I have tested slew rate feature in Ardusub_v3.5.3, by setting MANUAL_SLEW_RATE parameter in different modes…
In MANUAL mode, slew rate limiting works as expected by limiting the change in the motor pwm commands according to MANUAL_SLEW_RATE parameter value.
For STABILIZE and DEPTH_HOLD modes, MANUAL_SLEW_RATE parameter seems to be ineffective and controller applies pwm commands as fast as I change Joystick commands.
It would be great to have slew rate functionality, in other modes (STABILIZE and DEPTH_HOLD modes) to minimize current transients on ESCs and motors. Is there any other parameters to achieve this functionality?
You can reduce the gains of the stabilization controllers. Look for ATC_RAT_PIT and ATC_RAT_RLL and POS_Z parameters. There is not anything in place to limit the output on the forward/lateral channels, however.