Posted by Koen Delvaux on December 27, 2008 at 9:06am
Today my autopilot hardware took the sky for the first time. Although this maiden flight was successful, its only a first step.
The primary goal of the test was to see if the autopilot failsafe mechanisms operated fine:- no lockup on division by zero- instant regain of control after brown-out causing reboot- no lock on uncaught interrupts- handover to servo failsafe positions on RC reception lost- instant regain of control when RC signal returns- no erroneous lockups in main state machine when rebooting whilst in flightAll mechanisms operated fine and none where triggered during normal flight. This proves the autopilot is a stable and reliable platform for airborne operation.Built in mixer test.The autopilot has a built in mixer. On first use you need to tell the autopilot what the channel and mixer arrangement of your transmitter/airplane combination is. To put the autopilot in calibration mode, switch on the transmitter, put all sticks in the center and switch channel 6 to "ON". Now turn on the airplane.At this point you can calibrate the autopilot by putting all sticks in the center and subsequently actuating the aileron stick from full left to full right and back to center, followed by elevator (fullup, then down, then center), rudder (left, right, center) and throttle (zero throttle, max throttle, center). The autopilot will confirm completion of the procedure by turning the rudder full left, then full right and then back to center. From this moment on, you can operate the airplane with the controls as normal, but the calibration values are not saved yet.The last step in calibration is to calibrate the IR sensor for horizon detection. You do this by holding the plane level (or even better: flying it, turn down the throttle and trim for a best glide scope) and switching channel 6 to "OFF". At this moment, calibration values for the transmitter arrangement and the IR sensor are saved to the permanent memory of the autopilot.When you now fly the plane and engage autopilot mode, the autopilot uses the same channel mix,offset and endpoint adjustment as you programmed in your transmitter.This all works fine. When you switch to manual control, channels are passed transparently. This also works fine.Only when using part automatic / part manual control (like when using the autopilot for stabilization alone and operating rudder/throttle manually), the manual controls don't have the same midpoint and endpoint settings than when in manual mode. This still needs to be looked into.I would like some feedback on the first-use calibration procedure. Do you think it is valuable to have support for random channel assignments/mixes/atv/trims? Do you feel the initial calibration procedure it too complicated?
I think you are completely missing the point, how ugly an aircraft looks is irrelevant , the fact is that paper tape is NOT strong enough to withstand any stress!! Temperature, moisture and surface contamination will seriously affect the adhesion, not to mention the speed of the wind picking away at the edges! I have seen practically every UAV made to date and NEVER seen anything like this, look for yourself, would you board an airliner if it was cobbled together with paper tape if the Captain assured you that it would " break upon impact " Please, get real.
You got a valid point.I can't argue with the fact that my method of fixing stuff to a plane for testing is ugly. But I did consider how to affix components to minimize stress in case of unwanted flight conditions (spiral dive, inverted flight, negative G's. The tape gives good adhesion to the elapor. Receiver and autopilot are "suspended" in the cockpit using the tape. ESC is mounted away from other electronics, power cables to not run next to signal lines. Camera is a non-critical component but is affixed with a second safety line nonetheless. Also, bear in mind that "rigid" often means prone to vibration and breakage on impact.
This paper tape is strong enough to withstand any flight stresses, yet weak enough to break upon impact.
I think that the most " valuable " thing you could do next is to properly secure those components to your plane! I have never seen anyone attempt to fly anything so dangerous, ever. Lash ups like this are accidents waiting to happen and affect us all. If we are to succeed here in Europe, or any where else in the world for that matter, we have to adhere to a basic level of engineering standards, in our business things can go wrong without invitation. I see some posts on here that contain photographs that are truly inspiring, people with respect for AIRWORTHINESS!
No, I also use the front/back part, but for this test I wasn't trying to test the stabilization part, so I just taped over the front/back sensors for ease of mounting.
I'm still playing with the stabilization algorithms. When I have more progress on those, I'll report back.
Currently I'm evaluation 1) proportional only, 2) PID and 3) a self-calibrating algorithm I have designed myself.
Comments
I think you are completely missing the point, how ugly an aircraft looks is irrelevant , the fact is that paper tape is NOT strong enough to withstand any stress!! Temperature, moisture and surface contamination will seriously affect the adhesion, not to mention the speed of the wind picking away at the edges! I have seen practically every UAV made to date and NEVER seen anything like this, look for yourself, would you board an airliner if it was cobbled together with paper tape if the Captain assured you that it would " break upon impact " Please, get real.
This paper tape is strong enough to withstand any flight stresses, yet weak enough to break upon impact.
I'm still playing with the stabilization algorithms. When I have more progress on those, I'll report back.
Currently I'm evaluation 1) proportional only, 2) PID and 3) a self-calibrating algorithm I have designed myself.