Ontology-Based Conceptual Modeling of Military Mission Spaces

Ontology-based Conceptual Modeling of Military Mission Spaces

Haeran Kang*, Young Min Bae**, Kyong-Ho Lee*, Young Hoon Lee** and Jai-Jeong Pyun***

*Dept. of Computer Science

**Dept. of Information & Industrial Engineering

Yonsei University, 134, Shinchon-dong, Sudaemoon-ku, Seoul, 120-749, Korea.

***5thR&D Institute

Yuseong P.O Box 35, Daejeon, 305-600 Korea.

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Keywords:Conceptual modeling; mission space model; military ontology;task ontology;CMMS.

Abstract

In order to improve the interoperability and reusability of future defense models and simulations, the Conceptual Models of the Mission Space-Korea (CMMS-K) is being developed. CMMS-K is an ontology-based conceptual modeling framework formilitary mission spaces. This paper proposes a semantic language for describing a mission space model (MSM) as a main component of CMMS-K. A MSM is a conceptual model for military business processes and scenarios. Compared to previous approaches, the proposed MSM description languageis designed to maximize the interoperability and reusability of MSMs. Specifically, it provides a scheme to represent military scenariosmeaningfully with domain ontologies, which consist of entity and task ontologies. A MSM may be composed of an atomic process (action) and/or a composite process. The proposed method identifies and reuses military actions and tasks, which play a critical role in military scenarios, through the proposed task ontology. A task is defined as a composition of actions conducted by the same subject.To show the expressivity of the proposed MSM description language, a case study on a close air support scenario is illustrated.

INTRODUCTION

The use of modeling and simulation in the military domain is increasing. An efficient method of acquiring, representing, and maintainingdomain knowledge with the minimum effort is required. Particularly, the utilization of conceptual models facilitates the interoperability and reusability of simulation models in modeling and simulation.

Principle efforts in the conceptual modeling of military mission spaces include the Conceptual Models of the Mission Space (CMMS) [1] of the American Defense Modeling and Simulation Office and the Defense Conceptual Modelling Framework(DCMF) [2~4] of the Swedish Defense Research Agency (FOI). They are ontology-based conceptual modeling frameworks in the military domain.

Theoverall objectives ofCMMS and DCMF are to capture authorized knowledge of military operations; to manage, model and structure the obtained knowledge in an unambiguous way; and to preserve and maintain the structured knowledge for future reuse.However, it is revealed that some specifications of CMMS are vague in published materials and some part of DCMF such as its process description language still has a lot of room for improvement.

In order to support the semantic interoperability and reusability of simulation models, we are developing the Conceptual Models of the Mission Space-Korea (CMMS-K). CMMS-K is an ontology-based conceptual modeling framework formilitary mission spaces.

In addition to the overall introduction to CMMS-K, we propose a semantic language for describing a mission space model (MSM) as a main component of CMMS-K. A MSM is a conceptual model for military business processes and scenarios. It is a simulation and implementation-independent description of the real world entities and processes in the military domain, which can be used as a frame of reference for simulation development.

BOM++ [5], the representative MSM description language proposed by FOI, provides two alternative methods to extend the Basic Object Model (BOM). BOM is a Simulation Interoperability Standards Organization (SISO) standard and encapsulates information needed to describe a simulation component. The first method extends theBOM schemastructure and refers to an external ontology. In the second one, an independent BOM++ ontology is proposed based on OWL-S [6]. OWL-S is a de facto standard for describing the semantic information of Web services. The service model of OWL-S is used to compose component processes to perform a composite business process.

Compared to previous approaches, the proposed MSM description languageis designed to maximize the interoperability and reusability of MSMs. Specifically, it provides a scheme to represent military scenarios meaningfully with domain ontologies, which consist of entity and task ontologies. A MSM may be composed of an atomic process (action) and/or a composite process with the adoption of the control and data flow mechanism of OWL-S.

Unlike the conceptual models of general domains which are object-oriented or object-centered, conceptual modeling in the military scenariosshould be action-centric. However, previous approaches have limitation in terms of describingmilitary actions sophisticatedly and reusing them systematically.

The proposed method identifies and reuses military actions and tasks, which play a critical role in military scenarios. This paper proposes a task ontology as a component of CMMS-K to represent and reuse actions and behaviors. Specifically, the task ontology provides a scheme for representing domain knowledge about an action or a task, which is a group of actions performed by the same subject.Furthermore, the conceptual modeling of MSMs based on the predefined set of actions and tasks would permit the semantic interoperability and reusability of military simulation models.

To assess the feasibility of the proposed conceptual modeling approach, the paper illustrates a case study on developing a conceptual model for close air support scenarios. From the case study, it is found that our approach expresses mission space models effectively.

The rest of this paper isorganized as follows. Section 2 introduces the overview of CMMS-K. Section 3 describes the proposed domain ontologies, which represent the semantic hierarchy of nouns and verbs in military scenarios. Section 4 explains the proposed MSM description language in more detail. Section 5 shows the feasibility of the proposed MSM description language with a case study on a close air support scenario. Finally, conclusions and future works are summarized in Section 6.

CMMS-K OVERVIEW

CMMS-K is a standardized conceptual modeling framework for military mission spaces. Its goal is to improve the interoperability, reusability and composability of future simulation models. CMMS-K is being developed through aresearch project of the Agency for Defense Development (ADD) of South Korea.

CMMS-K consists of domain ontologies (entity and task), a MSM description language, a MSM modeling method, and a CMMS-K management system (see Table 1). To represent the knowledge of military domain, the entityand task ontologies, which support the semantic interoperability among simulation models, are designed.

Entity and task ontologies conceptually model nouns and verbs in the military domain, respectively. By using

Table 1. CMMS-K main components

Component / Description
Entity ontology / Specifiesreusable military entities such as organization, personnel, facility, etc.
Task ontology / Specifies reusable actions and tasks
MSM description language / Describes processes using components of domain ontologies
MSM modeling method / Displays guidelines for conceptual modeling and provides graphical user interface
CMMS-K management system / Stores and retrieves conceptual models

entity and task ontologies, reusable units of nouns and verbs can be predefined and reused. MSMs can be dynamically modeled utilizing these predefined reusable components of entity and task ontologies. More information about CMMS main components is described in our previous paper [7].

Figure 1. Storing and searching for conceptual models

The process of storing and searching for conceptual models using the CMMS-K management system is shown in Figure 1.A MSM provider describes MSMs using domain ontologies. To share MSMs, the service provider stores the MSM descriptions in the CMMS-K directory. A MSM requester specifies her (his) needs using domain ontologies. The user requirement is represented with a semantic template based on domain ontologies.

An example data flow among CMMS-K components and their relationships are shown in Figure 2. The data flow of CMMS-K is developed based on DCMF.The explanation of the task ontology is described in detail in Section 3.2.

CMMS-K DOMAIN ONTOLOGIES

The ontology configuration of CMMS-K is shown in Figure 3. The structure of our domain ontologies is shown in Figure 4. The entity ontologies are used in the task ontology. Domain ontologies are described in the form of Web Ontology Language (OWL) [8].

Figure 2. The data flow and relationship among CMMS-K main components

Figure 3. CMMS-K ontology configuration

3.1 CMMS-K Entity Ontology

The proposed entity ontology is divided into Organization, Facility, Materiel, Personnel and Location as shown in Figure 4. The proposed entity ontology has been built by applying Methontology [9], which is one of the prominent ontology development methodologies.

Methontology includes a process for the ontology developmentand the techniques required at each stage of the process. The ontology development process of Methontology consists of five steps: specification, conceptualization, formalization, implementation, and maintenance.Methontology further divides the conceptualization step into eleven phases and provides detailed guidelines of each phase.

Figure 4. The structure of CMMS-K domain ontologies

A few phases of conceptualization step for CMMS-K entity ontologyis illustrated as follows.

(1)To build the glossary of terms.We built a glossary including all terms related to the domain and their synonyms and acronyms.

Figure 5. An excerpt fromthe concept taxonomy graph in our materiel ontology

(2)To Build concept taxonomies.We built a hierarchy between concepts in the glossary of terms (see Figure 5).

(3)To build ad hoc binary relations. In this step, ad hoc binary relationships between concepts are illustrated (see Table 2).

Table 2. An excerpt from the ad hoc binary relations in our entity ontology

Concept / Relation / Concept
Artillery battalion / support / Task force
is supported by
Squadron / command / Fighter
is commanded by
Master control and reporting center / command / Squadron
is commanded by

3.2 CMMS-K Task Ontology

This section describes the proposed task ontology which is one ofthe domain ontologies of CMMS-K.Actions play a critical role for describing military simulation scenarios. This paper defines a group of actions performed by the same subject as a task. The proposed task ontologydescribes information about actions and tasks, both ofwhich are reusable units. There exist groups of actions which are used together frequently in military scenarios. The proposed task ontology allows us to store and reuse these groups of actions.

The task ontology is composed of actions (atomic processes), tasks (AKA composite processes), control constructs, parameter bindings, and properties among actions and tasks. An action is a minimum unit of activity which constitutes a task. A task is a group of actions conducted by the same subject to fulfill a mission.

Missions, military goals, could be classified from ones of strategic national level to ones of tactical level according to their performers. This mission classification is developed referring to theUniversal Joint Task List (UJTL) [10]. For example, strategic national missions are conducted by the highest level commanders such as a chairman of the joint chiefs of staffs and tactical level missions are carried out by low level personnel such as soldiers.

The proposed task ontology is layered following the mission classification. The task ontology is four-layered: Strategic Nationals (SN), Strategic Theater (ST), Operations (OP) and Tactical (TA) as shown in Figure 6.

Dependency relationships might exist between tasks in different layers. IfTask1 of Layer1 depends on Task2 of Layer2 andthe definition of Task2 is modified, the definition of Task1 must be modified. For instance, SN taskl depends on ST taskm. Thus, to change the definition of SN taskl, the definition of ST taskm must be also changed.

The proposed tactical task ontology, which is being developed, is based on the Korean tactical task list. The Korean tactical task list consists of maneuver, intelligence, fire, combat service support, command and control, and defense. Therefore, the top level tasks of the tactical task ontology are classified into the corresponding classes: maneuver, intelligence, fire, combat service support, command and control, and defense.

CONCEPTUAL MODELING OF MILITARY

MISSION SPACES

This sectionfocuses onthe proposed MSM modeling approach. A MSM is a military process model. To describe a MSM, CMMS-K utilizes predefined reusable units in the entity and task ontologies. Using the predefined static information, a MSM could be described dynamically according to the change of circumstances and user needs.

The proposed MSM description language is shown in Figure 7. The MSM description language consists of processes (atomic, simple, composite), control constructs, parameter bindings, and properties among MSM components.

In this paper, a MSM may consist of atomic process (action), simple process, and/or composite process. This process hierarchy is based on the OWL-S [6] service model. An atomic process corresponds to the process a service can perform by engaging it in a single interaction. A composite process indicates a process that requires multi-step protocols and/or multiple server actions.

A process is decomposable into other (noncomposite or composite) processes. A process can be viewed at different levels of granularity, either as a primitive, undecomposable process or as a composite process. In the former case, a simple process can be used to represent it.

Figure 6. The four-layer of task ontology

Figure 7. The proposed MSM description language

A simple process may be used either to provide a view of (a specialized way of using) some atomic process, or a simplified representation of some composite process (for a purpose of planning and reasoning). In the former case, the simple process is realized by the atomic process; in the latter case, the simple process expands to the composite process [6].

The proposed MSM description language utilizes control constructs and parameter bindings of OWL-S. The main properties of atomic and composite processes in our MSM description language are represented in Tables 3 and 4, respectively.

Table 3.The main properties of atomic process in the proposed MSM description language

Property / Description / Range
hasActivity / a verb which constitutes an action / verb
hasSubject / a subject which (who) performs an action / organization or personnel
hasDirectObject / a direct object (action) of an action / object or action
hasIndirectObject / an indirect object of an action / object
usesResource / resource which a subject uses to perform an action / object
takesPlaceInLocation / a place where a subject performs an action / location
hasInput / input information which is necessary for a subject to perform an action / input parameter
hasPrecondition / a condition which must be true before a subject performs an action / precondition
hasOutput / output information which is generated as a result of that a subject performs an action / output parameter
hasEffect / an effect that occurs as a result of that a subject performs an action / effect

Table 4.The main properties of composite process in the proposed MSM description language

Property / Description / Range
hasSubject / a subject which (who) performs a composite process / organization or personnel
hasActionList / actions which constitute a composite process / action
hasPurpose / a purpose of performing a composite process / object
hasDuration / duration while a subject performs a composite process / duration
hasPrecondition / a condition which must be true before a subject performs a composite process / precondition
hasEffect / an effect that occurs as a result of that a subject performs a composite process / effect
dependsOn / another composite process whose definition must be modified if a composite process definition is modified / composite process
usesResource / resource which a subject uses to perform a composite process / object
hasInput / information which is necessary for a subject to perform a composite process / input parameter
hasOutput / information which is generated as a result of that a subject performs a composite process / output parameter

The main properties of atomic and composite process in the proposed MSM description language provide grammars that can express more meaningfulinformation in military simulation scenarios than previous military conceptual models.

For instance, the property such as ‘dependsOn’, ‘hasDuration’ and ‘hasEffect’ express the dependency relationships between composite process, duration and effect of the composite process, whichcannot be expressed with previous military conceptual models such as BOM++. In addition, action properties ‘hasIndirectObject’, ‘takesPlaceInLocation’ and ‘hasEffect’ describe an indirect object, location and effect of an action, respectively, which are not expressable with BOM++.

Case Study: Close Air Support (CAS)

This section illustrates an example CAS scenario using theproposed MSM description languagebased on the task ontology.

Figure 8. Example CAS scenario

1. Unit detects target.
2. Unit decides to request CAS.
3. Unit passes CAS request to commander of squadron.
4. Commander of squadron coordinates with ground center commander.
5. Commander of squadron commands to scramble aircraft if there is no on-call aircraft.
6. Commander of squadron commands to scramble CAS if there is on-call aircraft.
7. Commander of squadron commands to send aircraft to a control/contact point.
8. Approaching the control/contact point, pilot contacts to commander of squadron to receive briefing.
9. Pilot bombs on target.

Figure 8 shows an example CAS scenario [11] while

CAS scenarios could be described in various forms in a real world. Table 5 shows the actions and tasksextracted from the example CAS scenario.

Table 5.Actions and tasks which constitute the example CAS scenario in Figure 8

TASK ‘Target detection and CAS request’
ACTION ‘Target detection’
ACTION ‘CAS request decision’
ACTION ‘CAS request’
TASK ‘Coordination and aircraft sending’
ACTION ‘Coordination’
ACTION ‘Aircraft scrambling command’
ACTION ‘CAS scrambling command’
ACTION ‘Aircraft sending command’
TASK ‘Receiving briefing and target bombing’
ACTION ‘Receiving briefing’
ACTION ‘Target bombing’

CMMS-K adopts control constructs and parameter bindings of OWL-S when describing MSMs. Figure 9 shows a MSM diagram representing the example CAS scenario utilizingthe actions and tasks in Table 5.

In Figure 9, control construct ‘sequence’ is used to connect actions and tasks. Control construct ‘if-then-else’ is used to connect action ‘Aircraft scrambling command’ and action ‘CAS scrambling command’.If there is no on-call aircraft, action ‘Aircraft scrambling command’ is performed.Otherwise, action ‘CAS scrambling command’ is carried out.