Position Mode (Multicopter)

  

Position is an easy-to-fly RC mode in which roll and pitch sticks control speed over ground in the left-right and forward-back directions (relative to the "front" of the vehicle), and throttle controls speed of ascent-descent. When the sticks are released/centered the vehicle will actively brake, level, and be locked to a position in 3D space — compensating for wind and other forces.

Position mode is the safest manual mode for new fliers. Unlike Altitude and Manual/Stabilized modes the vehicle will stop when the sticks are centered rather than continuing until slowed by wind resistance.

The diagram below shows the mode behaviour visually (for a mode 2 transmitter).

MC Position Mode

Care must be taken when landing in this mode. When first landing in this mode, be ready to switch to Manual/Stabilized in order to be able to disarm. If landing is correctly detected, motors will spin down after touch down and then disarm shortly after. If the motors keep spinning at higher RPM or start spinning up, first switch to Manual/Stabilized (MC), and then disarm. Be aware that the vehicle may tip over on the ground due to GPS drift.

Technical Summary

RC/manual mode where RPT sticks control speed in corresponding directions. Centered sticks level vehicle and hold it to fixed position and altitude against wind.

  • Centered RPT sticks (in RC deadzone) hold x, y, z position steady against any wind and levels attitude.
  • Outside center:
    • Roll/Pitch sticks control speed over ground in left-right and forward-back directions (respectively) relative to the "front" of the vehicle.
    • Throttle stick controls speed of ascent-descent.
    • Yaw stick controls rate of angular rotation above the horizontal plane.

  • Manual input is required (RC controller, or gamepad/thumbsticks through MAVLink).
  • This mode requires GPS.

Parameters

All the parameters in the Multicopter Position Control group are relevant. A few parameters of particular note are listed below.

Parameter Description
MPC_HOLD_DZ Deadzone of sticks where position hold is enabled. Default: 0.1 (10% of full stick range).
MPC_Z_VEL_MAX_UP Maximum vertical ascent velocity. Default: 3 m/s.
MPC_Z_VEL_MAX_DN Maximum vertical descent velocity. Default: 1 m/s.
RCX_DZ RC dead zone for channel X. The value of X for throttle will depend on the value of RC_MAP_THROTTLE. For example, if the throttle is channel 4 then RC4_DZ specifies the deadzone.
MPC_XXXX Most of the MPC_xxx parameters affect flight behaviour in this mode (at least to some extent). For example, MPC_THR_HOVER defines the thrust at which a vehicle will hover.
© PX4 Dev Team. License: CC BY 4.0            Updated: 2018-11-15 21:22:49

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