Research on Model Composition for Underwater Warfare Simulation in Engagement-Level

Transcription

1 3rd Internatonal Conference on Mechatroncs and Industral Informatcs (ICMII 2015) Research on Model Composton for Underwater Warfare Smulaton n Engagement-Level Janchun Zhang 1, 2, a *, Fengju Kang 1, 2, b 1 Marne College, Northwestern Polytechncal Unversty, X'an, , Chna 2 Natonal Key Laboratory of Underwater Informaton Process and Control, X an, , Chna a @qq.com, bkangfengju@nwpu.edu.cn Keywords: Model Composton, SES, HDEVS, Underwater Warfare, Ontology. Abstract. Ths artcle ntroduces a structural modelng approach and a rule-drven model composton method for underwater warfare smulaton to facltate the reusablty and composablty. Frst, a SES-based model structure s bult and the Hybrd Dscrete EVent System specfcaton (HDEVS) formalsm s proposed to model the combat entty. Utlzng the ontology, we descrbe the desgned models n the Underwater Warfare Smulaton Ontology (dubbed UWSO) to enhance the readablty and dsambguaton. Moreover, rules of model composton are performed n syntactc, semantc and pragmatc layers durng the ntegraton phase accordng to certan scenaro. Fnally, by prelmnarly applyng n underwater warfare system, the result shows effcency of the research. Introducton As modelng and smulaton (M&S) has been wdely utlzed n the mltary communtes, the varous developed combat models have contrbuted to assessng performances, analyzng tactcs, and plannng acqustons of underwater warfare [1]. In spte of ther past contrbutons, the exstng models suffer manly from low model reusablty and extendblty. When applyng these models to new weapon desgn or tactcal analyss, we are hard to modfy, ntegrate, and reuse the exstng models, whch results n large costs for the adaptaton to new applcaton scenaros. Creatng smulaton models by composton of predefned and reusable components s a way to reduce the costs and tme. The focus of ths artcle, therefore, s to ntroduce composable methods for a more reusable and extendable underwater warfare modelng and smulaton. We propose the overall model structure to understand the model constructon and mpled relatonshps between upper models and ther components usng system entty structure (SES). Ths model structure enables one to express the real system more effectvely and to reflect extendable underwater warfare scenaros. Then usng the DEVS formalsm, t enables a more straght-forward model comparson and the bgger model development wth less cost. Amng at overcomng dsadvantages and beneftng from the merts of hybrd smulaton, we adopt a representatve approach called HDEVS [2], whch conssts of hybrd coupled models, DEVS coupled models, DEVS atomc models, contnuous coupled models, and contnuous atomc models. Ths formalsm emphass, however, means users should develop separate models, not an ntegrated model from a hybrd system and these separate models cannot reflect the orgnal form of a target system. Hence, a modfed HDEVS formalsm to model the combat entty s proposed and the key mprovement s the unfcaton of defnton, known as hybrd coupled models (HCMs) and hybrd atomc models (HAMs). On the bass, UWSO s proposed to descrbe concepts and relatonshps, whch formally represents and shares doman knowledge as a set of concepts to mprove reusablty and nteroperablty [3]. Composablty has been defned as the capablty to select and assemble reusable smulaton components n varous combnatons nto smulaton systems to meet user requrements [4,5]. Syntactc composablty s concerned wth the compatblty of mplementaton detals [6,7]. Semantc composablty, on the other hand, s concerned wth whether the models that make up the composed smulaton system can be composed n a meanngful way. To enrch the elements of composton and promote smulaton system development, t needs to buld more complete rules to gude the composton process The authors - Publshed by Atlants Press 745

2 Ths artcle contans fve sectons. Secton 2 ntroduces the modelng approach usng SES and HDEVS and ontologcal descrpton method, and Secton 3 explan the proposed a model composton process wth detaled rules. Secton 4 llustrates the experment to prove the effcency of ths work. Fnally, Secton 5 concludes ths study and proposes future extensons for a more complete soluton. Model Desgn Overall Model Structure. To systematcally organze the famly of models nto a repostory, we use the system entty structure (SES) to descrbe the overall model structure for underwater warfare, whch offers a structural means of knowledge representaton. The model repostory characterzes taxonomc and decomposton relatonshps among component models to help compose the rght combnatons of alternatves to satsfy the partcular objectves, as llustrated n Fg. 1. Fg. 1. Overall model structure of underwater warfare usng SES Concretely, the underwater warfare smulaton model, an uppermost model, s dvded bascally nto envronment, combat entty and assessment models that we are nterested n modelng. The combat entty models are descrbed n three levels that nclude platform, module and component; the envronment model reflects envronmental effects such as weather patterns, temperature, salnty, artfcal features and more; the damage assessment model evaluates the engagement stuaton (e.g., the offensve combat entty model attacks the target or the defensve model defends aganst the attack);. In spte of the bref model constructon usng SES, the proposed model structure assures flexblty and extendblty to varous underwater warfare scenaros by herarchcal decomposton of focused objects and reduces correspondng system complexty. Especally, some equpment such as torpedo, mssle can also be decomposed nto several components and vewed as a specal platform n smulaton doman. HDEVS Formalsm for a Combat Entty. HDEVS s based on DEVS formalsm [8]. Each model has I/O ports and s nterconnected through couplng relatons. Models have ports for two types of data: 746

3 dgtal sgnals (representng contnuous sgnals) and dscrete events. When sgnals or events are need to be converted, the port mappng functons convert the data. Dgtal-to-Event (D/E) mappng functons are used for detectng state events trggered when a contnuous sgnal reaches a threshold level. Event-to-Dgtal (E/D) mappng functons generate mapped sgnals when a related event occurs. A focus of the proposed formalsm s the extenson of atomc and coupled models, as shown n Fg. 2. The modelng s dffcult because of the requrement about complex knowledge background: that s, the doman knowledge as well as the M&S knowledge at the same tme. To be specfc, each model s modeled nto two levels n terms of a layered structure through model abstracton: (1) a logcal model (LM) layer for the M&S knowledge; (2) a physcal model (PM) layer for the doman knowledge. The LM layer represents the abstract behavor of a PM, and t s sutably employed to descrbe models macroscopcally. For mcroscopc modelng, we adopt the PM layer to reflect detaled behavor of the same model by actons represented as varous functons or algorthms. Fg. 2. Structure from HDEVS Formalsm Defnton 1. Hybrd atomc models (HAMs) HAM =< XYSLV,,,,, F, δ, δ, λ, ta > (1) -- X = XevU Xs : Input; X ev : Set of Dscrete Events Inputs; X s : Set of Contnuous Sgns Inputs -- Y = YevU Ys : Output; Y ev : Set of Dscrete Events Outputs; Y s : Set of Contnuous Sgns Outputs -- S = L V : State Space; L: Set of Dscrete States; V : Set of Contnuous State Varables -- F : L ( V Xs V), Contnuous Evoluton Functon -- δ nt :( L L) F, Internal Transton Functon -- δ ext :( Q Xev) F S, External Transton Functon; Q= {(, lvt, e) te [0, ta()] l } -- λ: S Y,Output Functon -- ta: L R +,Tme Advance Functon Defnton 2. D/E nterface models (DEIMs) -- Ω ( Xs, T) : Set of Xs n Interval T Defnton 3. E/D nterface models (EDIMs) Defnton 4. Hybrd coupled models (HCMs) nt ext DEIM =< X, Y, T > (2) s ev ev Y T ev : Ω 2 ev (3) EDIM =< X, Y, T > (4) T : X Y s ev s 747 ev s s (5)

4 -- D : Name Set of Sub-models HDM =< XYD,,,{ M }, C, C, C, Select > (6) xx yx yy { M } = { HAM } U{ HCM } U{ DEIM } U { EDIM } (7) U U (8) C = X dx U X cx xx ev s j j U U (9) C = Y dx UY cx yx ev s j j U U (10) C = dy Y U cy Y yy ev j s j -- C xx : External Input Couplng (EIC); C xy : Internal Couplng (IC); C yy : External Output Couplng (EOC); dx : Set of Input Event n { } cx : Set of Input Sgn n { } dy : Set of Output Event n M ; M ; { M }; cy : Set of Output Sgn n { M } -- Select:2 D D: Te-breakng Functon In summary, HDEVS formalsm dvdes the combat entty model nto two parts and the groupng enables us to reconfgure the overall combat entty model by sharng the same nterface wthn the group. Also, the proposed model partton facltates concurrent modelng between the two vertcal layers at the model development phase. Ths reduces the complexty of model development and ncreases the productvty of modelng concepts. For smulaton of varous engagement scenaros (.e., reflecton of alternatve tactcal rules or applcaton of dverse search algorthms), modfcaton of the PM layer occurs more frequently than n the case of the LM layer. Therefore, ths model method mnmzes revson of models wthout modfyng LM layers. UWSO Ontology. Ontologes are conceptual models that capture and explan the vocabulary used n applcatons guaranteeng communcaton free of ambgutes n formats [3]. Ideally an ontology should focus on the descrpton of smulaton component to facltate model composton, as well as to support model dscovery and reuse wthn sets of classes. UWSO (Underwater Warfare Smulaton Ontology) s a proposed ontology to represent correspondng doman knowledge and detaled models. As shown n Fg. 3, the structure of proposed UWSO spans two drectons. Classes for keywords, parent, chld and category are defned to demonstrate the poston of entty n the organzaton of overall model repostory. Others represent the ndvdual nformaton of the entty mostly of behavor that s modeled as a fnte state machne startng from an ntal state and proceedng to a fnal state based on HDEVS. Transtons are trggered by an arrval event or an elapse n a tme nterval and change the state, whch may produce certan output. After the ndvdual entty s bult, the whole models n ths doman are organzed n the ontology developed n Protégé 4.3 referrng to overall model structure of underwater warfare. Fg. 3. UWSO Structure 748

5 Rule-drven Composton Method The typcal engagement of underwater warfare nvolves the attackng platform, whch fres weapons, and the target platform. Fgure 1 shows the partal smulaton scenaro and ts tasks that the platform should accomplsh n the engagement stage. Once the attackng platform detects some threats, t keeps n contact wth the threat to dentfy whether t can be a target or not. If the threat s regarded as a target, the platform tracks the target through target moton analyss (TMA) and approaches t to launch weapons under certan condtons. When the target s wthn the scope, the platform fres and gudes ts weapons, and fnally, the platform makes a detour operaton. Consequently, tasks for the attackng platform are relevant to patrol, target detecton/dentfcaton/trackng, attack, tactcal evason and so on. To be concrete, an attackng platform can be represented by a sngle or ntegrated component model whch has several behavoral states, and the states represent certan tasks. Addtonally, converson of tasks that mples engagement flow s descrbed as a state transton n the model, and a task s performed n the correspondng state. Therefore, the smulaton scenaro can be vewed as a dscrete event smulaton exchangng sgnals and nteractons between the models, and ths s why we have wdely used dscrete event modelng and smulaton n the mltary doman system. The composton process comprses two phases: model search; model matchng and composton. Durng the smulaton development process, the smulaton scenaro s parsed nto sets of tasks. Then we start dscovery, matchng and composton (DMC) process that conssts of the follow steps. 1) The keyword-based query s bult based on frst task and sent to the model repostory. The repostory returns a set of potental canddates correspondng to the query. 2) The canddate models are matched syntactcally, semantcally and pragmatcally wth the desgned rules. 3) Search models about the next task, the result ncludng canddate models can be used as refned condton for the fnal result. Iteratvely execute the steps above untl all tasks have been done and the composton rules (See Tab. 1)are decpted as follows. In the syntactc layer, composton s operated by checkng syntactc aspects of actons and messages that are concerned wth the compatblty of mplementaton detals. (Rule-1): The name of the message ncludng types of event and sgnal n the smulaton scenaro wth the one n the canddate model should be exactly matched. (Rule-2): The mode of acton assocated wth the message should be a combnaton of In acton of a model wth respectve Out acton of other models acceptng the message. (Rule-3): The quantty of parameters of an event or sgnal n the model wth those of the canddate should be equal. In the semantc layer, composton s operated by checkng semantcs of the message by usng the semantc nformaton. Ths semantc nformaton conssts of data type and unt of each parameter as well as the ontology of the event ntator and recever enttes. (Rule-4): The entty type for message sender and the one whch receves the message n both models should accord wth doman knowledge of correspondng model herarchy, such as the event of launchng torpedo should relate wth a platform and a torpedo, or a weapon module belong to certan platform and a torpedo. (Rule-5): The unt of a parameter n both sdes should be the same or can be convertble wthout loss of nformaton, such as converson between mle and klometer. (Rule-6): The type of parameters n both sdes should be compatble. (Rule-7): The range of output parameters n message sender should be n the scope of nput parameters of the model that receves the message. In the pragmatc layer, composton s operated by checkng the pre/post condtons defned as the relaton between post-condton of an Out acton and the pre-condton of the correspondng In acton. 749

6 (Rule-8): The mplcaton (PreCond_Send Λ PostCond_Send PreCond_Receve) should be held between message sender and the correspondng message recever. Tab 1. Composton Rules Composton Layer Element to be matched Content Rule Message Event/Sgnal Name Rule-1 Syntactc Acton Mode Rule-2 Parameters Number of Parameters Rule-3 Entty Type Rule-4 Semantc Unt Rule-5 Parameters Data Type Rule-6 Value Range Rule-7 Pragmatc State Machne Pre/Post Condton Rule-8 Case Study A typcal underwater warfare scenaro: one-to-one engagement, a submarne attacks a surface shp. Once the submarne detects the warshp by sonar, t keeps n contact to dentfy. When target s confrmed as enemy, the submarne tracks the target through target moton analyss (TMA) and launches a torpedo. After the submarne fres, t gudes the torpedo or let the torpedo autonomous moves. If the warshp fnds approachng torpedo, t makes a detour to be far from the torpedo. Relevant smulaton models are mplemented n ADEVS whch s a lbrary wrtten n C++ language and provdes smulaton engne for dscrete systems [9]. And many algorthms are realzed n form of dynamcally lnked lbrary (DLL) and embedded nto the functons. In ths scenaro several key tasks are nvolved wth the submarne, such as patrol, detecton, attack. Take the acton of launchng a torpedo as example, the sender and recever are submarne and torpedo. Frst, we dscover the needed enttes n the model repostory through the keyword-based query. The keyword ncludes name of enttes (submarne, fre control and torpedo), types of enttes (platform, underwater equpment and underwater weapon) and names of functons (launch and attack). After dscover phase, a canddate set s produced. Next s the matchng and composton phase. In syntax layer, the models of submarne and torpedo must have the nterface of launch torpedo and there should be fve parameters (tme, poston, sound level, velocty and headng) n the nterface. When n statc semantc matchng, the torpedo should belong to the class of submarne torpedo, such as t support the functon of wre-gude. The unt, data type and value should be correct or convertble. Usually the torpedo adopts knot to show ts speed and the data always belongs to type of double to meet the user requrement. In acton of launchng (Fg. 4), the pre-condton s that the target s detected successfully and post-condton s that the state of torpedo s startup. After fndng the target, the submarne keeps n weapon launch state and sends the event of launchng torpedo to the torpedo fre control system. As a result, the torpedo receves the event and goes nto startng state. At the same tme, the submarne starts to gude the torpedo. Here the condtons are also checked and the In and Out actons are matched both syntactcally and semantcally. After the accomplshment of all tasks nvolved n the scenaro, we obtan the overall executon sequence of model that s nput to the smulaton engne. The smulaton result (Fg. 5) clearly demonstrates the process of combat and ndcates the feasblty of proposed method. 750

7 Fg. 4. Informaton of State Machne Assocated wth Launch Event Shp_1 Tor_1 Surface Shp Torpedo Sub_1 Submarne Concluson Fg. 5. Smulaton Result In ths paper, a structural modelng approach and a rule-drven model composton method n syntactc, semantc and pragmatc layers for underwater warfare smulaton are proposed to facltate the reusablty and composablty. The combnaton technology of SES, HDEVS and ontology promotes the reuse and share of varous models. And the composton method mproves the effcency of model ntegraton. References [1] Andreas Tolk, Engneerng Prncples of Combat Modelng and Dstrbuted Smulaton, Wley, [2] C. H. Sung, and T. G. Km. Framework for Smulaton of Hybrd Systems: Interoperaton of Dscrete Event and Contnuous Smulators Usng HLA/RTI, 25th ACM/IEEE/SCS Workshop on PADS, (2011) 1-8. [3] N. Guarno, D. Oberle and S. Staab. What s an ontology? Handbook on Ontologes. Sprnger, Berln, [4] E. W. Wesel, M. D. Petty, and R. R. Melke, Valdty of Models and Classes of Models n Semantc Composablty, n Proceedngs of the Fall 2003 SIW, Orlando FL,

8 [5] M. D. Petty, E. W. Wesel, R. R. Melke, Overvew of a Theory of Composablty, Vrgna Modelng Analyss & Smulaton Center, Old Domnon Unversty, [6] Y. Hu, G. Tan, F. Morad, Automatc SOM Compatblty Check and FOM Development, n Proceedngs of 7th IEEE Dstrbuted Smulaton and Realtme Applcatons, The Netherlands, [7] C. Szabo, Y.M. Teo, On Syntactc Composablty and Model Reuse, n Proceedngs of the frst Asa Modellng Symposum, [8] [9] 752