Over the last couple of days I have been testing the Lidar based auto-landing code that will be in the upcoming 3.1.1 release of APM:Plane. I'm delighted to say that it has gone very well!
Testing has been done on two planes - one is a Meridian sports plane with a OS46 Nitro motor. That is a tricycle undercarriage, so has very easy ground steering. The tests today were with the larger VQ Porter 2.7m tail-dragger with a DLE-35 petrol motor. That has a lot of equipment on board for the CanberraUAV OBC entry, so it weighs 14kg at takeoff making it a much more difficult plane to land well.
The Lidar is a SF/02 from LightWare, a really nice laser rangefinder that works nicely with Pixhawk. It has a 40m range, which is great for landing, allowing the plane plenty of time to lock onto the glide slope in the landing approach.
APM:Plane has supported these Lidars and other rangefinders for a while, but until now has not been able to use them for landing. Instead they were just being logged to the microSD card, but not actively used. After some very useful discussions with Paul Riseborough we now have the Lidar properly integrated into the landing code.
The test flights today were an auto-takeoff (with automatic ground steering), a quick auto-circuit then an automatic landing. The first landing went long as I'd forgotten to drop THR_MIN down to zero (I normally have it at 20% to ensure the engine stays at a reasonable level during auto flight). After fixing that we got a series of good auto flights.
The flight was flown with a 4 second flare time, which is probably a bit long as it allowed the plane to lose too much speed on the final part of the flare. That is why it bounces a bit as it starts losing height. I'll try with a bit shorter flare time tomorrow.
Here is the video of one of the Meridian flights yesterday. Sorry for missing part of the flight, the video was shot with a cell phone by a friend at the field.
Here is another video of the Porter flying today, but taken from the north of the runway
I'd like to thank Charles Wannop from Flying Finish Productions for the video of the Porter today with help from Darrell Burkey.
Comments
@mP1,
The 915MHz 3DR radios are setup for Australia. The Australian ISM band near 900MHz is from 915 to 928.
The mobile phone network uses frequencies below 915MHz.
Cheers, Tridge
Its seem the SF02 is out of stock at the moment. Does anyone know of a supplier source for this as I want to get one ASAP. Thanks.
Hi Gray,
We used the 3.3V ADC (the 5 pin DF13) and set RNGFND_PIN=13. We set RNGFND_SCALING to 12.12. We used the ADC as we don't have a spare UART on the Pixhawk (as we have two telemetry radios and have two GPS modules).
Cheers, Tridge
Hi Tridge !
Thanks for all your contribution for the benefit of the RC community. Hats off to you man !
I am in the flying field at the moment and just did a test flight using Arduplane 3.1.0, APM2.52, uBlox-6M GPS and Sky Eye EPO FPV/Glider w/Flaps 2000mm, compass disabled, sonar installed but disabled, airspeed sensor installed but disabled at the moment. With default parameters it did quite well in stabilized and auto mode.
Pls suggest If I can use sonar for auto landing. My APM is quite away from the large current carrying wires , should I try auto take off by enabling compass ?
I am also taking with me a high 70'' winger trainer with OS46 engine, if every thing went well I shall also give a try to that also.
Did you shared your telemetry flight logs at Droneshare ? Pls give link if yes and pls provide your parameters of your (Meridian sports plane with a OS46 Nitro motor)
@Gray,
Right now we don't account for terrain changes on landing approach. Small changes like drainage ditches won't be a problem as it does do some smoothing on the barometric->terrain correction value, but larger depressions will indeed make a big difference.
If the depression is big enough to show up in the SRTM terrain database then we could account for it using SRTM corrections (we don't do that yet though). If it's too small in size for that then we'd either need the pilot to setup an adjustment in the mission, or we'd need two rangefinders, one at 45 degrees in front and one straight down.
You are right that this is a real effect. The strip I've been using for testing has about a 4m dip on the Northern approach. The first landing came up short as it went down into this dip, then flared too early as the ground rose up. I just shifted the landing point a few meters along the runway to fix that (which meant the dip happened at a higher altitude, so it could handle it fine).
Cheers, Tridge
@Jack, plenty of things do go wrong, I just don't tend to write posts about them! For some photos of plane carnage see our photo site
@ausdroid, the code flown in these videos is in ardupilot git master now. I'll probably do a new release in a few weeks time. The SF/02 is connected to the 3.3V analog port on the Pixhawk, and is getting its power from that port (it's the 5 pin DF13 port).
@chris, just two GPS modules and the EKF. For the takeoff and final part of landing it just uses a summed gyro to hold constant heading
Hi Joe and Gisela
What about you? 66kgs is a big machine.. Is it still a tailwheel?
Sorry, I see your point. Didn't clarify that very well did I? Getting a aircraft both off the ground and back again down is the hardest part. Not least with a tail dragger that wants to ground loop. But hate giving a draggy nose wheel a free ride everywhere. So code just for tailwheel aircraft is even better. This is very impressive.
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