Basic setup for Pixhawk + FBL

Some basic steps for Pixhawk+FBL :

Arducopter Heli Version 3.3.3 stable

Tip#1: calibration of accelerometer is much easier before you put the Pixhawk in the helicopter.

Tip#2: Advanced Compass Setup

         states 'Compass orientations are relative to the flight controller, not the airframe !' while MP tells you 'On a PX4 or Pixhawk with an external compass the correct value is zero if the compass is correctly oriented.'

WARNING !!! Remove blades or pinion or motor wires etc.

Insert the Pixhawk between RX and FBL. RC1 = aileron, RC2 = elevator, RC3 = collective pitch, RC4 = rudder, RC8 = ESC, RSC, throttle whatever it is called

If necessary change the TX output (channel number, servo direction) to achieve the correct movements in Radio Calibration.
In Radio Calibration make sure the bars move with your stick left and right for aileron and rudder.
The collective pitch is called throttle and should correspond to your stick movement as well.
The elevator must go down (lower numbers) for helicopter nose down stick movement and must go up (higher numbers) for nose up stick movement.

WARNING !!! MissionPlanner tries to help you and changes your input to the recommended minimum or maximum value. Unfortunately these values are most of the time for multicopters and not for helicopters. Therefore it is recommended to use Full Parameters List/Tree and Refresh to check if the value is what YOU want.

ACRO_TRAINER = 0 (this gives the FBL full control in ACRO mode)

H_CYC_MAX = 4500 (you adjust this to limit the aileron and elevator output for your FBL setup)
H_COL_MAX = 1900, H_COL_MIN = 1100 (you adjust this to limit the collective pitch for your FBL setup)

H_SV1_POS = 90 (aileron)
H_SV2_POS = 0  (elevator)
H_SV3_POS = 180

Check rudder and swash movement (collective, aileron, elevator) and adjust as needed using
HS1/2/3/4_REV = 1 / -1 (1 or -1 to change direction)
DO NOT use the TX to reverse servo direction !


RATE_PIT_FF = 0.4 (adjust as needed)

RATE_RLL_FF= 0.4 (adjust as needed)

RATE_YAW_FF = 0.3 (adjust as needed)

ACCEL_Z_P = 0.3 (adjust as needed, many helicopters oscillate on collective using standard value 0.5)

DISARM_DELAY = 0 (if you can't arm because after arming software disarms)

WARNING !!! Remove blades or pinion or motor wires NOW.

Check FAIL SAFE, what happens with TX off, what happens with TX on, RX off and Pixhawk on, etc.

Check ACRO mode FBL correction direction before EVERY flight !
Check STABILIZE mode correction direction before EVERY flight !

Landing using any flight mode that uses the barometer can be problematic as there is quite often a dramatic pressure change at touch down.

In case you have problems using Loiter,  Andrew Tridgell suggested to try :

I'd suggest you halve the following parameters:

  • VEL_XY_P
  • VEL_XY_I
  • POS_XY_P

and also drop VEL_XY_FILT_HZ to 2Hz.


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  • What advantages you might get by adding an external rate controller in series to pixhawk ? Actually this could be a nice, redundant solution if put in parallel to pixhawk, using a multiplexer for example. 

    • For me Pixhawk only was o.k. solution, but I always liked the behaviour of my FBL systems better. The newer ones have a rescue function that might help one day as well, if Pixhawk goes crazy (the EKF doesn't like 3D) but still allows switching to ACRO. Flying AUTO and landing on an model-airport can be done with Pixhawk without FBL for sure.

      • I agree with this idea, feel Pixhawk control of Acro mode, far less than the control handle manually FBL system under, so in essence keep the manual control mode, FBL has a good feel of the flight control, control for helicopters basic skills of the pilots, it is a good chance of rescue helicopters, while there may be the ability of 3D flight.

  • thank you very much!

    Now I feel the lack of some details

    What way, be able to use a single connection Pixhawk s.bus of s.bus out to FBL system (Vbar, SK540 / 720) of s.bus in it? 

    we just enable SBUS out with BRD_SBUS_OUT. We set it to 150Hz frame rate.


    so had to use ordinary single-channel corresponding connection, I do not know where the problem occurred!

    • Sorry haven't yet tried SBUS, but Tridge used it.

      • Okay, thanks! I asked to look Tridgell

This reply was deleted.


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