I am flying a DIYdrones quad with the APM 2.5. Mission planner and APM are both up to date on firmware. This happened in a mission I flew yesterday.
Flew around for a couple of minutes doing Loiter and RTL. Both worked rather well.
Landed and set up a waypoint mission.
Took off, pointed the quad in the direction of the first waypoint.
Engaged automode.
Waypoint was to the west but the quad veered north and took a wide arcing path to the first waypoint.
Rest of the mission went fine.
My question is why did the quad decide to take such a weird path to the first waypoint when I already had it pointed in the correct direction?
Auto compass declination and auto mag offsets are both turned off. Compass declination was entered manually and mag offsets were done using the log telemetry option seen here under option C.
Logs are attached. Waypoint mission starts at around 13:06:00 on the mission time.
Replies
It's caused by the compass heading being incorrect most likely because of interference from the motors, pdb, ESCs and wires connecting them all. It's clear to see if you graph the mag_field vs the throttle.
It depends where you live in the world but normally the mag-field is about 330 but yours is way up around 530 with the throttle off and drops to about 480 with the motors on.
You can see it more clearly by firing up your engines with your copter strapped to the ground. I suspect you'll see the heading changes by 30degrees (although it depends which way the copter is facing because the interference is in the body-frame while the earth's magnetic field is in the earth-frame).
Anyway, to resolve it you should try moving the APM up a bit away from the wires and electronics underneath it.