Hi all,
We installed engine gearbox with bigger prop to increase UAV thrust in the hot weather.
Today we had strange anomaly of autopilot behavior. During the climb autopilot also increased rudder and UAV started to slip and became unstable so we had to take over in manual control. We suspect that it might be driven by wrong sign in Rudder from Y acc. PID or wrong measurement of the yaw accelerometer.
I'm attaching the files. Please check the log file log20151019_174331 at 159-165 sec., log20151019_162350 at 61-67 sec and 89-94 sec.
I'm not sure what drives the rudder behavior. Compass is disabled. Could you please help me to understand the root cause and suggest the correction actions?
Regards,
Yuri
Replies
In flight, the rudder from yacc loop is active. if you plot the throttle versus y accelerometer there is some correlation between high throttle and high y accelerometer value so when the throttle goes up the vibration increases and that causes an accelerometer bias. Your next course of action is to improve the vibration damping of the autopilot. We have had good results using Enidine wire rope isolators. http://www.enidine-aviation.com/Products/Wire-Rope-Isolators/
Regards,
Kevin Surminski
MicroPilot Support