@Murdanny_Mukhtar
Where you able to get your setup working? If not, I would be happy to check your flight log.
@lenorin
Have you run a test using the Land mode, instead of Loiter? If so, maybe it would be helpful if I could look at the flight log.
@samucs
The only way I think this can be accomplished with the standard firmware is if you are able to stop the landing procedure at 5 meters. However, off the top of my head, I am not sure if that is easy to do, or not.
Best,
Thomas
I donāt think the latest precision landing code will work without a rangefinder (sonar/lidar/etc.):
https://github.com/ArduPilot/ardupilot/blob/master/libraries/AC_PrecLand/AC_PrecLand.cpp#L154
It would be easy to test in the sim though.
@Anthony
If you are using a rangefinder, we strongly recommend the SF10/A (for now).
If you do not have a rangefinder, you can still test the precision landing feature with our previous firmware.
Arducopter_PL_Quad_3.3.3-rc2.px4
(Read more about the previous firmware here: https://irlock.readme.io/docs/firmwaresoftware-links)
@umbraclet16 @rmackay9 @lenorin @Murdanny_Mukhtar @Anthony
Just FYI: Here is the video of an RC5 precision landing test, again. Thanks, Stephan!
Thanks. I am really trying to find out what is the reason why it is not working with the Rc6.
Kind Regards,
Murdanny
Thanks. That is interesting. I have one lidar laying around somewhere. We test it out.
Kind Regards,
Murdanny
Hello, I wrote the precision landing code that is in master now. The previous code that I replaced āworkedā without a rangefinder but was not robust. It worked by assuming that the beacon is at the origin altitude and that the barometer hasnāt drifted, etc. If these assumptions were not true, it could cause the landing to go unstable and result in a crash.
With the inertial data fusion that precision landing has now, the height error would cause issues. I decided to remove the functionality. I have a longer term project to enable proper depth estimation, however it is not yet functional. It is theoretically possible to perform a precision landing with nothing but a camera and an IMU, but it requires very accurate timing of camera frames, an accurate intrinsic calibration on the camera, etc.
@jschall we fly sometimes fly with GPS RTK which provides a fairly accurate altitude fix. Much better than the standard GPS-corrected barometer altitude you get in a standard set up.
My question: do you think the GPS RTK quality of altitude work well with the mini-EKF filter in the precision landing guidance as a drop in replacement for the range finder? If that were the case it would be great to see that in future versions, as the vehicle gets a bit cramped (and expensive!) with all of these sensors. Additionally, it seems like GPS RTK is going to be an increasingly common hardware component for multirotors looking at the industry.
Send me a message and I would be happy to provide you with some logs that may be able to give you an estimate of āprecisionā of RTK versus range finder estimates.
Is there any chance that precision loiter will be implemented in Copter 3.4 or later?
Thanks, Stefan
Not for 3.4. Later releases can be, we are always looking for improvements. What is your idea behind it? A regular loiter but when it detects a beacon it stays on top of it?
Additional testing confirms that the Pixhawk is not able to power RFD900+, GPS RTK and associated radio, IRLock camera, Lightware SF11/C as well as standard GPS/compass. When all peripherals are connected none of them boot, which to me looks like a brownout. Might be able to power SF10/A, do not have one on hand for testing. However, as it stands, this might create a fundamental incompatibility in using IRLock + range finder vs GPS RTK.
Performed tests with powering off of BEC powered servo rail rather than standard pixhawk power, as well as turning radio power way way down to save energy. No positive results.
Exactly.
A precision loiter would be pefect to take off under problematic circumstances.
We offer inspection services with our copter, and so we often have to take off in urban areas with buildings nearby, but limited free space around the takeoff point. The typical backyard situation 
Precision landing makes life easier in this situations, a kind of precision loiter during takeoff would be perfect.
That looks normal to me, too much power required from Pixhawk. If I remember correctly, I saw someone say a few days ago that an RFD900 should be powered separately. Iām not a hardware guy, so Iāll be of little help there.
I would think that an RTK GPS would be better for your application as it should allow a better loiter accuracy throughout all your flight. You also might want to look at the WP_NAVALT_MIN parameter, it limits the navigation to a minimum altitude, but it only works in auto-takeoff and auto-landing (and by auto I mean not pilot controller, but can be Guided or Land mode for example).
RTK is not really the better alternative. We already use RTK, but in urban conditions with a lot of higher buildings around you, it is often quite difficult to get a stable RTK fix.
I did not mean to get us off topic discussing the applications and the pros and cons of the GPS RTK system, apologies.
Just meant to say that requiring both an RTK system and an IRLock Pixycam/laser range finder combo will be too much draw on the Pixhawk. I turned the RFD900+ power all the way down to like 30mW and it still did not work so donāt think powering the RFD900+ separately is the answer. If anything, powering the range finder saparely is the answer. However, this complicates harnessing substantially, and is frankly unecssary as the RTK altitude should theoretically be good enough. Although the latter remains to be proven, and this is more of a qualitative judgement.
@lenorin @fingadar
Regarding RTK altitude input: This is an interesting idea for the commercial precision landing applications with fixed landing stations (example shown below). In particular, I like the idea of setting the āaltitude offsetā based on the relative position of the landing platform and RTK GPS module. However, I am not exactly sure how accurate/reliable the RTK GPS altitude measurements are.