Hi. If the inner loop runs at 40 Hz with dead reckoning you will get a position each 0,025 sec. If the craft's groundspeed is 300 km*h^-1 the flight computers navigation engine will get a position every 2 meters. It is within range to control a craft like this with DCM. See the Matrixpilot team / Premerlanis work on dead reckoning for some info.
Fair enough. I do not know the inner workings of the DCM either. The fast running PID loops with a lower rate DCM on top approach sounds like a sensible way to keep down the computational requirements.
John, there are lots of people here smarter than me on this subject, including the DCM inventor, Bill Premerlani There has been much discussion and research in the team around oversampling, undersampling, interpolation, and running direct-sampled PID loops at faster speed on top of the DCM. Indeed, that's implemented in the quad code. But it's all over my head, so I'll leave it to others to comment.
Chris: You mentioned DCM running at 70hz and that there is no reason to run it any faster. Is the sensors data also acquired at 70hz? What about the nonlinearity of sensor data? I am referring to the argument that higher refresh rates will give more accurate results when doing linear readings on nonlinear data. Not sure how it translated to the DCM algorithm, but for a normal gyro you get a much better heading hold if you read the sensor as often as you can (1khz+).
Needless to say, I was kidding about autopilot software not being able to keep up. Computer reaction times are almost always faster than humans (that's why the ArduPilot stabilization mode is so effective in improving your flying). The limiter for autopilots is usually the gyros, which max at out 600 degrees/sec. That's not a function of forward speed but acrobatics. If your plane can roll faster than twice a second, you can saturate the gyros in most hobby-class autopilots during aggressive acrobatics.
For what it's worth, I have heard that newer digital servos can respond to PWM signals faster than 50hz. I haven't tested that out myself, but something to keep in mind for future software and hardware designers.
@Taylor
on that kind of model you cannot put a lot of cherosene , at maximum speed do you have 4.5 minutes of flight ... is possible to put other kind of motor on BaioJet this model normaly mount a electric motor with 6S lipo pack ... so is possible to use this platform for different kind of test
In my case...it would definitely be the wallet that would kill me...and the parents that control my wallet..and my girlfriend lol. Thats one high tech device. I certainly hope it would be for that price :)
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I've seen rather many jet's but never this.. just plain sick it's like a pylon racer but with jet :P
on that kind of model you cannot put a lot of cherosene , at maximum speed do you have 4.5 minutes of flight ... is possible to put other kind of motor on BaioJet this model normaly mount a electric motor with 6S lipo pack ... so is possible to use this platform for different kind of test
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