Mitsubishi Electric MELSERVO-J5 MR-J5 Series User Manual page 213

Backlash estimation function [G] [WG]
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 reciprocating positioning four times 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 [%] 10 [%]
Item Description
Travel distance Based on the values of [Pr. PF66.0-3 Gear for backlash estimation - Numerator], [Pr. PF66.4-7 Gear 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. When any one of [Pr. PF66.0-3 Gear for backlash estimation -
Numerator], [Pr. PF66.4-7 Gear 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 numerator for backlash estimation/gear denominator for backlash
estimation
Servo motor speed A speed not exceeding 1/2 of the rated speed and the overspeed alarm detection level ([Pr. PC08]) is automatically set.
Acceleration time constant Acceleration and deceleration time constant are determined in order for the acceleration/deceleration torque to become the
Deceleration time constant 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.
Dwell time This is automatically set by calculating the time from the command completion to the servo motor tracking completion in the
servo amplifier. The actual calculated dwell time is Max (200 ms, 9800/[Pr. PB07 Model control gain])
The progress status is displayed during backlash estimation. The backlash estimation completes 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 for backlash estimation - Numerator] or [Pr. PF66.4-7 Gear 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 only.
When a value other than "0" is set in [Pr. PF66.0-3 Gear for backlash estimation - Numerator] and [Pr. PF66.4-7 Gear 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 perform control again
using commands from the controller, reset the communication, cycle the power, or execute the software reset.
Revolving positioning operation is repeated four times.
20 [%] 30 [%] 40 [%]
Load
Motor Motor
side
side side
50 [%] 60 [%] 70 [%]
Load
side
4 APPLICABLE FUNCTIONS
Time
80 [%] 100 [%]
Backlash estimated
211
4.5 Machine diagnosis
4