Checking the servo loop stability
In velocity mode:
Disable the motor brake, enable the drive, and check the servo loop stability at standstill: in case of loud noise in
the motor, check the rigidity of the mechanical transmission between motor and load (backlashes and elasticity in
motor and couplings). If required, start a new Autotuning procedure by selecting a lower Bandwidth. If the
instability remains, start a new Autotuning procedure by activating the Antiresonance filter. If necessary, adjust
more accurately the servo loop stability by adjusting the Gain scaling factor.
Move the axis in both directions (low velocity set point value), and check the servo loop stability in movement: in
case of loud noise in the motor, during the displacement, the Speed measurement filter time constant can be
increased. For high frequency noise or mechanical resonances, use the 3rd order low pass Current command
filter and adjust the 3 cut-off frequencies with the most appropriate values.
Move the axis in both directions (higher velocity set point value), and check the servo loop time response. In case
of an undesired overshoot for a step-like velocity set point change, increase the Damping speed gain value and
reduce the Proportional speed gain value accordingly.
In position mode:
Disable the motor brake, enable the drive, and check the servo loop stability at standstill: in case of loud noise in
the motor, check the rigidity of the mechanical transmission between motor and load (backlashes and elasticity in
motor and couplings). If required, start a new Autotuning procedure by selecting a lower Bandwidth. If the
instability remains, start a new Autotuning procedure by activating the Antiresonance filter. If necessary, adjust
more accurately the servo loop stability by adjusting the Gain scaling factor.
Move the axis in both directions with a low Profile velocity value, and check the servo loop stability in movement.
In case of loud noise in the motor during the displacement, the Speed measurement filter time constant can be
increased. For high frequency noise or mechanical resonances, use the 3rd order low pass Current command
filter and adjust the 3 cut-off frequencies with the most appropriate values.
Move the axis in both directions with a higher Profile velocity value and check the motor positioning behaviour.
In case of loud noise in the motor during the acceleration and deceleration phases, set Feedforward
acceleration gain value to 0. In case of an undesired position overshoot at the end of the deceleration phase,
reduce the Feedforward speed 1 value.
NOTE
In Profile velocity mode, only the speed regulator gains are active.
In Profile position mode, all gains of both speed and position regulators are active. However, if the Autotuning was
executed in the Velocity mode, all the position loop gains are equal to 0 and the motor cannot move.
In Interpolated Position Mode, Feed forward Acceleration Gain must be manually cleared after Auto-tuning
procedure.
