Mitsubishi Electric MR-J5 Series User Manual page 164

Backlash estimation function [A]
Start the backlash estimation by clicking the estimation start button of MR Configurator2 during a servo motor stop. When the
start button for the backlash estimation is clicked during servo-off, the status automatically shifts to servo-on, and the backlash
estimation will be started. In addition, if the backlash estimation is started in the servo-off status, the servo motor automatically
switches to servo-off after the completion/cancellation of the backlash estimation.
In the backlash estimation, the servo motor performs four times of reciprocating positioning by the calculated travel distance
either from the forward rotation to the reverse rotation or from the reverse rotation to the forward rotation. From the servo
amplifier internal data on the four times of to-and-fro positioning operation, the backlash is estimated. During backlash
estimation execution, the movement direction, the maximum velocity at the to-and-fro positioning operation, and the
acceleration/deceleration time are calculated inside the servo amplifier.
Servo motor speed
0
Progress 0 [%]
Item
Travel distance
Servo motor speed
Acceleration time constant
Deceleration time constant
Dwell time
Progress status is displayed during the backlash estimation. The backlash estimation is complete when the progress reaches
100 %.
After backlash estimation, "0000" is displayed in the error code status, and the backlash estimate is displayed in the
"estimation result".
When [Pr. PF66.0-3 Gear ratio for backlash estimation - Numerator] or [Pr. PF66.4-7 Gear ratio for backlash estimation -
Denominator] is set to "0", the backlash estimation value is outputted as the rotation angle on the servo motor side. In a
mechanism in which multiple gears are connected like a planetary gear, the backlash estimation amount is calculated by
enlarging the actual backlash by the reduction ratio.
When a value other than "0" is set to [Pr. PF66.0-3 Gear ratio for backlash estimation - Numerator] and [Pr. PF66.4-7 Gear
ratio for backlash estimation - Denominator], a backlash estimated amount is outputted in consideration of the gear ratio for
backlash estimation.
After the backlash estimation is executed, control by the command from the controller is disabled. To control by the command
from the controller again, reset the communication, cycle the power, or execute the software reset.
4 APPLICABLE FUNCTION
162
4.3 Machine diagnosis
Revolving positioning operation is repeated four times.
10 [%] 20 [%] 30 [%]
Motor
side
Description
Based on the values of [Pr. PF66.0-3 Gear ratio for backlash estimation - Numerator], [Pr. PF66.4-7 Gear ratio for backlash
estimation - Denominator], and [Pr. PF67 Backlash nominal value], the travel distance is automatically set with the following
equation. If the result is less than one rotation, the travel distance is 1. Any one of [Pr. PF66.0-3 Gear ratio for backlash
estimation - Numerator], [Pr. PF66.4-7 Gear ratio for backlash estimation - Denominator], or [Pr. PF67 Backlash nominal
value] is set to "0", the travel distance is two rotations in the forward direction and two rotations in the reverse direction.
Travel distance [rev] = 4 x Backlash threshold x gear ratio numerator for backlash estimation/gear ratio denominator for
backlash estimation
A speed not exceeding 1/2 of the rated speed and the overspeed alarm detection level is automatically set.
Acceleration and deceleration time constant are determined in order for the acceleration/deceleration torque to become the
inputted torque. However, when the inputted torque is larger than the torque limit value that has been set in backlash
estimation, the acceleration time constant and deceleration time constant are automatically set below the torque limit value.
In the initial value, the acceleration time constant and the deceleration time constant are automatically set below the rated
torque of 120 % and also below the torque limit value that is set at the start of the backlash estimation.
This is automatically set by calculating the time from the command completion to the servo motor tracking completion in the
servo amplifier.
40 [%] 50 [%]
Load
Load
Motor
side
side
side
60 [%] 70 [%] 80 [%]
Backlash estimated
Time
100 [%]