'follow me' mode in the qGround Control. Is that mode not available for simulation?

    Clifton Hipsher said:

    You are reinventing the wheel.

    A Pixhawk or an APM with a GPS and telemetry radios will follow either an Android device or a laptop.  Its called "Follow Me"..

    http://ardupilot.org/copter/docs/ac2_followme.html

  • Clifton Hipsher November 12, 2016 at 3:46pm

    You are reinventing the wheel.

    A Pixhawk or an APM with a GPS and telemetry radios will follow either an Android device or a laptop.  Its called "Follow Me"..

    http://ardupilot.org/copter/docs/ac2_followme.html

    Follow Me Mode (GSC Enabled) — Copter documentation
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