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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

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.

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.

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

'

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,

'

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

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.

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.

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

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,

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

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.

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

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

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).