Subject: TAKENAKA
Date: Wed, 19 Jan 2000 06:02:39 -0600
From: "Imafuku, Nobuhiro" <Nobuhiro.Imafuku@mts.com>
To: "Rood, Omar" <Omar.Rood@mts.com>, "Larson, Rod" <Rod.Larson@mts.com>
CC: "Katabami, Yoshihiro" <Yoshihiro.Katabami@mts.com>

Hello, OMAR & ROD san.

1. We had a trouble this Monday. After tuning system with table, we did
maximum performance test and 100 gal THD test (0.5, 1, 3, 5, 8 & 10 Hz)
for our reference. Both test results were quite good (I want to send you
test results but I$B!G(Jm sorry I can NOT send you today because I forget
floppy disk at TAKENAKA site). Then, after finishing AIC tuning, we run
KOBE earthquake. We use 2 minutes 33 second length earthquake.
1)      When we tuned system with $B!H(JImpulse Response : 1 sec$B!I(J &
$B!H(JAnticipation : 0.33 sec$B!I(J, I think these parameters worked OK
(normally we use these parameter for existing table tuning).
2)      When we tuned system with $B!H(JImpulse Response : 4 sec$B!I(J &
$B!H(JAnticipation : 1.33 sec$B!I(J, I$B!G(Jm not sure these parameters worked OK or
not. We tuned system about 15 minutes at AIC training. After passing
about 50 second, actuator suddenly extended about + 43 cm position then
retracted about - 51 cm position (I assume actuator moves maximum
velocity). Then, we pushed E-Stop button.
3)      We checked system, but unfortunately table slide bearings were
broken. The reason why actuator stopped about - 51 cm position, we had
steel stopper at this position.
4)      We disassembled table yesterday and sent all slide bearings to
vender factory.
2. We are still NOT sure why actuator suddenly goes unstable. But, I
assume one reason is caused by AIC control loop. I still do NOT
understand AIC control concept completely, but I think we have some
limitation to use AIC such as noise level because this trouble happens
at very low level (Table noise level is less than 5 gal). I understand
we have no responsibility for table design. But, I think we have to help
TAKENAKA to fix this trouble. Please reply your comment.
3. I have some questions.
1)      What kind of controller did you use to calibrate load cell ?
Because this system controller is TestStar IIs but we have calibration
disk and shunt cartridge for TestStar II. Is this OK or not ?
2)      Both actuators performance is quite good and it is so easy to
perform 140 - 150 kine at 0.3 - 1 Hz range. Are these actuator so high
performance ? I think this is so dangerous for this system.

REGARDS     FUKU
