My new Easy Star switched from Auto to RTL mid flight but instead of flying home it nosed in. I am including the narrative of the event and events leading up to this as well as the log file. I hope someone can chime in and help me to identify the problem.
Yesterday, I performed two seperate one hour long Autonomous flights for the purpose of navigation tuning. The second flight was nearly flawless as I watched the aircraft continually hitch each waypoint and redraw the same blue line is it did the previous pass. So today flight had two purposes: verify that system consistancy and see if it will fly the same as did yesterday and carry an Eagle Tree e-logger to measure the current draw of the motor at different elevator trim positions for the purpose of finding the most efficient flight attitude.
I added the e-Logger and its GPS into the nose and added some tail weight to correct the CG. The flight started without issue. I launched in Manual, continued to climb out in FBW-A and then switched to Auto. The aircraft started hitting waypoints as it did the previous day. The elevator trim started at 20 clicks nose up. This is a common position I use for take off, sometimes more, sometimes less. I flew a few circuits and then started decreasing the up elevator trim by five clicks every 2 minutes.
The last trim adjustment moved the trim to five clicks nose up (from center). It continued from waypoint 1 to waypoint 2 and as it entered the right hand turn through waypoint to is when it switched to RTL, nosed over and maintained its turn all the way to the ground. The reported attitude exceeded the attitude limitations set in the configuration. Also, the dirt impacted in the nose supports the impact angle reported by the attitude indicator.
The good news is that even though the ground speed was 57 MPH at impact there is no repairs required to the airframe or other obvious damage to the electronics.
Upon returning to my shop I connected the aircraft battery and connected to it with the Mission Planner. All servos/linkage appear to be fine. The attitude indicator is slowly pitching and rolling to extreme angles while the aircraft is stationary in an aircraft stand. I powered down the aircraft and rebooted and all seems fine. I can't get the tumbling attitude indicator to repeat the issue. I tried to use the e-logger yesterday but it appeared to prevent the attitude indicator from reporting correctly so I didn't use it. My buddy was able to use it on his APM bird. So I retried today and it seemed to be okay. Could the e-logger be causing this issue?
Any help to identify this issue would be appreciated.
JJ
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I took it back out for a flight and all went fairly well with a few anomolies. For some reason, the flight control reactions were delayed and intermittant but they were fine when doing bench testing. Rebooting "everything" a few times did nothing so I reloaded the software. That seemed to fix it. But then I couldn't reverse the rudder/elevator as needed via the Radio Calibration screen. No matter what was selected it wouldn't reverse the channels consistently. I could reset to factory settings, reboot the aircraft, reboot the Mission Planner but it was extremely random. This has happened before to this system and the same happens with my friends.
I finally got it in the air and it fly well in all modes including RTL. I then sent it on its way in AUTO and clicked on the Set Home Alt button twice like I did on the fligth when it crashed. I then commanded RTL and it did as it is supposed to. I then put it back in AUTO, did a re-write of the Flight Plan and commanded RTL again and it performed as advertised. All is well, but I think I still have a Spektrum RX issues and I am getting a better solution in the morning.
Thanks to all who have helped on this.
After reviewing the log files, crash photos and inputs from the experts who gave their inputs on this thread, I believe I have narrowed down the cause of this crash.
Narrative: After 10+ minutes of autonomous flight, with no pilot input other than minor adjustments to the elevator trim the Mission Planner announced "Flight Mode RTL" and the aircraft rolled right, nosed down, maintained throttle and impacted the ground at 57 MPH.
Causal Factors: Review of the log files show that at the moment the incident began, all inputs from the Spektrum receiver stopped the output of all servo output pulses. Zero input on channel eight (Flight Mode Selection) of the APM would have commanded the APM to switch to RTL Flight Mode. This is comfirmed by the report from the Mission Plannner and review of the log files. The cause of this was likely a combination of the fuselage, internal wiring, aluminum trailer and the pilot's body all blocking the command signal between the R/C transmitter and receiver. By design, if the receiver looses the command signal it changes all output signals to zero.
When the aircraft entered RTL it did follow a logical flight path but did not maintain altitude. In fact, it descended very rapidly. It is likely that an erroneous RTL altitude was loaded which was below field elevation. The cause of this is unknown but there is a slight possibility that selecting the "Set Home Alt" button in flight may have induced this RTL altitude error.
PS: if you're otherwise happy with your EasyStar PIDs, we can post them in the config file repository. We don't have one for the EasyStar yet.
Looks like it was flying great until you finished the mission and it switched from auto to RTL. Anything funky about your "home" settings?
That's a nice pattern. Are those the stock PID settings?