6. NORMAL GAIN ADJUSTMENT 
6 -  19 
 
6.3 Auto tuning 
6.3.1 Auto tuning mode 
The servo amplifier has a real-time auto tuning function which estimates the machine characteristic (load to 
motor inertia ratio) in real time and automatically sets the optimum gains according to that value. This 
function permits ease of gain adjustment of the servo amplifier. 
 
(1)  Auto tuning mode 1 
The servo amplifier is factory-set to the auto tuning mode 1. 
In this mode, the load to motor inertia ratio of a machine is always estimated to set the optimum gains 
automatically. 
The following parameters are automatically adjusted in the auto tuning mode 1. 
 
Parameter Symbol  Name 
PB06  GD2  Load to motor inertia ratio 
PB07  PG1  Model loop gain 
PB08  PG2  Position loop gain 
PB09  VG2  Speed loop gain 
PB10  VIC  Speed integral compensation 
 
POINT 
 
The auto tuning mode 1 may not be performed properly if all of the following 
conditions are not satisfied. 
The acceleration/deceleration time constant to reach 2000 r/min is 5 s or 
shorter. 
The speed is 150 r/min or faster. 
The load to motor inertia ratio is 100 times or smaller. 
The acceleration/deceleration torque is 10% or higher of the rated torque. 
Under operating conditions which will impose sudden disturbance torque during 
acceleration or deceleration or on a machine which is extremely loose, auto 
tuning may not function properly, either. In such cases, use the auto tuning 
mode 2 or manual mode to make gain adjustment. 
 
(2)  Auto tuning mode 2 
Use the auto tuning mode 2 when proper gain adjustment cannot be made by auto tuning mode 1. Since 
the load to motor inertia ratio is not estimated in this mode, set the value of a correct load to motor 
inertia ratio in [Pr. PB06]. 
The following parameters are automatically adjusted in the auto tuning mode 2. 
 
Parameter Symbol  Name 
PB07  PG1  Model loop gain 
PB08  PG2  Position loop gain 
PB09  VG2  Speed loop gain 
PB10  VIC  Speed integral compensation