1 INTRODUCTION

Autonomous ships are receiving significant attention

from the academic community and industry in recent

years. The new upsurge will have a profound impact

on maritime industry to great extent, in which it will

affect shipping companies, maritime operations,

shipbuilders and their operational mode. In 2012 and

2015, the funding of the "Maritime Unmanned

Navigation through Intelligence in Networks

(MUNIN)" project by the European Union [1] and

Rolls-Royce led "Advanced Autonomous Waterborne

Applications Initiative (AAWA)" [2] to outline the

concept of autonomous ships and the vision of

turning remote and autonomous shipping into a

reality. At the same time, International Maritime

Organization (IMO) also take some steps to

investigate safety, security and legal issues for

autonomous ships in IMO instruments [3-6, 29].

Regardless of the developing stage of autonomous

ships, the key issue needs to be emphasized is that

the ship be capable of an equivalent level of safety to

the conventional ships.

The ability of a ship to monitor its own health,

establish and communicate what is around it and

make decisions based on that information is vital to

autonomous operations. At the current stage, how to

better achieve autonomous navigation has become a

top priority. Fully autonomous navigation for the

Quantitative Processing of Situation Awareness for

Autonomous Ships Navigation

X.Y. Zhou

Dalian Maritime University, Dalian, China

National University of Singapore, Singapore

Z.J. Liu, Z.L. WU & F.W. Wang

Dalian Maritime University, Dalian, China

ABSTRACT: The first ever attempt at fully autonomous dock-to-dock operation has been tested and

demonstrated successfully at the end of 2018. The revolutionary shift is feared to have a negative impact on the

safety of navigation and the getting of real-time situation awareness. Especially, the centralized context

onboard could be changed to a distributed context. In navigation safety domain, monitoring, control,

assessment of dangerous situations, support of operators of decision-making support system should be

implemented in real time. In the context of autonomous ships, decision-making processes will play an

important role under such ocean autonomy, therefore the same technologies should consist of adequate system

intelligence. At the same time, situation awareness is the key element of the decision-making processes.

Although there is substantial research on situation awareness measurement techniques, they are not suitable to

directly execute quantitative processing for the situation awareness of autonomous ships navigation. Hence, a

novel quantitative model of situation awareness is firstly proposed based on the system safety control structure

of remotely controlled vessel. The data source is greatly limited, but the main result still indicates that the

probability of operator lose adequate situation awareness of the autonomous ship is significantly higher than

the conventional ship. Finally, the paper provides a probabilistic theory and model for high-level abstractions

of situation awareness to guide future evaluation of the navigation safety of autonomous ships.

http://www.transnav.eu

the International Journal

on Marine Navigation

and Safety of Sea Transportation

Volume 13

Number 1

March 2019

DOI: 10.12716/1001.13.01.01

duration of the whole voyage is extremely difficult to

realize in recent years, which based on existing level

of technological development. Remote-controlled

mode will be a feasible solution. However, removal

of vessels from direct control and the visual field of

operator inevitably reduces their ability to directly

attain adequate situation awareness (SA) of the vessel

and its surroundings.

SA is a prerequisite to rational decision-making in

many contexts, from individual operator to team

cooperation, and reflects the ability of a human to

perceive elements in their environment, comprehend

their meaning and project their state in the near

future [7]. It plays a crucial role in effective risk

reduction for operators. Currently, because of the

complexity of real ship maneuvering system, there

are few research and method are applied to enhance

SA successfully in the maritime industry. Previous

research shows that the training procedure using

simulator is an positive way to improve SA,

operational effectiveness and safety [25]. In the

relatively advanced training framework, different

information can be collected from the simulator scene

and from the real world to provide data support

(Figure 1), such as audio, video, bio-metric data from

eye-trackers. Furthermore, the application of

Wearable Immersive Augmented Reality (WIAR)

technology [26] also offer a new solution of next

generation navigation system, enhanced and remote

monitoring, and improve operator performance.

Figure 1. The gaze plot when operator wearing eye-tracker

However, the emergence of the concept of

autonomous ships in remote-control mode, the

complexity in autonomous navigation systems

reaching a new high-level, and some unnecessary

complexity adds to captains' or operator's confusions

as it changes the context of the interaction. For

example, captain's responsibility from the bridge to

shore-based control centre (SCC), and the decision

support system is integrated to maintain safety of

navigation. For this reason, the centralized context

onboard would shift to a distributed context [27]. In

the substantive research of SA, the physics and

cognition of operators are considered to be fixed in a

centralized system. And few are paying attention to

how SA might be influenced in distributed working

domains. In such system, the operator needs to

maintain an adequate situation understanding to

ensure the safety of ships, which is critical.

At present, the research of remotely-controlled

ships navigation possesses very little in the way of

shore-based situation awareness and focus on

qualitative analysis. And the design of the system is

still being developed and the final structure remains

uncertain, therefore it is difficult to explore all the

possible scenarios that may arise from the

combination of components' behavior [8]. Any

inaccuracy situational representation will propagate

into decision-making process. When adding

autonomy in order to increase situation aware-ness, it

is important to take into account the possibility that

operators located on shore may be unfamiliar with

the technology or uncertain over its capability [9],

and over-reliance may skew the decision-making

process.

In order to maintain an equivalent safety level,

better serve the construction of the remote control

system and the training of shore-based operators, it is

necessary to quantify the SA in autonomous ships

navigation.

In this paper, we propose a novel model for

quantifying the SA of autonomous ships navigation

focuses on "remote control" mode. The next section

lays down the overview of autonomous ships and

determine the object in this paper. Section III

introduces the theoretical background of SA and

discuss the current SA measurement techniques.

Section IV proposes a new quantitative method for

modeling the SA of autonomous ships navigation

considering the probability with each known

awareness element. Section V discusses the result of

model. The paper ends with conclusions and

potential future works in section VI.

2 THE OVERVIEW OF AUTONOMOUS SHIPS

The idea of autonomous ships is partly derived from

the Unmanned Surface Vehicle (USV), and the

concept of autonomous ship was first described by

Schönknecht in 1983 [10]. Subsequently, Japan

explored this concept in more depth to minimize

crew costs and built several automated ships. Recent

technological advancements in big data and

communication infrastructure, intelligent ships have

entered people's field of vision as the highest level of

automation. Compared with conventional ship,

autonomous ship will be a highly integrated ship of

various systems, which is the advanced stage of

intelligent ship development.

According to the design concept of autonomous

ships, nearly all subsystems of autonomous ships will

be controlled by remote or autonomous mode,

including collision avoidance decision-making and

ship state monitoring. The vessel may be manned

with a reduced crew or unmanned with or without

supervision and have the capabilities to make

decisions and perform actions with or without

human in the loop. To a varying degree, it can

operate independent of human interaction. In

general, the control mode can be divided into four

categories (Figure 2). The remotely-controlled

merchant vessel will play an important role for

maritime transportation system, and become a reality

in recent years, even though there are many

challenges. In this paper, we focus on the "remote

control" mode supported by SCC.