Axis 670 Manuel d'instructions télécharger pdf (Page 36)

12.

Tum

R28

until

the

first overshoot

minimized. See Figure 6.

Figure 6.

: CH1:

•CH2

:...

r, 1

....

••••• ^

i..T...:....:...

+ CHi=Position Out

I CH2=Posltion In

t •

: : •

. . .

[,....!....

1 .... 1 .

: :

• • •

. . .

EHiii

200inV

Ch2 20(lmV ViM

Sms Ext /

346mV

13.

To increase the speed ofthe system (decrease the step response time) still further, slowly

tum R31 CW

few more tums, then re-tweak the other trimpots

before

make the

waveform look critically damped again. This can be continued until the desired small-angle

step response time

obtained or the system begins

resonate or "ring".

this ringing

occurs, immediately tum back the trimpots starting with R31, then R28, then R25, and then

R59 until this stops. Tum each trimpot CCW gradually and evenly, similar to when the loop

gain was increased. Do not operate the system with the loop gain tumed up so high that the

servo rings anywhere in the field. Experience with the system will determine how fast

should be tuned. Call Cambridge Technology Inc. for more information on this subject.

Refer to figure #7 for how the waveform should appear after iterating through the above

steps.

Note the critical damping in

figure

There is no

appreciable overshoot nor undershoot. The step

response

for

this scanner/servo system

about

2msec. The scanner

considered settied ^\iien

the position signal has settied to within about 1%

ofthe length ofthe step. The exact step response

time will vary from system to system depending

on load dynamics and scanner size.

Figure 7.

•

• • • f •

: CH1:

•CH2

................^.........

: : . t .

• CH1=PositionOut

. PH^BPncifinn

....:....:....:..

.1...:....

:::::;:

: : : : i ;

. . . . 1 •

[JHA

20irmV

\ ai2

200mV

2.5ms

•

Ext

346mv

1 2 ... 31 32 33 34 35 36 37 38 39 40 41 ... 67 68

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Axis 670 Manuel d'instructions Page 36

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