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camera on it) as the copter flies the mission. The autopilot will attempt to retake yaw control as the vehicle
passes the next waypoint.
Ending a mission
Missions should normally have an RTL as their final command to ensure the copter will return after the
mission completes. Alternatively, the final command could be a LAND with a different location. Without a final
RTL or LAND command the copter will simply stop at the final waypoint and the pilot will need to retake
control with the transmitter.
Remember that when using RTL, the copter will return to the “home” position which is the location where the
copter was armed.
As the copter touches down at the end of the mission the pilot should move the throttle to zero at which point
the autopilot will disarm the motors if it also believes that it has landed.
3.6.5 PosHold Mode
The PosHold flight mode (previously known as “Hybrid”) is a new mode for AC3.2. It is similar to Loiter in that
the vehicle maintains a constant location, heading, and altitude but is generally more popular because the
pilot stick inputs directly control the vehicle’s lean angle providing a more “natural” feel.
When switched on, PosHold mode will automatically attempts to maintain the current location, heading and
altitude. Good GPS position, low magnetic interference on the compassand low vibrations are all important in
achieving good loiter performance.
How to control
The pilot can control the copter’s location horizontally and vertically with the control sticks.
Horizontal location can be adjusted with the Roll and Pitch control sticks with the default maximum lean angle
being 45 degrees (angle can be adjusted with the ANGLE_MAX parameter). When the pilot releases the
sticks, the copter will lean back to bring the vehicle to a stop.
Altitude can be controlled with the Throttle control stick just as in AltHold mode
The heading can be set with the Yaw control stick
You may arm in PosHold mode but only once the GPS has 3D lock and the HDOP has dropped to 2.0 or
lower.
The HDOP value can be made clearly visible through the mission planner’s Quick screen by double clicking
and then selecting “gpshdop” from the large grid of checkboxes.
The maximum brake-angle can be set with the PHLD_BRAKE_ANGLE parameter (i.e. 3000 = the vehicle will
lean back up to 30degrees).
The speed the vehicle rotates back to the maximum angle can be set with the PHLD_BRAKE_RATE
parameter (i.e. 8 = rotates back at 8 degrees per second)).
3.6.6 RTL Mode
This very simple flight mode simply stops the vehicle as soon as possible using the Loiter controller. Once
invoked, this mode does not accept any input from the pilot. This mode requires GPS.
RTL mode (Return to Launch mode) navigates Copter from its current position to hover above the home
position. The behavior of RTL mode can be controlled by several adjustable parameters.
When RTL mode is selected, the copter will return to the home location. The copter will first rise to RTL_ALT
before returning home or maintain the current altitude if the current altitude is higher than RTL_ALT. The
default value for RTL_ALT is 15m.
