User Manual

If you use i2c-gps, you can watch the status led on the i2c-board. (this is the blue led on
Navigatron).
* 3 short flash at startup
* blinks once per second if GPS is sending data but no position lock yet
* blinks twice fast, then off for a second if GPS 2D position is available
* blinks 3 times fast, then off for a second if GPS 3D position is available
* or goes on for a second, off for a second, (long pulse) if not getting any NEMA sentences for
over 5 seconds
In the GUI the gray donut around the heading indicator should blink when GPS (either serial os
i2c) is communicating with the Flight Controller.
In GUI poshold and rth box should change color when copter is armed and a solid gps lock is
achieved (numSat>=5).
First test Position Hold
Once a solid GPS lock is achieved, home position is set when copter is armed. So plug your
battery, wait for GPS lock and fly to your home position (I recommend at least 5/10 meters away
from you) land, disarm and arm again. This sets the home position. Copter must be well
trimmed and in level mode.
Now takeoff, and try PosHold. It works best if there is minimal horizontal speed when
activating. If copter is moving when you activating PosHold, you will experience a couple of
swings before it settles. You can try increasing poshold_rate D only by 0.001-0.002 at a time. If
hold is not good enough you can increase P terms, also by 0.01-0.02 at a time. If copter swings
or circles then decrease it, or increase D.
Once Poshold is ok, then you can try RTH.
Fly away some distance from your home location, and first activate poshold, let the copter settle
for a couple of seconds, and then activate RTH. With the default tail control settings your copter
should turn towards the home point and start approaching. Once it's arrived it will switch to a
poshold and rotate it's head to the same direction as it was when armed. Please note, tail control
works only when magHold is enabled.
Additional information
There is an excellent PID tuning simulator (http://diydrones.com/profiles/blogs/ac2-loiter-
tuner-sim), which can help to understand the role of the POSHOLD and POSHOLD_RATE
settings It's made by Jason Short from DIYDrones who is the genius behind Arducopter loiter
code. The simulator is using the same algorithm that the current code use. You cannot take
values from the simulator and enter them into your MultiWii, but you can experiment with
different settings, and learn what value does what.