Set Target Position Return Value

majorpr13 · June 16, 2018, 10:57pm

Does the SET_POSITION_TARGET messages return any value or acknowledge the command? I am sending the command and the vehicle in simulation responds accordingly, however, I do not receive a MAV_RESULT_ACCEPTED or anything of that nature.
Thanks.

peterbarker · June 17, 2018, 6:56am

Does the SET_POSITION_TARGET messages return any value or acknowledge the command? I am sending the command and the vehicle in simulation responds

It does not. MAV_RESULT_ACCEPTED related to mavlink commands, not
mavlink messages generally (FWIU).

accordingly, however, I do not receive a MAV_RESULT_ACCEPTED or anything of that nature.

Your best bet is to monitor the POSITION_TARGET messages.

Yours,

majorpr13 · June 19, 2018, 3:02am

I set up my software to listen for the position target messages (both global/local variants just to be sure) and I am not seeing them fire at all. I am currently running this through the simulation. Can anyone confirm that these messages are indeed reported when streaming the set_position_target commands to the autopilot?

majorpr13 · June 19, 2018, 3:20am

While interestingly it appears that the GCS common implements a call only to the global target as seen below

case MSG_POSITION_TARGET_GLOBAL_INT:
    CHECK_PAYLOAD_SIZE(POSITION_TARGET_GLOBAL_INT);
    send_position_target_global_int();

and both arducopter and arduplane overload the imposed virtual function from gcs_mavlink, however there never appears to exist a case MSG_POSITION_TARGET_LOCAL_NED to perform the callback. So far I have only been testing in the LOCAL NED frame. I will check tomorrow but I believe this is the root cause of why I am not seeing the message as it has yet to have been implemented.

peterbarker · June 19, 2018, 3:57am

While interestingly it appears that the GCS common implements a call only to
the global target as seen below

case MSG_POSITION_TARGET_GLOBAL_INT:
CHECK_PAYLOAD_SIZE(POSITION_TARGET_GLOBAL_INT);
send_position_target_global_int();

This is the send-side; this is sending the GCS the current position target
in global frame.

MSG_POSITION_TARGET_LOCAL_NED to perform the callback. So far I have only
been testing in the LOCAL NED frame. I will check tomorrow but I believe
this is the root cause of why I am not seeing the message as it has yet to
have been implemented.

github.com

ardupilot/ardupilot/blob/master/ArduPlane/GCS_Mavlink.cpp#L1475


      
          #endif
              return 0.01 * (global_position_current.alt + plane.altitude_error_cm);
          }
          
          uint8_t GCS_MAVLINK_Plane::high_latency_tgt_heading() const
          {
              // return units are deg/2
          #if HAL_QUADPLANE_ENABLED
              const QuadPlane &quadplane = plane.quadplane;
              if (quadplane.show_vtol_view()) {
                  const Vector3f &targets = quadplane.attitude_control->get_att_target_euler_cd();
                  return ((uint16_t)(targets.z * 0.01)) / 2;
              }
          #endif
                  const AP_Navigation *nav_controller = plane.nav_controller;
                  // need to convert -18000->18000 to 0->360/2
                  return wrap_360_cd(nav_controller->target_bearing_cd() ) / 200;
          }
          
          // return units are dm
          uint16_t GCS_MAVLINK_Plane::high_latency_tgt_dist() const

That’s where you can set the position target in local NED

You are absolutely correct - surprisingly, we don’t actually send out
POSITION_TARGET_LOCAL_NED messages!

Peter

majorpr13 · June 19, 2018, 11:00am

@peterbarker Shall I create a github issue for it?

peterbarker · June 19, 2018, 11:14am

Please do. It’s something we should do once we have the message-intervals
PR in.

majorpr13 · June 19, 2018, 11:38am

Github issue has been created. For those looking to have a record trace, the github issue can be found here. https://github.com/ArduPilot/ardupilot/issues/8686

majorpr13 · June 19, 2018, 5:20pm

@peterbarker is there a way to confirm that POSITION_TARGET_GLOBAL_INT is even being transmitted?
I am sending the SET_POSITION_TARGET_GLOBAL_INT command at the required interval and not seeing this being advertised.

peterbarker · June 20, 2018, 3:05am

I implemented the sending of POSITION_TARGET_GLOBAL_INT in Copter less
than a month ago - it probably isn’t in the 3.6 betas.

Are you in a position to try master?