5 Adjustments
5.1.4 Safety Precautions on Adjustment of Servo Gains
5-8
5.1.4
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
4.3.2 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 can be occurred.
For details, refer to
4.6 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.
Refer to
4.4.3 Electronic Gear
.
∗2.
To check the Pn102 setting, change the parameter display setting to display all parameters (Pn00B.0 = 1).
At the end of the equation, a coefficient is shown as
"
×
(1.2 to 2).
"
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 gen-
erated 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.
The following example outlines how the maximum limit for position deviation is calculated. These conditions
apply.
• Maximum speed = 6000
• Encoder resolution = 131072 (17 bits)
• Pn102 = 400
•
CAUTION
• If adjusting the servo gains, observe the following precautions.
• Do not touch the rotating section of the servomotor 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.
Position Error [reference unit] =
Motor Speed [min ]
-1
60
Encoder Resolution
*1
Pn102 [0.1/s]/10
*2
Pn210
Pn20E
Pn520 >
×
×
×
(1.2 to 2)
Max. Motor Speed [min ]
-1
60
Encoder Resolution
*1
Pn102 [0.1/s]/10
*2
Pn210
Pn20E
Pn210
Pn20E
1
1
=
