Methodology for Efficient Design of Continuous/Discrete Co-Simulation Tool

Transcription

1 Methodology for Efficient Design of Continuous/Discrete Co-Simulation Tool, H. Boucheneb, L. Gheorghe, F. Bouchimma Ecole Polytechnique de Montréal Tel : (514) ext 5434 Fax: (514) gabriela.nicolescu@polymtl.ca

2 Continuous/Discrete Systems Two types of components integration Continuous timed Discrete event Illustrative systems Electro-mechanical Mixed-signal Radio Hybrid 2

3 Continuous/Discrete Systems Design Collaboration between different teams Incremental refinements through different abstraction levels with specific execution models Validation requires joint execution of heterogeneous execution models Discrete Continuous Co-Simulation Technique 3

4 Challenges for Continuous/Discrete Co-Simulation Continu Discret Continu Discret Interface de cosim. ad-hoc Interface de cosim. ad-hoc Co-Simulation Bus Defining new tools facilitating cooperation between different teams Exploiting powerful existing tools (Simulink, SystemC, ) Taking into account implementation choices Enabling easy specification, automatic generation for cosimulation interfaces 4

5 Outline Introduction Methodology for co-simulation tool Application for CODIS design tool design Conclusions 5

6 Continuous/Discrete Systems - Heterogeneous Execution Models Concept Model Discrete Processes activation rules It advances Processes are discretely sensitive to events Continuous It advances by PiecewiseProcesses are integration steps (IS) Continuous signals executed at each IS Time Communication means Set of events Events exchanged between the two models the discrete models Sampling events D is c r e te Continuous Update signal events State events 6

7 Continuous/Discrete Systems - Heterogeneous Execution Models D is c r e te Continuous t Simulation Step State Event t Discrete Model Continuous Model Synchronization Signal Update/Sampling Event 7

8 Methodology for Co-Simulation Tool Design Generic Stage Definition of the synchronization operational semantic Discrete Continuous Distribution of the synchronization functionality to co-sim. interfaces Interfaces behavior formalization and verification Definition of the internal architecture and co-simulation library Implementation stage Sim. tools analysis Library elements implementation Implementation validation 8

9 Méthodologie de conception des outils de co-simulation Generic Stage Definition of the synchronization operational semantic Continu Discrete Distribution of the synchronization functionality to co-sim. interfaces Interfaces behavior formalization and verification Co-Simulation Interface Co-Simulation Interface Co-Simulation Bus Definition of the internal architecture and co-simulation library Implementation stage Sim. tools analysis Library elements implementation Implementation validation 9

10 Méthodologie de conception des outils de co-simulation Generic Stage Continu Discrete Definition of the synchronization operational semantic Distribution of the synchronization functionality to co-sim. interfaces Interfaces behavior formalization and verification Definition of the internal architecture and co-simulation library Couche 1 Couche 2 Couche 1 Couche 2 Couche 3 Couche 3 Couche N Couche N Co-Simulation Bus Implementation stage Sim. tools analysis Library elements implementation Implementation validation 10

11 Méthodologie de conception des outils de co-simulation Generic Stage Continu Discrete Definition of the synchronization operational semantic Distribution of the synchronization functionality to co-sim. interfaces Biblio. Co-Sim. Interfaces behavior formalization and verification Definition of the internal architecture and co-simulation library Continu Discrete Implementation stage Sim. tools analysis Library elements implementation Co-Simulation Interface Implementation validation Co-Simulation Interface Co-Simulation Bus 11

12 Méthodologie de conception des outils de co-simulation Generic Stage Definition of the synchronization operational semantic Continu Discrete Distribution of the synchronization functionality to co-sim. interfaces Biblio. Co-Sim. Interfaces behavior formalization and verification Definition of the internal architecture and co-simulation library Continu Discrete Implementation stage Sim. tools analysis Library elements implementation Co-Simulation Interface Implementation validation Co-Simulation Interface Co-Simulation Bus 12

13 Outline Introduction Methodology for co-simulation tool Application for CODIS design tool design Conclusions 13

14 Synchronization Operational Semantic Based on DEVS DEV = X, S, Y, δint, δext, λ, ta X = { (pd, vd) pd InPorts, vd Xpd } - set of input ports and their values in the discrete domain Y = {( pd, vd) pd OutPorts, vd Ypd } - set of output ports and their values in the discrete domain S = is the set of sequential state (locations) e = the elapsed time from the last transition Q = {(s,e) s S, 0 e ta(s)} is the total state set δint : S S - internal transition function δext : Q x X S - external transition function where: λ : S Y - output function ta : time advance function real and positive, can be 0 and. 14

15 Synchronization Operational Semantic DESS = X, Y, Q, f, λ X = {(pc, vc) pc InPorts, vc ℜ } set of input ports and their values in the continuous domain Y = {( pc, vc) pc OutPorts, vc ℜ} set of output ports and their values in the continuous domain Q = set of states f: Q x X Q is the rate of change function λ: Q(+X) Y output function 15

16 Hétérogénéité continu/discret D is c r e te Continuous t t Modèle Discret Modèle Continu q = δ ext (q ) synch = 1 flag = 1 ( λ ( s d ),t a ( s d )); flag := 0 s d ),t a ( s d ));synch:= 0 ( sd, ed )! ( sd, ed ); q?( λ ( q 16

17 Hétérogénéité continu/discret D is c r e te Continuous t t Modèle Discret Modèle Continu 17

18 Distribution de la fonctionnalité de synchro aux interfaces de co-sim. Continuous Discrete Co-Simulation Interface Co-Simulation Interface Co-Simulation Bus Start () from discrete event -detection of the end of discrete simulator simulation cycle - get data from the discrete event simulator - send data to co -simulation bus to discrete event simulator - send time of next event to co simulation bus statevent wait event from the continuous sim. to co -simulation bus to co -simulation bus statevent - get data from the co -simulation bus - send data to the discrete event simulator - get time of state event from the co-simulation bus - activate state event detection module - get data from the co -simulation bus - send data to the discrete event simulator wait data from the continuous simulator - wait data from the continuous simulator Stop Stop 18

19 Distribution de la fonctionnalité de synchro aux interfaces de co-sim. Continuous Discrete Start () Co-Simulation Interface Co-Simulation Interface Co-Simulation Bus - get data from the co -simulation bus - send data to the continuous simulator - send time of next event to the continuous simulator to continuous simulator - get data from the continuous simulator from continuous simulator - was a state event detected yes no - activate state event detection module -send time of state event to the co-simulation bus - send data from the continuous simulator to the co -simulation bus to co-simulation bus to co-simulation bus - send data from the continuous simulator to the co -simulation bus - wait data from the discrete simulator - wait data from the discrete simulator Stop Stop 19

20 Verification of Co-Simulation interfaces using UPAAL Continuous Domain Interface 20

21 Verification of Co-Simulation interfaces using UPAAL Discrete Domain Interface 21

22 Verification of Co-Simulation interfaces using UPAAL 22

23 Verification of Co-Simulation interfaces using UPAAL Properties verification No deadlock Timing synchronization All state events are detected No false state events 23

24 Generic Architecture for Continuous/Discrete Co-Simulation Discrete execution model Continuous execution model Détection d'événements Synchronization Détection fin du cycle et envoilayer du temps Communication layer Synchronization Détection d'événements layer Changement de contexte Co-Simulation interface Communication layer Cosimulation bus 24

25 Generic Architecture for Continuous/Discrete Simulation Discrete execution model State events consideration End of discrete sim. cycle detection, event sending Context switch Communication layer Continuous execution model Indication of state events and time sending Events detection Co-Simulation interface Context switch Communication layer Cosimulation bus 25

26 Définition architecture interne des intf. et éléments de la bibliothèque Data from/to the continuous model Data from/to the discrete model Continuous Domain Interface DEE DD CS Discrete Domain Interface CC CC CS DE DED N=(X,Y,D, {Md d D}, EIC, EOC, IC) EIC (External Coupling) X={(p, v) p Input InPorts, v Xp} set of input ports and values EIC={((N,ipN),(d,ipd)) ipn IPortsN, d D, ipd IPortsd} Y={(p, v) p OutPorts, v Yp} set of output ports and values EOC (External Output Coupling) D - set of components names EOC={((d,opd),(N,opN)) d D,opd OPortsd, opn OPortsN,} M =( Xd, S, Yd, δint, δext, λ, ta ) is a DEVS with IC d(internal Coupling) X={((a,op input ports and d - set of),( IC b,ipb)) a,b D, opvalues a a OPortsda, ipb IPortsb} Yd - set of output ports and values 26

27 CODIS Framework Simulation Flow Input Flow Continuous D is c r e te Co-Simulation Interfaces Generation Co-Sim. Library Discrete execution model Output Flow Continuous execution model Détection d'événements Synchronization Détection d'événements Synchronization Détection fin du cycle et envoilayer du temps layer Changement de contexte Communication layer Cosimulation interface Communication layer 27

28 Generation of Continuous Model Interfaces Simulink input specification Co-Simulation Library Simulink Co-Simulation Library Blocks Simulink Specification with co-simulation interfaces State-Event detection and signalling Integration Step Adjustment Synchronization with sampling and update events Communication 28

29 Generation of Discrete Model Interfaces Based on a SystemC Co-Simulation Library State events management blocks Communication blocks Automatic generation of co-simulation interfaces by a code generator that has as input userdefined parameters Data types No. and type of ports Synchronization model 29

30 CODIS - Continuous/Discrete simulation SystemC/Simulink accurate simulation Easy integration, generic library elements Systemc Simulink 30

31 CODIS - Applications Control applications - Robot arm manipulator, Bottle filling system Mixed signal application: Σ/Δ Converter Wireless application: Radar system 31

32 Conclusions Continuous/discrete systems designs requires global validation Co-simulation Technique Challenges for continuous/discrete co-simulation Definition of global execution models Automatic generation of co-simulation interfaces Methodology for co-simulation tools design Application for SystemC/Simulink 32

33 Performances analysis Inter-Simulators Communication overhead Overhead caused by the Simulink integration step adjustment 20% of the total simulation time max. 5% of total simulation time SystemC Synchronization overhead max. 0.2% of the total simulation time 33

34 Continuous/Discrete Systems - Synchronization Models Synchronization model Synchronization Step Advantages Inconvenient Full synchronisation mode Each discrete step and/or state event occurrence General Synchronization overhead Improve performances The prediction of update/sample events is required Rollback may be required Predictible events mode Each update/sampling events and/or state event occurrence Unpredictable events Each mode update/sampling events and/or state event occurrence Non-periodic update/sample events 34