9.1 Type of Adjustments and Basic Adjustment Procedure
9-7
Adjustments
9
9.1.4
Safety Precautions on Adjustment of Servo Gains
Set the following protective functions of the SERVOPACK to the correct settings before starting to adjust the
servo gains.
(1) Overtravel Function
Set the overtravel function. For details on how to set the overtravel function, refer to
8.4.2 Overtravel
.
(2) Torque Limit
The torque limit calculates the torque required to operate the machine and sets the torque limits so that the out-
put torque will not be greater than required. Setting torque limits can reduce the amount of shock applied to
the machine when troubles occur, such as collisions or interference. If a torque limit is set lower than the value
that is needed for operation, overshooting or vibration may occur.
For details, refer to
8.6 Limiting Torque
.
(3) Excessive Position Error Alarm Level
The excessive position error alarm is a protective function that will be enabled when the SERVOPACK is used
in position control.
If this alarm level is set to a suitable value, the SERVOPACK will detect an excessive position error and will
stop the servomotor if the servomotor does not operate according to the reference. The position error indicates
the difference between the position reference value and the actual motor position.
The position error can be calculated from the position loop gain (Pn102) and the motor speed with the follow-
ing equation.
• Excessive Position Error Alarm Level (Pn520 [1 reference unit])
∗
1.
The 10th digit of the model number of the servomotor provides information about the encoder resolution.
∗
2.
To check the Pn102 setting, change the parameter display setting to display all parameters (Pn00B.0 = 1).
∗
3.
This coefficient is used to add a margin that prevents a position error overflow alarm (A.d00) from occurring in
actual operation of the servomotor.
Set the level to a value that satisfies these equations, and no position error overflow alarm (A.d00) will be generated
during normal operation. The servomotor will be stopped, however, if it does not operate according to the reference
and the SERVOPACK detects an excessive position error.
If the servomotor’s maximum number of rotations is 6000 min
-1
and Pn102 is set to 40 with an encoder resolution of
20-bit (1048576), the setting of Pn520 is calculated as shown with the following equation.
CAUTION
If adjusting the servo gains, observe the following precautions.
• Do not touch the rotating section of the motor while power is being supplied to the motor.
• Before starting the servomotor, make sure that the SERVOPACK can come to an emergency stop at any time.
• Make sure that a trial operation has been performed without any trouble.
• Install a safety brake on the machine.
Failure to observe this caution may result in injury or damage to the product.
Position Error =
×
Motor Speed [min ]
-1
60
Encoder Resolution
*1
Pn102 (1/s)
*2
Pn520 >
×
×
(1.2 to 2)
*3
Max. Motor Speed [min ]
-1
60
Encoder Resolution
*1
Pn102 (1/s)
*2
SGMGV-
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Symbol
Specifications
Encoder resolution
8
20-bit absolute
1048576
