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14. USING A LINEAR SERVO MOTOR
(c) Thrust deviation error detection level
Set [Pr. PL04] to "_ _ _ 4" to enable the thrust deviation error detection.
When you compare the command thrust ( 5)) and the feedback thrust ( 6)) in figure 14.1, if the
deviation is more than the value of [Pr. PL07 Torque/thrust deviation error detection level] (1% to
1000%), [AL. 42.3 Servo control error by torque/thrust deviation] will occur and the linear servo
motor will stop. The initial value of this detection level is 100%. Replace the set value as required.
(d) Detecting multiple deviation errors
When setting [Pr. PL04] as shown below, multiple deviation errors can be detected. For the error
detection methods, refer to (1) (a), (b), (c) of this section.
(2) Auto tuning function
The auto tuning function during the linear servo motor operation is the same as that of the rotary servo
motor. However, the calculation method of the load to motor mass ratio (J ratio) differs. The load to
motor mass ratio (J ratio) on the linear servo motor is calculated by dividing the load mass by the mass
of the linear servo motor primary side.
Example) Mass of linear servo motor primary side
Load mass (excluding the mass of the linear servo motor primary side)
Mass ratio
For the parameters set by the auto tuning function, refer to chapter 6.
[Pr. PL04]
4
[Pr. PL04]
Setting
value
POINT
The auto tuning mode 1 may not be performed properly if the following
conditions are not satisfied.
Time to reach 2000 mm/s is the acceleration/deceleration time constant of 5 s
or less.
The linear servo motor speed is 150 mm/s or higher.
The load to mass of the linear servo motor primary-side ratio is 100 times or
less.
The acceleration/deceleration thrust is 10% or less of the continuous thrust.
Thrust deviation error detection enabled
Position deviation
Speed deviation
error detection
error detection
1
2
3
4
5
6
7
14 - 25
Thrust deviation
error detection
= 2 kg
= 4 kg
= 4/2 = 2 times
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