Title Automatic Control of the Ship Model Towing Carriage ... · 150 S. HiRANo and Y. KAsA! and...
Transcript of Title Automatic Control of the Ship Model Towing Carriage ... · 150 S. HiRANo and Y. KAsA! and...
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Title Automatic Control of the Ship Model Towing Carriage (I)
Author(s) Hirano, Susumu; Kasai, Yoshihiko
Editor(s)
CitationBulletin of University of Osaka Prefecture. Series A, Engineering and nat
ural sciences. 1965, 13(2), p.145-158
Issue Date 1965-03-31
URL http://hdl.handle.net/10466/8090
Rights
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145
Automat ic
T Control
owing C
of the
arriage
Sh(I)
.
IP Model
Susumu HIRANo* and Yoshihiko KAsAI**
(Recelved Novernber 30, 1964)
The automatic controller of the ship model towing carriage has been installed in the
Towing Tank of University of Osaka Prefecture. In the controller system, digital and analog
techniques were combineded. Though the device has not been adjusted perfectly, accuracy
of O.2 % of operating speed was achieved over 30:1 speed range by the tests.
This paper illustrates the controller and describes the test results.
1. Introduetion.
Recently, tank expeiiments have a tendency to be required quantitative measurements
than qualitative. Then, accuracy of the experimental device which has been employed in
the towing tank, must be heighten.
The renbponse of the measuring instrument which has been employed in the ship
model experiment, is relatively slow because of large mass of a ship model. Furthermore,
the length of the tank is limited.
Photo 1. Automatic Controller ofthe Towing Carriage.
*
**
Department of Naval Architecture, College
Department of Research, Sanei Instrument
of Engineering.
Co., Ltd.
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146 S. HIRANo and Y. KAsAi
To measure a experimental value of a steady state, it is necessary to shorten the accele-
rate and decelerate distance of the carriage and to lengthen the measuring distance.
To this end, an automatic controller which is built in an automatic accelerator, deceler-
ator and speed controller, is required. An acceleration and a deceleration of the car-
riage must be done in the limit of slip ofthe wheel. The slip limit was tested, and O.07 g
for acceleration and O.06 g for deceleration are seemed to be a slip limit, respectively.
As for the automatic speed controller, there are two control systems, the one is analog
system and the other is digital.
As to the analog system, accuracy of O.1 % of operating speed is achieved in narrow
control range. But in the speed control of the carriage, the control range is 30:1. Then
the analog system is not suitable for this purpose.
This problem is solved by using the digital system, but this system is considerably
more complicated and expensive than the analog systcm. As the system which is combined
digital and analog techniques has been developedZ), the automatic controller has been
adopted this combined systern.
The test results have shown the suitability of the controller.
2. Towing carriage and driving installations.
The size of the Towing Tank of University of Osaka Prefecture is 70m long,2.95 m
wide and 1.6 m deep. The towing carriage is mounted on the rail of the tank side top and is driven by the
5kw d-c shunt motor whose shaft is connected directly to the fore wheels.
The construction of the carriage is a box type and the weight is 2.4 ton, and the diameter
of the wheel is 160mm, ・
Th'e source of the driving motor is supplied by the 15kw d-c shunt generator which
is driven by the 20kw three phase induction motor. The speed of the carriage is con-
trolled by the Ward-Leonard system. The induction motor and d-c generator are settled
on the floor and the power of the d-c motor is supplied through the trolley wires.
The speed control range of the carriage is from O.1 m/s to 3.0 m/s.
3. Controller of the towing carriage.
The controller consists of next three parts,
1). Speed signal detector and digital to analog converter.
2). Mixer circuit of reference and error signal.
3). Power amplifier circuit.-
The block diagram of the controller is shown in Fig.1.
3-1. Speed signal detector and digital to analog converter.
In this circuit, the frequency proportional to the speed is detected by the magnetic
pick-up which is attached to the speed detecting wheel through a gear, and converted to the
square wave, and then converted from the digital signal to the analog, that is, th.e frequency
signal is converted to the d-c voltage. The relation between the speed of the carriage and
the detected frequency is shown in Fig. 2.
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Automatic Control of the Ship Model Towing Carriqge (I) !47
'
Power Supply(ac 220V)
Parallel
Inverter (SCR)
d-c generator
Synchre
120cls
TriggerGenerator
Switching Relay
3-phaseInduction Moter
High
Power Amp.
Amp.
High SpeedSignal Amp.
d-e motor carnage
High
peed Detec Re!ay Circuit.
e
Lead Network
Lii-,J-
ow
LowSpeedSignalAmp. L
IIMIt
MixerCircuit
PowerAmp.
Low PowerAmp.
m
ErrorAmp.
Rectifier :Filter
Magnetic Pick Up.
iHigh
Potentio-
meter
Referencemax 12V30KC--3Ml'S
ptL
Low
Low
SaturatlngTransformer[Digital to
Anolog(Converter
'References
max 12V6KC-O.6MIS
Switching
Amp.SchmittTrigger
n ru HHigh
lf4
CounterSchmitt
Trigger
rml'LHigh
Fig. 1.
fl
Emitter
Follower
tSignal
Amp.
-=v-
Block dia
Counter , High 10KC-IMC: Low IKCK),IMC
controller.
-[v
gram of the
30
AoM 20Vh'
88
g¢
g6ses 10
o
Fig.2. Cqrriagesp
Carriage speed (m!s)
eed qnd detected signal frequenCY・
3
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'
148 S. HiRANo and Y. KAsAr
The control characteristic of the Silicon Control Rectifier (SCR) is non-linear (refer to
Fig. 10). To linearize the speed set up scale and to gain good speed performance, this part
has two circuits, i.e. a low speed range and a high speed range. The low speed range is
from O.lmls to O.6 m/s and the high speed range is from O.6 m/s to 3.0 m/s.
In the high speed range, the detected frequency is divided into a quarter, to gain a
good characteristic of the saturating transfbrmer. The relation between the detected
frequency and the d-c output voltage of the D-A converter is shown in Fig. 3.
12
en."- 86>1-n
soY4v
o
Low speed
24Detected frequency (KC)
Fig. 3.
6
12
o.hm
..8'e-
>s-Q
6Ya4v
o
High speed
10 20Detected frequency (KC)
Characteristic of D-A converter.
30
The behaviour of the circuit is as fbllows. The detected signal from the magnetic
pick-up is a sinusoidal wave and the voltage is from O.05 volts to O.5 volts. This signal
is amplified and put into a wave form circuit (schmitt circuit).
The schmitt circuit converts the signal to the square pulse signal. The output of
the schmitt circuit is entered into the switching amplifier, directly in the case of the low
speed range and divided into a quarter in the high speed range. The power transistor to
drive the saturating transfbrmer is driven by the signal. This part of the circuit is shown
in Fig. 4.
e
r Ji-u-
o
Fig.
1 e
4. Switchingamplifiercircuit,
'
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Automatic Control of the ShiP Mbdel Tawing Carriage (I) 149
R.t
Pulse generator - N.
Ns
RL
Fig. S. Characteristic ofthe satulating trans.
Then, as shown in Fig.5, the input pulse signal is converted to the signal proportional
to the input frequency by the saturating transformer. The output becomes d-c voltage
by a rectifier and ripple is eliminated by the futer.
The time constant of the filter was made low value compared with the time constant
of the controller.
Signal to noise ratio (s/n-ratio) of the d-c voltage is more than 84db at minimum speed
of the carriage. Furthermore, as to the thermal drift of the saturating transfbrmer, many
experiments have been done and special construction was employed.
3-2. Mixer circuit of reference and error signal. , In order to coinside with the characteristic of the speed signal detector to D-A con-
verter, the circuit of the reference signal voltage has also a low and a high speed range.
The relation between the speed set up scale and the reference signal voltage is shown in
Fig. 6. The source of the reference voltage has a high stable stabilizer. The thermal
drift of the source is less than O.1 % and s/n-ratio is more than 82 db.
-
12
ositn 8
6>s'
=y¢
℃4ec
Low speed
o
12
¢gtu 8
;t
g.".O
..o 4
High speed
O.2 O,4 O,6 ' O 1 2Speed set up scale. (MfS) Speed set up scale (M!S>
Fig. 6. Speed setup scale-reference voltage.
3
The reference voltage is set up by the potentiometer. This voltage is amplified by
the power amplifier through the error amplifier and put into the mixer circuit, this circuit
is shown in Fig. 7. The shaft of the potentiorneter is connected to the synchronous motor
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150 S. HiRANo and Y. KAsA!
and this equipment is
period is 3.4 seconds.
employed to accelerate or decelerate the carrlage. The driving
Reference
in put
Reference Reference
in put in put
Rl
R2
R3
Rl=R2>R3
orl
d-c-
generator
armature
bo
I
d-c generator armature
Detected signat in put
Fig. 7. Error amplifier and mixer circuit.
The error signal amplifier, as shown in Fig. 8, compares with
voltage and the reference signal voltage, and amplifies the difference
same time amplifies the feed back signal from the d-c generator.
the detected
of them and
signal
at the
Signal input
a-c 220V
Out put
Fig. 8. 0ut put circuit.
This output is superposed to the reference signal voltage in the mixer circuit. The
signal voltage is amplified by the low or the high speed signal amplifier and the power
amplifier, and drives the trigger generator. ・ The output of the power amplifier is employed to drive the speed detecting relay.
3-3. Power amplifying circuit.
The power voltage of the controller is gained by the SCR. The SCR. is controlled as
fo11ows; the trigger generator is driven by the uni-junction transistor (UJT). The UJT.
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A"tomatic Control of the Ship Mbdel Tewing Carriage (I) 151
is synchronized with the source of the SCR. and the trigger with oscillating frequency
of the generator is given to the gate of the SCR., and the SCR. is controlled.
The circuit of the trigger generator is shown in Fig.8. In the circuit of the trigger
generator, the transistor is employed instead of a resistor of oscillating time constant CR.
and by giving the signal to the base of the transistor, the internal impedance of the transistor
is changed proportional to the input signa!, and then the oscillating period is varied propor-
tional to the input signai. The relation between the output of the SCR. and the input
signal voltage is shown in Fig. 9.
25
A>N-.
obeg 156>Gati 8o
Low speed
100
E 6s&s6>S 38Qe 25o
High speed
O.1 O,3 O.6 O.61 2Speed $et up scale (mls) Speed set up scale (m,ts)
Fig. 9. Speed set up scale-output voltage.
3
In the SCR. circuit, various protecting circuits are inserted to protect the SCR. from
an abnormal voltage.
The power characteristic of the SCR. is shown in Fig. 10. As the characteristic of
the SCR. with the signal input of the UJT. trigger generator is non-linear, the low
speed and the high speed signal amplifier have a special amplifying characteristic.
A>Yooo
g5>
-=a-=o
100
25
Signal voltage
Fig. 10. SCR output characteristic.
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152 S. HiRANo and Y. KAsAr
4. Control system ofthe towing carriage.
The block diagram of the control system ofthe towing carriage is shown in Fig. 11.
Reference
Voltage
Error
Amp.
&
Signal Amp. andMixer Trigger PowerCircuit Gene Amp.
ig N
d-c Gonerator
igP7le+1
d-c Motor
ag
KlPTi+1
pTPT÷1
thP(P713+1)
Lead Network
Towing Carriage
l
Signal Detector
and D-A Converter and Rectifier and Filter.
Fig. 11. Block diagram ofthe control system.
To determine the time constant of each element, the indicial
The response of the circuit between the magnetic pick-up and the
response is measured.
ripple filter due to the
2.0
dEN5:oB 1.0&N6>'s-'
a・=-・
o
O O.1 O.2 O.3 ' O,4 O,5 Time (sec)
Fig. 12. Response ofthe pick up to error amp. (this curve isaresponse to O.1 m/s speed step.)
i
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Automatic Control of the Ship Mbdel Towing Ctxrri`age (I) 153
/
step of Ikc at 3kc level, is shown in Fig. 12, and that between the error amplifier and the
output of the SCR. due to the step of 2volts at 6volts level, is shown in Fig. 13, and that
between the error amplifier and the output of the generator due to the step of 2 volts at 6
volts leve!, is shown in Fig. 14.
.
・6
5
4
ts,
tib
83 bets&-es
6>2!,9
k
1
x
o
o
Fig. 13.
.2 .4 .6 ,8 1・O 1.2 1,4 Time (sec)
Response of error amp. to generator field (For 2 vplts step at error amp.)
From these tests, the constants of the system are as fo11ows.
K,
K,
K,
K,
K,
K,
T,
T,
T,
T,
Low speed range.
4.04 db.
23.78 db
19.15 db
18.10 db
-38.33 db
1.06 db
8.92 db
O.093 second
O.3 second
1.9 second
High speed
-9.96
21.85
40.26
range.
db
db
db
The attenuation diagram of the system is shown in Fig. 15,
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154 S. HIRANo and Y. K.AsAl
.
4,O
3,5
3.0
2,5
-eE8& 2.0
oets&g9 1.s
g6・
1,O
.5
o
.
O .2 .4 .6 .8 1,O Time (sec)
Fig.14. Responseoferroramp.togeneratoroutput. by 2volts step at the error amp.
1.2 1,4 1,6・
This curve was gained
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AgeeR
bo:
8spt
1oo
200
300
Dv.scu
oo
50
100
Automatic Control of the Ship Medel Totving Carriag,e (l) 155
Ceti
Phase
ltIOi-NeL
Angle
Od6 HighSpeedKgt=41.91dbLowSpeedK2i---18.98d'b
O.Ol O.1 1 !O '・ 1oo' Frequency.
Fig. 15. Attenuation diagram ofthe control system.
5. Testresults
5-1. Responseofthesystem. ' The response of the system produced by 2 volts step of the reference voltage is shown
in Fig.16. The speed of the carriage was detected by d-c tacho-gene. ' '
.34
kco
s K co
.12 .. ,.91
Time (sec)
Fig. 16. Response ofthe system to the 2volts step of reference voltage.
5-2. Fluctuationofspeed.
Fluctuation of the carriage speed was measured with automatic and manual control,
The result is shown in Fig.17 and Fig. 18 respectively.
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156 S.HIRANo and Y. KAsAI
1・・出小_一轟一一一》一}
工伶mm10
工幡勘
工伶mm5
工βmm5
0980田ノs
●一劇《㌔一一画圏■一cO.712 m/s
0.584:n/s
0.325m/s
〔〕.128m/s
5mm!・;[、~》》一
10mm/・エ
ユOmm!・ユ
10mm/・工
5mm/・工
5mm/・工
0 5 10 .15
Time(sec)
Fig.17. Speed fluctuation in automatic contro1.
1、838副s
LO35 m〆s
20
聡伶m4240
0.283m/s
・。.、、エ》へ噸》W一}
30
」
@
Q0
@ 10
(昌
烽ュ》芒。ヒ己①」3口§弱hgoΣ
0 5 10 15
Time(sec)
Fig.18. Speed nuctuation in manual controL
30
9 て
谷 臼 $20
芒 2 岩 塞
旨 拓 巨
“ 10 δ ぢ
0 10
Fig.19.
20 30
Step voltage
Sta鴬slip test.
40
20
0 0,5 1.01
Carriage sp㏄d(m!s)
Fig.20. Stop slip test・
15
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Automatic Control of the Ship Mbdel Towing Carriage (l) 157
5-3. Acceleration and deceleration ofthe carriage.
Acceleration and deceleration of the carriage are limited by a slip of the wheel. To
determine the limit of slip at the start, a step voltage was given to the carriage at standstill
and then the armature current of the d-c motor was measured. If it happens that the
carriage slips in the instant, the armature current will decrease.
O.5
o
1.0
c.
g .s
Baen o
1.4
.7
o
o
Fig.
Time (sec)
21. Automatictart-stop stest
15
(a) Forward.
20 25
O.5
o
1.0
Ae! asE
U8o,,q,
1.4Start mark Stop mark
O.7.
o
o 5
Fig. 21
10 15 .Time (Sec)
. Automatic start-stop test (b) Baekward.
20 25
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158 S. HmANo and Y. KAsAi Accordingly, the relation between step voltage and qrmature 'current sh(rws the 1imit
of the slip. This relation is shown in Fig. 19.
Concerning the limit of the deceleration, a reversa! break at zero voltage was applied
to the running carriage, and armature current of the motor was measured. This is shQwn
From the results, limit of the acceleration is O.07 g and limit of the deceleration is
O.063.g.
Automatic acceleration and deceleration of the carriage was recorded. The results are
shown in Fig. 21.
6. Problems
The maximum frictional coeMcient between the rail and wheel is O.09 which is calcurat-
ed from the result of the slip test (refer to Fig.19 and 20). Then, the maximum accelera-
tion without slip becomes O.07 g. In the start-stop test of the automatic controller, the
acceleration was O.OS g. To increase the acceleration, it is necessary to increase the fric-
tional coeMcient, and this is solved by using a rubber wheel and a concrete rail.
The speed fluctuation of the carriage is compared with the manual and automatic con-
trol in Fig.17 and 18. In the manual control, there is a speed drift, but the drift is eliminat-
ed by the automatic controller. The disturbance of the record is based on the disarran-
gement of the rail, and decreased by the resetting of the rail.
In the indicial responce of the system, there is comparatively large over shoot. This
characteristic is understood from the small phase margin in the attenuation diagram of
the system (refer to Fig.15). At present the inner loop of the system does not serve.
To improve the characteristic of the system, it is necessary to increase the gain of the
outer loop, and to improve the inner loop.
Reference.
1) Francis T. thompson,.lburnal of AIEE.,3, 23, (1962).