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
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
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.
Looking good,
Nathaniel