International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 1
Number 4
December 2007
381
Study on Integration of VTS Simulator into Net
System of Ship-handling Simulators
Yi Zhang
Wu-song VTS Centre of Shanghai Maritime Safety Administration, Shanghai, China
Merchant Marine College, Shanghai Maritime University, Shanghai
Jun Ma
Shanghai Maritime Safety Administration, Shanghai, China
Chaojian Shi & Qinyou Hu
Merchant Marine College, Shanghai Maritime University, Shanghai, China
ABSTRACT: VTS Simulator Training has been a part of VTS operator training program according to
IMO/IALA documents. It is a developing direction of VTS simulator to offering a more real-like simulative
training as in actual practices. This paper proposed an approach to integrate VTS simulator with Internet
system of multiple ship-handling simulators. Utilizing Agent/MAS technology, VTS simulators will play the
role of VTS in participating in the interactive simulated training based on Internet. It facilitates a real
environment in the VTS training and thus entails better effects.
1 BACKGROUND
With the development of VTS around the world,
maritime countries and organizations demand more
and more from VTS operators and pay at the same
time more attention to the training and management
thereof. Operators’ competence is the key factor in
the effectiveness of VTS. Based on the knowledge
and experience, VTS operator makes judgments
about the situation, coordinates between vessels,
organizes the traffic flow, and gives advices to ships.
So the personnel’s ability exerts a direct effect not
only on VTS authority’s image but also on ship’s
safety and environment protection.
The main demands on VTS personnel in
accordance with Guidelines for Vessel Traffic
Services by IMO (IMO, 1997) are as follows:
− recommend that VTS Authorities be provided
with sufficient staff, appropriately qualified,
suitably trained and capable of performing the
tasks required, taking into consideration the type
and level of services to be provided;
− describe the skill and knowledge qualifications
required by VTS Operators to provide vessel
traffic services.
The main aspects of training for VTS personnel
stand as follows: Language; Traffic Management;
Equipment; Nautical Knowledge; Communication
Co-ordination; VHF Radio; Personal Attributes;
Emergency Situations (Maritime and Coastguard
Agency, 2001).
Simulator training and assessment for VTS
personnel, though a necessary part in the recommen-
dations of IMO/IALA, haven’t got enough emphasis.
2 CURRENTLY DEVELOPEMENT
At present, many institutions and companies have
already developed a variety of VTS simulators,
which fully comply with or exceed the international
VTS personnel training requirements set by
IMO/IALA and have been certified by authorities.
There also emerge some institutions which have
been authorized to provide VTS simulator trainings.
For example, Maritime Research Institute
382
Netherlands, which built VTS simulator in 1998 and
got it upgraded in 2003 and further in 2006, has been
authorized by the Dutch Ministry of Transport to
provide training for Dutch (inland and sea) VTS
operators, Dutch pilots as well as foreign VTS
operators in cooperation with NNVO (Maritime
Research Institute Netherlands, http://www.marin.nl).
For further developing, VTS simulator should
offer more real-like situation as in actual practices.
In fact, the situation which VTS operator faces is
always changing, since different crew of different
ship, coming from different countries and hence
having different language abilities, culture
backgrounds and experiences, will react immediately
and differently to the same VTS operator.
Therefore, we propose to integrate VTS
simulators into the NetSHS (Internet Integration
System of Ship-handling Simulators). While playing
the role of VTS in Visual Sea Area (VSA) in
interacting with ships controlled by ship-handling
simulators around the world, it implements a real-
communication environment for VTS trainees. We
state its virtues as follows:
− Apart from evaluating the effects of the training,
VTS simulator also promotes the language skills,
the equipment-handling skills as well as the
ability to organize the traffic flow, to coordinate
between ships and to counteract emergencies of
VTS personnel;
− The consistence between the simulate training
and the reality in the pattern and environment of
VTS enables trainees to adapt quickly later on;
− Trainees’ performances and behaviors dealing
with ship-handling simulators constitute a
feedback from those ships on the service and
management of VTS personnel and hence offer a
lot of advices for the adjustment and
improvement of the current VTS pattern.
3 INTRODUCTION OF NETSHS
NetSHS, which we developed in IAMU project, is a
original platform for interactive simulation based on
the Multi-Agent System (MAS) technology in
accordance with FIPA standards. In that project, we
described related specifications for the integration of
multiple Ship-handling Simulator (SHS) and
established its infrastructure, which enables local
seafarers and those in the long distance to receive
training together in VSA with interactive
communication.
Agent is a problem solving entity relying on
hardware, software or both, and its properties
including autonomy, sociality, reactivity, pro-
activeness and so on (Wooldridge & Jennings.
1995). It functions automatically and flexibly in a
particular environment to achieve the goal it is
designed for.
Several agents composed of Multi-Agent System
to solve more complicated problems, communicating
each other by its content language and Ontology (see
Section 4.1.2). In FIPA agent systems agents
communicate with one another, by sending
messages. Three fundamental aspects of message
communication between agents are the message
structure, message representation and message
transport. The structure of a message is a key-value-
tuple and is written in an agent-communication-
language (ACL) based on Speech-Act Theory, such
as FIPA ACL. The content of the message is
expressed in a content-language, such as KIF
(Knowledge Interchange Format) or SL (Semantic
Language). The messages also contain the sender
and receiver names, expressed as agent-names which
are unique name identifiers in system. (FIPA, 2000)
In NetSHS, developing based Jade platform
which is one of MAS, implemented three basic kinds
of Agents: SHS Agent (SA), VHF Agent (VA), and
Facilitator Agent (FA). The data interface designates
one SA and one VA to each ship-handling simulator,
the former responsible for exchanging data with
local SHS and interacting with FA, while the latter,
affiliated to the former, helping it in the management
of simulative VHF sets and data exchange. FA,
functioning in the server, is the core agent
responsible for coordination and communication. It
responds to requests from SA, dynamically manages
the existing SA in the system, and is in charge of
message transmission as well as the decomposition,
matching and management of tasks (Zhang et al.
2005).
FA is established at the start-up of the simulative
platform. Then SA is set up in every simulator and
registered on FA. Simulators need a VSA to perform
the simulative navigation. And they can choose to
join in an existing VSA or apply to FA for creating a
new VSA on the platform. When a SHS enters a
VSA, SA exchanges the data of its own ship and
VHF audio with those in other SHSs in the same
VSA through FA. Then, based on this information,
SHSs create the virtual sea surroundings and other
ships’ model and update them continuously.
383
I n t e r n e t
...
Ship
handling
Simulator
II
SHS
Agent
Firewall
Ship
handling
Simulator
I
SHS
Agent
Firewall
Ship
handling
Simulator
N
SHS
Agent
Firewall
Facilitator
Agent
Firewall
Interface
Interface
Interface
Interface
Data
Fig. 1. Structure of NetSHS
4 DESIGN OF VTS SIMULATOR
INTEGRATION BASED ON NETSHS
According to IALA Recommendation V-103 (IALA,
1998), VTS simulator training should contain cases
of equipment and system in the VTS centre and
promote the knowledge and capability (the ability to
manage the traffic and to handle equipments) of
trainees.
4.1 Simulator Integration
To integrate VTS simulators into NetSHS, a new
type of Agent should be created in the system: VTS
Agent (VTA). And a VTS Agent and a VHF Agent
should be planted in one VTS simulator.
4.1.1 Function Definition of VTS Agent
VTS Agent planted in the VTS simulator is in
charge of communication with the FA and local VA:
− Exchange information with VTS: record property
of local VTS simulator; notify VTS simulator of
some necessary information, i.e. the login and
logout information about long-distance ships, or
information about a VSA start-up/close; forward
the real-time updating information of VSA to
local VTS simulator.
− Interact with FA and other Agents via Internet:
register on FA; apply for join/quit a VSA; send
real-time VHF data to agents; receive and process
the long-distance updating information from FA.
− Maintain the data list and update it at all time in
running, provide it to display part of simulators;
− Provide simulator’s instructor with a visible
interface, through which, instructor can operate
VTS Agent including making instructions or
receiving information.
− Communicate with local VHF Agent.
VTS Agent’s lifetime is the period of time from
the moment when the agent starts up connecting
with NetSHSs to when it exits the system through
Internet. It is the whole process of interaction of
VTS simulator.
4.1.2 Ontology of VTS Agent
Ontology is an important module for successful
interaction among agents in MAS. The function of
ontology in the system is to reduce or deracinate
confusions in conceptions and words so as to obtain
a state of sharing (FIPA, 2000). Ontology contains
conception, relationship and description about some
glossaries.
There are three types of ontology in NetSHS:
System-object Ontology, Data-object Ontology, and
Relational Ontology. Since what VTS Agent sends is
only VHF voice data, corresponding to the those
categories in Data-object Ontology, what we need is
merely small adjustment in System-object Ontology
and Relation Ontology.
1 System-object Ontology
A new type will be added in the set of System-
object Ontology: VTS
To facilitate uniform and abstract descriptions of
different VTS simulators in the domain, we
formulate properties as follows:
Table 1. Property list of VTS Ontology.
__________________________________________________
Property Data’s type Signification
__________________________________________________
Name String The name of VTS simulator
Producer String The producer of VTS simulator
Owner String The owner of VTS simulator
Compatible String The compatibility of VTS
simulator
__________________________________________________
2 Relation Ontology
There are two types of Relation Ontology:
Contain and Participate. The involvement of VTS
Agent casts an effect on Participate and hence
renders it necessary to adjust the property set to
include the properties of VTS as follows:
Table 2. Property list of Participate Ontology.
__________________________________________________
Property Data’s type Signification
__________________________________________________
Vsanickname String The nickname of the VSA
Shsnames String The set of SHS names which
join in this VSA
Vtsname String The name of VTS simulator
which join in this VSA
__________________________________________________
4.1.3 Structure Design of VTS Agent
There are five main functional modules in SA
based on its function definitions above: Data
384
Interface Module for data exchange with VTS
Simulator, Communication Behavior Module for
interaction with Facilitator Agent, Display Module
for instructors’ interaction, VHF Interacting Module
for data exchange with simulative VHF set, and
Data Processing Module(Shi & Hu, 2005.10, Shi &
Hu, 2006.10).
Interface
Module
Module
Display
Module
Communication
Behaviours
Module
VTS Agent
Ontology
VTS
Simulator
User
Database
Facilitator
Agent
VHF Interface
Module
123
456
789
*
8#
Data
Fig. 2. VTS Agent Structure
VHF Interacting Module is actually the VHF
Agent of the system. Other modules will be
described in detail in the following passages.
1 Data Processing Module
This module, functioning mainly in the process of
the system, processes VHF voice data and the
dynamic data of long-distance ships which other
modules may invoke at any moment, and saves
related historical data for the sake of achievement
evaluation of training later on.
2 Communication Behaviors Module
This module, mainly in charge of the interaction
and communication between VTS Agent and
Facilitator Agent, sends out local data and
receives updated data from long distance.
Different from SA, it only sends VHF voice data.
3 Display Module (VTS Agent GUI, VTAG)
This module provides related information for
instructors, including properties of local VTS
simulators and information of the operation in
each VSA on the platform, and responds to
instructors’ commands, including start-up/quit of
the system and the command of activating VTS
Agent’s behaviors.
The commands of the interface are listed as
follows:
Table 3. List of commands on VTAG
__________________________________________________
Commands Notes
__________________________________________________
Start Activate data interface for one time, get current
data of VTS Simulator.
Register Activate the behavior of register.
Deregister Activate the behavior of deregister.
Join String Activate the behavior of joining in a VSA.
Quit Activate the behavior of quitting the VSA.
Exit Kill the VTS Agent and quit the integrated
platform.
__________________________________________________
4 Data Interface Module
This module’s main task is to exchange data with
local VTS simulators.
4.1.4 Design of Interactive Behaviors
According with the function definition above,
VTS Agent performs behaviors as follows in its
lifetime:Register; Join in a VSA; Send local data;
Receive updated data; Quit the VSA; Deregister.
The behavior design and data structure of
message transmission in VTS Agent is basically the
same as those in SHS Agent, except that there are
only VHF voice data in the message. The time
sequence of message sending in VTS Agent is as
follows:
SA: GetAndSendBehaviour
FA: ReceiveUpdateResponder
SHS
update inform
perform
Action()
Fig. 3. Time sequence of message from VTS Agent to FA
The content format of the message in the stage of
“update inform” will be described by VHFData
format. The structure of the message is as follows:
Fig. 4. Structure of message in “update inform” action
4.2 Additional considerations in the design
4.2.1 Logical rules
Though similar to SHS, VTS simulator plays a
role totally different from that of SHS. Thus, its
integration into the NetSHS demands formulation of
385
related logical rules of operation to facilitate its
relationship with ships on the virtual platform. For
example, it should be stipulated that one VTS for
one VSA to avoid multiple VTSs disturbing each
other, which means that other simulators playing the
role of VTS couldn’t join in the VSA if there already
exists a VTS.
4.2.2 Extra Ship-handling Simulators
In the neighborhood of VTS simulator should
also be established some SHS which can join in the
NetSHS integration system. For one thing, in
addition to VTS simulative training, trainees should
also receive training in SHS, so as to familiarize
them with nautical language and terms, to strengthen
their navigational skills, to broaden their knowledge
about how and how much weather, sea and currents
affect navigation, to accumulate their experience and
hence to promote their overall competence. This is
very crucial, since VTS trainees usually have little
chance to take part in actual navigation and thus
have little opportunity to learn.
For another, based on the logical rules mentioned
above, we can create a new VSA and simulated
ships using those SHSs in the neighborhood if no
VSA is favorable and still carry on the training. To
meet requirement of training, there should be enough
simulative ships in one VSA. When there is
insufficient workload for training, extra SHSs could
running several own-ships to actively communicate
with VTS trainees, and more virtual ships which be
simulated by additional Agents planting in them.
4.2.3 Further Improvement of NetSHS
Communication among simulators in NetSHS is
satisfied but the system is still original needing
further improved. For more practical, the system is
to be developed with supportes of global relative
institutions for more perfect training and evaluating.
5 CONCLUSION
Personnel are the crucial factor in VTS. Without
personnel improvement, advanced equipments alone
can neither reduce accidents nor effectively organize
traffic flow in the water area. Therefore, the
construction of VTS is to a large extent the building-
up of expertise. Personnel’s competence and the
management thereon directly determine the
effectiveness and advancement of VTS.
VTS simulative training based on NetSHS can
create a real environment in training, where trainees
operate and interact as in actual practices but make
mistakes which only result in disorders or accidents
in the VSA.
With the development of simulator, VTS
simulator training will be more and more diversified.
Because that openning thoughts and technology will
be prevailing developing trend gradually, and
integration of simulators should be more explored.
This paper proposed the integration of VTS
simulator into NetSHS as an approach to develop
VTS simulative training. And we call for higher
participation of experts and designers, more new
simulative technology and training methods, and
definitely more practices.
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