Mitsubishi MELDAS MDS-C1 Instruction Manual page 186

(3) Disturbance observer
The disturbance observer can reduce the effect caused by disturbance, frictional resistance or
torsion vibration during cutting by estimating the disturbance torque and compensating it. It also is
effective in suppressing the vibration caused by speed leading compensation control.
<Setting method>
<1> Adjust VGN1 to the value where vibration does not occur, and then lower it 10 to 20%.
<2> Set the load inertia scale (SV037: JL) with a percentage in respect to the motor inertia of the
total load inertia.
<3> Set the observer filter band (observer pole) in the disturbance observer filter frequency
(SV043: OBS1), and suppress the high frequency disturbance estimate to suppress the
vibration. Set "100" as a standard.
<4> Set the observer gain in disturbance observer gain (SV044: OBS2). The disturbance observer
will function here for the first time. Set 100 first, and if vibration does not occur, increase the
setting by 50 at a time to increase the observer effect.
<Measuring the load inertia>
If the load inertia is not clear, it can be estimated with the following method.
1) Set the torque offset (SV032: TOF) for the unbalance torque. (Refer to "4-3-5 (2) Unbalance
torque compensation".)
2) Set JL = 100, OBS1 = 600 and OBS2 =0, and reciprocate the axis within the range that it can
be moved smoothly. Set the acceleration/deceleration time constant so that the
acceleration/deceleration torque is larger than the stall (rated) torque (100% or more).
3) Measure the estimated disturbance torque with the D/A output, and raise JL until the
disturbance torque during acceleration/deceleration is small (until it cannot be observed).
Even if the torque offset is set and JL is an appropriate value, if the axis has a large friction,
the frictional torque will remain in the estimated disturbance torque. Judge the JL setting value,
with frictional torque remaining, as the machine's load inertia scale as shown below.
Speed
command
0
Estimated
0
disturbance
torque
No. Abbrev. Parameter name
SV037 JL Load inertia scale
Disturbance
SV043 OBS1
observer filter
frequency
Disturbance
SV044 OBS2
observer gain
POINT
4. Servo Adjustment
0
0
Time
JL: Too small
Set "the motor inertia + motor axis conversion load inertia" in respect to the
motor inertia.
Jl + Jm
SV037 (JL) =
Set the disturbance observer filter band.
Set to "100" as a standard.
To use the disturbance observer, also set SV037 (JL) and SV044 (OBS2).
When not using, set to "0".
Set the disturbance observer gain. The standard setting is "100" to "300".
To use the disturbance observer, also set SV037 (JL) and SV043 (OBS1).
When not using, set to "0".
1. The estimated disturbance torque can be output to the D/A output even if the
disturbance observer gain is zero (OBS2 = 0), and the disturbance observer
is not functioning.
2. Sections where the machine is not moving smoothly can be estimated as
the disturbance.
3. The lost motion compensation must be readjusted when the disturbance
observer is started.
Frictional
torque
Time
JL: Appropriate
Explanation
Jm : Motor inertia
× 100
Jm
Jl : Motor axis conversion load inertia
4 - 15
0
0
JL: Too large
Setting range
0 to 5000
(%)
0 to 1000
(rad/s)
0 to 500
(%)
Time