Mavlink region of interest (ROI) enum/ command

[James Goppert]

Currently we have a message named MAV_NAV_ORIENTATION_TARGET which
allows us to pass a desired heading to the vehicle based on a fixed
lat/lon/alt coordinate system. Several users have been asking for a
more general command that will allow us to point the vehicle towards
various regions of interest "ROI's" during the mission. I have
addressed this issue by adding an ROI enum:

<enum name="MAV_ROI">
<description> The ROI (region of interest) for the vehicle. This can be
be used by the vehicle for camera/vehicle attitude alignment (see
MAV_CMD_NAV_ROI).
</description>
<entry name="MAV_ROI_WPNEXT" value="0"><description>Point toward
next waypoint.</description></entry>
<entry name="MAV_ROI_WPINDEX" value="1"><description>Point toward
given waypoint.</description></entry>
<entry name="MAV_ROI_LOCATION" value="2"><description>Point
toward fixed location.</description></entry>
<entry name="MAV_ROI_TARGET" value="3"><description>Point toward
target of given id.</description></entry>
</enum>

In addition, i have renamed the existing MAV_NAV_ORIENTATION_TARGET to
MAV_NAV_ROI:

<entry name="MAV_CMD_NAV_ROI" value="80">
<description>Sets the region of interest (ROI) for a sensor set or the
vehicle itself. This can then be used by the vehicles control
system to control the vehicle attitude and the attitude of various
devices such as cameras.</description>
<param index="1">Region of intereset mode. (see MAV_ROI enum)</param>
<param index="2">Waypoint index/ target ID. (see MAV_ROI enum)</param>
<param index="3">ROI index (allows a vehicle to manage
multiple ROI's)</param>
<param index="4">Empty</param>
<param index="5">x the location of the fixed ROI (see MAV_FRAME)</param>
<param index="6">y</param>
<param index="7">z</param>
</entry>

Please give me your feedback on this change and let me know if it
meets all of your requirements. You can check out this change using:

git clone git://github.com/pixhawk/mavlink.git -b roi

-James

[Jason Short]

The problem with MAV_NAV_ORIENTATION_TARGET is that it was ill conceived in the scheme we have now. Nav commands block until they are verified. Do Now commands don't block. This command would interfere with navigation if sent interactively by the GCS. We could just ignore it and treat it as a do now command, but I was worried that it would be confusing.

So the thought is you would send an orientation command and target command separately?
Would I now need to implement a stored list of ROI targets to do orientation?
I would prefer to simply send :
MAV_CMD_DO_ORIENTATION: Yaw_Mode, altitude, lat, lon

The GCS would handle anything more complex such as ROI lists.

Thanks,
Jason

[James Goppert]

We have 7 parameters in the standard message. I think it would be a
waste not to make the command more general. The proposed structure
would be able to accommodate your message and a lot of other
possibilities.

I do agree that we should probably change it to MAV_CMD_DO_ROI as the
message has no condition and executes immediately. In my code I'm
evaluating the proceed condition on a per-message basis, are you
somehow evaluating it on the id range, or is this just a naming issue
with the CMD_DO?

Here is how the command would work for your example message:
mode: MAV_ROI_LOCATION
x,y,z: lat/lon/alt if you use MAV_FRAME_GLOBAL
the rest of the fields wouldn't matter for you

I think the confusing issue here was my wording on the ROI ID, this is
intended to allow your vehicle to have a camera 1, camera 2, turrets,
vehicle attitude etc. If you don't want to use that feature just pass
whatever you like and ignore the field. Another option,as you
suggested, would be to have an enum of commonly used objects.

-James

[Jason Short]

Yes, I look at the ID range to tell if it's a Do_now, Navigate, or Conditional. I think this was the intended procedure. And I think people want to read the name to understand what it is supposed to do.

OK, so let me know exactly how I would receive and parse the following pseudo command:

- Yaw towards a target (while flying) with these coordinates X, Y, Z

It's the last thing for me to finish the beta!

Thanks!
Jason

[James Goppert]

if (id==MAV_CMD_DO_ROI && msg.p1 == MAV_ROI_LOCATION)
{
 yawTargetMode = true;
 target.lat = msg.p5;
 target.lon = msg.p6;
 target.alt = msg.p7;
}

If that looks good to you let me know and I"ll commit the change to
the roi branch, i'll change the id to be at the end of the current do
cmd's.

[Jason Short]

If I want to clear that command and have the copter point towards the next Waypoint. How would I do that?
Jason

[James Goppert]

By the way, i think i'm going to make it MAV_CMD_DO_SET_ROI, ID: 201

if (id==MAV_CMD_DO_SET_ROI && msg.p1 == MAV_ROI_WPNEXT)
{
  yawTargetMode = false;
(or however you want to handle it)

[Jason Short]

OK,
I want to have a disable option. Maybe this is a better enumeration?

MAV_ROI_NONE 0
MAV_ROI_WPNEXT 1
MAV_ROI_WPINDEX 2
MAV_ROI_LOCATION 3
MAV_ROI_TARGET 4

Thanks,
Jason

[James Goppert]

Yeah, looks good. I'll push it up. In the apm code you'll need to
change my mavsim checkout script to git clone ... -b roi to get this
version. I'd push it to master but want to give everyone a few days to
have some input. Also, I think tridge was saying the raw_pressure
message would have to change or something like that, so be careful
there when you update the apm libraries.

-James