how to control vehicle to takeoff in offboard via VehicleCommand::VEHICLE_CMD_NAV_TAKEOFF?

[xiaobai-cai-hold]

trafficstars

I find that someone control vehicle to takeoff in offboardcontrol.cpp by using (publish_offboard_control_mode() publish_trajectory_setpoint(0.0, 0.0, 2) ).

however , I found VehicleCommand::VEHICLE_CMD_NAV_TAKEOFF in vehiclecommand.msg, I am confused ,why not use it to control vehicle to takeoff?

I test this command by using the following code , I failed in gazebo, how to use VehicleCommand::VEHICLE_CMD_NAV_TAKEOFF to takeoff?

  void OffboardControl::publish_takeoff_from_local_position() const
  {
      VehicleCommand msg{};
      msg.timestamp = timestamp_.load();
      msg.param1 = 0.0;//pitch
      msg.param2 = NAN;
      msg.param3 = NAN;
      msg.param4 = NAN;//yaw
      msg.param5 = this->lat;
      msg.param6 = this->lon;
      msg.param7 = this->alt +20;
      msg.command = VehicleCommand::VEHICLE_CMD_NAV_TAKEOFF;
      msg.target_system = 1;
      msg.target_component = 1;
      msg.source_system = 1;
      msg.source_component = 1;
      msg.from_external = true;
  
      vehicle_command_publisher_->publish(msg);
  
  }

I am a student ,first to touch this ,can you provide some instruction to help me learn to control vehicle via ros2? thanks

[xiaobai-cai-hold]

At first I make the vehicle to work offboard mode , I send

publish_vehicle_command(VehicleCommand::VEHICLE_CMD_NAV_VTOL_LAND) or publish_vehicle_command(VehicleCommand::VEHICLE_CMD_DO_SET_MODE,1.0, 4.0,2.0)

the vehicle in gazebo can land successfully.

According to the way I send this command

publish_vehicle_command(VehicleCommand::VEHICLE_CMD_NAV_VTOL_TAKEOFF)

however it dosen't takeoff , a little upset.

[TheSpecialOne45]

Hi @xiaobai-cai-hold !

I'm reviving this thread as I have the same problem, were you able to solve it in the end (taking off using ROS2, without using the offboard position mode) ?

[AumJasani]

I tried to do the same thing but I haven't found any success. I found that if the vehicle is in OFFBOARD MODE, the VEHICLE_CMD_NAV_TAKEOFF won't work. But, even if it is not on offboard mode, I am getting this message WARN [navigator] Already higher than takeoff altitude and the vehicle disarms it self after spinning the props for 1 or 2 secs.