Depth Hold Problems?

williangalvani · August 2, 2021, 5:50pm

Thank you for your investigation! Did you actually try any of these changes?

The integrator reset was removed to fix the depth hold bounce-back issue: AC_PosControl_Sub: do not reset accel_z integrator when relaxing by Williangalvani · Pull Request #12952 · ArduPilot/ardupilot · GitHub

Apparently it resulted is this other issue. The integrator shouldn’t be touched in manual/stabilize, which is why I suspect this is to blame:

github.com

ArduPilot/ardupilot/blob/master/libraries/AC_AttitudeControl/AC_PosControl.cpp#L728


      
          void AC_PosControl::init_z_controller_stopping_point()
          {
              // Initialise the position controller to the current throttle, position, velocity and acceleration.
              init_z_controller();
          
          
    get_stopping_point_z_cm(_pos_target.z);
              _vel_desired.z = 0.0f;
              _accel_desired.z = 0.0f;
          }
          
          
// relax_z_controller - initialise the position controller to the current position and velocity with decaying acceleration.
          ///     This function decays the output acceleration by 95% every half second to achieve a smooth transition to zero requested acceleration.
          void AC_PosControl::relax_z_controller(float throttle_setting)
          {
              // Initialise the position controller to the current position, velocity and acceleration.
              init_z_controller();
          
          
    // init_z_controller has set the accel PID I term to generate the current throttle set point
              // Use relax_integrator to decay the throttle set point to throttle_setting
              _pid_accel_z.relax_integrator((throttle_setting - _motors.get_throttle_hover()) * 1000.0f, POSCONTROL_RELAX_TC);
          }

This is called every time the controller is initialized, which includes mode changes.

Do you still have the .bin log for these plots? I’m wondering if the mode change coincides with the jump in the integrator.

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Depth Hold Problems?

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