Recently our I have experienced catastrophic failure during auto mission.
The mission composed of followings.
- Copter takes off from near GCS site with Joystick input from 3DR radio telemetry.
- RC controller is located in the landing site about 1 km away from GCS
- Mission is: Take off and waypoint navigation to target site and get back to home location
- With Joystick input enabled and throttle in middle, copter takes off with AUTO mission and when airborne, Joystick disable <-- This is where problem occur!
- When the copter reaches its destination, RC signal available and take control to guide the copter to a goal.
- Then RC switch to AUTO again and the copter get back to its home location and done.
We tested this setup for several time successfully without a glitch.
One day, we started the copter with Joystick enabled, throttle in middle, take off the copter with AUTO mission.
The copter took off nicely as usual however, right after we disable the Joystick input, suddenly the flight mode changed to Stabilized mode and then disable all motors at once. Then nothing left.
The copter crashed from about 20 m high and disintegrated.
Now I am wonder if anybody have experienced such case.
Today we tried to investigate this issue by trying to simulate the case.
I first suspect if no RC input may cause this problem. But this was not the problem.
Even without RC switch ever be ON, the copter behaves normally.
After several attempts, we finally can reproduce the case.
Copter take off with AUTO mission and disable joystick and then flight mode changed to STABILIZE mode and free fall.
Strangely, this happens on and off. The ratio is about 2~3 out of 20 attempts.
I could not exactly tell which causes this problem.
Maybe disabling Joystick in midair simply is not a good idea?
Anybody can help me figure out what may have contributed this problem?