My UAV DevBoard Project
Hi,
My autopilot is the UAV DevBoard from Sparkfun. Mine is the "old" green board which is now superseded by this red board http://www.sparkfun.com/commerce/product_info.php?products_id=9038
I'm posting this in the hope that others will share their experiences of using this board.
It has worked perfectly and I have tested each firmware update as the designer, Bill Premerlani, has released it. It is installed in a Multiplex Twinstar which is powered by two standard Speed 400 motors. The model is quite stable, quite light and flies very slowly, so it doesn't handle wind or turbulence very well.
Although the PitchRollDemo program moved the pitch servos reasonably, at first the AileronCopilot program seemed unresponsive in pitch. I increased the PITCHGAIN from 0.125 to 0.25.
I am now using the AileronCopilot program and after each flight I adjust the control gains. When I have it returning-to-launch-point nicely I will extend the program to fly a route.
My walk around testing of the RTL function was unsatisfactory. The ailerons did something every two seconds and sometimes it was as expected. I thought it was better when I walked faster, so I tried it in the air.
The manual and stabilization modes have been good from the start. In the following video you can see the plane being buffeted by the wind just before I turn the stabilization on at 20 seconds.
At first the RTL mode was taking a very long time to turn the plane, so I reduced the ROLLKP from 0.25, first to 0.1875, then to 0.125 for the video flight. I will reduce it to 0.0625 before the next flight.
This is the 2 minute video of today's flight:-
http://s441.photobucket.com/albums/qq131/Electric_Brian/?action=vie...
The camera always points at the plane, so it not clear that the plane is about 300 yards upwind when the RTL mode is selected. The wind's speed is about 50% of the plane's airspeed, so it always ends up downwind after the turn. Most of the time the track corrections were OK, but once or twice I thought the corrections were too small and very slow.
My autopilot is the UAV DevBoard from Sparkfun. Mine is the "old" green board which is now superseded by this red board http://www.sparkfun.com/commerce/product_info.php?products_id=9038
I'm posting this in the hope that others will share their experiences of using this board.
It has worked perfectly and I have tested each firmware update as the designer, Bill Premerlani, has released it. It is installed in a Multiplex Twinstar which is powered by two standard Speed 400 motors. The model is quite stable, quite light and flies very slowly, so it doesn't handle wind or turbulence very well.
Although the PitchRollDemo program moved the pitch servos reasonably, at first the AileronCopilot program seemed unresponsive in pitch. I increased the PITCHGAIN from 0.125 to 0.25.
I am now using the AileronCopilot program and after each flight I adjust the control gains. When I have it returning-to-launch-point nicely I will extend the program to fly a route.
My walk around testing of the RTL function was unsatisfactory. The ailerons did something every two seconds and sometimes it was as expected. I thought it was better when I walked faster, so I tried it in the air.
The manual and stabilization modes have been good from the start. In the following video you can see the plane being buffeted by the wind just before I turn the stabilization on at 20 seconds.
At first the RTL mode was taking a very long time to turn the plane, so I reduced the ROLLKP from 0.25, first to 0.1875, then to 0.125 for the video flight. I will reduce it to 0.0625 before the next flight.
This is the 2 minute video of today's flight:-
http://s441.photobucket.com/albums/qq131/Electric_Brian/?action=vie...
The camera always points at the plane, so it not clear that the plane is about 300 yards upwind when the RTL mode is selected. The wind's speed is about 50% of the plane's airspeed, so it always ends up downwind after the turn. Most of the time the track corrections were OK, but once or twice I thought the corrections were too small and very slow.
Replies to This Discussion
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Permalink Reply by William Premerlani on -
Hi Scouser,
I sent you a message concerning your latest waypoint code, I am not sure if you received it:
Where you use atan2, it should be atan2( y , x ), not atan2( x , y ). Sorry about that, when I told you about atan2, I had the arguments reversed.
Bill -
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Permalink Reply by Scouser on -
Hi Bill,
I just got lucky, because I wanted degrees clockwise from North, when I put atan2( "opposite" , "adjacent" ) and converted from radians to degrees, it gave the right answer. I checked the maths with some trial values and my dummy fixes program.
Best Regards,
Scouser -
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Permalink Reply by Scouser on
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Hi again Bill,
I re-read your guide about the roll and yaw gains. After I increased the YAWKP to 1.0, I left it there and tried lots of changes to ROLLKP. I think that I need to tune the gains better before I make more radical change.
Best regards,
Scouser -
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Permalink Reply by William Premerlani on
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Scouser,
I agree that you should get the gains fined tuned before you dive into your waypoint code.
Yes, you got lucky with atan2( x , y ) producing angles that are clockwise from the north.
However, the variable desired_dir, which the control firmware uses to steer the plane, is measured counter-clockwise from the east. You adjusted for the east-north issue, but I do not think you addressed the clockwise, counter-clockwise issue. I could be wrong, but I think you better take a closer look at how you compute desired_dir, I don't think its right. It could be that you missed flipping a sign.
Bill
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Permalink Reply by Scouser on
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Bill,
Thank you for your patience.
You are right. Every time you have suggested this, I have looked at my test figures and not seen the error
I will correct this error and then concentrate on tuning.
Best Regards,
Scouser
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Permalink Reply by Scouser on
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Lost Model Aircraft
My Twinstar UAV model was lost in July. It came down in a built-up area where there are some well fenced vacant lots, so I assume that either the local kids got it or else it is lying somewhere I can't search.
I was testing a waypoint flying program and obviously I lost the plane because my program was faulty. However, I think that the main reason that I lost it was because I chose a waypoint that was too far away. The second waypoint was 500 yards downwind and the plane was circling around as if it might get the waypoint. Then a flock of pigeons flew between me and the plane and I lost sight of it. By the time they were gone the plane was too far away to see properly and over the built-up area.
I will get another plane and autopilot but probably not this summer.
Regards,
Scouser
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Permalink Reply by Angus McLeod on -
Link to 2-minute flight crashes every browser I've tried. YouTube?
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Permalink Reply by William Premerlani on
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Angus,
The last post from Scouser was in September, I have not heard from him since then. I suspect that the link is "stale", and the video is no longer there.
There has been a lot of other postings in the meanwhile, with videos. See for example, the blog postings of Bryan Cuervo.
Best regards,
Bill
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Permalink Reply by Scouser on
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Angus,
Scouser is alive and well. I have moved house (to Pembroke, on the South West tip of Wales).
I have an Easystar ready to build, and ordered a new UAV board yesterday. I couldn't get in to Sparkfun's Free Day. Their server was too overloaded, so I paid full price after the madness died down.
There is a lot to do in the new house but I hope to be flying as soon as the weather warms up. I am staggered by the progress that has been made with the board since last July.
Best regards,
Scouser
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Permalink Reply by Angus McLeod on
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I too spent 1h45m clicking "Try Again" during SFE's Free Day. When the madness passed, I paid full price for my order. It did NOT include a UAVDB, but it DID include a 50 Channel GS407 Helical GPS Receiver. While the UAV board looks good so far, I'm not 100% decided as yet as to whether it will work for me. I'm nearly finished reading all the posts on the discussion board and will make a comments/queries post of my own when I'm done.
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Permalink Reply by William Premerlani on
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Scouser,
As you may know, there has been a lot of progress since your last post. Waypoints are working, we now have provision for 5 PWM inputs and 6 PWM outputs, there is telemetry, support for many types of airframes, camera stabilization, etc. We even have provision to fly the plane upside down.
For more information, you might want to visit the project website and/or join the uavdevboard group.
Best regards,
Bill
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