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1. sseeeeeeees 54 APPENDIX Ill GENERATED SOFTWARE eneen 55 Wiel ontrolier Use case ANSI Cena eenander eenen 55 MT 2C ontroler Wse Case ET E 56 11 5 20mm vs TO enen eene 57 111 4 Producer Consumer ee 61 UE e 64 1 Introduction 1 1 Control Software Real time control systems typically consist of multiple sensors and actuators that operate simultaneously They can contain more then one control loop The processing of the sensor data and calculation of the output to the actuators has to be done within certain time limits The embedded software that is running on such a system must also perform several tasks like supporting a user interface and safety tasks To be efficient and reliable the software should reflect this natural concurrency A single processor can only execute one operation at a time instant It is not possible to run more than one task at the same time in the presence of just one processor A single processor system on which such a control systems runs will therefore require a scheduling mechanism The calculations of the output to actuators have to be done before a certain hard time limit or the complete system can fail The real time control system has to be able to meet these time constraints Either the hardware is fast enough for all software tasks or the control system will have to be able to make use of priorities It is possible to implement concurrency on a single processor system by directly controllin
2. Sensors Both shafts Power Amplifier Input voltage range Controlled output current range Controlled output voltage range Maxon 0 073 36 63 5 e 6 97 3 e 6 20 40 120 108 Philips 78 4 180 170 33 8 e 6 1 37 e 3 4 103 0 72 0 34 HP5540 5 1 33 28 2260 815 51 216 200 Nm A V kgm kgm mm mm 3112 384 01361 Nm 210 mm N m N m kgm kgm mm 200 steps revolution lt gt lt APPENDIX II Sequence of Tree elements Tree element Possible children Condition SYSTEM BIOS One BIOS allowed PROCESSOR SYSTEM PROCESSOR One CUSTOM allowed Teen CUSTOM CHANNELIN CHANNELOUT CHANNELIO VARIABLEIN VARIABLEOUT VARIABLEIO CUSTOM PAR SKIP STOP One of these allowed PRIPAR READER WRITER SEQ TIMESLICER CODE PAR CUSTOM PAR SKIP STOP PRIPAR READER WRITER SEQ TIMESLICER CODE PRIPAR CUSTOM PAR SKIP STOP PRIPAR READER WRITER SEQ TIMESLICER CODE SEQ CUSTOM PAR SKIP STOP PRIPAR READER WRITER SEQ TIMESLICER CODE GUARDIN CUSTOM PAR SKIP STOP One of these allowed pa PRIPAR READER WRITER SEQ GUARDOUT CUSTOM PAR SKIP STOP One of these allowed PRIPAR READER WRITER SEQ GUARDTIMEOUT CUSTOM PAR SKIP STOP PRIPAR READER WRITER SEQ GUARDSKIP CUSTOM PAR SKIP STOP PRIPAR READER WRITER SEQ All other elements can t have a child These elements are CHANNELIN CHANNELOUT CHANNELIO VA
3. amp Refe Controller Refe Encl amp Cont SafetyLayer Cont Enc2 amp Save Linix Save amp Enc1 amp Enc2 void Reference double Output void Controller double Reference double Encoder double control void SafetyLayer double Controller_in double encoder2 double Control_value void Linix double current_input double Encoderl_out double Encoder2_out 56 UL 2 Controller Use case Java EE AI AAT ANALA ID TALIA TILE LIISA IAT EIA AT System name Main Class name Main Date and time Mon Feb 02 02 02 02 2002 EE IPL ITL ASI EE ER ILI PITT TEI TEI I TET ELITIST PIT IIA ITI I IT IER import files 2MPorL CSP langs LMPOLrE CSP Lang Process import csp lang Double pubic class Main publie Stat ne vold Maintouring args 4 new Main public Main final Double Refe new Double final Double Cont new Double final Double Save new Double final Double Encl new Double final Double Enc2 new Double Process Seq new Sequential new Process new Reference Refe new Controller Refe Be le Cont new SafetyLayer Cont Enc2 Save new Linix Save Enc1 Enc2 II 3 20 sim vs Topo Controller The Linix system with controller 31 reference control u Kp Kiki encoder1 The controler submodel From this model also shown in figure 3 5 a simulation in 20 sim is performed In this simulation the o
4. cout lt lt n After compiling and running this program the results can be compared with the results from the 20 sim simulation Time sec Reference Angle pully2 Reference Angle pully2 Cem ri 20 sim Ba 2 5 86353 1 52614 5 865033285529 1 526051631923 31241335 17 3443 24 13496671643 17 34395976869 40130 131 7673 29 99999999608 31 76771474944 2 30 29 9478 29 94783813783 61 UL A Producer Consumer Example The tree based description model of the example is Main ER Processor Aa MyProcess ven channell Channel_of_Integer 2 channel Channel ot Integer par CA Producer 2 ie outl channell Channel_of_Inteqer 2 dl out channel Channel_of Integer tet object Integer A Code Aa Twolonsumers Ind channell Channel_of Integer si inz channele Channel_of Integer ae Seq CA Consumer a in inl Channel ot Integer tet object Integer A Code Aa Lonsumere in ine Channel_of_Integer e object Integer It shows a Producer process and two Consumer processes which run sequentially For this example Topo generates five sources MyProcess java Producer java TwoConsumers java Consumerl java and Consumer java MyProcess java FIPTIPILITITAE TIT ILS ELLI OT ET PTT TIT AT PEE T PTE TTT TPIT IPA PII TT TT TTT System name Main Class name MyProcess Date and time Mon Feb 02 02 02 02 2002 PERE ER EE EE ET EE EE EE EE EE EE EE EE EE E SC E EE E EE ECE RC EE EE EE EE
5. Broenink 1999 20 sim shows this hierarchical structure in a tree In figure 2 7 a 20 sim model of a robot is shown This demo model comes with the 20 sim package The hierarchy shows all the submodels in a tree structure Every submodel in 20 sim has an interface The interface specifies the ports and parameters of a submodel The interface of the n the tree hierarchy selected submodel in figure 2 7 controller2 is also shown as a tree structure by 20 sim Lat 0 s m Editor on ScaraRobot em File Edit Miew Insert Model Drawing Jools Help Interface Eren rr er ee ee ej ilo Aeee wk E kk kk fe Bs iss S te Se a model PDlimiter bluelight signal Position Hierachy gt controller signal SetPoint 4 controller B signal Steering B limiter m signal Velocity B pd B controllers LN lirnitter c A De SetPoint PD steering Sl motor lr B motor LN scara setpoint Position Yelocity mad setpoint setpoint ee Ku Be O EE S le opened E Figure 2 7 The hierarchy of the submodels and the interface of submodel controller2 2 5 Tree based Description Model 2 5 1 Introduction The CSP paradigm offers a language to specify the behavior of software The algebra of the CSP language is not a pleasant modeling language for developing software The user prefers a graphical user interface and have the tool handle the mathematics Recently several design and specification
6. 9 and for starting the code generators section 5 10 5 3 The Tree Structure View This view shows the tree based description model which is discussed in section 2 5 The user can delete an element from the model modify an existing element or add an element to the model Tree elements can be deleted from the tree by selecting the element using the mouse or the arrow keys of the keyboard 7 and pressing the Delete key The tool will instantly remove the selected element and all its children from the tree The tool will not ask for confirmation and a redo facility is not present Modifying existing elements takes place by double clicking in the tree on the element Topo will then show a dialog window in which the user can modify the item belonging to the 37 element The tool will use the same dialog window as for new tree elements The title of this window however begins with the word Modify instead with the word New For entering new elements for the tree structure the menu is used Not all menu items can be selected The syntax rules checker first checks which type of elements can be entered For example a system element can have only one bios element The syntax rules checker will first check if the system element has a bios element before enabling the Bios menu item If there is a bios element present then the menu item for bios will be disabled In appendix II a table can be found with the rules whi
7. EES E CECT TITT import files import csp lang import csp lang Process import csp lang Integer import csp lang Double public class MyProcess public static void main String args new MyProcess public MyProcess final Channel_of_Integer channell new Channel_of_Integer final Channel_of_Integer channel2 new Channel_of_Integer Process par new Parallel new Process new Producer channell channel2 new TwoConsumers channell channel2 par run 62 Producer java FIT ILI TIE IIATALS TATI ITS LAST STATS IA IA IT TTS LAS SS IA TI TA AIA I SALA IIIA AIT System name Main Class name Producer Date and time Mon Feb 02 02 02 02 2002 TILE ET AIP I TTA EE TI IIT ITI ATTA TIA import files import csp lang import csp lang Process import csp lang Integer import csp lang Double class Producer implements Process ChannelOutput_of_Integer outl ChannelOutput_of_Integer out2 Integer object public Producer ChannelOutput_of Integer outl_gen ChannelOutput_of Integer out2 gen outl outl_ gen out out gen object new Integer public void rund 4 object value 100 outl write object object value 200 out2 write object TwoConsumers java 1 1 1 1 111 1 1 1 11 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 111 11 11 System name Main Class name TwoConsumers Da
8. The four sections of the custom process element The process identification section identifies the process The custom process in the tree can be folded or unfolded If the process element is unfolded all the children of the element are shown For large models with many custom processes it would show to many details For large models the user can unfold only those custom process elements he is interested in and leave the others folded The process interface section shows the process interface Communication takes place using variables and channels In the case channels are used the process interface can consists of channel input elements channel output elements 4 and channel pass through elements i In the case variables are used the process interface can consists of variable input elements 4 variable output elements 4 and variable pass through elements Every process interface element is specified by its local name In figure 2 9 these are code and result These process interface elements are connected to a declaration element or a process interface element that is in scope The process interface element result is connected to the declaration element current The name of the declaration element is placed after the equal sign together with its type The process interface element code is connected to the interface element amplifier es MyFrocess z gain Channel_ot Integer Eu Process amplifier gain Chann
9. among a distributed processor system Communication between processes located on different processors should take place using channels and link drivers 1 4 2 Outline of the report Chapter 2 describes several aspects for designing control software In chapter 3 a use case is described It shows the different steps from modeling using a communication graph simulation model enhancement using a composition graph to add CSP aspects in order to the automatic generation of concurrent Java code In chapter 4 the developed software tool is deseribed and in chapter 5 consists of a user manual of the tool 2 Designing Control Software 2 1 Introduction This chapter describes several concepts which are useful for the development of control software Section 2 2 will give a short description on the Communication Sequential Processes CSP theory In Section 2 3 the two CSP diagrams the communication graph and the composition graphs are explained The Tree based Description Model is described in section 2 4 2 2 Communicating Sequential Processes The theory of CSP is bases on the idea of several sequential tasks which can run in parallel in sequence or by some choice Hoare 1985 Parallel processes can run on distinct processors or on one processor if they are being scheduled This creates two problems how do these processes communicate and how are they synchronized When two processes on two different processors communicate with each other then t
10. and the topographic view select view B iel x BEE Topo Topo HJ Eile Edit View Build Window Help DEE eel Rr 5 8 Main Topographic view S ste V C Communication Graph A en Composition Graph C Extended C Rectangles Graph C Deployment Graph Producer For Help tree structure view topographic view Figure 5 1 Screen view of Topo The menu structure of Topo is described in section 5 2 The tree structure is described in section 5 3 This section also describes the editing of the model The select view is described in section 5 4 The topographic view can show four different graphs the communication graph the composition graph the rectangles graph and the deployment graph These are described in the sections 5 5 through 5 8 In section 5 9 the use of the semantic rules checker which is used before generating the software s described and in section 5 10 three option dialog boxes are described 5 2 Menu Structure of Topo The menu structure is shown in figure 5 2 Only the menu items specific for Topo are discussed The others are standard for window applications For entering new elements in the tree structure the Add Child or Insert Sibling submenu of the Edit submenu has to be selected The Insert Sibling submenu has the same sub options as the Add Child submenu Not all menu items in these submenu s can be selected The elements Alternative PriAlternati
11. composition relation composite relation Di Figure 2 5 a The composite symbol b composite construct The use of the composite is limited to one level To extend this technique an index can be placed next to the composite symbol When there is no index placed next to the composite symbol it implicitly means that it has index one Figure 2 6 shows 3 examples ope opd 5 a F opl GO op R ops 3 ope ops S F opl CID op Rj ops s Si 5 E 5 d ch F opl CU ope A j ops Figure 2 6 Three composition graphs 2 4 20 SIM 20 sim is a software tool which can be used to model and simulate real time systems Broenink and Kleijn 1999 20 s m models are hierarchical structured and encapsulation is fully supported 20 sim supports equations block diagrams bond graphs Paynter 1961 Breedveld 1985 iconic diagrams and any combination of these four ControlLabs Product B V 2000 A bond graph describes a physical system as a number of physical concepts the elements connected by energy flows the bonds A bond between two elements transfers power from one element to the other An iconic diagram uses icons which look like the corresponding parts of the physical model These icons are also connected by energy flows the connections The equations behind the bond graph elements icons and submodels are specified as equalities this means that the variables need not be tagged as inputs or outputs yet Broenink 1999 The
12. de structuur van het model De tool laat de communicatie graaf en de compositie graaf zien aan de hand van het tree based description model Dit had echter andersom moeten zijn De gebruiker zou de wijzigingen in het model moeten kunnen doorvoeren in het grafische model De tool zou dan aan de hand hiervan de boom structuur moeten aanpassen Ook 20 sim hanteert deze methode Een aanbeveling is om dit in de tool te wijzigen MI Contents TINTRODUC HON tss tementen besturende 1 bt Stee l 1 2 Comm nieating Sequential Proeeses a a eeen l 13 8tepwse Refnement ses deu 2 Eeer 3 ASL The objectives of the ass cnment aussen une 3 le 2 ET EE 4 2 DESIGNING CONTROL SOFTWARE nnen nenenenn 5 DAs TOU 100 sn 5 2 2 Commi nic t ng Sequential Processes sur 5 25 CSP Das ans naar een 5 2 3 1 Commumeaton Graph u ae eu 6 232 COMPSON Graph ee eine 6 DO IN Meee ae eee a ae et ces ec ser net 8 2 5 Tree based Description Models ae 9 2 9 1 1Atrod etion seen nein asia 9 25 2 Treesbased deserpuon mod an een ee en eee 10 2 5 3 The Global Variable Declaration Element eenen 12 20 rette 12 27 The Deployment Graph sn dd 15 EE 15 Eege 17 DEEGEN erneer entend ee ende E enabelen 17 3 2 Ihe LINDE System 17 3 3 Physical systems Mode lne sense mund 18 SAS Oma MCL CSU ON aussen ee ee ee 19 sd The controller aa 19 SE E 20 3 4 DS Ua on ze en eine etende 22 3 5 Embedded control systems implementation ccccccccccceeseeeeeeeeeeeee
13. interfaces are ports each with two variables being computed n opposite directions For example a resistor has one port the variables are current and voltage If the current is the input then the model calculates the voltage and vice versa When a computation is made for a model a special routine has to derive a causal form of these equations Using this causality the equations can then we rewritten to assignments statements and have to be sorted It then is possible that the statements of one submodel are placed between the statements of another submodel If a CSP diagram is created for such a model then the topography of the processes will not be the same as the topography of the submodels in 20 sim Both the bond graph model and the Iconic diagram model are used to model a physical system Developing generating software for these models is only useful to simulate the behavior of the physical system on a computer In contrast the implementation of control laws do not use energy flows Models used for controllers contain only information processing parts The connections between two elements are not based on energy flows but on signals data The model of a controller in 20 sim is therefore comparable with a communication graph 20 sim models are hierarchical structured The model on the top of the hierarchy is called a mainmodel The models on the lowest level are called elementary models and are sets of equations or assignment statements
14. not necessary to work with a complete composition graph The designer is only interested in those relations which are essential for his design If the designer wants process SafetyLayer run parallel to the other processes then he will have to define all the relations to the process SafetyLayer as a parallel composition The resulting graph is shown n figure 3 12 together with the tree based description model In figure 3 13 the composition graph of the same model is shown using the composite symbol a Main 2 an Boie Float tet Encl Float Cont Channel ot Float Enc Channel ot Float Save Channel_of Float a Far Bj Seq Eu Reference ll Output Refe Float CA Controller hl Reference Refe Float Encoder Enct Float ef control Cont Channel ot Float BS Linie a current_input Save Channel_ot_Float 2 ei Encoder _out Enc Channel ot Float te Encoderl_out Enc1 Float CA SafetyLayer controller_in Cont Channel_ot_Float a encodere Ence Channel_ot_Float al Control value Save Channel ot Float SafetyLasrer Controller Figure 3 12 The Linix system with submodel SafetyLayer running in parallel a Tree based description model b Composition graph 25 SafetyLasrer Figure 3 13 The Composition graph using the composite symbol Reference 3 6 Code Generation The software tool Topo s used to generate software for the developed controller This tool was developed for this assign
15. option using four radio buttons is chosen Erik Volkering developed a program for his thesis which shows the tree based description model Volkerink 2000 Using this program it became clear that for models with many interface elements it was difficult to see the hierarchy of the processes clearly An option to show the tree based description model without the interface elements would solve this A disadvantage of this is that the interface is no longer visible 20 sim shows the interface elements of the selected submodel in a separate window By implementing such a window in Topo the user can view the hierarchy of processes in a compact manner and at the same time see the interface elements of one process 30 In figure 4 3 an example of the select view is shown Topographic view El Producer Communication Graph C Composition Graph C Rectangles Graph C Deployment Graph Extended Figure 4 3 The select view The leftmost part of this view shows the interface elements of the selected process in the tree structure view If the selected element in the tree structure view is not a process element then the parent process of the selected element is shown with its interface elements The middle part of this view contains three radio buttons 1 20 sim the tree based description model in the tree structure view is shown comparable with the software package 20 sim For Topo this means that only the system elements and pro
16. previous phase developed software is implemented on the target hardware and val dated The measurements on the real system can be checked with the simulation results The first two stages are currently very well covered by 20 s m Broenink and Kleijn 1999 20 s m s a software package for modeling and simulation of the dynamic behavior of dynamic systems The tool has build in support for designing control laws Using 20 sim means that the Physical Systems Modeling Control Law design and the verification of these two stages through simulation can be done with one software package 20 s m has an ANSI C code generator which automatically converts a complete 20 sim model or submodel into C code The generated C code has a sequential framework The generator creates several source and header files After compilation an executable is created that simulates the model 20 sim therefore has a limited support for the phases 3 and 4 the Embedded Control Systems Implementation and Realization In the rest of this thesis the focus will be on the three aspects e Relationships For the first two phases Physical Systems Modeling and Control Law Design software tools like 20 sim and Simulink can be used In these software tools the user can view the sub system as equations or as graphical models A graphical model for a controller in 20 sim is a block diagram model These graphical models show building blocks and their relations with each other These
17. relations are data oriented These building blocks or processes with their communication relations can be viewed in a communication graph The developed tool shows a communication graph e Enhancement Before the software can be generated decisions has to be made on the execution order of the communicating processes Concurrency can be added If the software runs on a multiple processor system the processes have to be divided over the separate processors deployment For the communication between the software processes with the hardware linkdrivers must be used For this the support of the composition graph and the tree based description model is useful The developed tool shows a composition graph and a tree based description model e Automatic generation of concurrent software The Communicating Threads for Java CTJ package Hilderink et al 1999 which implements the CSP model in Java is used in the tool to generate control software in Java 1 4 Overview of this report 1 4 1 The objectives of the assignment The objectives of this assignment is to build a tool which shows the tree based description model together with the CSP diagrams Both the communication graph and the composition graph can be shown individually The topography of the CSP diagrams should be comparable with the graphical models shown in 20 sim The tool should be able to generate concurrent Java code using the CTJ package It should be possible to distribute processes
18. relatively easy The disadvantage however is that because of the differences between the target languages the general algorithm for code generation is not easy to develop Also the database for the language dependency can become very complex The advantage of the second alternative is that the code generator can be customized for a specified target language The current implementation of the code generator is based on a separate code generator for each target language Currently two code generator algorithms are implemented One for ANSI and one for Java The code generator for Java uses the CTJ package Hilderink et al 1999 The code generator for ANSI C generates the code using a sequential framework This generator can easily be enhanced to make use of the CTC software package Hilderink 1999 4 8 Outline In this the design of the software package Topo bases upon the tree based description model is described Topo can show the CSP diagrams and generate software code Several tests have shown that the software code generated by the tool compiles and runs The next chapter will give a users manual of Topo 34 35 5 Users Manual 5 1 Introduction In this chapter a users manual of Topo is given The tool is based on the tree based description model This model shows the hierarchy of the processes in a tree structure In figure 5 l a screen view of the program is shown The screen view shows the tree structure view the select view
19. xout K2 ref_out KL lin_out double inertial_f 0 double inertial_phi 0 double inertia2_f 0 double inertia2_phi 0 double belt_x 0 void linix double in double out double amplifier_I 0 double dcmotor_T 0 double bearingl_T 0 double bearing2_T 0 double belt_F 0 double pullyl_T 0 double pully2_T 0 const double K_amp 0 266 const double km 0 073 60 const double d 0 001 const double J1 9 73e 005 const double J2 0 00262 const double k_belt 680 Je const double radiusl 0 04 const double radius 0 108 amplifier I K amp in dcmotor_T km amplifier Es bearingl_T d inertial_f belt_x inertial_f radiusli inertia2_f radius2 step belt_F k_belt belt_x pullyl_T radiusi belt_F inertial_f demotor T bearingl_T pullyl T J1 step inertial_phi inertial_f step bearing2_T d inertia2_f pully2_T radius2 belt_F inertia2_f p lly2 T bearing2 T J2 step inertia2_phi inertia2_f step out inertial_phi void display double in if tijd gt 1 99998 amp amp tijd lt 2 00001 tijd gt 2 99998 amp amp tijd lt 3 00001 tijd gt 3 99998 amp amp tijd lt 4 00001 tijd gt 4 99998 amp amp tijd lt 5 00001 cout lt lt tijd cout lt lt tijd cout lt lt Be cout lt lt in cout lt lt ia cout lt lt inertia2_phi
20. ANSI C program file can be generated The tool generates one program file The name of the file is initially set to the name of the system with extension cpp The user can change the filename and the directory where the file will be placed The tool uses the standard file dialog window of Windows for this The generated program has a sequential execution framework For every custom process tree element a function is generated In Figure 5 19 the generated source file is shown next to the tree based description model 47 Wdddddddddddddddddddddddddddddddddddddddddddgdddddddddddddddddddddddd System name Main Date and time Mon Feb 02 02 02 02 2002 erdee gedeelde ie egens der I SIE SITE PEST EI include files include lt iostream h gt void PCMainl void Producer int Var_out void Consumer int Var_in void main PCMainl Main void PCMainl SE Processor pn int variable 0 a PCMain Producer amp variable u variable Integer Consumer variable Ely Sequential A A Producer void Producer int Var_out a e Var out variable a er oe I a CodeBlock CA Consumer void Consumer int Var in f Var In variable EF CodeBlock cout lt lt Var in Figure 5 19 a generated ANSI C code b the tree based description model The source code is generated in five stages l 2 The header The header shows the name of the system and the date and time of generatio
21. C SET 32000 20u00 Figure 3 6 Encoder output encoder output would follow the line A B D The safety layer will use this control signal as a maximum value for the signal send to the Linix system The maximum value of 32000 is used and not 2 1 to allow some overshoot Figure 3 7 shows the model of the system including the safety layer and the submodel SafetyLayer The output of Encoder2 of the Linix system is always smaller then the output of encoderl because the two pulleys have a different diameter The submodel Gainl in the submodel SafetyLayer compensates this difference a b Control Gain1 Safety encoder2 Reference Controller_in Figure 3 7 a The Linix system with safety layer b The SafetyLayer submodel Both the Safety and Choice submodels are equation submodels See figures 3 8 and 3 9 Table 3 1 lists the connections between the input signals and the output signals 21 ports signal in encoder in signal out safe value signal out safe Code end parameters real K 0 0001 real encoder_start_max 20000 real encoder_abs_max 32000 equations if encoder in gt encoder start max then safe value encoder abs max encoder in safe_code 1 else safe code 0 end Figure 3 8 The submodel Safety ports signal in cont roller in Signal in safe_value Signal in safe_code signal out control_value end equations if safe_code gt 0 5 then if controller_in lt s
22. ITS SS AV IAT IGA II AIS TELS TILT E ST EIS SAS EE EE E EE EE System name LinixC Date and time Mon Feb 02 02 02 02 2002 LISA EE EE EE EE EE ALIA SID SPS AD ISD SADA DISD AIDA SIDA LIDS DAI AL IID SEIT include files finclude lt iostream h gt include lt math h gt include lt stdlib h gt include lt time h gt void Linix void reference dsuble outi double out2 void control double ref_out double lin_out double out void linix double in double out void display double in void main Linix double step double tijd void Linix 0 0001 0 double control_out 0 double reference_outl double reference_out2 0 double linix_out 0 for int ii 100000 1ii gt 0 ii reference amp reference_outl amp reference_out2 control reference_out1l linix_out amp control_out linix control_out amp linix_out display reference_out2 void reference double outl double out2 const double start_time 1 const double stop_time 4 const double amplitude 30 const double pi 3 14159 if tijd lt start_time Oia 0 else if tijd gt stop_time outl amplitude else outl 2 pi tijd start_time stop_time start_time EE amplitude u sin out1 2 pi tijd tijd step xout2 HOE 15 void control double ref_out double 111 Gute double out const double K1 0 37037 const double K2 0 5
23. RIABLEIN VARIABLEOUT VARIABLEIO LINKDRIVER SKIP STOP READER WRITER CODE TIMESLICER CHANNEL VARIABLE GLOBAL One of these allowed One of these allowed 55 APPENDIX Ill Generated Software In chapter 3 a controller was developed The software tool Topo was used to generate the software In III 1 the ANSI C code is shown for the controller as shown in figure 3 11 Appendix III 2 shows the generated Java code for the process Main of the controller as shown in figure 3 12 Only the structure of the code and the interfaces are generated the processes do not contain a code block In Appendix III 3 the 20 sim simulation for the model shown in figure 3 5 is compared with the results from the software generated using Topo Appendix III 4 shows the generated Java code for a producer consumer example IL Controller Use case ANSI C FILILALI CIELA LEIA ATE IILIT ELLI TIP IS ANNEER NAE ISIN System name Main Date and time Mon Feb 02 02 02 02 2002 E EE EE EE AA IAAL AAAS AL AP IL AS IAD TIA EE EE EE void Main void Reference double Output void Controller double Reference double Encoder double control void SafetyLayer double Controller_in double encoder2 double Control_value void Linix double current_input double Encoderl out double Encoder2_out void main Main void Main double Refe 0 double Cont 0 double Save 0 double Encl 0 double Ene2 0 Reference
24. University of Twente Faculty of Electrical Engineering Realization of Tool Support for CSP Diagrams and Generation of Concurrent Java Software J P A Hendriks Master s Thesis Supervisors prof dr ir J van Amerongen dr ir J F Broenink ir D S Jovanovic ir G H Hilderink December 2001 Report 025R2001 Control Engineering Faculty of Electrical Engineering University of Twente P O Box 217 7500 AE Enschede The Netherlands Summary In the Control Engineering Laboratory a structured method for the development of control software for real time embedded control systems is being developed This method considers the implementation process as a step wise refinement from physical system models to efficient computer code This method consist of four iterative stages l Physical Systems Modeling modeling and simulating the behavior of the appliance 2 Control Law Design designing and simulating control laws using the acquired model 3 Embedded Control System Implementation transforming the control laws to software 4 Realization implementing the generated code on the target hardware The first two stages are currently very well covered by 20 sim 20 sim is a software package for modeling and simulation of the dynamic behavior of dynamic systems 20 sim has an ANSI C code generator which automatically converts a complete 20 sim model or submodel into C code The generated C code however has a sequential execution
25. afe_value then control value controller in else control value safe value end else controt value controller in end Figure 3 9 The submodel Choice Reference Output Controller Choice control value Linix current input Safety save value Choice save value Table 3 1 The connections of the input and output signals If the encoder output reaches a value of 20000 then the submodel Safety calculates the maximum value of the control signal save_value and sets the output signal safe Code to one The submodel Choice will then calculate the minimum value of the control s gnal from the controller controller_in and the save_value of the submodel Safety This minimum value is used as output s gnal to the Linix model If the encoder output is 22 lower then 20000 the submodel Choice will use then use the control signal from the controller controller_in to steer the Linix model 3 4 3 Simulation This controller can be verified by simulation For this an experiment was setup in 20 sim As a reference source a cycloid function s used The result of this experiment is shown in figure 3 10 The simulation shows that between the points A and B the control value of the safety layer is used 40 40 Title 4 op 20 rn 3 reference D AD a 20 20 a EN UI fe Da B o 0 z e Zio 10 Be m Oo 0 0 10 10 0 2 4 5 S 10 time s Figure 3 10 Simulation of the Linix model with the safety layer 3 5 Embedded control system
26. at the process should be allocated on this processor This is currently not implemented 5 8 Deployment Graph The rectangles graph shows in principle all processes and the parallel and sequential constructs The deployment graph was meant to show only the available processors and those processes which are candidates to be allocated on another processor Currently the deployment view only shows a rectangle for each processor included in the tree structure 5 9 Semantic Rules Checker Every tree element in the process interface section variable input 4 variable output channel input and channel output 4 have to be connected to a declaration element The data entry part of Topo however does not enforce this Topo allows the user to enter the elements in the process interface section and to make the connections later The semantic rules checker check for the absence of these connections and reports them in a window The user can run this routine using menu option Build Check code Java or the menu option Build Check code ANSI C Both menu options currently run the same routine 5 10 Software Generation The tool can generate ANSI C code and Java code Before the code is generated Topo checks whether all the tree elements of the process interface section are connected to a declaration element Using Topo showed that the absence of this connection was the most commonly made error 5 10 1 ANSI C code generation An
27. ating undesirable conditions such as raze hazards deadlocks livelocks and starvation The theory of CSP provides fundamental concepts for realizing concurrent software for embedded real time control software The CSP model has been introduced into Java threads Hilderink et al 1999 Several packages have been created which enable reliable implementation of a design based on the CSP concept These packages are available for Java C and C The CTJ package for Java provides a small set of design patterns that are sufficient for concurrent programming in Java Hilderink 2001 An important advantage of CTJ is that the programmer has a small but sufficient set of rules or guidelines available that help designing and implementing reliable and robust software without undesirable conditions Using the CSP model for structuring software a tree based description model has been developed Volkerink 2000 A prototype tool that uses this model has been created This tool enables a way to design describe software based on the CSP model A CSP diagram is a graph of processes and their relationships Hilderink 2001 A CSP diagram can specify real time and parallel software architectures The graphical presentation expresses the execution model of a network of processes Some relationships are communication oriented and some are composition oriented Therefore there is a distinction between the communication oriented view and the composition oriented vi
28. cess element in the tree view Topo will then show the communication graph for this process In figure 5 13 an example is shown The user can move these rectangles around the screen using the mouse The new place of the rectangles is written to the database When the user enters a new custom process in the tree view the place of the rectangle of this new process will always be the same When more then one process element is added they will all be placed on the same spot left upper corner of the view 44 a bj 5 8 Main ER Frocessor Aa Custom o Par proct proc Fy Seg proc3 AS procd Figure 5 13 a tree based description model b communication graph of the same model D Figure 5 14 Intermediate points on connections 20 sim 20 sim has the ability to add or remove intermediate points on these lines Figure 5 14 shows 8 intermediate points Topo always has always one intermediate point on each line This intermediate point can be either visible or invisible This point cannot be removed Initially this point is always placed on the middle of a line If a process rectangle is moved the lines are redrawn and the point is again placed on the middle Only when the user moves a point to a different location with the mouse the point stays fixed on this new position figure 5 15 To bring the point back to its initial state the user has to place the point using the mouse on the coordinate 0 0 this is the top left corne
29. cess elements are shown See figure 4 4 a 2 Compact besides the elements shown in the 20 sim options this option also shows the processor elements the codeblock elements and the elements for the composition relations like parallel priority parallel and sequential See figure 4 4 b 3 Extended all the elements in the tree based description model are shown in the tree structure view See figure 4 4 c a 20 SIM bi Compact c Extended SR Main Main Main Eu MyProcess ER Frocessor SE Processor Producer CA MyProcess A A MyProcess AS Consumer A par channel Channel ot Integer es Producer o par E Code Se Producer 5 4 Consumer 2 2 l out channel Channel_of Integer CH Code rg object Integer 8 Code Aa Consumer in channel Channel ot Integer object Integer EY Code Figure 4 4 The tree based description model of the Producer consumer example In the rightmost part the user can select which graph Communication graph Composition graph Rectangles graph or Deployment graph is shown in the topographic view 4 5 The Tree Structure View Because this research is a continuation of the work of Erik Volkerink the design of this view was based on his design of the tool Embedded Volkerink 2000 This view shows the tree based description model which is discussed in section 2 5 Editing a model in Topo can only be done by changing the tree based description model The model cannot be changed in the t
30. ch the syntax rules checker enforces For entering the data for the tree elements seven dialog windows are used for the following groups of elements Subsystem 3 bios processor and linkdriver S Declaration of variable channel and global variable Parallel construct Il and priority parallel construct 1T Custom process ZA Variable input ail variable output 4 channel input ei and channel output 4 Code segment Sequential construct a ee E Ee These dialog windows are shown in the section 5 3 3 through 5 3 9 The Producer Consumer example of figure 5 3 will be used to show each of these dialog windows Main S POLE Dialog 1 processor CA MyFProcess channell Channel_of Integer Dialog declaration channel Channel ot Integer En Dialog 3 parallel construct ee Producer 7 7 7 Dialog 4 custom process outl channell Channel_of_Inteqer Al out2 channel2 Channel_of Integer Dialog 5 output channel tek object Integer d Cage o ee Dialog 6 code segment Aa Twolonsumers a Ind channell Channel_of Integer i in channel Channel_of_nteger Ey Gene OH KH Dialog 7 sequential construct es Consumer 2 a In ind Channel_ot_Integer e object Integer A Code Aa Lonsumere ei in ing Channel_of Integer e object Integer amp Code Figure 5 3 Producer Consumer example Each of the dialog windows has three it
31. code The alternative and prialternative construct processes are not further discussed in this thesis a bi Seg SED Process Process ba Process Process oU PriPar PRIPAR Process3 Process 3 u Process4 Processd A Par FAR Process5 Process5 AO Process Process6 Figure 2 10 Compositions of processes a The construct process b pseudo Occam code Eric Volkerink defines also the elements Skip Reader Writer and TimeSlicer in his thesis Volkerink 2000 These elements and the alternative and prialternative elements are not further discussed in this thesis 2 5 3 The Global Variable Declaration Element Using the tree based description model for developing software in ANSI C to run a simulation of the Linix system it became clear that a global variable can be useful A new tree element can be created called the global declaration element In the example of software code in Appendix III 3 for example a global variable is used for the time In the tree based description model these global variable declaration elements are placed between the process interface section and the local variable channel declaration section Figure 2 11 shows an example es MyFrocess 2 ae gain Channel_ot Integer BS ProcessA ai amplifiersgain Channel_of Integer o gt current Integer Aa FrocessE a code amoplifier Channel_of_Integer tel resultscurrent Integer E time Integer vee count Channel_of_Inte
32. d 2 The composition graph shows the processes and their composition relationships This graph uses the same topography for the processes as the communication graph The processes are shown as rectangles The routine used for showing these rectangles in the communication graph can be used for the composition graph The relationships are shown as lines with a label which indicates the type of the composition gt Il il it The alternative relationships o 5 are not supported by Topo Showing all the possible relations between all processes is not necessary The tool should initially make a selection of all possible relationships and show these The user should then be able to indicate which relationships he wants to see The most important relationships to show initially are the relationships between the child processes of a parallel or sequential construct The sequence in which these child processes are placed in the tree based description model indicates the direction of the sequential and priority parallel composition Figure 4 6 gives an example a Main bi ER Frocessor 5 49 Main ER Sec A Process Process MS Process Processl Process Figure 4 6 The composition graph of three sequential processes 32 Only the relationship between Process1 and Process2 and the relationship between Process and Process3 are shown A problem occurs if one of these child processes is a parallel or sequential construct Such a co
33. derink G H 2001 CSP diagram an introduction internal document Hilderink G H J F Broenink and A W P Bakkers 1999 Communicating threads for Java Proc 22nd World Occam and Transputer User Group Technical Meeting Keele UK Ed 243 261 Hoare C A R 1985 Communicating Sequential Processes Prentice Hall 0 13 153271 5 0 13 153289 8 PBK Legius M 1999 Volvo S80 PT Embedded Systems 10 15 Paynter H M 1961 Analysis and design of engineering systems MIT Press Cambridge MA Volkerink H J 2000 CSP Design Models Methodology and Tool support for Real Time Embedded Distributed Heterogeneous Software MSc thesis Faculty of Electrical Engineering Control Laboratory University of Twente Enschede Netherlands
34. e class The class PCMainl is defined In this class two methods are generated namely main and PCMainl In method PCMainl a Channel of Integer is declared Also a process par s declared as a Parallel object The Parallel object itself is a process and its arguments are processes which will be run in parallel when the run method of the object Parallel s called In figure 5 21 the source file for the custom process Producer is shown 49 LLL System name Main Class name Producer Date and time Mon Feb 02 02 02 02 2002 kbvb e EL import files import csp lang import csp lang Process import csp lang Integer class Producer implements Process ChannelOutput_of_Integer out Integer object public Producer ChannelOutput_of_Integer out_gen out out_gen object new Integer public void run object value 100 out write object Figure 5 21 generated Java code for custom process Producer 5 11 The Options Dialogs There are three option dialog windows used in Topo l General options using this dialog window the user can indicate whether Topo has to show the intermediate points on the communication relationships in the communication graph 2 ANSIC using this dialog window the user can indicate which include files the ANSI C code generator should generate in the code 3 Java using this dialog window the user can indicate which Java libraries should be imported in the genera
35. e of the input channel is inl Out when a output variable cq output channel of a child process is connected to this declaration element then the item out contains the name of this child process and the name of the output variable cq output channel In figure 5 5 the name of the child process is Producer and the name of the input channel is out 1 39 New channel This channel is used for the communication between the process Producer and the process Twolonsumers Figure 5 5 Dialog 2 channel variable and global variable 5 3 4 Dialog 3 Parallel and priority parallel construct New parallel process The processes Producer and TwoConsumers run in parallel Figure 5 6 Dialog 3 parallel d and priority parallel II This dialog window is used for the parallel Il and priority parallel T The window contains the three common items Name Description and Sequence 40 There is one other item in the window e Priority when the element is a priority parallel construct then the checkbox is set Changing a parallel construct to a priority construct can be realized by setting this checkbox 5 3 5 Dialog 4 Custom process New custom process A Name Producer sequence o Mr of terations i Description This is the Producer process en Figure 5 7 Dialog 4 custom process This dialog window is used for the custom process amp The window contains the three common items Name Descripti
36. ed description model are shown in the tree structure view See figure 5 12 c a 20 SIM cj Extended Main 2 3 Main an si MyFrocess ER Processor A Producer GA MyFrocess sf e TwoConsumers Channel Channel_of_Integer En Berner 2 channel Channel_of_Integer ol Consumer a f par CA Producer 2 outl channell Channel_of_Inteqer b Compact 2 el aut channel Channel_of Integer ee object Integer G R Main 2 EJ Code mik Processor TwoConsumers ak MyFrocess ai Ind channell Channel_of Integer St par ai in2 channel Channel ot Integer Gi Producer Seq ER Code Consumer ER si Tweptonsumers 2 ai in inl Channel_of Integer Ee Seq tt object Integer Consumer ES Code ER Code Consumer ok Lonsumere ai in ing Channel_of Integer EX Code 2 m object Integer AM Code Figure 5 12 The tree based description model of the Producer Consumer example In the rightmost part labeled Topographic view the user can select which graph Communication graph Composition graph Rectangles graph or Deployment graph is shown in the topographic view In the edit field next to the rectangles graph the user can enter a number This number is used by the rectangles graph for the number of levels shown in this graph 5 5 Communication Graph The communication graph shows the custom processes as rectangles The communication relationships are shown as lines with an arrow head De The user selects a custom pro
37. eeeeeeeeeeeeeeeeeeees 22 Sn Model Enhance cement mn seventeen 22 EE 25 327 EI 25 4 THE DESIGN OF TOPO zu nee 27 Ad Iattoduclion ee 27 LOVE ACN ee ee ee ee 27 RE 28 14 THE De ler View ereen eneen 29 4 5 Ihe Tree Stee View asien 30 eege 31 AT he Code Generi Or see ee 33 e 33 5 USERS MANUAL zu nannten 35 SKI 35 5 2 Monu SUMICHITE OF EE able 35 3 3 The Tree Structure View eta ener etat lesen 36 IV 39 5 The sequence Of the 1ree C ements aan 38 5 3 2 Dialog 1 Subsystem bios processor and linkdriver nn 38 5 3 3 Dialog 2 Declaration of variable channel and global variable 38 5 3 4 Dialog 3 Parallel and priority parallel construct eeen 39 5 3 5 Didor aA Custom process are 40 5 3 6 Dialog 5 Channel variable input output ccccccccccccccccceceeeeeeeeeeeeeeeeeeeeeeeeees 40 93 1 Dialog 6 Code seminare E a ia eenden 41 3 3 8 D1alos EES EE 42 SY A A o E E EE EEES E E EE E IOE 42 DO CONU C OR ee 43 3 6 C 0mMpos110n Graph oaa AA 44 DP IRC CUA OCS EEN 45 3 8 Deployment Graph reine ee 46 3 9 Semantic AE E 46 5 10 Sorlwate Creme CACO I een 46 SO lee ee 46 5 102 Java Ode General on ann anal 47 JLI Ihe Options Dalo88s u een ee ee 49 6 CONCLUSIONS AND RECOMMENDATIONS EENS 51 GL Gone STO antennen ebde deepest deeg 51 OEE aaa NG HO aL NEO 52 APPENDIX I TECHNICAL SPECIFICATIONS OF THE LINIX SYSTEM 53 APPENDIX Il SEQUENCE OF TREE ELEMENTG
38. el ot Integer o gt current Integer Aa FrocessB ji code samplifier Channel ot Integer e result current Integer mg count Channel ot Integer S type Integer AQ ChildProcess Figure 2 9 Connections of the interface elements The local variable channel declaration section declares the local channels and variables These locally declared channels and var ables can be used by the child process section of MyProcess In figure 2 9 there are 4 declaration elements gain current count and type The process declaration section forms the body of the process It can consist of a custom process element a code segment or a construct process In figure 2 9 an example of a custom process as the body of a process is shown The body of ProcessA consists of the custom process ProcessB A code segment contains the code of the process 12 A construct process is a composition of processes The construct process does not have a process interface section or a local channel variable declaration section The only valid child processes for a construct process are process elements There are five different construct processes parallel priparallel sequential alternative and prialternative These are the five defined CSP compositional relationships Hilderink 2001 In figure 2 10 an example using parallel sequential and priparallel construct elements is shown The tree based description model is shown together with the pseudo occam
39. ems in common 1 Name the name is used as the label for the tree element in the tree structure 2 Description this is a text field where a description for the tree element can be entered The code generator will generate comments in the source using this description However not all tree elements are treated as such 3 Sequence this field gives the user the ability to change the sequence of the elements in the tree structure This is explained in section 5 3 1 38 5 3 1 The sequence of the tree elements The tool will in principle append a new child to the already existing children The sequence in which they are shown is the same as the sequence they are entered The only exception is the sequence of the sections of the custom process element The sequence of the five sections of the custom process process identification process interface global declaration local declaration child process cannot be changed The user can change the sequence of the tree elements within one section Also the sequence of the children of a construct element for example parallel sequential can be changed by the user The tool will not change the sequence directly The sequence will be changed during the loading the file from the disk Therefore after setting all relevant sequence numbers the data has to be saved to disk and reloaded before the changes take effect 5 3 2 Dialog 1 Subsystem bios processor and linkdriver New processor Ei Name Proc
40. erarchy of the execution framework and the patterns of communication Hardware section The tree always starts with a system element 3 in figure 2 8 called Main A system can consist of multiple subsystem elements 3 one or more processors CR and only one bios element 21 A processor element can consist of one bios element I and one custom process element amp This custom process element is the start of the process section The bios element describes the basic input output functions of a processor or system The bios element can have multiple child bios elements and multiple link driver elements S The bios elements are introduced to structure the link driver elements Process section The processor element can have one custom process child For the processor in figure 2 8 this element is called MyProcess The custom process element can have a list of child elements This list can be classified in four sections 1 the process identification section 2 the process interface section 3 the local variable channel declaration section and 4 the process declaration section This is more clearly illustrated in figure 2 9 11 ProcessB lj process identification section s code amplifier Channel_ofInteger 2 process interface section Sg el result current Integer count Channel oi Integer 3 local variable channel declaration section type Integer AO ChildProcess 4 child process section Figure 2 8
41. essor Sequence o Description The desctiption of this processor The description can consists multiple lines oe Figure 5 4 Dialog 1 Subsystem bios 4 processor E and linkdriver E This dialog window is used for the elements subsystem 3 bios processor and linkdriver The window contains only the three common items Name Description and Sequence 5 3 3 Dialog 2 Declaration of variable channel and global variable The dialog window is shown in figure 5 5 This dialog window is used for the elements channel variable and global variable The window contains the three common items Name Description and Sequence The other items in the window Type this item defines the type of communication Currently there are four types of communication defined integer double floating point character and boolean Initial for a global variable or a variable it can be useful to set a initial value For a channel declaration this element is ignored Constant for a global variable or a variable it can be useful to define the variable as a constant For a channel declaration this element 1s ignored In when a input variable cq input channel of a child process is connected to this declaration element then the item in contains the name of this child process and the name of the input variable cq input channel In figure 5 5 the name of the child process is TwoConsumers and the nam
42. ew of the model The topographical locations of the processes is the same in both views The communication oriented view presents a communication graph which shows the communication relations between processes The composition oriented view presents a composition graph which shows the compositional relationships between processes These two graphs will be further explained in chapter 2 1 3 Stepwise Refinement In the Control Laboratory at faculty of EE of the University of Twente a structured method for the development of control software for real time embedded control systems is being developed This method considers the implementation process as a step wise refinement from physical system models to efficient computer code Broenink and Hilderink 2001 The design trajectory of a controller consists of 4 iterative stages see figure 1 1 Physical Control Embedded System Law Control System Modeling Design Implementation Realization Verification by Simulation Veritication Verification Verification by by by Simulation Simulation simulation Figure 1 1 The Design Trajectory l Physical Systems Modeling The dynamic behavior of the appliance is modeled and can be simulated The purpose is to create a competent model of the system So only relevant and dominant aspects need to be considered The model can be simulated to verify whether it satisfies its goals If possible the model can be validated e compared with measu
43. ew output channel This is a output channel This channel is connected to the declaration element channel Figure 5 8 Dialog 5 input variable 4 output variable input channel and output channel ef 5 3 7 Dialog 6 Code segment New codeblock objectvalue 100 outl writefobject objectvalue 200 oute writefobject This is de code for the Producer process The value 100 is written to channel outl The value 200 is written to channel out Figure 5 9 Dialog 7 code segment E 42 The dialog window is shown in figure 5 9 This dialog window is used for the code segment The window contains the three common items Name Description and Sequence There is one other item in the window e Code This is a text editor in which the user can enter the statements The code generator uses this text literally 5 3 8 Dialog 7 Sequential construct New sequential Ei Name Seq Sequence o Mr of terations i Description The processes Consumerl and Consumer run sequentially cones Figure 5 10 Dialog 7 sequential construct This dialog window is used for the sequential construct The window contains the three common items Name Description and Sequence There is one other item in the window e Nr of Iterations this item is used by the code generator to decide whether a for loop or a while loop has to be generated This loop is placed around the child process elements of this e
44. f the controller is connected to the input signal current_ input of the Linix model The encoder has a resolution of 2000 steps per revolution The amplification factor of submodel Encoder correction is therefore 2 pi 2000 The feedback signal must be corrected for the transmission ratio between the two pulleys because the feedback signal is taken from the encoder on the first pulley while we want to steer the second pulley For this correction the submodel Encoder correction is used The amplification factor in this submodel is 0 37037037 The proportional gain of the submodel Kp has the value 0 5 20 3 4 2 Safety Layer The output of the encoders is converted to a binary 16 bit representation This means that the value of the encoders must not exceed 2 1 To make sure that these values will not be exceeded a safety layer will be added When for example a constant signal is added to the input signal current_ input of the Linix model then the electromotor will start running with a constant speed The output of the encoders will constantly rise until they reach the value of 2 1 In figure 3 6 this is shown by the line from A to C After that point the value will instantly drop to the value of 2 The safety layer contains a P controller with a low proportional gain This P controller calculates the control signal which is needed to steer the output of the encoder slowly to a maximum value If this control signal is used the
45. file for the first custom procedure in the tree structure This source file will include the main method In Figure 5 20 the generated source file for this first custom procedure is shown next to the used tree based description model 48 benede eee eed dede beed FEST System name Main Class name PCMainl Date and time Mon Feb 02 02 02 02 2002 E E EE E import files import csp lang import csp lang Process import csp lang Integer publie class PCMainl public static void main String args new PCMainl public PCMainl final Channel_of_Integer channel new Channel_of_Integer Process par new Parallel new Process new Producer channel new Consumer channel II par run PCMain 2 channel Channel_ot_Integer par Producer at channel 2 e object Integer Consumer in channel object Integer amp Code Figure 5 20 a generated Java code b the tree based description model The source code is generated in three stages l The header The header shows the name of the system the class name and the date and time of generation 2 The import files The user can choose which include files have to be included in the source using a options menu Currently only the import files csp lang Integer csp lang Process and csp lang can be selected This options menu can be reach using the menu View Options Java Th
46. framework and reflects the structure of the code the simulator in 20 sim uses to perform the simulations Therefore 20 sim has a limited support for the phases three and four The CSP concept provides fundamental concepts for realizing concurrent software for real time and embedded systems It contains formal proofs for analyzing verifying and eliminating undesirable conditions such as raze hazards deadlocks livelocks and starvation The CSP model has been introduced into Java threads The CTJ package for Java provides a small set of design patterns that are sufficient for concurrent programming in Java The research presented here is part of the research done at the University Twente to enable the integration of the CSP concept with the software package 20 sim and for support of the phases three and four During this assignment a tool has been developed which shows the tree based description model together with the communication graph and the composition graph The tree based description model is able to describe the CSP aspects visually The CSP constructs are shown in a tree structure like 20 sim uses for its model hierarchy The communication graph is a graph of processes and their communication relations The composition graph shows the processes with their compositional relationships Examples of composition relationships are the sequential and parallel relationships The compositional graph shows the processes in the same topography as the co
47. g the threads that are related to the various processes Writing these kind of programs is difficult and error prone Drunen 2000 Threads are low level entities that are difficult to control and to understand from a high level point of view Directly controlling threads involves a good understanding of the flow of control of concurrent processes This increases the complexity and development time of this kind of programs In contemporary control systems the total system is often distributed For example the Volvo S80 car uses a distributed control system consisting of 18 computers Legius 1999 The advantages are processing speed reliability scalability flexibility reusability and concurrent engineering If each specific task can run on its own processor many of the problems mentioned above can be avoided In addition control system consists of different types of hardware The control software should be divided into hardware dependent and hardware independent code Otherwise all code needs to be reviewed whenever for example a sensor or actuator s replaced 1 2 Communicating Sequential Processes The theory of Communicating Sequential Processes CSP specifies fundamental synchronization constructs based on processes compositions and channel communication Hoare 1985 CSP provides a mathematical notation for describing patterns of communication using algebraic expressions It contains formal proofs for analyzing verifying and elimin
48. ger a type Integer AQ ChildProcess Figure 2 11 example of a global variable time 2 6 The Rectangles Graph This graph shows a completely different view In th s graph not only the custom process elements are shown but also the parallel and sequential constructs All these elements are shown as rectangles If two processes run parallel they are shown next to each other within a rectangle of the tree element parallel If they run sequentially they are shown below each 13 other within a rectangle of the tree element sequential This s best seen with an example In figure 2 12 the same model as in the tree based description model of figure 2 10 is shown as a rectangles graph a Seq h me Process Process Frocesse SAT FriFar Q Process ad d s Frocessd aans Par AS Process5 lS Process Fripar Process3 Process Par Processi Process Figure 2 12 a the construct process b the Rectangles Graph This graph shows that the Process1 Process2 Pripar and Par run sequential that Process3 and Process4 run parallel Process3 running with a higher priority then Process4 and that Process5 and Process6 run parallel This graph shows the hierarchy of processes as a nesting of rectangles A parallel construct is shown by placing the rectangles beside each other a sequential construct is shown by placing the rectangle below each other The rectangles graph can be used to make changes in the composi
49. he CDatabaseElement object has all the necessary attributes for such a line Table 4 1 shows several attributes of CDatabaseElement The connection between the elements is implemented using pointers This means that for example the label of the parent element can be found very fast It also makes the use of efficient recursive routines possible 29 El Main S Frocessor oe Fohdain channel Channel_ot_Integer ER par sf e Froducer ei out channel Channel ot Float ve e object Integer A Code oe Consumer e s in channel Channel oi Float tk object Integer Figure 4 2 Tree based description model of a producer consumer svstem nique label Type Parent Next_ sibling ID enumerated pointer pointer to to 4 channel Channel PCMainl Pr PCMainl 6 Producer_ Custom Je Consumer out 8 object _ Variable Producer Code 9 Code Code Producer Null Table 4 1 Some attributes of a database element 4 4 The Select View The topographic view can show one out of four different graphs The user has to have a way to indicate which graph he wants to see There are three methods which can be used for this l Keyboard a special keystroke is used for each of the four graphs 2 Menu option have the user use the menu system 3 Buttons four radio buttons are placed inside the program window one for each graph Because the selection of which graph is shown is an important feature of the program the third
50. here has to be a hardware connection for example RS232 between the two processors This hardware has to be addressed In CSP channels are used to pass data from one process to another process A CSP channel is an object which is placed between two processes One process writes to the channel the other reads from the channel The sending process waits until the receiving process is ready or the receiving process waits until the sending process is ready before communication takes place This means that CSP channels are unbuffered and synchronized processes according to the rendezvous principle The link driver concept can be used to separate hardware dependent and hardware independent code The hardware independent code communicates with their environment using CSP channels A linkdriver contains all the necessary hardware dependent code and takes care of the communication with the hardware A link driver can be plugged into a channel The hardware independent code communicates to the linkdriver using this channel see figure 2 1 The process is therefore not aware of the hardware it just communicates using channels channel Software k process Hardware independent Hardware dependent Hardware a process Linkdriver Figure 2 1 Linkdriver 2 3 CSP Diagrams The CSP diagrams are introduced by G H Hilderink Hilderink 2001 There are two kinds of CSP diagrams One of them is the communication graph The other kind is the compos
51. hese elements are shown as rectangles If two processes run parallel they are shown next to each other within a rectangle of the tree element parallel If they run sequentially they are shown below each other within a rectangle of the tree element sequential This is best seen with an example In figure 5 17 the same model as used in the composition graph of figure 5 16 is shown as a rectangles graph Figure 5 17 The rectangles graph From this graph we conclude that proc3 and proc4 run sequential and that procl proc2 and the sequential construct Seg run in parallel This graph shows a nesting of rectangles The most outer rectangle is the tree construct selected in the tree view The maximum number of levels can be set by the user in the select view The user can use the mouse to move each of the rectangles By pressing the left mouse key on a rectangle and moving the mouse the rectangle can be moved Every rectangle including the rectangle representing the sequential or parallel constructs can be moved this way 46 If in the model more than one processor is present then these processors are shown as rectangles next to each other In these rectangles the processes running on these processors are shown An example is shown in figure 5 18 Pentium Pentium Process Process Process3 Figure 5 18 Three processors in a rectangles graph Selecting a process for example Process1 and moving it to the processor Pentium2 would indicate th
52. inix model SignalGenerator Figure 3 3 Signal source and Linix The simulation is shown in figure 3 4 In this simulation three signals are shown l Reference this is the output of the signal generator a pulse 2 Angle pullyl this is the angle of pully in radian 3 Angle pully2 this is the angle of pully2 in radian 19 2 40 Title 10 angle pullyl 1 5 7 5 1 3 en en Ke reference Ke Es 5 E angle pully 2 CN d 2505 25 255 zn E OL Do br LA LA Son 0 0 DO D i 3 I a I dy I NJ a I I LD I LD 0 1 2 3 d time s Cr Figure 3 4 Simulation of Linix with pulse as reference 3 4 Controller Design 3 4 1 The controller For this example a P controller is used The reference signal is the angle of the second pulley A value of 1 V of the reference means that pulley2 has to rotate to a position of 1 rad As feedback signal the output signal encoderl out of the Linix model will be used Figure 3 5 shows the Linix system with controller and reference and the data flow diagram of the controller control Ki encoder1 Transmission Encoder correction reference Figure 3 5 a The Linix system with controller and reference b the controller The output of the reference is connected to the input signal reference of the controller The output signal encoderl_out of the Linix model is connected to the input signal encoder1 of the controller The output signal control o
53. iption model can then be changed to this new situation Because the rectangles graph shows the processors as rectangles this graph can be used to allocate processes on another processor The deployment graph shows the processors which are defined in the tree based description model as rectangles places next to each other Inside these rectangles the processes that run on these processors and which are candidates to be allocated on another processor are shown as rectangles These processes can then be moved drag and drop to another processor The deployment graph is in effect a more compact version of the rectangles graph If a process that communicates with another process on the same processor is allocated on another processor then the communication has to take place using a linkdriver To make this visible to the user the communication relationships between the processes and the available linkdriver on each processor should be visible in the deployment graph The deployment graph should let the user choose which linkdriver should be used 33 4 7 The Code Generator The code generator uses the contents of the database to generate software code To develop the code generator two alternatives were considered l Design a general algorithm for code generation and use a separate database for the language dependency 2 Create a code generation algorithm for each language Using the first alternative makes adding a new target language
54. iption model in three different ways l 2 3 Extended The processes are shown together with the communication relationships and the compositional relationships It provides the most detailed view of the tree Compact Only the processes and the compositional relationships are shown 20 s m Only the processes are shown in the tree The tree is shown with the same detail as 20 sim shows its submodels Using the tool proved that this was a useful feature In a design with many interface elements it can be difficult to see the hierarchy of the processes By removing the communication and compositional relationships from the view the hierarchy stands out more clearly The tool can also show a so called rectangles graph This graph shows the processes and their composition relationships as rectangles It shows the hierarchy of the processes and the compositional relationships very well The tool is capable of generating ANSI C code This code uses a sequential execution framework For every process in the tree based description model a separate function is generated The tool can also generate Java code The Communicating Threads for Java CTJ package which implements the CSP model in Java is used to generate concurrent software For every process in the tree based description model a class is generated The generated code for both target languages therefore reflect the hierarchy of the processes in the tree The choice for using an inte
55. ition graph 2 3 1 Communication Graph The communication graph is a graph of processes and their communication relations A communication relationship is defined as a directed relationship which represents message flow between a sender and a receiver process The communication relationships are data oriented The communication graph is actually a data flow diagram DFD which represents a network of processes that communicate through channels A communication relationship is symbolized as an line with arrow head De between two processes See figure 2 2 Producer Figure 2 2 Communication relation Figure 2 2 shows two processes and their communication relation which represents message flow between a sender process Producer and a receiver process Consumer In this case the producer performs sending data to the consumer 2 3 2 Composition Graph The composition graph shows the processes with their compositional relationships A compositional relationship is defined as a labeled relationship between two processes whereby the label is a two way or binary operator that expresses their compositional behavior The compositional graph shows the processes in the same topography as the communication graph The composition graph is control oriented and represents a special kind of control flow diagram that can express concurrency and non deterministic behavior This includes scheduling priority and choices operator Figure 2 3 Compositi
56. ket 20 sim Tijdens deze opdracht is een tool ontwikkeld die het tree based description model laat zien samen met de communicatie graaf and the compositie graaf Het tree based description model kan de CSP aspecten visueel laten zien De CSP constructies worden getoond in een boom structuur zoals ook 20 sim gebruikt voor de model hi rarchie De communicatie graaf bestaat uit processen en hun onderlinge communicatie relaties De compositie graaf toont de processen en hun compositie relaties Voorbeelden van deze compositie relaties zijn de sequenti le en de parallelle relaties De compositie graaf toont de processen in dezelfde topografie als de communicatie graaf Verder is de communicatie graaf van een controller vergelijkbaar met het grafische model zoals dat in 20 sim getoond wordt De tool kan parallelle Java code genereren die gebruik maakt van het software pakket CTJ Voor ieder proces in het model wordt een aparte klas gegenereerd De tool kan tevens ANSI C code genereren met een sequentieel executie frame Voor ieder proces in het model wordt dan een aparte functie gegenereerd De gegenereerde code reflecteert de hi rarchie van de processen in de boom structuur De structuur van de door 20 sim gegenereerde code komt overeen met de structuur van de code die de simulator in 20 sim gebruikt voor de simulaties Een aanbeveling is om de code generator van 20 sim te wijzigen zodat de structuur van de door 20 sim gegenereerde code overeenkomt met
57. lement There are three possibilities 4 The value of the item is equal to zero a while true loop will be generated 5 The value of the item is equal to one no loop is generated The value of the item is greater then one a for loop is generated 5 4 The Select View In figure 5 11 an example of the select view is shown Tree view C 2051M Topographic wiew El Consumer level C Composition Graph C Rectangles Graph C Deployment Graph Figure 5 11 The select view The leftmost part of this view shows the interface elements and the declaration elements of the selected process in the tree structure view In this example the process Producer is 43 shown If the selected element in the tree structure view is not a process element then the parent process of the selected element is shown with its interface elements The middle part of this view labeled Tree view contains three radio buttons 1 20 s m the tree based description model in the tree structure view is shown comparable with the software package 20 sim For Topo this means that only the system elements and process elements are shown See figure 5 12 a 2 Compact besides the elements shown in the 20 sim options this option also shows the processor elements the codeblock elements and the elements for the composition relations like parallel priority parallel and sequential See figure 5 12 b 3 Extended all the elements in the tree bas
58. ment and is described in chapter 4 and 5 The software tool Topo was used to generate the software For the controller as shown in figure 3 11 ANSI C code is generated This code can be found in appendix III 1 For the controller as shown in figure 3 12 Java code using the CTJ package is generated Appendix III 2 shows the generated Java code for the process Main Only the structure of the code and the interfaces are generated the processes do not contain a code block In Appendix III 3 the results of a 20 sim simulation for the system as shown in figure 3 5 1s compared with the results of the generated software from a tree based description model of the same system 3 7 Outline This chapter described a use case for the development of a controller for the Linix system The tree based description model communication graph and the composition graph of the developed controller were shown The generated software for this model can be found n appendix III The code is generated using the Topo This tool will be described in the next two chapters 26 27 4 The Design of Topo 4 1 Introduction In this chapter the development of the design tool called Topo will be described The program is written in Microsoft Visual C In section 4 2 an overview of Topo is given The tool can be divided in five parts the database the select view the tree structure view the topographic view and the code generator In the sections 4 3 to 4 7 these pa
59. mmunication graph Furthermore the communication graph of a controller is comparable with the graphical models shown in 20 sim The tool is capable of generating concurrent Java code using the CTJ package For each process in the model a separate class is generated The tool can also generate ANSI C code with a sequential framework For every process in the tree based description model a separate function is generated The generated code therefore reflects the hierarchy of the processes in the tree The code generated by 20 sim reflects the structure of the code the simulator in 20 sim uses to perform the simulations It is recommended to enhance the code generator of 20 sim to let 20 sim generate code that reflects the structure of the model The tool shows the two topographical views based on the tree based description model This should be the other way around The user should create and change the model using any topographic view The tool should then change tree based description model accordingly This is also how 20 sim handles its user interface It is recommended to enhance the software to support this II Samenvatting Op de leerstoel regeltechniek van de faculteit Elektrotechniek is een gestructureerde methode voor het ontwerpen van control software voor real time embedded systemen ontworpen Deze methode beschouwd het implementatie proces als een stapsgewijze verbetering van model van het fysische systeem naar effici nte computer c
60. n The include files In this example only iostream h is included The user can choose which include files have to be included in the source using a options menu Currently only the include files iostream h math h time h and stdlib h can be selected This options menu can be reach using the menu View Options ANSI C Declaration All the generated functions PCMain1 Producer and Consumer are declared in this section Main procedure The main procedure is generated This procedure simply calls the first custom process which is defined in the tree structure Functions For each of the custom processes in the tree based description model a function is generated The input parameters are passed by value the output parameters are passed by reference The procedure body of PCMainl calls the two functions Producer and Consumer and the procedure body of the functions Producer and Consumer consist out of a code segment 5 10 2 Java Code Generation The code generator for Java generates a separate class file for each custom process in the tree structure For tool will use the name of the custom process as the name of the file and for the name of the class These names should not be changed The tool uses the standard file dialog window of Windows In this window the directory in where the files are generated can be changed The filename used in this window should not be changed The tool first generates a source
61. n a processor The deployment graph is in fact a compact representation of the rectangles graph 2 8 Outline In this chapter three different ways to show the priority parallel and sequential constructs have been described The tree based description model as developed by Eric Volkerink shows the constructs in a tree structure The other two the composition graph and the rectangles graph shows the construct in a more graphical way The composition graph shows the model using the same topography as the communication graph The rectangles graph uses rectangles to show the structure of the design Both graph are capable of adding or removing concurrency to a design 16 17 3 USE CASE 3 1 Introduction The use case presented here is the development of a controller for the Linix system The Linix system is described in section 3 2 The method used for developing the controller is as follows 1 Physical Systems Modeling In section 3 3 a model of the Linix system is created and simulated in 20 sim 2 Control law design In section 3 4 a controller is designed using block diagrams and simulated in 20 sim 3 Embedded control systems Implementation In section 3 5 the composition graph is used to add concurrency to the design 3 2 The LINIX system The Linix is a system build at the Engineering Control Laboratory figure 3 1 It is used for educational purposes It consists of an voltage controlled current output amplifier an electromo
62. ng Double class Cosumer2 implements Process ChannelInput_of_Integer in Integer object public Cosumer2 ChannelInput_of_Integer in gen in in_gen object new Integer public void run in read object java lang System out println object 64 REFERENCES Breedveld P C 1985 Multibond graph elements in physical systems theory Journal of the Franklin Institute 319 1 2 1 36 Broenink J F 1999 20 Sim software for hierarchical bond graph block diagram models Simulation Practice and Theory T 481 492 Broenink J F and G H Hilderink 2001 A structured approach to embedded control systems implementation Broenink J F and C Kleijn 1999 Computer aided design of mechatronic systems using 20 SIM 3 0 Proc 2nd Workshop on European Scientific and Industrial Collaboration WESIC 99 Newport United Kingdom Ed 27 34 ControlLabs Product B V 2000 Helpfile 20 sim Douglass B P 1998 Real Time UML developing efficient objects for embedded systems Addison Wesley Longman 0 201 32579 9 Drunen J M v 2000 Realization of link drivers implementing CSP channels on 20 controller MSc thesis Faculty of Electrical Engineering Control Laboratory University of Twente Enschede Netherlands Hilderink G H 1999 Communicating Threads for C internal document Hilderink G H 2001 Communicating Threads for Jave CTJ internet home page http www rt el utwente nl javapp Hil
63. nstruct is not shown as a process in the graph For this situation the composite symbol el has to be used Figure 4 6 shows the use of this composite symbol if the Process2 of figure 4 5 is replaced by a parallel construct a 2 8 Main b 8 Processor 5 49 Main Ee Seq ve Process ol Par 2 Frocess AO Process2 e e Customs Frocess2 Frocessl Processa Figure 4 5 The composition graph using the composite symbol The rectangles graph shows the processes as rectangles The rectangles for child processes are placed inside the rectangle of the parent process For a sequential construct the child processes are placed below each other and for a parallel construct the child processes are placed next to each other The size of the rectangle for the parent process has to be changed so that all the child processes will fit into this rectangle The rectangles graph shows the hierarchy of the processes in the tree based description model Because the number of levels in the tree based description model can be large the number of levels shown in the rectangles graph have to be limited In the select view the user can be set the number of levels the rectangles graph will show The rectangles graph can be used to make changes in the compositional relationships between processes This can be done by using the mouse to move the rectangles and drop them on their new position The structure of the tree based descr
64. ode Deze methode bestaat uit 4 iteratieve stappen l Physical Systems Modeling modellering and simulatie van een fysisch systeem 2 Control Law Design ontwerpen en simuleren van een controller voor het model 3 Embedded Control System Implementation ontwerpen van de software 4 Realization implementatie van de gegenereerde code op de hardware De eerste twee stappen worden momenteel zeer goed ondersteund door 20 sim 20 sim is een software pakket voor het modelleren and simuleren van het gedrag van dynamische systemen 20 sim bevat een ANSI C code generator die een compleet 20 sim model of submodel kan converteren in C code De gegenereerde code heeft echter een sequentieel executie frame De structuur van de gegenereerde code komt overeen met de structuur van de code die de simulator in 20 sim gebruikt voor de simulaties Daarom worden de stappen drie en vier slechts beperkt ondersteund door 20 sim Het CSP concept bevat fundamentele concepten voor het realiseren van parallelle software voor real time en embedded systemen Het bevat formele bewijzen voor het analyseren verifi ren en elimineren van ongewenste condities zoals raze hazards deadlocks livelocks en starvation Het CTJ software pakket voor Java bevat een kleine set van ontwerp regels die afdoende zijn voor het parallel programmeren in Java Dit onderzoek is onderdeel van het onderzoek dat gedaan word aan de Universiteit Twente om de CSP concepten te integreren in het software pak
65. on and Sequence There is one other item in the window e Nr of Iterations this item is used by the code generator to decide whether a for loop or a while loop has to be generated This loop is placed around the child process elements of this element There are three possibilities l The value of the item is equal to zero a while true loop will be generated 2 The value of the item is equal to one no loop is generated 3 The value of the item is greater then one a for loop is generated 5 3 6 Dialog 5 Channel variable input output The dialog window is shown in figure 5 8 This dialog window is used for the variable input variable output channel input et and channel output 4 The window contains the three common items Name Description and Sequence There is one other item in the window e Connected A channel or a variable input output element has to be connected with a channel declaration element or a channel interface element from the parent process The tool will select all the available possibilities and show them in a selection list The value not connected is added to enable the user to first enter these elements and to create the declaration elements and the connections to them at a later time In the tree name of the declaration element will be shown after the name of input output element In figure 5 8 the channel output element out2 is connected to the declaration channel element channel2 41 N
66. onal relation Compositional relationships in the CSP diagram are based on the CSP and CSPP operators Thus operator e gt 1 i li 0 O Di Table 2 1 gives an overview of these operators Sequential Parallel Priority parallel Table 2 1 Operators Not all of the possible relations between processes have to be shown If all possible relations are shown the graph is a complete composition graph A complete composition graph of n processes would therefore show n n 1 2 relations For example figure 2 4a shows three processes P Q and R and the relations opl and op2 Figure 2 4b shows a complete composition graph in contrast to figure 2 4a a 7 opi EE Figure 2 4 a incomplete composition graph b complete composition graph There exists a relation between process P and R namely op3 Sometimes it is possible to uniquely determine the relation op3 between process P and R from the relations opl and op2 If a relation between two processes can be uniquely determined from another path of relations between these processes then this relation is called a deduced relation So far we have considered the compositional relations between two processes For a compositional relation between a process and a group of processes we need a notion of grouping such as using brackets is needed For example P Q R For this a special composite symbol for the compositional relation is introduced see figure 2 5
67. onships with no alternatives e The deployment view currently only shows the available processors The processes which run on these processors have to be placed inside those rectangles The user should be able to move these processes to another processor e The linkdrivers should be made visible in the deployment view When a process is moved from one processor to another and this process has an communication relationship w th another process then the user should be able to choose between the available linkdrivers e The rectangles graph could provide an graphical interface for changing concurrency in the model It should be investigated whether this could be a useful technique e The tool currently only shows the sequential parallel and priority parallel compositional relationships It should be investigated how the alternative and priority alternative can be added to the model APPENDIX I Technical Specifications of the LINIX System Motor Type Motor constant Nominal Voltage Inertia without pulley Inertia with pulley Transmission Diameters of the pulley on the motor shaft Diameters of the pulley on the load shaft Transmission belt type Transmission belt stiffness Transmission Transmission 2 Inertia of the pulley on the motor Inertia of the pulley on the load Number of belts Distance between shafts of the pulleys Inertia ratios Transmission 1 20 mm 120 mm pulleys Transmission 1 40 mm 108 mm pulleys
68. opographic view In 20 sim this is different Editing of a model in 20 sim can only be done in the topographic view To enter new elements in the design the menu structure is used Before the user can select a menu item to enter a new element the syntax rules checker first checks which type of elements can be entered The same syntax rules as used in the program Embedded are 31 implemented in Topo For example after a variable declaration element one is not allowed to add any child The syntax rules are described in Appendix II 4 6 The topographical view The topographic view can show four different graphs These graphs use the contents of the database to create the graphs Changing the contents of the database is done by the tree structure view 1 The communication graph shows the processes and their communication relationships This graph should be comparable with the way 20 sim shows a data flow diagram The processes are therefor shown as rectangles and the relationships as line with a arrow head When there is more then one relationship between two processes these relationships have to be shown separately In figure 4 5 two ways to archive this are shown al b A P A Figure 4 5 two ways to show two relationships between two processes Because 20 sim uses the intermediate points as shown in figure 4 5b this method is also used in Topo To minimize the programming effort only one intermediate point will be supporte
69. ption model and the rectangles graph is important for the sequential and the priority parallel construct Because the user can easily place the rectangles below above left or right of another rectangle this sequence can be easily changed If in the model more than one processor is present then these processors are shown as rectangles next to each other In these rectangles the processes running on these processors are shown An example is shown in figure 2 14 Pentium Pentium Processl Process Process Figure 2 14 Three processors in a rectangles graph Selecting a process for example Process1 and moving it to the processor Pentium2 would indicate that the process should be allocated on this processor In an ideal case the tool should show the communication relationships between the processes and the available link drivers between the processors When the user moves a process to another processor the tool should then let the user choose which link driver should be used for which communication relationship 15 2 7 The Deployment Graph The rectangles graph shows in principle all processes and the priority parallel and sequential constructs The deployment graph shows only the available processors and those processes which are candidates to be allocated on another processor The always has at least one processor in its design The deployment graph would then show the processor s and a list of processes which can then be allocated o
70. r of the topographic view window The software will then set he point to its initial state These intermediate points can be made visible through the menu view options general options Producer Figure 5 15 The tool has one intermediate point 5 6 Composition Graph The composition graph shows the processes with their composition relationships The topography of the processes is the same as with the communication graph Because of this Topo uses the same routine for placing the rectangles of the processes on the view Instead of looking at the communication relationships the tool will now look for the tree elements parallel and sequential These tree elements form the compositional relationships 45 In the tree based description model of figure 5 13a the following compositional relation ships can be recognized l Procl and proc2 run parallel A parallel compositional relation is drawn 2 Proc3 and proc4 run sequential Logically a sequential compositional relation is drawn 3 Proc2 run parallel to the sequential construct with the name Seq This has as a result that the tool draws a parallel compositional relation with the composite symbol The resulting composition graph is shown in figure 5 16 Figure 5 16 The composition graph 5 7 Rectangles Graph This graph shows a completely different view In this graph not only the custom process elements are shown but also the parallel and sequential constructs All t
71. rements on the real system 2 Control Law Design The control laws are designed using the acquired model The model used to derive the control laws is normally a simplified version of the acquired model of the previous phase It is possible that certain operating conditions require a set of control laws Normally the next rather common procedure is used e Derive a simplified model The model obtained by the previous phase is either reduced automatically e g by linearization and or order reduction or diminished by hand to obtain a model suitable for control law design e Verify the simplified model The simplified model can be verified by performing the same simulations as with the detailed model The results should not be significally different e Derive the control laws Using the simplified model derive the control laws For this normally external software such as Matlab is used e Verify the control laws The control laws can be verified by simulation The performance of the control laws can be checked against the demands 3 Embedded Control System Implementation In this phase the control laws are converted into computer code Facilities for safety of the system have to be specified and designed Reaction to external commands user input is taken into account For this phase the industry uses other modeling approaches for example structured methods or object orientation like UML Douglass 1998 4 Realization The in the
72. rnal database proved to be correct The time spend programming the database routine was limited compared to the time spend on programming the other parts of the tool 52 6 2 Recommendations e The tool demands the user to enter the compositional relationships in the tree structure before the tool can show the topographic views It would be better if the changes in the design would be made possible through the topographic view like in 20 sim The tool should then change the tree structure to reflect these changes e The tool generates source code that reflects the hierarchy of the processes in the tree based description model It is recommended to change the code generator of 20 sim so that the generated code by 20 sim also reflect this hierarchy e The addition of the global variable tree element is not allowed in the CSP concept It is advised to have it removed e Several tree elements have an attribute which the code generator uses to determine whether a loop for whileloop has to be generated Conditional loops can only be expressed inside a code segment This is not visible in the tree based description model Loop control s an important issue in software To make these loops visible n the tree structure a new tree element loop has to be designed e The user should have more influence on which composition relationships are shown in the composition graph Currently there is one routine which shows a selection of the relati
73. rts are described 4 2 Overview The structure of the tool is shown in figure 4 1 Tree Structure view select View syntax Rule Checker Tree based description model Topographic View Communication Database le Composition Graph Kectangles Code Generator Graph Semantic Rule Checker Figure 4 1 Overview of Topo Deployement 28 From this figure we can divide the tool in 5 parts 1 The database contains the information shown in the tree structure view and the topographical view 2 The select view shows the input output variables channels of a process and can be used by the user to set how much detail the tree view is shown The user also uses this view to define which of the four possible topographic views are shown 3 The tree structure view shows the data as a tree It shows the tree based description model Volkerink 2000 This view also takes care for the interaction with the user for entering new data to modifying data or removing data from the database For entering new data a syntax rule checker is used 4 The topographical view shows the information as a graph There are four different graphs possible the communication graph the composition graph the rectangles graph and the deployment graph 5 The codegenerator performs the conversion from the database contents to software code Currently the languages ANSI C and Java are supported In the next sections these five parts will be di
74. s implementation 3 5 1 Model Enhancement Most of the sub systems in 20 sim are I O SEQ meaning that they first read all their input before giving an output When these submodels are converted into software each submodel can in fact be represented as a software routine Figure 3 11 shows the tree based description model the communication graph and the composition graph of the Linix system as shown in figure 3 7a in case all the processes are run sequentially Not all the possible relations in the composition graph are shown in this example The example shows a deduced composition graph This means that every relation between two processes which is not shown can be deduced from the graph For example the relation between Controller and Linix is a sequential relation from Controller to Linix 23 al og Rete Float 2 Cont Float tet Save Float tet Encl Float tet Enc2 Float D 7 Seq es Reference tel Output Refe Float CA Controller lk Reference Rete Float os Encoder Encl Float ae control Cont Float CA SafetyLayer es Controller_in Cont Float oh encoder Enc Float tel Control value Save Float BA Linie current_input Save Float z Encoder _out Enct Float te Encoder _out Enc Float D SafetyLasrer Reference Controller C SafetyLasrer Reference Figure 3 11 The Linix system a Tree based description model b Communication graph c Composition graph 24 In a design it is
75. s methods have been developed The UML method Douglass 1998 is currently widely used The research behind CTJ showed that the CSP concepts could be modeled in UML in the form of design patterns However describing the CSP concepts in UML does not always give a easy overview of the design Volkerink 2000 10 The Tree based Description Model has been developed by Eric Volkerink Volkerink 2000 This model is able to describe the CSP aspects visually The CSP constructs are shown in a tree structure like 20 sim uses for its model hierarchy and the interface of the submodels The purpose of the tree based description model is to integrate the CSP concept with the modeling and simulation package 20 sim The next section gives a description of this tree based description model 2 5 2 Tree based description model Figure 2 8 shows a tree based description model of a producer consumer process In this tree a hardware section and a process section can be recognized Main ER Processor SE Bios Eb ZS RSs232 Hardware section sf e MyProcess Software section channel Channel_of Integer a Il par GA Producer out channel Channel_of_Integer tet object Integer Aa Consumer in channel Channel ot Integer object Integer amp Code Figure 2 8 Producer Consumer example In the hardware section we find the elements system 3 processor bios and linkdriver In the process section we find the hi
76. scussed 4 3 The Database For implementing the database there are basically two main alternatives e Using an external database e g Microsoft Access e Create the database internally in memory An external database has the advantage that existing tools can be used to test and read the database Most existing databases have built in safeguards to maintain the integrity of the database This can be of great help during the development of the tool The disadvantage is that the tool has to access the database using SQL Several years of experience in programming databases have shown that it is not always easy to implement queries for databases Implemented the database internally in C means that the database will be in memory constantly Because a object oriented language is used to implement the tool a good separation of the database object and the other parts of the tool can be created using features like data protection and information hiding In addition the Microsoft Foundation Classes makes it very easy to read and write internal data to persistent media As a result it was decided to implement the database internally as a C object To implement the database two classes where used a database class Cdatabase and an element class CDatabaseElement In figure 4 2 a tree based description model is given of a Producer Consumer system as an example Every line of this model corresponds with one instance of the database element object T
77. te and time Mon Feb 02 02 02 02 2002 EE EE EE EE EE EE EE EE EE EE EE ALAS IID SIS AT IAS E EE EE EE import files import csp lang import csp lang Process import csp lang Integer import csp lang Double class TwoConsumers implements Process ChannelInput_of_Integer inl ChannelInput_of_Integer in2 public TwoConsumers ChannelInput_of_Integer inl_gen ChannelInput_of_Integer in gen inl inl gen in2 in gen public void run Process Seq new Sequential new Process new Consumerl inl new Consumer2 in2 63 Consumer l java Ee System name Main Class name Consumerl Date and time Mon Feb 02 02 02 02 2002 LIISA SASSI ISTLTST LITAS TS EE EE EE EE EE EE EE EE import files import csp lang import csp lang Process import csp lang Integer import csp lang Double class Consumerl implements Process ChannelInput_of_Integer in Integer object public Consumerl ChannelInput_of_Integer in_gen in in_gen object new Integer public void run 4 in read object java lang System out println object Consumer2 java FIAT SHIT E HT EI IASI ATE EE EI SI SI II ST II II SI TI FIT TS II FIT TI IIIT SI IT IT E System name Main Class name Cosumer2 Date and time Mon Feb 02 02 02 02 2002 LTD E AAA IAAL ALATA CL AT ATTA ATA EE E import files import csp lang import csp lang Process import csp lang Integer import csp la
78. ted Java code These ANSI C and the Java dialog windows are shown in figure 5 22 The General options dialog window is shown in figure 5 23 al bi Includes Import i iostream h 7 csplang I math h i csp lang Process T time h IT csp lang Integer m idib k M csp lang double ou on Figure 5 22 a ANSI C option dialog b Java option dialog 50 Figure 5 23 General option dialog 51 6 Conclusions and Recommendations 6 1 Conclusions A tool was implemented which shows a model as a tree based description model together with its communication graph or its composition graph Changes made in the tree based description model are also directly shown in the communication or composition graph The tree based description model shows the hierarchy of processes in a tree structure together with the communication relationships and the composition relationships like sequential and parallel The hierarchy of processes is best shown in the tree based description model The communication graph shows the communication relationships better then the tree based description model The composition graph shows the compositional relationships better then the tree based description model During the testing of the code generator for ANSI C it became clear that a tree element for defining a global variable for example for the time would be useful Consequently a global variable tree element was added The tool can show the tree based descr
79. tional relationships between processes The user can use the mouse to move each of the rectangles By pressing the left mouse key on a rectangle and moving the mouse the rectangle can be moved Every rectangle including the rectangle representing the sequential or parallel constructs can be moved this way The idea behind this s that when for example the rectangle of Process4 is moved and dropped by releasing the left mouse key just below Process5 that the tool will then change the structure of the tree based description model accordingly to make Process4 sequential to Process6 The new structure is shown in figure 2 13 An optimization routine can then be used to remove the priority parallel construct Pripar This construct only contains Process3 and can be removed Placing a rectangle not below but beside before or after an other rectangle would indicate that these processes should run parallel Using this technique the sequential and parallel constructs can be manipulated Creating a priority parallel construct can be done by first creating a parallel construct and afterwards changing this construct to a priority parallel construct 14 a Seq bi Zeg Q Frocess Processl wll Process z EI Fripar u Processa I II Far A Process5 AD Process6 Pripar lS Processd Par Process mei Figure 2 13 a the changed construct process b the new Rectangles Graph The sequence in which the processes are shown in the tree based descri
80. tor and two pulleys which are connected through an elastic band a flexible transmission belt The amplifier has a 5 Volt input voltage range The output current is between 1 33 Ampere Both pulleys have a certain inertia The positions of both pulleys are measured by optical encoders These encoders have a resolution of 2000 steps revolution The output of these optical encoders are converted into a 16 bit binary representation Figure 3 1 The LINIX system The detailed technical specifications for the LINIX system are in Appendix I 18 3 3 Physical Systems Modeling A model of the LINIX system is created in 20 sim using iconic diagrams figure 3 2 The connections between the displayed icons are energy flows The model has two output signals encoderl out and encoder2 out and one input signal current input The icons Encoderl Encoder2 and MSf are responsible for converting energy flows to signals or vice versa Encoder encoder1_out current MSf hh X IX 77T Anplifie Bearing1 Inertial _BeltPulley1 Belt Inertia2 LL z XX Ground1 VO 777 Bearing BeltPulley2 current_input encoder2 out Encoder Figure 3 2 Linix model in 20 sim To simulate this model with 20 sim we need to add a signal source The source is a pulse generator and gives an output of amplitude 1 between 0 5 and 1 second The output of the signalgenerator is connected to the input signal current_ input of the L
81. utput signal of the reference and the angle of the second pully of the Linix system are shown reference 40 30 20 ER O Title 40 N N oO angle pully2 rad time s 58 Using the design tool Topo a tree based description model is created This model is shown together with the composition graph and the communication graph Unter ER Processor BA Linie 2 Ss step 2 tijd pg Control out Float 2 ven reference _outl Float 2 ven reference _oute Float e linix_out Float Fly Sequential a reference communication graph tel outl reference_outl Float tel out2 reference_out Float tet start_time Float tet stop_time Float amplitude Float tet pi Float A Code es control Zi ab ref_out reference_outl Float lin_out linix_out Float 2 SC e out control_out Float tet K1 Float control BD linix Zu in control_out Float tel out linix_out Float jnertial_f E inertial oh E inertiad_f E inertia _phi Zi beltx e amplifier_l Float tet demotor_T Float tet bearingl_T Float tet bearing2_T Float e belt_F Float te pully _T Float se pulyz_T Float e K_amp Float krm Float Des d Float tet J1 Float pg J2 Float tt k_belt Float tet radiusi Float tet radius2 Float CA display E ab In reterence cute Float composition graph For this tree based description model the tool Topo generates the next ANSI C code 59 dE LIT
82. ve Reader Writer Skip Stop TimeSlicer Input Guard Output Guard Skip Guard and Timeout Guard are not supported by Topo and are currently disabled The entering of new elements to the model s further discussed in section 5 3 36 T Channel Declaration SS Variable Declaration nen Ose Sarre Global V anable Parallel mare As me quent al File Print Alternative Print Preview PriP ar allel Print Setup PriAlternative list of recent files Process Reader Exit Writer la Undo kip Cut Stop l Copy Timeolicer Edt Faste Code Add Child Insert Sibling C hannel Input Channel Output Process Interface Channel 10 Toolbar Variable Input Status Bar G eneral options Variable Output View Split ANSI C Variable IO O pt os Java Input Guard Output Guard ANSI C pH Check Code ER G uar ds Skip Guard f Timeout Guard SE ANSI C Generate Code Tee Subsystem Processor Bios Hey Window Link driver Cascade Window Tile Arrange Icon list of window s Help Topics Help About aster i Figure 5 2 Menu structure The Insert Sibling submenu has the same sub options as the Add Child submenu The submenu Options in the submenu View has three menu items General Options ANSI C and Java These menu items each start a dialog box for options These dialog boxes are further discussed in section 5 11 The submenu Build contains the submenus Check Code and Generate Code These are used for running the semantics rules checker section 5

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