11-6
11-3 Realtime Autotuning
OMNUC G5-series AC Servomotors and Servo Drives User’s Manual (with Built-in EtherCAT Communications)
11
Adjustment Functions
11-3 Realtime Autotuning
Realtime autotuning estimates the load inertia of the machine in realtime, and operates the
machine by automatically setting the gain according to the estimated load inertia. At the same
time, it can lower the resonance and vibration if the adaptive filter is enabled.
Refer to 11-6 Adaptive Filter on page 11-18 for details about adaptive filters.
Realtime autotuning is enabled for any control to adjust the speed loop PI control.
Precautions for Correct Use
 Realtime autotuning may not function properly under the conditions described in the following
table. In such cases, use manual tuning.
 With realtime autotuning, each object is fixed to the value in the machine rigidity table at the time
the machine rigidity is set. By estimating the load inertia from the operation pattern, the operation
coefficient for the speed loop gain and the integral time constant are altered. Doing this for each
pattern can cause vibration, so the estimation value is set conservatively.
 The torque feed-forward function cannot be used when realtime autotuning is being used. Set both
the Torque Feed-forward Gain (3112 hex) and Torque Feed-forward Command Filter (3113 hex)
to 0.
SM
RE
Position/Speed
command
Speed feedback
Position/Speed
control
Current
control
Torque
command
Load
Friction torque
compensation
Position feedback
Estimate load
inertia.
Conditions under which realtime autotuning does not operate properly
Load inertia
• If the load inertia is too small or too large compared with the rotor inertia
(less than 3 times, more than 20 times, or more than the applicable load inertia
ratio).
• If the load inertia changes quickly.
Load
• If the machine rigidity is extremely low.
• If there is a non-linear element (play), such as a backlash.
Operation
pattern
• If the speed continues at below 100 r/min.
• If the acceleration/deceleration is below 2,000 r/min in 1 s.
• If the acceleration/deceleration torque is too small compared with the unbalanced
load and the viscous friction torque.
• If either a speed of 100 r/min or higher, or an acceleration/deceleration of 2,000 r/
min/s does not last for at least 50 ms.
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