Software for automated experimental investigation of seakeeping and manoeuvring qualities of ship and off-shore structure models

Lab. v.

Scheepsbouwkunck

Technische

Hogeschool

KOH$EPEHUOA no

MOPEX0A1-161M KA4ECTBAM CHLOB 0 FIAA13914X TEXHWECKVX _COOP>KEH0c1

Ce.msabpb 1983 Bapma

SOFTWARE FR 'AUTOMATED _{EXPERIMENTAL INVESTIGATION OF SEaKEEPING AND} MANOEUVRING QUALITIES OF SHIP aND 02F-SHE STRUCTURE _MODELS

D. Radev, A. Stephanov

I. Introduction

The experimental investigations of

manoeuvring and Beekeeping qualities rep-resent one of the most important stages of the technology for development of new

ty-pes of ships and floating structures, as

well 48 of the process of improvement of their technical or exploitational

charac-teristics.

In the BSHC experimental tanks, tests with both free-running and captive models are carried out. The free-running tests

are conducted with models of 3-4 m length in the manoeuvring and seakeeping basin (MB). The apparatus complex mounted on the model includes systems for control,

drive and ultrasonic trajectory indication

(LISS), as well as a number of _measuring

devices for registration of model oscilla-tions along and about its inertial axes. Output from different transducers is tran-smitted to shore via a multichannel

tele-metric system (TMS).

The tests with captive models are

carried out in the deep water towing tank,

(DdT).

The transducer's outputs are

con-nected directly to the analog inputs of

the system for laboratory _{investigations} based on mini computer PDP 11/10. The ma-noeuvring experiments are carried out using the Planar Motion Mechanism (PMM). Forced

horizontal oscillations ars generated du-ring towing of the model and its force

characteristics are measured.

The tests described, involve opera-tions for measurement of a large number of physical values, characterized by differ-ent (usually high) process frequencies; their transmittance to shore; acquisition and registration of experimental data

55 1

CONFERENCE on

SEAGOING QUALITIES OF SHIPS AND MARINE STRUCTURES

September 1983 Varna

enormous in volume in real time;processing and analysis of the measured _information. All these tests characteristics _{are a key} moment, determining the duration of the

experiment and the loading of _facilities. Complex automation of all _experimental stages based on contemporary measuring _and computer technique, the use of efficient mathematical methods for planning of the

investigations, data processing and repre-sentation, ensure conduct of tests in time

and at high quality and scientific _level. The multitude of hardware and soft-ware for carrying out hydrodynamic tests

comprise an automated system. The hardware part of the automated system _{developed at} BSHC for investigation of the _seakeeping and manoeuvring qualities of ships and off-shore structures

(AleaX),

as well as

the basic information flows are represent-ed in Fig. 1.

The measuring and computer complex of MSB on the basis of minicomputer _{PDP 11/34} is shown in Photo 1. The connection bet-ween the computer systems in the

_DT

_and MSB ensuring the seakeeping _and manoeuv-ring tests is off-line realized by a mag-netic carrier at present.

Basic aim of the paper is to _present structure and functions of the ANNEX auto-mated system program part.

2. General considerations of software desiAn

The main requirements to software for seakeeping and manoeuvring tests are the

following;

- to offer the necessary software for rea-lization of the whole complex of manoeuv-ring and seakeeping tests in all HSHC ex-perimental facilities;

ARCH1Et

-r.

DATA PROM SEAKEEPING

AND/OR

MANOEUVRING

TEST

Photo I

to ensure

quick

and convenient service

of experimental researches at minimum ope-rator's interference;

to ensure maximum test capacity of the

experimental tanks;

to be based on algorithms, optimum with regard to accuracy, quick response and

me-mory;

to present the output results in synthe-sized form with enough information about

the investigated object's qualities. The structure and organization of the 3oftware satisfying the above requirements must contain preconditions for minimiza-tion of the efforts and time for its

de-velopment, its eventual extension and

mo-difications.

Two approaches to the design and de-velopment of specialized program systems

are available. In the first one the wide range of tests necessitates the elabora-tion of a great number of systems for

.au-tomated carrying out of the tests with the respective software. Usually for each sys-tem of this type closely specialized soft-ware is developed which presupposes ra-ther great total time consumption and ef-forts for its development. 1,pparently, ex-penses might be increased due to the

bro-adening the range of experimental investi-gations offered oy BSEC [1].

In the second approach the functions of the software of a definite automated system are divided into two categories

functions independent of the particular type of the teat, whose software is

com-mon for all tests;

functions depending on the specificity of the test, whose realized software is

individual.

in this case it is necessary that at the design of the software structure the common part's components and the specia-lized part's components are differentiated

In

seaprate modules, and an _appropriate program interface is established _between

them.

At the chosen structure of the soft-ware of an automated system _for experi-mental investigations _{a common part is} de-veloped which is predominating in volume and complexness, once realized and a coi-bination of definite-submaltitudes _{of the} specialized part, oriented _{according to} the type of test. The main load in the

establishment of software having the

above organization is _{transferred to the} common part. The development of the modu-les of the separate submultitudes, as well as the addition of new ones can be carried out at minimum efforts by not so highly qualified specialists.

In view of its economical unified

multiscope and functional feature, the se-cond approach has been chosen by BS-r.: in

the establishment of the software for au-tomated experimental investigations of se-akeeping and manoeuvring qualities of ship models and floating structures whose prin-ciple scheme is shown in gig. 2.

The whole software is developed on the basis of common data base. The soft-ware for initialization of the data base for real time and for preliminary proces-sing from the point of view of execution is started consequently. The realization of the remaining software parts depends on the type of the tests and their proces-sing. The software for visualization. and

graphical representation has its own sepa-rate importance, being connected only with the data base.

Common data base reduce the problems that arise when data processing is carried out. Redundancy of data generation is

re-duced because growth is simplified since each alternation of data case need be do-ne just once, instead of once for each program.

Common data base consists of the fol-lowing three files:

2ile head - the information in this

file specifies experimental conditions and establishes data processing parameters.

All

information in this file can be upda-ted by "Software for data base

initializa-tion".

Raw data file - this file created by "Real time software" and contains regist-rated data from all channels.

-\

ot

1. \<" 4,4." of'". ktI4ate N9' cE4

cP

0 cr

_{co .f}

(1. or. .<cs N.` soc

pre'

s1/441§ cote P.SkE -Sox, IP DATA BASE

TE.srs

COMMON Nb

_Gkip

6'/C

(,.

13

ri

1.',, <., -s,_A

S

-z. TA IS

_z

o en 1.,

3

,.. .... ,k.

0

0

0

CO 0 1,'

0

..5* Sr 3.1.2. Real

timesoftware-Carrying out manoeuvring and seakeeping tests necessitates aoftware back-up for the

following functions in real time:

experimental data acquisition and regist-ration from TM3 and UM for free - running model tests and from analog digital

con-verter (ADC) and serial interface for

tests with PM;

ship model trajectory and speed determina-tion and their graphical presentadetermina-tion _at. manoeuvring tests with free-running MO-dels (Photo 2)[i0];

= model movement control at free model tests.,

The model control regimes are two - regime

of course changing and regime

_of

_course

stabilization. For the second regime, di-rect control with telecommand system (TOS) is realized. The software ensuring _this

function is under development.

1

FIG.?

Single channel data file - this file contains data for one channel selected by

"Software for preliminary processing" from Raw data file. Single channel data file is

a base for subsequent data processing and

visualization.

3.

Software description

3.1. Data registration software

3.1.1.- Software for data-base initi-,

alization

The software for data base initiali-zation includes entering the necessary

ini-tial test parameters according to its type,

as well as information regarding registra-ting devices. Effective dialogue 1e provide&

all the parameters are easily

control-led, the changes are immediately registered. The zero levels of the separate channels are also registered. The trarsducere are autos.

matically calibrated.

-SYSTEM INITIATION SIGNALS FREQUENCIES DETERMINATION

Photo 2

DATA ACQUISITION REGISTRATION TEST FOR STATIONARITY

WA<

FILTRATION

Fig. 3

55- 5

Real time software structure

corsists

of a driver and applied program modules

re-alizing the above functions. The driver

wee the measuring and control equipment. :'ne

interaction between the driver and the

se-parate atplied modules is realized 'by

mon memory area. This strut:tire allows

SRAN coding of applied modules.

3.1.3. Software for preliminary

Using the programa included

part, conversion of the measured values

7:

physical, their evaluatior. with

L=2;lif-tion and calibraL=2;lif-tion coefficient3 is

Also, the values are sorted up accorai

channels in a comu.on file from

for a given channel can be derived if

desi-COMMON

_DATA

_BASF.

TINE SERIES DATA SELECTION

coz-

2.C.:.-Ceasing

red. The delivered temporary series

can

be

visualized on a display. Digital

filtration

can be done.

The software includes a module

which

can be used to

input

data received

in-dependently (not using the above

described

software for real time), and its processing.

A generalized flow chart

of the

data

registration software is presented in Fig.3.

3.2. Software for seakeeping tests

The programs for Beekeeping tests

are

universal f6

,

7]

.

Close connection with the

softwa.re providing visual and graphical

out-put after each program operation is realized.

The basic functions of this package are

as follows (Fig.4):

statistical analysis;

histograms and distributions;

regular wave data processing;

auto-correlation function;

cross-correlation function;

spectral analysis of experimental

data,

comparison of the results with

standard

spectra, computation of spectral moments;

cross-spectral analysis;

calculation of response amplitude

opera-tors.

GRAPHICAL AND TABULAR OUTPUT

Fig.!.

3.3. Software for manoeuvring tests

3.3.1. Software for free-running model

tests

The software for free-running

model

tests is most closely connected with the

re-al time software(41

.

The developed

soft-ware ensures the conventional

manoeuvring

tests:

turning;

spiral;

zig-zag:

stop manoeuvre.

The connection with the software

for

visualization and graphical

representation

with which the test is directly

controlled

is extremely useful, as well as the

form-ation of graphical outputs

characterizing

typical manoeuvres.

The basic functions of this

software

are as follows (Fig.5):

determination of X and Y coordinates

of

ship model centre of gravity;

computation of model motion parameters

linear speed, heading angle, rate of turn,

drift angle, turning diameter;

determination of ship model

trajectory

parameters at turning test;

obtaining spiral curve;

K-T analysis of zig-zag test results;

I I 11

JA_

POWER HISTOGRAMS AND DISTRIBUTIONS AUTO-cORRELAT ION FUNCTION AMPLITUDE SPECTRUM SPECTRUM AND SPECTRAL GENERATED THEORETICAL SPECTRUM RESPONSE AMPLITUDE OPERATOR MOMENTS

C OHM ON

DATA

_BASE

-TURNING TEST

SPIRAL AND PULL-OUT TESTS

5.3.. Software for manoeuvring

tests

with-planar motion mechanism (PAM) 18].

The software for model

manoeuvring

tests with PMM comes in sequence after

the

programs ensuring data acquisition,which are

two types: acquisition and registration

of

experimental data as time series via ADC,and

acquisition and registration of integral

va-lues from front-end PAM microprocessor(Fig.1)

Direct connection with the software for

visualization and graphical output is

re-alized, which serves for effective controlof

the experiment, as well as for drawing up of

output documentation.

The basic functiors of this

software

are as follows(Fig.6):

determination of prescribed forced

os-cillation parameters for a given project;

processing of results of statics and

dyna-mic model tests;

determination of hydrodynamic forces

by

use of electromechanical Fourier analyser,

obtaining their sine and cosine components;

obtaining force harmonics using the

digi-tal approach (Fourier transformation);

coefficients' computation of the

equation

of motion;

Fig. 5

55- 7

STOP NANCEUVRE TEST VG

GRAPHICAL AND TABULAR OUTPUT

ZIG-ZAG TEST

by means of least squares method,

using regression dependencies.

On the basis of results obtained

from

PMM

.tests, a program module for

manoeuvr-ing simulation is developed [3 I

.

A system of differential equations

is

solved, whose coefficients are

received

from model tests. All kinematic

characteris-tics for time duration at predicted standard

manoeuvres, are obtained.

The simulation and free-model test

out-puts are unified by the graphic system.

3.4. Software for visualization

and

graphical representation

This software is oriented towards

on-line connected plotters, type "Calcomp"

and

videodisplay,type DEC VT55. The basic

soft-ware includes subprograms for drawing

of

vectors in absolute and relative

coordinate

system, for drawing symb:,lic fields,

for

drawing coordinate axis, etc. The

creation

of unified basic software facilitates

writ-ing applied programs in which the

_drawing

output is initially displayed and after that

if desired, is copied on the plotter.

This

software is base for creation of two

uni-versal programs for visualization and

STATIONARY EXPERIMENTS

GRAPHICAL AND TABULAR OUTPUT

OFFICIAL DOCUMENTS PRINTING

unified to be applied to different test

ty-pes.

With the minimum of exertions and ex-penses, without radical modifications, au-tomation of new test types can be realized upon necessity. The ,MMEX system is

easi-ly operated by the experimentator.

Jpeci-OFFICIAL DOCUMENTS PRINTING DYNAMIC EXPERIMENTS IN

U7

NI\37

REFERENCES

1. Bogdanov P., 'Dynamic Development of

the Bulgarian Ship Hydrodynamics Centre in

the Period 1971-1981 ard iqain Future Tasks

and Activities", Jubilee Scientific Session

of the BSHC, 1961, vol.'.

HYDRODYNAMIC COEFFICIENTS

aiscrete

Fig. 6

fied data structure serves as a good ba-representation of time series and _{sis for adapting some program modules} for functions allowing definition of _{prediction of seakeeping and} manoeuvring

window, drawing of several graphics of a

qualities to the automated system, as well

diagram, scaling, etc.pl,

7.i0 show typical experimental

as for development of a manoeuvring

simu-lator. i. program module is under develop-graphics from plotter.

meat at present, which arranges the

out-4. Conclusions and recommeidations put information files in accordance with In the present repert the structure the standards recommended by the XVI ITT° and functions of software for seakeeping [5]. The capabilities of ,01Kila will

in-and manoeuvring tests of ships and float- crease by establishing a DECINST which to

ing structures are discussed. connect the computer resources of

Der

and The program apparatus is considerably M6B.

TABLES

/STA/ _SPECTRUMAMPLITUDE

TABLES

/DYN/ FREQUENCY_SPECTRUM

Galchook V.Y., Solovyov A.P., "Sci-entific Experiments Technique", Leningrad, Sudostroenie, 1982 (in Russian).

Milanov E., Hadjimikhalev P., "Ship

Manoeuvring Simulation by Use of Computer",

Conference on Ship Manoeuvrability are

Hand-ling, BSHC, Varna, 1976 (in Russian).

4, jilanov E., Radev D., _{"Experimental}

Automated Investigation of Ship _Manoeuvring Cualities by Mears of Free-Running

Model",

Jubilee Scientific Session of the BSHC, Var-na, 19s1 (in Russian).

"Proposed Standard Format for

Ex-Change of Seakeeping Data on Computer-Com-patible Media", 16th ITTC Proceedings, 1961, vol.1, p.494-503.

Radev D., Stefanov A., "Program Sys-tem for Statistical Processing of Time

Se-ries by Optimization Algorithms for .ini-computer", Rouse, 1981 (in Bulgarian).

Radev D., Kishev R., Stefanov A.,St

nev Z.,"Sea-Keeping Qualities Experimental

Investigation of Ship by Automated System" S.I., Varna, 1952 (in Bulgarian).

Radev D., Milanov E., Stefanov

A.,

Jpasov Sy., "On the Software Development of Planar Motion Mechanism Tests at BSHC", SMSSH'82.

Stefanov Kostova T., "Basic

3oftware for Graphic Display", Rouse, 1981 in Bulgarian).

Stefanov Martinov P., "Real

Time Software for Experiments with

Free-Running Ship Models", XVII Scientific Sees Dedicated to Radio Dz.y, Sofia,May 1982 (in Bulgarian).

Radev D., M.Sc.

Stephanov

A.,

Physicist

Bulgarian Ship Hydrodynamics Centre Varna 9003, Bulgaria

REGULAR WAVE TEST F,g.7

mDDEI. M04162

FROUDE ND 1.22

HEIDI. 182 DEC

EP0rPA:,121AFIC::CTE:a ABTO::ATZZA:Z:

HCCaU0BAEZE:AHFEPEIHOMPEZ0Z-LI

KAIECTB

Y.ozn-,2 CY4B Z ITAEAZY.

COOPYEEHZ2

Paccmorpeim ocHosInle

cood::azeHmE 70'

apoeltrilposairm nporpammE01

g3CTM.8BTOer::-3mp0138RRo2 czcfeml npoaezeima maHeapeHHEx

I

mopexozmix

2caRr8imp2 (A=E). ZocrzrHyra

Ylmotmlcauma nporpammioro annapara

ZAR pas

Jam.= mica mcnErair0. Onmcalni

trma:zo-HaJILHue BO3MOEHOCTM cracTemm.

reHOn

:=-maJILHEx yclund2 m sarraT,

des

.7.9=1,a711HLX

msmeirelixt, ripm neodx(127.mccrm mor7T nITID

2B-.

Tomarmszposaal m }Josue Tram

mcniaaInv%Cmc-Tema AMEX yzonia

ATM

10.77s3olia3Cul sr.cEez.7

meliraTopom.

Fazes Z., H.C., mar.

Crecloilos A., H.C., #331K

E0.711-8pCHMR miermryT IILTTOAH21131I01 cyAlia

Beplis 9003

Boarapur

REGULAR WAVE TEE7 Fig.b

IARE.GULAR WAVE TEST

IRREGULAR WAVE TEST

F4E2LENZ.Y 1H2721138ELLa !WEL NC MON2 Fft2ilDEa 2.22 rtErti:MV ,42 LF7 tile. 3, m:Jc2 rmuwe SO 2.22 NEAN2 1o2 2E2

.611 411

Zia 1:201.11

FSEDUENCY NZ; MODEL SCIRLE

move. SO m22.32 ,M,DE 2.22 .12,2 Fig.9 -IN GM LW LW

aftLu

1L1.

TIME CSE'S), MODEL SCRLE 7.

b.

9. L.,

10. A.,