bnp-b2365(eng)b.pdf - 第235页
4. Servo Adjustment 4 - 36 <Adjustment method> [1] Set the servo specifications (SV017: SPEC )/bit1 to 1, and turn the NC power ON again. [2] Measure the position droop overshooting while increa sing the dual feedb…
4. Servo Adjustment
4 - 35
4-4-3 Dual feedback control (Optional function)
If the motor and machine coupling or machine system's rigidity is low (ex. large machine, etc.) when
using a closed loop system, the response during acceleration/deceleration will vibrate and cause
overshooting. This can cause the position loop gain from increasing. The dual feedback function is
effective in this case.
To validate the dual feedback function, use position feedback with a motor end detector in ranges with
high acceleration to enable stable control. In ranges with low acceleration, use position feedback with
the tool end detector (scale). This will make it possible to increase the position loop gain.
Dual feedback control
The state will approach the semi-closed loop system as the primary delay filter's time constant
increases, so the position loop gain limit will increase. Note that the limit of the position loop gain
increased with the dual feedback function is the same as the position loop gain limit for a semi-closed
system that does not use a tool end detector(scale, etc.). In addition, the positioning time will increase
as the primary delay filter time constant increases.
POINT
1. Dual feedback control is a function that compensates symptoms resulting
from insufficient machine rigidity. If there are items that can be improved on
the machine (improvement of scale installation position, etc.) improve those
first.
2. The position loop gain limit will not increase compared to the semi-closed
loop system even when using dual feedback control.
3. Dual feedback control is an optional function. If the option is not set in the
NC, alarm 37 (at power ON), or warning E4 and error parameter No. 103
(2303 for M60S/E60 Series NC) will be output.
Position control
Primary
delay filter
High frequency
FB element
Low frequency
FB element
dead band
SV052
SV051
Position
command
+
-
Position droop
Servo-
motor
ENC
Linear scale
Table
Speed
command
Tool end
p
osition FB
Motor end position FB
+
-
+
-
4. Servo Adjustment
4 - 36
<Adjustment method>
[1] Set the servo specifications (SV017: SPEC)/bit1 to 1, and turn the NC power ON again.
[2] Measure the position droop overshooting while increasing the dual feedback control time
constant (SV051: DFBT) in increments of 5ms. Adjust to the time constant where overshooting
does not occur.
[3] For the final setting value, set a value 1.5 to 2-fold the value adjusted in 3.
No. Abbrev. Parameter name Explanation Setting range
SV017 SPEC* Servo specification
selection F E D C B A 9 8 7 6 5 4 3 2 1 0
spm mpt mp abs vdir fdir vfb seqh dfbx fdir2
bit Meaning when "0" is set Meaning when "1" is set
1 dfbx Dual feedback control stop Dual feedback control start
SV051 DFBT
Dual feedback
control time constant
Set the control time constant in dual feed back.
When "0" is set, the actual value that is set is 1ms.
The higher the time constant is, the closer it gets to the semi-closed
control, so the limit of the position loop gain is raised.
0 to 9999
(ms)
SV052 DFBN
Dual feedback
control non-sensitive
band
Set the non-sensitive band in the dual feedback control.
Set to "0" as a standard.
0 to 9999
(
µm)
4. Servo Adjustment
4 - 37
4-5 Settings for emergency stop
Emergency stop in this section refers to the following states.
[1] Emergency stop was input (including other axis alarms)
[2] NC power down was detected
[3] A servo alarm was detected
4-5-1 Deceleration control
With the MDS-C1-V1/V2 servo drive unit, if the deceleration stop function is validated, the motor will
decelerate following the set time constant while maintaining the READY ON state. READY will turn
OFF and the dynamic brakes will function after stopping.
If an alarm, for which dynamic brakes are designated as the stopping method, occurs, the motor will
stop with the dynamic brakes.
<Features>
When the load inertia is large, deceleration stop can be executed at a shorter time than the
dynamic brakes.
(The stop time for the normal acceleration/deceleration time constants will be achieved.)
(1) Setting the deceleration control time constant
Set the time for stopping from the rapid traverse rate (rapid: axis specification parameter) in the
deceleration time constant for emergency stop (SV056: EMGt). The operation stops with the
position loop step when 0 is set.
If linear acceleration/deceleration is selected for rapid traverse, the same value as the
acceleration/deceleration time constant (G0tL) will be the standard value. If another
acceleration/deceleration pattern is selected, set rapid traverse to linear acceleration/deceleration
and adjust to a suitable acceleration/deceleration time constant. Use that value as the standard
value.
<Operation>
When an emergency stop occurs, the motor will decelerate at the same inclination from each
speed.
Deceleration control sequence
Forced READY OFF range
RAPID
SV056
Constant inclination
decele
r
ation
Motor speed
Time
Motor brake control output (CN20)
OFF
ON
Servo READY (READY)
ON
OFF
In-position (INP)
ON
OFF
READY OFF after in-position
SV055
Emergency stop (EMG)
ON
OFF