PX4 HITL + AirSim: No GPS Lock problem

[ibrahim-aydin]

I have been testing my algorithms using the v.1.2.2 tag branch until today. After seeing mr @clovett 's commits (12th Dec) I have decided to checkout to master to see if they solve some of my problems (Repeating Critical Navigation Failure and sensor data losses, freezing when AirSim is close and etc.). But unfortunately now AirSim neither does send GPS data nor it gets actuators from my Pixhawk2Cube. I think there is a problem with my old AirSim settings(.json) as the Pixhawk settings are now updated (params are added and all).

I am running on the following system:
Pixhawk2Cube + v1.9.2 fmu
Pixhawk and AirSim are connected through serial port (use_serial=true)
QGroundControl communicating to my Pixhawk through telem1 port (another direct mavlink instance, instead of the AirSim udp port)
A joystick with RC_IN_MODE = Virtual RC by Joystick

My settings are as follows:

    "Vehicles": {
    "PX4": {
      "VehicleType": "PX4Multirotor",
      "QgcHostIp": "127.0.0.1",
      "QgcPort": 14550,
      "ControlIp": "127.0.0.1",
      "ControlPort": 14560,
      "SerialBaudRate": 115200,
      "SerialPort": "*",
      "SimCompID": 42,
      "SimSysID": 142,
      "UseSerial": true,
      "UseTcp": false,
      "VehicleCompID": 1,
      "VehicleSysID": 142,
      "LocalHostIp": "127.0.0.1",
      "params": {
        "NAV_RCL_ACT": 0,
        "NAV_DLL_ACT": 0,
        "LPE_LAT": 47.641468,
        "LPE_LON": -122.140165,
        "COM_OBL_ACT": 1
                }
    }
}
}

[ibrahim-aydin]

I have checked if the problem can be reproduced using sitl. The problem is consistent only in the hitl case and gps is successfully sent from AirSim to px4_sitl

[lovettchris]

Did you build this version of AirSim and the Unreal environment you are using yourself or are you using pre-canned binaries from someplace?

[ibrahim-aydin]

I've built it them by myself on Ubuntu 18.04. I think I am misusing the settings but I could not figure out it yet

[ibrahim-aydin]

I have partially figured out the problem, I think the failure in passing sensor data to HITL is caused by one of the flags in MavLinkMultirotorApi: 98 -> if (sensors_ == nullptr || !connected_ || connection_ == nullptr || !connection_->isOpen() || !got_first_heartbeat_). This is applicable in SITL but not in HITL. As if-notting results a successful pass of sensor data but no actuators yet.

[lovettchris]

I accidentally broke the PX4 serial connection when I did the lockstep fixes. My very sincere apologies for the time you've had to waste on this, I thought I tested serial, but not well enough.

Can you try this fix: #2397

I tested this fix on Pixhawk2 cube since that is what you are using, QGroundControl installed PX4_FMU_V3, version 1.10.1 firmware.

[ibrahim-aydin]

Mr @clovett , thanks! Now the connection is okay but the sensors problem is insisting. The GPS and sensor data are not being sent yet. I have ammended the 98th line in MavLinkMultirotorApi.hpp as if ((sensors_ == nullptr || !connected_ || connection_ == nullptr || !connection_->isOpen() || !got_first_heartbeat_) && 0)
return;
as a workaround to this (so this line is disabled and has no effect at all) and now I can run my tests with no problems and better than before thanks to your fixes 👍