Hi all,
We tried an autonomous takeoff with a V-tail plane and it was quite successful. The vehicle then started to perform the mission that I drew in auto mode. However, as can be seen from the screenshot, it suddenly entered and exited RC failsafe. In the meantime, I think it tried to enter circle mode due to short failsafe, but then it returned to auto mode because the RC connection was reestablished, and since this happened several times, it lost its balance and crashed.
First of all, the vehicle’s PID values ​​were not autotuned (we planned this flight for this, but it crashed before we could autotune it), so its parameters are not good. However, there seem to be problems with airspeed in the vehicle’s general behavior. Adjusted cruise is 18 m/s.
In light of all this, I am curious about your thoughts on the problems in the vehicle and the crash.
I have no logs.
Screenshot mission planner:
flight video: flight - Google Drive
Params: params.param - Google Drive
Thank you
Do NOT use automatic and assisted flight modes before completing autotune.
IMHO something is wrong with your RC, you shouldn’t have unreliable uplink at this range and Ardupilot shouldn’t be going between modes if short failsafe times out, it should go to RTL or whatever was configured and stay in the mode until the pilot changes mode.
Your first flight should be, manual takeoff followed by afew circles in manual to check pitot probe calibration if you have it or just getting feel of the throttle for configuring pitot-less operation. Then your second flight should be manual takeoff, climb to safe altitude and switch into AUTOTUNE followed by manipulating controls to give Ardupilot necessary inputs to facilitate tuning as described in the wiki.
The plane is too agressive that’s why it is impossible to fly in manual mode. We need to get some help from autopilot. In first flight the vehicle could manage to complete its mission without being autotuned. Of course it wasn’t that stable but completed the mission succesfully.
Should we calibrate the pitot manually or with autocal? How unsafe to fly without pitot calibration?
Thank you
It isn’t very dangerous unless your pitot static system is way off. It can lead to inadequate or excessive gain being applied at speeds different than actual tuning airspeed. Unless you have that stupid system with internal static port (typically a piece of tube sticking out of the differential pressure sensor with a foam cap) the default value should be good enough for the first flight.
You can use MAN_EXPO_PITCH/ROLL to make the plane easier to control in MANUAL mode.
I used autocal but set the final value manually because autocal was fluctuating a tiny bit. You can do it live if you have a dedicated GCS operator or using logs.
That “managed” doesn’t inspire confidence in the tune. First time it worked, second time a few step inputs caused it to leave controllable state. The plane should be pretty much rock solid in the air when you have a good tune, even with gusty wind.
1 Like