175
1 INTRODUCTION
Ship supports human life by transporting many
things such as product, passenger, and energy
resource. Shipping industry is very important and
closetoourlife.However,theshippingindustryhas
manyproblemssuchasreductionofmariners,aging
mariners officer, and labor expenses (Fukuto et al.
2007,Nishiietal.2014).
Aspreviousstudy, One Person Bridge Operation
hadbeendevelopedforimprovingtheproblems.One
Person Bridge Operation had been aim
ed at
controlling ship by one mariner (Imazu et al. 2010).
However, One Person Bridge Operation remained
technologicalproblemsandonemanerror(Shimono
etal.2009,Shimonoetal.2010,Ya
bukietal.2016).On
the other hand, recently, information about
unmannedshiphas been announced by Rolls‐Royce
(Rolls‐Royce 2016). However, unmanned ship also
has problems such as law, insurance, autopilot, and
shipbuilding cost. Therefore, it takes more time to
buildunmannedship.
In this pa
per, the concept of telexistence (Tachi
2009,Tachi etal.2010,Tachi etal.2011)isadaptedto
ship from another aspect to solve the problems of
shipping industry. The concept of telexistence on a
shipistomaneuverashipbetweenlandandshipby
atleast two mariners such as navigation officer and
helmsman (Sasaki et al. 2016). Navigation officer
works on a ship as usual, and helmsman supports
shipfromland.Therefore, thetel
existenceonashipis
oneofthesolutionforreductionofmariners,agingof
mariners, and labor expenses. Moreover, the
problems of One Person Bridge Operation and
unmannedshipsuchasonema
nerror,technological
improvementmightbesolved. Therefore,asthefirst
step of telexistence on a ship, remote maneuvering
system considering communication delay was
Development of Telexistence on a Ship by Using
Satellite Communication
S.Sasaki&T.Okazaki
TokyoUniversityofMarineScienceandTechnology,Tokyo,Japan
ABSTRACT:Nowadaysshippingindustryhasproblemssuchasreductionofmariners,agingofmariners,and
laborexpenses.Tosolvetheproblems,OnePersonBridgeOperationwasdevelopedasnavigationsupporting
system. However, One Person Bridge Operation remained technological problems and one man error.
Therefore,inthi
sstudy,telexistenceonashipwasproposedbyusingsatellitecommunication.Telexistenceon
ashipisaconceptofmaneuveringbetweenlandandshipwithatleasttwomarinerssuchasnavigationofficer
and helmsman. Navigation officer works on ship as usual and helmsman supports ship from land. In thi
s
paper,remotemaneuveringsystemwasdevelopedasthefirststepoftelexistenceonaship.Forevaluatingthe
effectiveness,shipexperimentwascarriedout.Fromtheresult,navigationofficerandhelmsmancouldalter
ship’scourseto20degreeswithin60secondsandlessthan5%overshootintheproposedremotemaneuvering
system.
http://www.transnav.eu
the International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 11
Number 1
March 2017
DOI:10.12716/1001.11.01.21
176
developed by using satellite communication. Then,
ship experiment was carried out for evaluating the
effectiveness of the proposed remote maneuvering
system.Astheresult,totaltimeof20degreesaltering
course was within 60 seconds in the less than 5%
overshoot in the proposed remote maneuvering
system.
In this paper,
first, ordinary maneuvering and
remote maneuvering is described in Section 2 and
Section 3. In remote maneuvering, communication
delay influences maneuvering a ship. Therefore,
remote maneuvering system considering
communicationdelayisproposedin Section4.Then
theeffectivenessoftheproposedremotemaneuvering
system is indicated from experimental result in
Section 5. Finally, future work for telexistence on a
ship is indicated as consideration in Section 6, and
conclusionofthisstudyisdescribedinSection7.
2 ORDINARYMANEUVERING
In ordinary maneuvering, navigation officer usually
maneuvers a ship with helmsman (Ito et al. 2012).
Navigation officer orders rudder angle, then
helmsmansteersfollowing navigationofficerʹsrudder
order(Kobayashietal.2012).Inthissection,ordinary
maneuveringby navigation officer andhelmsman is
described.
2.1 OrdinaryManeuvering
Sea transportation does not exist visible route like
landtransportation.Therefore,navigationofficeruses
nautical chart and writes down course line from
present
port to next port as objective course.
Navigation officer maneuvers a ship while
recognizing the course line, and then navigation
officer sometime alters shipʹs course in the situation
suchaswindingincapeandbays,andavoidingother
ships(Hashiomotoetal.2012).
2.2 Alteringcourse
In altering course, first,
navigation officer orders
rudderangletohelmsman.Thehelmsmanrepeatsthe
rudder angle after understanding what navigation
officer ordered. Then the helmsman steers while
obeying the rudder order. After confirming ship’s
rudderangle,thehelmsmanreportstothenavigation
officer.Forexample,inthecaseoftakingrudderof10
degrees on the starboard side, navigation officer
orders as “starboard 10” to helmsman. Next, the
helmsman repeats “starboard 10” to the navigation
officer,andthenthehelmsmansteersof10degreeson
the starboard side. Finally, after confirming rudder
angle,thehelmsmanreportstothenavigationofficer
as“starboard10,sir”
becauseship’srudderdoesnot
changeinstantly.ThisprocedureisshowninFigure1.
InFigure1,t1indicatestimewhennavigationofficer
ordered, t2 indicates repeat time of ordered rudder
angle,t3indicatestimewhenhelmsmansteers,andt4
indicates time when helmsman confirms ship’s
rudder angle and reports
to navigation officer. For
instance,whennavigationofficeraltersshipʹscourse
to 20 degrees from present course, the navigation
officer orders rudder angle in several times to
helmsman. First, navigation officer orders rudder
angle as “starboard 10” for turning to the target
course. Second, the navigation officer orders rudder
angle
as “midships” reducing rate of turn on
starboardsideatthetimewhentheship’scoursehas
been changed to 15 degrees. Then the navigation
officer orders rudder angle as “port 5” for stopping
turning on starboard side at the time of changing
shipʹs heading to 19 degrees. Finally,
the navigation
officer orders rudder angle as “midships”. In the
altering,helmsman steers, repeats and reports while
obeyingrudderorderfromnavigationofficer.
Figure1.Procedureofordinarymaneuvering
3 REMOTEMANEUVERING
Ordinary maneuvering is conducted by navigation
officer and helmsman as shown in section 2.
Navigation officer orders rudder angle, and
helmsman steers while obeying what navigation
officerordered.Navigationofficerandhelmsmanalso
need to maneuver a ship as usual in remote
maneuvering. Therefore, in remote maneuvering
system,
mastersystemandslavesystemaresetupin
landandshiprespectively,andconnectedbysatellite
communication as shown in Figure 2. Navigation
officerordersrudderangleontheshipintheremote
maneuvering. On the other hand, helmsman steers
and checks the ship state on land by observing
information which is sent from the slave system by
satellitecommunication.
Figure2.Satellitecommunicationbetweenlandandship
3.1 ConfigurationofRemoteManeuveringSystem
Configuration of remote maneuvering system is
showninFigure3.Theremotemaneuveringsystemis
consistedofmastersystemonlandandslavesystem
177
onaship,andthemastersystemandtheslavesystem
areconnectedbyusing satellitecommunication. The
master system is consisted of handle for steering,
microphoneforvoiceinput,speakerforvoiceoutput,
andhostPCformanaginginformation.Ontheother
hand,theslavesystemisconsistedof
microphonefor
voice input, speaker for voice output, client PC for
managinginformation,andshipmeasurementcontrol
server for observing and controlling ship. For
telexistenceona ship,a robotis necessaryasoneof
theslavesystemforsupportingnavigationofficerand
obtaining va rious information. However, remote
maneuveringsystem
isonlyconsistedofhostPCand
client PC for communicating ship information
becausethispaperisfocusedonmaneuveringasthe
firststepfortelexistenceonaship.
Figure3.Configurationofremotemaneuveringsystem
3.2 AlteringCourseinRemoteManeuveringSystem
Altering course in remote maneuvering system is
basicallysameastheordinarymaneuveringinsection
2. First, navigation officer orders rudder angle to
slavesystem.Therudderorderisrecognizedbyvoice
recognitionat slave system, and the rudder order is
changedtosimple
codeforreducingpacketsize.Then
the code is sent to master system by using satellite
communication. At the master system, the code is
changed to voice output for helmsman. After
helmsman recognized the rudder order of voice
output, the helmsman repeats the rudder angle,
steers,andreportstonavigation
officer.Thesignalsof
repeat, steering, and completion report are also sent
fromthemastersystemtotheslavesystembyusing
satellite communication. The procedure of remote
maneuveringby navigation officer andhelmsman is
showninFigure4.InFigure4,t1indicatestimewhen
navigationofficerordered,s1indicates
timeofvoice
recognition, satellite communication, and voice
outputfromtheslavesystemtothemastersystem,t2
indicates repeat time of ordered rudder angle, t3
indicatestimewhenhelmsmansteersafterrepeating
rudder order, t4 indicates time when helmsman
confirms ship’s rudder angle and reports to
navigation officer, and
s2 indicates time of voice
recognition, satellite communication, and voice
output from the master system to the slave system.
Here, t1, t2, t3, and t4 are same process as ordinary
maneuvering,ands1ands2arecommunicationdelay
ofremotemaneuveringsystem.s1ands2mightmake
navigationofficerfeelstress
andmightbedifficultfor
navigationofficertomaneuverashipasusual.
Figure4.Procedureofremotemaneuvering
4 REMOTEMANEUVERINGSYSTEM
CONSIDERINGCOMMUNICATIONDELAY
Inremotemaneuveringsystem,communicationdelay
of voice recognition, satellite communication, and
voiceoutputmightinfluencemaneuvering.Therefore,
assistance functions are added to the remote
maneuvering system for considering communication
delay. In this section, the assistance functions of
repeat,steeringandcompletionreportare
described.
4.1 OverviewofAssistanceFunction
Intheremotemaneuveringsystem,thesystemofthe
operation side is defined as master system. On the
other hand, the systemwhichis operated by master
system is defined as slave system. Therefore,
helmsman is regarded as master system side, and
navigation officer
is regarded as slave system side.
However, rudder order is ordered by navigation
officerattheslavesystem.Therefore,theproblemsof
communication delay are also considered from the
aspectofnavigationofficer.
Theremotemaneuveringsystemmainlyhasthree
problems.Thefirstproblemofcommunicationdelay
is repeat from helmsman.
The second problem is
steering. Rudder angle from helmsman might be
delay because of satellite communication. The third
one is completion report from helmsman. In this
study, assistance functions for repeat, steering, and
completionreport are added to the slave systemfor
consideringcommunicationdelay.
4.2 AssistanceFunctionofRepeat
Navigation officer expects that the repeat from
helmsman comes back instantly because navigation
officerconfirmsthathelmsmanunderstoodcorrectly.
However, in the remote maneuvering system,
communication delay which is voice recognition,
satellitecommunication,andvoiceoutput,influences
the repeat time. Therefore, assistance function of
repeat is added to the slave system.
The assistance
function performs voice output of repeat when
rudderorderfromnavigationofficerisrecognizedby
voice recognition at the slave system. The details of
theassistancefunctionofrepeatisindicatedinFigure
5.InFigure5,δoindicatesvoicecodeofrudderorder
from navigation officer. Voice
output of repeat is
performedbyvoicecodeδoattheslavesystemwhile
sending voice codeδo to the master system.
178
Therefore, navigation officer can focus on
maneuvering instead of waiting for repeat, and
understand that rudder order sends to helmsman
correctly. However, navigation officermightmake a
mistake of rudder order to helmsman, or helmsman
might make a mistake of repeat. In ordinary
maneuvering, the mistakes are usually noticed and
improved because navigation officer and helmsman
point out the mistakes each other. Therefore,
confirmation function is also added to the slave
systemasoneoftheassistancefunctionofrepeat.δγ
which is repeat of rudder order from helmsman is
comparedwithvoiceorderδo,andifδγ andδo
are
different, voice output of confirmation is performed
tonavigationofficerattheslavesystem.
Figure5.Assistancefunctionofrepeat
4.3 AssistanceFunctionofSteering
Navigation officer requires that helmsman steers
instantlywhileobeyingrudderorder.Forexample,if
the response of steering is delayed, ship might face
dangerous situation. However, in remote
maneuvering system, after navigation officer orders
rudderangle,ship’srudderdoesnotmoveforawhile
because of
communication delay. Therefore,
assistance function of steering is added to the slave
system. The assistance function of steering is
performed while obeying rudder order from
navigationofficer.Thedetailofassistancefunctionof
steering is shown in Figure 6. Rudder order is
recognized by voice recognition at the slave system,
andtherecognizedrudderorderischangedtorudder
ordervalueδov.Therudderordervalueδovissentto
ship measurement control server as control signal,
and the ship’s rudder is moved. In the meanwhile,
rudderorderδoissentfromtheslavesystemtothe
master system. At the
master system, the rudder
orderδo is changed as voice output for helmsman.
Then,thehelmsmansteersatthemastersystem, and
the rudder angleδis sent to the slave system via
satellite communication. Finally, the rudder angleδ
andrudderanglevalueδovarecomparedattheslave
system,and
ifthedifferenceofδandδovislessthan
±1,therudderangleδfromthemastersystemisinput
toshipmeasurementcontrolserver.
Figure6.Assistancefunctionofsteering
4.4 AssistanceFunctionofCompletionReport
Navigation officer received completion report from
helmsmanafterthehelmsmanfinishedsteering.Then
navigation officer prepares for next action of
maneuvering. In the remote maneuvering system,
communication delay of voice recognition, satellite
communication, and voice output also influences
completion report from helmsman. Therefore, the
rudder
angleδand rudder angle valueδov are
comparedsameastheassistancefunctionofsteering
intheSection4.3.Thenifthedifferenceofδandδov
islessthan±1,voiceofcompletionreportisoutput.
5 EXPERIMENT
Ship experiment was carried out to clarify the
effectiveness of proposed remote
maneuvering
system which assistance functions were added for
consideringcommunicationdelay.
5.1 ExperimentSettings
Shioji Maru which is a training ship of Tokyo
University of Marine Science and Technology was
usedforshipexperiment.Theprincipaldimensionof
ShiojiMaruisshowninTable1.
Table1.PrincipaldimensionofShiojiMaru
_______________________________________________
Lengthoverall49.9[m]
Breadth10.0[m]
Draft2.8[m]
Grosstonnage425.0[ton]
_______________________________________________
In the ship experiment, measurement experiment
ofcommunicationdelaytimeand20degreesaltering
course in remote maneuvering were carried out. In
themeasurementexperimentofcommunicationdelay
time,eachtimeoftaskinordinarymaneuveringand
remote maneuvering was measured. On the other
hand,in20degrees altering
course,previousremote
maneuveringsystemwhichassistancefunctionswere
notadded,andproposedremotemaneuveringsystem
which assistance functions were added for
consideringcommunicationdelaywerecompared.In
this ship experiment, for considering safety, master
system was set to a room in the ship. The master
system was connected to the
slave system on the
bridge by using satellite communication. In remote
maneuveringsystem,navigationofficermaneuvers a
ship on the bridge by using the slave system, and
helmsmansteersattheroomintheshipbyusingthe
mastersystem.
5.2 MeasurementExperimentofCommunicationDelay
Forconfirmingcommunicationdelay,
t1,t2,t3,andt4
of ordinary maneuvering in Figure 1, and t1, t2, t3,
and t4 of remote maneuvering system in Figure 4
weremeasured. Themeasurementresultineachtime
of ordinary maneuvering and remote maneuvering
system is shown in Figure 8. In Figure 8, the
horizontal axis indicates
each task of ordinary
179
maneuvering and remote maneuvering, vertical axis
indicateseachtime.Blackbarchartindicatesordinary
maneuvering, and slash bar chart indicates remote
maneuvering. Communication delay s1 and s2 in
remote maneuvering was 1557msec and 1482msec
respectively. The result showed that navigation
officer waits for response from helmsman about 1.5
secondslonger
inremotemaneuvering.
Figure8. Time of each task in ordinary maneuvering and
remotemaneuvering
5.3 20DegreesAlteringCourseinRemoteManeuvering
As the result of measurement experiment, the
communication delay obviously influenced remote
maneuvering. Therefore, for evaluating the effective
nessofassistancefunctions, comparativeexperiment
was carried out by using previous remote
maneuvering system which assistance functions are
notadded,andproposedremotemaneuvering
system
whichassistancefunctionsareaddedforconsidering
communication delay. As the comparative
experiment, 20 degrees altering course was carried
out. The result of previous remote maneuvering
system was shown in Figure 9, and the result of
proposedremotemaneuveringsystemwasshownin
Figure9.
Figure9.Remotemaneuveringbyprevioussystem
Figure10.Remotemaneuveringbyproposedsystem
Figure 9 indicates the result of previous remote
maneuveringsystemin20degreesalteringcourse.On
the other hand, Figure 10 indicates the result of
proposed remote maneuvering system. In Figure 9
andFigure10,horizontalaxisindicatestime,vertical
axis of above graph indicates heading, and vertical
axis of below
graph indicates rudder angle. Starting
point of horizontal axis is defined as the moment
whennavigationofficerorderedrudderangle.Inthe
previousremotemaneuveringsystemofFigure9,the
total time of 20 degrees altering course was 80
seconds, and overshoot of heading was 2.8 degrees
whichis14%
inthetargetcourse20degrees.Onthe
other hand, in the proposed remote maneuvering
system in Figure 10, the total time of 20 degrees
altering course was 60 seconds, and overshoot of
heading was 1.0 degrees which is 5% in the target
course 20 degrees. In addition, for comparing the
difference of maneuvering, time series of rudder
angle of previous remote maneuvering system and
proposed remote maneuvering system is shown in
Figure11.
Figure11.Rudderangleincomparativeexperiment
Thedottedlineindicatesrudderangleofprevious
remote maneuvering system, and the solid line
indicates rudder angle of proposed remote
maneuveringsystem.Startingpointofhorizontalaxis
is defined as the moment when navigation officer
ordered rudder angle. In Figure 11, the result of
previous remote maneuvering system was 4.4
secondsforrepeat,5.0secondsforsteering,and10.3
secondsforcompletionreport.Ontheotherhand,the
result of proposed remote maneuvering system was
1.3 seconds for repeat, 2.0 seconds for steering, and
6.0secondsforcompletionreport.
180
6 CONSIDERATION
Remote maneuvering system considering
communicationdelaywasdevelopedinthisstudy.As
the result of measurement experiment of
communication delay, total time of communication
delay s1 and s2 was about 3 seconds in remote
maneuvering. In comparative experiment of 20
degrees altering course, the total time of proposed
remote maneuvering system was shorter than total
time of previous remote maneuvering system. From
theexperimentalresults,effectivenessoftheproposed
remotemaneuveringsystemwasindicated.However,
fromFigure8,t1,t2,t3,andt4ofremotemaneuvering
systemwerelongerthant1,t2,t3,andt4ofordinary
maneuvering.
Thedelaymightshowthatnavigationofficerand
helmsman feel stress by using remote maneuvering
system.Therefore,thedelayoft1,t2,t3,andt4willbe
focusedwhenassistancefunctions willbedeveloped
in the future. In addition, navigation officer
maneuvers a ship in many situations such as open
sea,
harbor, and berthing. Therefore, assistance
functions are also necessary to expended to each
situation because maneuvering method and nautical
instrumentweredifferenceineachsituation.
On the other hand, ship information service
system was considered as the future work. In this
study, maneuvering was focused. However, lookout
is also important
as another work of helmsman.
Therefore,othershipsinformationisalsosenttoslave
system in the ship information serves system. Thus,
the helmsman checked other ships, and if the
helmsmanfounddangerous ship, the helmsmancan
reporttheshiptonavigationofficerwhoworksonthe
shipvia satellitecommunication.
Therefore, the ship
informationservicesystemwillbeusefulforfinding
othershipsonland,andhelpfulfornavigationofficer
tofindothershipsinadvance.
7 CONCLUSION
In this study, telexistence on a ship was developed.
Theconceptoftelexistenceonashipwastomaneuver
a ship by
at least two mariners such as navigation
officerandhelmsman.Asthefirststepoftelexistence
onaship,remotemaneuveringsystembetweenland
and ship was developed by using satellite
communication. In the remote maneuvering system,
communicationdelaysuchassatellitecommunication
and processing delay influenced maneuvering.
Therefore, assistance functions
of repeat, steering,
completion report were added to remote
maneuvering system for considering the
communicationdelay.Toevaluatetheeffectivenessof
proposed remote maneuvering system, ship
experimentwascarriedout.Astheresultofproposed
remotemaneuveringsystem,totaltimeof20degrees
alteringcoursewasshorter20secondsthan
thetotal
time of previous remote maneuvering system which
assistance functions are not added. In addition,
overshoot of the proposed remote maneuvering
system was reduced from 14% to 5%. From the
results, the effectiveness of the proposed remote
maneuveringsystemwasindicated.Inthefuture,the
remote maneuvering system will be
adapted to
various situations and ship information service
systemwillbedevelopedforlookout.
ACKNOWLEDGEMENT
ThisworkwasfinanciallysupportedbyFundamental
Research Developing Association for Shipbuilding
andOffshore.
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