POSITION_TARGET_GLOBAL_INT is never sent by Arducopter despite being requested using SET_MESSAGE_INTERVAL

arduouspilot · November 5, 2021, 6:30pm

I was thinking it would be nice to get confirmation that the drone has received my MAVLINK_MSG_SET_POSITION_TARGET_POSITION message to send the drone to a particular location. I request that message using MAV_CMD_SET_MESSAGE_INTERVAL in my start up code.

Unfortunately, I never receive the MAVLINK_MSG_ID_POSITION_TARGET_GLOBAL_INT which I was expecting to get. This would hopefully tell me that the drone had updated its target to fly to.

I had a look at the Arducopter source code and found this in GCS_Mavlink.cpp:

void GCS_MAVLINK_Copter::send_position_target_global_int()
{
    Location target;
    if (!copter.flightmode->get_wp(target)) {
        return;
    }
    mavlink_msg_position_target_global_int_send(

We also have this in mode_guided.cpp:

bool ModeGuided::get_wp(Location& destination)
{
    if (guided_mode != Guided_WP) {
        return false;
    }
    return wp_nav->get_oa_wp_destination(destination);
}

So far it looks like I should be receiving it. How can I know where the drone is flying to?

Thanks.

hendjosh · November 7, 2021, 4:18am

What version of copter is this?

Would please post a TLog and a Bin Log?

I quite sure you should automatically receive that message as it is part of a stream. (Setting the message interval should be unnecessary unless you want to change the rate of the message.)

arduouspilot · November 7, 2021, 6:32pm

I’ll post the log tomorrow. Thanks.

arduouspilot · November 10, 2021, 12:40pm

@hendjosh

Please find my log here:

The password for the zip is simply my username.

I would like to add that I found my code had a mistake so it did not explicitly request the MAVLINK_MSG_ID_POSITION_TARGET_GLOBAL_INT message, however based on what you said, I should be seeing this message regardless.

Many thanks.

hendjosh · November 10, 2021, 7:07pm

Hmm. There is only one GUID log message there. So you only tried to set the guided mode once.

What exactly are you sending over mavlink? Type-mask is extra important.

Do you have a tlog?

hendjosh · November 10, 2021, 7:10pm

It seems that the message will only get sent out for sub modes WP and POS.

Note I have a PR to fully support Position_Target_Global_Int message.

github.com/ArduPilot/ardupilot

GCS_Mavlink: move send_position_target local & global up, Add these to Sub

ArduPilot:master ← hendjoshsr71:pr/move_local_global_pos_target_up

opened 01:46AM - 05 Sep 21 UTC

hendjoshsr71

+587 -272

This moves `send_position_target_global_int()` & `send_position_target_local_int…()` up into GCS_Common `send_position_target_global()` - Adds TypeMask output dependent upon control mode - Adds output of Accel & Velocity dependent upon mode Sub: Based on request in Discord it adds `send_position_target_global_int()` & adds `send_position_target_local_int()` ~~I choose to place the top level virtual helper functions for moving these into AP_Vehicle as they were similar to helper functions there being used by scripting already. But they might be better placed into GCS.~~ Note: This builds upon PR https://github.com/ArduPilot/ardupilot/pull/17344 and uses some of its commits Typemask Settings per vehicle & mode: This needs triple checking per mode. Most of the testing has been on Copter besides the Sub addition. Autotest changes: Terrain portion of this is not working yet. I'm getting issues with mavproxy's ElevationModel.GetElevation() and AP_Terrain::height_amsl() differing by many meters for the same location. Autotest TODO: Cover all the possible available guided modes right now we test them separately but all of the combinations

arduouspilot · November 10, 2021, 9:15pm

It was doing a takeoff to 10m followed by ascent to position target another 5m up and finally an attempt to set an attitude target. To be honest, there was only one position+yaw target set (with type mask set to only allow position i.e. POSITION_TARGET_TYPEMASK_VELOCITY_IGNORE | POSITION_TARGET_TYPEMASK_ACCELERATION_IGNORE | POSITION_TARGET_TYPEMASK_YAW_RATE_IGNORE) but still I did not see the Position_Target_Global_Int messages.

Thank you for your work on that pull request. It makes sense to have it enabled during GUIDED mode, especially since you can request position targets so why not receive confirmation of them?

I know that it is possible to receive POSITION_TARGET_LOCAL_NED when in GUIDED mode, for instance, so your pull request makes sense.

Cheers.

hendjosh · November 11, 2021, 9:56am

Are you able to receive the POSITION_TARGET_LOCAL_NED messages if you request them?

Possibly, the reason you aren’t getting that message is that terrain data is still pending download and thus is not available to convert the altitude frame. This means we don’t send Position_Target_Global_Int messages. Not 100% on this though as I can’t replicate the behavior in SITL.

Maybe try ensuring the terrain data is available by downloading it from the server for your locale?

github.com

ArduPilot/ardupilot/blob/00da3520bc76b098a941466e842b287df424266e/ArduCopter/GCS_Mavlink.cpp#L87-L90

    
      
          // convert altitude frame to AMSL (this may use the terrain database)
          if (!target.change_alt_frame(Location::AltFrame::ABSOLUTE)) {
              return;
          }

My PR is just to fill out the data set further. I might follow-up with a PR to ensure for example in takeoff we send and log the targets which doesn’t seem to be occurring.

arduouspilot · November 11, 2021, 12:17pm

My code is basically this:

    com.param1 = (float) MAVLINK_MSG_ID_POSITION_TARGET_LOCAL_NED;
    com.param2 = (float) 500 * 1000;
    if(send_command(&com) != 0)
        return -1;

    com.param1 = (float) MAVLINK_MSG_ID_LOCAL_POSITION_NED;
    com.param2 = (float) 500 * 1000;
    if(send_command(&com) != 0)
        return -1;

    com.param1 = (float) MAVLINK_MSG_ID_GLOBAL_POSITION_INT;
	com.param2 = (float) 250 * 1000;	// us between messages
    if(send_command(&com) != 0)
			return -1;

	com.param1 = (float) MAVLINK_MSG_ID_POSITION_TARGET_GLOBAL_INT;
	com.param2 = (float) 250 * 1000;
    return send_command(&com);

With my drone sitting on the ground unarmed, I only get MAVLINK_MSG_ID_GLOBAL_POSITION_INT and MAVLINK_MSG_ID_LOCAL_POSITION_NED messages. Do I need to be in GUIDED mode or flying to get the POSITION_TARGET messages?

Thanks.

arduouspilot · November 12, 2021, 11:08am

The type-mask is set to POSITION_TARGET_TYPEMASK_VELOCITY_IGNORE | POSITION_TARGET_TYPEMASK_ACCELERATION_IGNORE | POSITION_TARGET_TYPEMASK_YAW_RATE_IGNORE

I do not have a tlog as I am not using Mission Planner to control the drone.

I think it’s best that I repeat my tests with an explicit request for the position targets as by default it does not seem to work. I’ll post here with updates.

Thanks for your help.

arduouspilot · November 12, 2021, 6:18pm

I had a look at but it seems you only need terrain data if the TERRAIN_ENABLE parameter is set to 1.

hendjosh · November 12, 2021, 6:31pm

You had terrain_enable set to 1 in your log that I reference where you are unable to download terrain data.

arduouspilot · November 12, 2021, 6:43pm

Ah! Guilty I am then! Sorry.

I will disable it and do some flight testing next week.

hendjosh · November 12, 2021, 7:01pm

Yes, you must be in GUIDED to get POSITION_TARGET_LOCAL messages.
POSITION_TARGET_GLOBAL_INT is available in other modes RTL (all submodes but Landing), Smart_RTL (similar to landing), Auto, Follow, and Guided (when in WP mode, Pos control mode)

Have you tried using your code in SITL?? That is what I would do next.

arduouspilot · November 12, 2021, 7:23pm

I’ve never used SITL before but I’ll give it a try.

arduouspilot · November 24, 2021, 11:17pm

Okay, I did some more flying today and it seems that MAVLINK_MSG_ID_POSITION_TARGET_GLOBAL_INT must be explicitly requested. At least that is what I am seeing in GUIDED mode. I do get the message when I ask for it.

I am potentially seeing a discrepancy in the position target fields vs what I request. This may be an issue with float truncation maybe. I’m not sure yet.

arduouspilot · November 25, 2021, 4:28pm

Okay, I found the problem. I was requesting a position target of x,y,z and also yaw. BUT:

POSITION_TARGET_GLOBAL_INT does not return the yaw. In my situation for example, it sets the type mask to:

MAVLINK_MSG_SET_POSITION_TARGET_POSITION |
MAVLINK_MSG_SET_POSITION_TARGET_VELOCITY |
MAVLINK_MSG_SET_POSITION_TARGET_YAW_ANGLE |
MAVLINK_MSG_SET_POSITION_TARGET_YAW_RATE

but it only tells you the x, y, z. IMO this is a bug. Should I raise an issue do you think?

hendjosh · November 25, 2021, 5:45pm

Yeah that it partly what my PR above is trying to address in regards to the reporting in guided mode. *Though i still have to add the yaw bit though that shouldn’t be too bad.)

Right now the output from the message is quite limited.

I think there is an issue for it somewhere just having trouble finding it.

arduouspilot · December 23, 2021, 7:08pm

I have recently discovered what appears to be a small bug with the Arducopter POSITION_TARGET code.

With SITL, if I set a position target with SET_POSITION_TARGET_POSITION of:
6193715 -23766382 20.360001
lat_int lon_int alt
int32 int32 float

I receive a POSITION_TARGET_GLOBAL_INT message with:
6193716 -23766381 20.359999

Something in Arducopter is slightly corrupting these values. Using a real drone, I see a difference as follows:

Was looking for 2897889 57051 29.790001
but saw 2897889 57051 29.789999

I am investigating why this happens and hopefully I’ll find the bug.

arduouspilot · December 24, 2021, 4:40pm

I submitted an issue here for anyone reading:

https://github.com/ArduPilot/ardupilot/issues/19607