Autonomous Senior Telemaster
I have just posted a youtube video showing my autopilot flying a senior telemaster. I included the take off and landing (both manually flown) because I thought it looked cool.
Here is the youtube link (I don't know how to embed the video here in the forum area.):
Here are a few details. Aircraft is a Senior Telemaster, electric powered. An 8000 mah (5 cell) battery yields 30+ minutes of flight if I slow cruise at 30 kts. The avionics are powered by a gumstix verdex running the main loop at 50hz. The IMU is a vector nav. We are running a 15 state kalman filter that produces a good estimate of roll, pitch, and yaw by combining the inertials with the gps data.
Recently I have been working on code to estimate the wind vector and true airspeed. I can use these estimates to plot stable up wind courses and roll out of my turns in time so that my ground track lines up with the target ground track (even in strong head winds or tail winds.)
As you can see from the windsock on the landing, the winds during this flight were gusting up a bit. On the next flight I was recording winds in the 14-16kt range at altitude. The aircraft was bouncing around more than the clip I show here, and at times I was crabbing more than 45 degrees to maintain my target ground track.
Replies to This Discussion
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Permalink Reply by Nathaniel Caner on -
Build it and they will come! :) Nice vid! I had my maiden with my Senior Telemaster today, all went well. I haven't installed the AP system yet, that will come this week. I also have a FlycamOne2 V2. This is probably the best video I have seen from the Flycamone2. Where do you have the camera mounted? Is it between the landing gear? It looks as though you might have it pointed down slightly, is this true? Can you post a picture of the way you have it mounted?
Looking good,
Nathaniel
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Permalink Reply by Curt Olson on -
Hi Nathaniel, thanks for the kind words. There's nothing magical with the camera mount. I taped it to the top of the left wing about halfway out (far enough to get clear of the prop since I didn't want that in the video.) I used electrical tape since that's what I had handy in my tool box. I did angle it down a bit since I was hoping to see more of the ground and less of the sky. I've untaped the camera now so I can't really get you a picture.
The way the camera naturally fits on the airplane, it makes the video upside down, so I puzzled out a combination of ffmpeg and mencoder that will rotate the video by 180 degrees (actually I do a flip + a mirror) and write it back out in a format that is usable. I also had to mess around and convert the 8 bit audio track since I then import into cinelerra to splice clips together and it doesn't like the raw flycamone audio track.
I'm not a video expert (obviously), but I've been experimenting a bit ... trying to find interesting/cool camera angles and trying to decide what kind of sequences work and what doesn't. I'm also trying to figure out what to include or not include (and how much) so the video isn't totally boring. Also it's interesting to see my flying skills (or lack there of) :-) from the airplane's perspective. It's maybe like an athlete reviewing a tape of their competition. You can look at what you do from a different perspective and see a lot of things that you wouldn't otherwise see or realize or even think about.
I'm also learning a bit about video editing with cinelerra which is a pretty cool non-linear video editing program. The only nit I have is that it crashes a lot ... I've learned to save after every operation ... some days it's that bad.
Here's a video I did a couple days ago that I thought turned out pretty decent ....
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Permalink Reply by jaron on -
Curt, the FlyCamOne² can record video and pictures rotated by 180°. If you've got a newer firmware and push the ON button a second time after the camera booted, the the display will be rotated and so will the recorded video.
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Permalink Reply by Nathaniel Caner on
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Curt,
After I posted my last comment I realized you probably had it mounted out on the wing. Ditto Jaron's comments get the updated firmware! Is that video editor a shareware/freeware? I read a reply you made to Jeremy's post about Pitot tube location. Q: you Telemaster is from a kit yes? I'm trying to figure out how to get the Pitot tube installed in the wing, it's an ARF remember. I actually have thought about making a false rib that would slide on the wing joiners between the Wing panels, it would have a pedestal that would protrude up above the wing to get the Pitot tube out of the airstream. This would allow me to have the functionality without modifying the wing. Might look a little strange though.
Ntahaniel
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Permalink Reply by Curt Olson on
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I'm not a pitot tube expert, but here's how I installed the pitot tube on my telemaster. I epoxied it to the bottom of the wing and then poked a small hole in the covering and ran the flexible tubing through the same channel as the servo wire.
I'm not convinced I have the best placement for the tube, but it's functional. Most installations I've seen have hung the pitot tube a short distance *below* the wing, not above, but I just glued the tube to the bottom of the wing.
This is the yellow senior telemaster ARF. The fuselage was crushed/damaged in shipping and I got bored waiting for the replacement so I just hacked away the covering and discovered it would pretty easy to fix. I couldn't match the yellow covering so I just redid the whole fuselage in red. I think it somehow adds to the old fashion feeling of the airplane. :-)
For my telemaster I put all my avionics guts inside, including gps and maxstream antennas. On the one hand it's kind of cool to have all sorts of bits outside the airplane ... looking like a wired up techno-porcupine, but on the other hand, it's kind of cool to have nothing outside the airplane. The only hint from the outside that this is any thing other than a basic RC airplane is the pitot tube subtly extending forward of the one wing. When your top speed can barely break 40 kts, it doesn't matter too much aerodynamically, but in my view the fewer things sticking out, the less chance of snagging a wire, or breaking off an antenna, etc.
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Permalink Reply by Nathaniel Caner on
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Curt,
Thanks for the photo, that looks like a good way to do it. Perhaps eventually I'll open a bay and install a plate to which I can attach a pod mounted pitot slung below the wing. Food for thought...
That's your active port, what did you do with the static port?
BTW I love the whole "techno-porcupine" description...very funny!
Nathaniel
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Permalink Reply by Curt Olson on
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Right now I'm flying the DIY drones analog pressure sensor so I've just left the static port open in the cabin.
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Permalink Reply by Curt Olson on
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@Nathanial: You asked "What is your experience with the wing struts on the Senior Telemaster. Do you fly with them installed? I haven't tried any loops or rolls yet,even with the struts...that's a pretty big wing!"
My thoughts are that if you fly gently, you shouldn't need the load struts. However, there is always the chance that you'll get knocked out of kilter from a wind gust, or get crossed up on the controls, or something goofy will happen with your autopilot and you'll end up at an odd attitude close to the ground and require and expedited high speed pull up. So with that in mind I think it's worth putting a little extra effort into completing the load struts. I would recommend following the instructions in the manual. However, I thought it would be fun to experiment a bit.
Here's what I did. I went to the hobby shop and purchased a 36" length of aluminum tube with a tear drop cross section. I cut this in half to make two struts. Then refer to the pictures below. I cut lengths of metal strips (brass?) chosen from stock that was just wide enough to fit inside the aluminum strut. Then I cut some hardwood blocks and glued them on each side of each strip as per the pictures. I sanded these blocks down to the inside shape of the aluminum tube so there was a nice tight fit. I glued these inside the ends of the struts (being careful to work out the over all final length of the strut.) Finally, not trusting metal on wood glue joints, I drilled a hole through the entire "sandwich" and pinned it, again securing the pin with a liberal amount of epoxy.
I see that I did this about 3 and a 1/2 years ago now, and after many many flights, the load struts are still holding up and solid.
I have to say that I never fly crazy with this airplane, but there was one day when my IMU gyros decided to misbehave and the acceleromter pulled my attitude solution to the correct value on the ground so I thought everything was good ... but in the air everything blew up and I ended up in a straight vertical dive towards the ground. I wasn't ready for this and ended up flipping every switch on my transmitter before I found the right one (the manual override!) so I indeed did an expedited high speed pull up that day and it sure looked like those poor wings really flexed a lot ... but she held together, I fixed the gyro problem, and life has been pretty good ever since.
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Permalink Reply by Nathaniel Caner on
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Curt,
You hit the nail on the head. It's those unintended departures from "normal" flight that worry me, not controlled loops and rolls (though I have been wary of trying this). I'm very comfortable with any maneuver in the book, but I look at the hard-points in the wing, and I just don't like the way they look. I've read some real horror stories about the hard-points failing, and the wind disintegrating mid flight. I guess I'll just have to place trust in the joints and allow personal experience to give me confidence in the system.
Regards,
Nathaniel
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Permalink Reply by Sonia Kouassi Eba Kaudjhis on -
Hi, Curt Olson , Thanks you for your demonstration I saw that it was great, I would like to ask some questions about your work on your UAV's controller
1 - How do you get 15 variables state of Filter of Kalman ? Did you do some manual tests flights to get datas from your aircraft and build control loops on matlab with these datas ? or Do you get a aircraft model from company which made aircraft ?
2- How do you build you Kalman filters ?
Thanks for your answers
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Permalink Reply by Curt Olson on
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Hi Sonia,
The 15 state kalman filter is a C version of the basic algorithm published in "GNSS: Applications and Methods" ISBN: 1-59693-329-1. The book includes a CD with a full matlab version of the filter. Unfortunately the C implementation that I've been working with has not been authorized for open-source release. I personally am not a kalman filter expert. The bulk of the work translating the matlab->C code was done by someone else. I'm learning though ... little by little (emphasis on little!)
I don't fully understand all your questions about the aircraft model. I have a very approximate dynamics model setup in FlightGear. I can use this allows me to prototype basic things and tune PID's to be in the approximate ball park of reality. I have a hardware in the loop system setup so I can run the actual autopilot controller on the embedded processor and test out most of my code using FlightGear as the standin for reality. But then eventually I go fly the real model and I carefully look at the resulting data and decide what control parameters to tune and by how much. I've found that replaying and visualizing the flight data is very useful. I've also started putting a camera on board at different angles looking at different control surfaces and that has been very eye opening as well. I personal don't use matlab in my work. I don't mind using commercial tools when they are available, (and I do some commercial software development of my own since I have to feed my family) but I tend to gravitate towards open-source solutions where ever I can.
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