SD710 Series Servo Drive Technical Manual Chapter 6 Adjustment
2
6.1 Pre-adjustment considerations
6.1.1 Adjustment type
Tuning is a function that optimizes responsiveness by adjusting the servo gain of the servo unit.
The servo gain is set by a combination of several parameters (velocity loop gain, position loop gain, filter, friction
compensation, rotational inertia ratio, etc.), which affect each other, so the setting must take into account the balance
between the individual parameter settings.
The factory setting of the servo gain is a stable setting. Please use various adjustment functions to further improve the
responsiveness according to the state of the user's machinery.
Adjustment types include adjustment-free function, inertia recognition, gain adjustment, filter adjustment, friction
compensation, A-type vibration suppression control, low frequency vibration suppression, Easy FFT, etc.
6.1.2 Safety precautions during adjustment
When making adjustments, the servo unit protection function shown below should be set to a more appropriate value.
(1) Overtravel setting
(2) Torque limitation
The torque limiting function is a function that calculates the torque required for machine operation and limits the output
torque so that it does not exceed that value. It can reduce the shock in case of a malfunction such as a disturbance or
collision of the machine. If the torque is set lower than the value required for operation, overshoot or vibration may
occur. See "5.1.12 Torque Limiting" for details.
(3) Position deviation threshold
The excessive position deviation alarm is an effective protection function when using the servo unit for position control.
If the motor movement does not match the command, an abnormal condition can be detected and the motor can be
stopped by setting an appropriate alarm value for excessive position deviation.
The position deviation is the difference between the position command value and the actual position, as detailed in
function codes Pn264 and Pn266.
The position deviation can be expressed as the follow equation for the position loop gain (Pn101) versus motor speed.
Motor speed(rpm)
=
60
Pn206
P
n101
Position
deviation
“
Instruction
unit
”
P
n204
Encoder resolution
x
x
When the acceleration or deceleration of the position command exceeds the tracking capability of the motor, the
following hysteresis will become larger, and thus the position deviation will not satisfy the above relationship. Please
reduce the acceleration and deceleration of the position command to the value that the motor can track, or increase the
value of the excessive position deviation alarm.
(4) Excessive position deviation alarm value at servo ON
If the servo is set to ON when the position deviation is accumulated, the motor will return to the original position in order
to make the position deviation "0", which may cause danger. To avoid this, set an alarm value for excessive position
deviation when the servo is ON to limit the movement.
(5) Vibration detection function
Please set the appropriate value for the vibration detection function via "
Online vibration monitoring (Fn402)
