MC gyro cutoffs - Reduce IMU_GYRO_CUTOFF to 30Hz and disable MC_DTERM…

…_CUTOFF.

A low gyro cutoff is needed for most medium/large size drones as the structural natural and blade-pass frequencies are low.
A higher value is still desirable for small platforms surch as racers
or well isolated autopilots and should be tuned by the user.
Specific values for config files are untouched.
The cutoff filter for the D term is disabled here as the required
cutoff frequency for the default D term of the rate controller is higher
than the gyro cutoff. In that case, enabling the D term cutoff would
just add some undesired phase lag to the derivative.

src/modules/mc_att_control/mc_att_control_params.c

@@ -538,6 +538,8 @@ PARAM_DEFINE_FLOAT(MC_TPA_RATE_D, 0.0f);
  * The D-term uses the derivative of the rate and thus is the most susceptible to noise.
  * Therefore, using a D-term filter allows to decrease the driver-level filtering, which
  * leads to reduced control latency and permits to increase the P gains.
+ * A good rule of thumb is to fix the time constant of this filter equal to one tenth of the
+ * derivative time constant: MC_DTERM_CUTOFF = 10 * MC_(ROLL|PITCH)RATE_P / (2 * pi * MC_(ROLL|PITCH)RATE_D)
  * A value of 0 disables the filter.
  *
  * @unit Hz
@@ -547,7 +549,7 @@ PARAM_DEFINE_FLOAT(MC_TPA_RATE_D, 0.0f);
  * @increment 10
  * @group Multicopter Attitude Control
  */
-PARAM_DEFINE_FLOAT(MC_DTERM_CUTOFF, 30.f);
+PARAM_DEFINE_FLOAT(MC_DTERM_CUTOFF, 0.f);
 
 /**
  * Multicopter air-mode

src/modules/sensors/sensor_params.c

@@ -220,7 +220,7 @@ PARAM_DEFINE_INT32(SENS_EN_THERMAL, -1);
 * @reboot_required true
 * @group Sensors
 */
-PARAM_DEFINE_FLOAT(IMU_GYRO_CUTOFF, 80.0f);
+PARAM_DEFINE_FLOAT(IMU_GYRO_CUTOFF, 30.0f);
 
 /**
 * Driver level cutoff frequency for accel