计算机系统发展

1、International Conference on Advances in ComputationalModeling and SimulationThe semi-physical simulation system design of micro-satellite based-on HLA Xue Sheng, Xuekui Liu, Zhaowei SunResearch Center of Satellite Technology, Harbin Institute of Technology? Harbin150001?ChinaAbstractThe ground simul

2、ation validation is an important process during small satellite sdevelopment. Givingconsideration to the characteristics of small satellite and a type of ground simulationrequirements, a smallsatellite hardware-in-loop simulation system based-on HLA is established. Systemstructure, the interactionda

3、ta table, hardware interface unit and the federal members flow chart are designed.The simulation andvalidation are done to a certain small satellite through the designed hardware-in-loop simulation system.The results show that the simulation system is able to simulate dynamics and control subsystem,

4、 powersupply subsystem and payload subsystem and realize accessing physical equipment of control subsystemmuch better, and has good practical application value.? 2011 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of KunmingUniversity of Science and TechnologyKeywords:

5、micro-satellite; hardwire-in-loop; Simulation System; HLA.1. IntroductionWith the development of civil space, high-performance civilian spacecraft are needed urgently. However,because the private enterprises are limited by financial resources, it s impossible totake a large investmentto large output

6、 routine. In order to gain greater economic benefits through lessinvestment, we have toimprove the traditional development means that are used to design and researchspacecraft. To improve the* Corresponding author. Tel.: +86-451-86402357.Xue Sheng et al. / ProcediaEngineering 31 (2012) 801806functio

7、nal density and the quality, shorten the research cycle and reduce theresearch costs, a lot ofsimulations and testing on the ground are necessary during the spacecraft researchand development process,which ensure the success rate during spacecrafts running on-orbit.The simulation of satellite system

8、, as an important part of the satellite development,is an effective waywidely used to test and verify the overall satellite parameters of the space missionsand the satellite system.Furthermore, domestic and foreign space agencies have proved that the advancedmathematical design andsimulation techniq

9、ues are important means to improve the performance of thespacecraft, ensure thedevelopment quality, reduce development costs and risks, shorten the developmentcycle and ensure reliableoperation on-orbit1.Domestic and foreign scholars have carried out extensive research in the spacecraftsimulation sy

10、stem,for example, the University of Turin(Italy) andAlenia Space have developed theparallel developmentenvironment to facilitate the parallel developmentof space missions, and theelectrical companyCAE(Canada)has developed a graphical simulation platform of spacecraftsoftware environment. Althougha s

11、imple mathematical simulation is capable of meeting the needs of mission assessment, the timing ofsimulation is one of the limited factors. Hardwire-in-Loop Simulation (HIL) means that some kind ofphysical objects need accessed by mathematical simulation systems, hence, the time, interface, performa

12、nceand other parameters will be verified by the HIL simulation platform. In the reference 3, Wang Feng andhis collaborators have established the hardwire-in-Loop simulation platform for the micro-satellite controlsystem; In the reference 4, Chang Tong li and his collaborators have established the ha

13、rdwire-in-Loopsimulation platform for space docking. However, all of these have considered theirscalability and openness.Researches on data storage and time management issues have been studied inreference 5 and 6, but thedetails for building large-scale systems simulation and accessing a variety of

14、data orsoftware have not beenelaborated clearly. As the increasing of collaboration during the process ofspacecraft research, it s a mostpressing issue that an open and scalable hardwire-in-loop simulation platform is required to establish.In view of the above requirements, the purpose of this paper

15、 is to establish simulation platform with openand scalable interface for micro-satellite, which is base-on HLA (High Level Architecture) framework.Therefore, the main work includes architecture and interfaces designing forsimulation system, giving thesystem-level data flow as well as the specific ta

16、sk requirements of a model simulation, and then running thecase and gain the simulation results.2. Framework for simulation system based-on HLAIn order to simplify the micro-satellite system development and to achieve the future expansion andreuses, component of the system will be transferred to mod

17、ular design in accordance with its function,which is based-on the characteristics and requirements of its simulation process. As for the components ofdifferent function, its corresponding simulation model should be designed, and a visual interface panel isused to control and achieve its functions. T

18、he federal member is interconnected by LAN, using M? K RTI3.0 as its Run Time Infrastructure. Lib RTI from RTI is loaded to each of the federal program, the servicewill be extended to developers of federation. The function that federal information exchange between thefederal members and others is ac

19、hieved through the HLA interface.The basic task of hardwire-in-loop simulation for micro-satellite is to complete validation for hardwareand software of its subsystem(s). It means subsystems for a micro-satellite will be assigned to a differentcomputer to complete the mathematical simulation, and th

20、e hardware sub-systems will need to be verified inphysical form during the simulation. The data communications between the various subsystems based-onHLA and entire satellite system is built naturally. The hardwire-in-loop simulation fora micro-satellite Xue Sheng et al. / Procedia Engineering 31 (2

21、012) 801 806 803 system based-on HLA, including eight subsystems (federations), the simulation hostcomputer, statusdisplay subsystem, dynamic systems, power subsystem, satellite service subsystem, thermal controlsubsystem, payload subsystem and data management subsystem, Figure 1 shows the block dia

22、gram forhardwire-in-loop simulation system.Federate 6Interface UnitFederate 5Flight missionsubsystemFederate 7PayloadsubsystemFederate 8Data managementsubsystemControl subsystemSOCFED fileRTI?Run -Time Infrastructure?Federate 1Simulation hostcomputerFederate 2Status displayFederate 3Dynamicsubsystem

23、Federate 4PowersubsystemFig. 1. Block diagram for simulation systemThe blocks function of hardwire -in- loop simulation system is described as follows?(1) Simulation host computer taken as the management terminal during simulation is the simulation corepart to management and control the entire model

24、s and simulation platform. Its main functions are as follows:x Subsystems are modeled separately, and host computer for simulation is used to delete and add thefederation, so its functions for the subsystems simulation models are integrated into an entirety. Basedon the parameters from pre-optimized

25、 interface, data communication protocols, according to the realfeatures of physical devices, on-board data and control flow, then simulation and verification forx In addition to the above, the host computer also the control center in the process of distributedsimulation, is used to set simulation pa

26、rameters(such as the simulation step interval, the initial orbitalparameters, the environment perturbation considered in the simulation, thresholds for the control system,etc. ).(2) Subsystem of status display can access to satellite status parameters from the HLA/RTI, and then thesimulation results

27、 presented to the user by STK anddata sheets. What need toexplain is that statusparameters as mentioned before include orbital parameters, attitude parameters, sensor parameters andactuator parameters, etc.(3) The main function of dynamics computer is to solve the orbital dynamics model, attitude dy

28、namicsmodel, space environment models and sensor models of the satellite.(4)Simulation computer of power system hasestablished solar array model,battery and powercontroller model based-on MATLAB. Users can complete the satellite power system design and preliminarysimulations. At the same time, modul

29、e for collecting the telemetry parameters and displaying the numericalresults using the dynamic curve of power system is established synchronously.(5) Flight mission system is the important subsystem of data processing and control, the success orfailure of the micro-satellite depends on whether its

30、performance and timing series being correct or notdirectly. The physical object for Hardwire-in-loop simulation mentioned above mainly refers to the flightmission system which takes SOC as the primary platform. 804Xue Sheng et al. /Procedia Engineering 31 (2012) 801806(6) Interface unit is intermedi

31、ate computer for data exchange between physical hardware and HLA/RTI.Physical equipment mainly executing attitude and orbitcontrol algorithms, and itshardware platform isSOC.(7) Payload subsystem computer has established themodels of the satellitepayloads (such as earthremote sensing payload and ear

32、th imaging payload, etc.), then has gained itsperformance of simulation andevaluation. This system is an important foundation for the overall mission analysisduring the integrationmathematical simulation of the whole satellite, the system can be linked with theintegrated simulation.(8) Data manageme

33、nt subsystem as a federation ofsimulation is a key member tostore and accesssimulation data. Specifically, the simulation computer possess real-time databaseand complete the dynamicdata collection during simulation.Each simulation subsystem needs to send or receive date. These data isencapsulated as

34、 an object classrespectively, and each data corresponds to an object class attribute. Eight objectclasses of federation aredefined. These data are maintained, published and ordered among federationmembers. The host computerpublishes its simulation object class, which contains the user s configuratio

35、ninformation of the simulationsystem, the information of initial parameters and federal information. In order to show the simulationparameters to the user timely, the simulation host should order the federate data from Status, Dynamics,Payload and other federates. Other subsystems are similar to the

36、 host computer.3. Interface unit for physical deviceDue to thelimited physical device interface, it s difficult to access to HLAco-simulation environmentdirectly. Hence, it is required to design hardwareinterface unit for SOC. Thehardware interface unitsincludes SOC management module, real-time data

37、 collection module, data conversion module, datadistribution management module, time management module, and HLA interface, as shown in Figure 2.While the hardware access to the systems successfully, the interface between the hardware and HLA isneeded, and this interface unit requires achieving the f

38、ollowing two functions:(1) Function for data format conversion: in HLA, information interactive is achieved by updating andreflecting the objects attributes, sending and receiving interactive information. Usually, the performance ofnetwork transition is optimized through conditions updating and rout

39、ing. The information exchange ofhardware system commonly uses the custom wayof sending and receiving, whichis a periodicaltransmission and fixed structure. The both possess different protocols and the mechanism of informationexchange. Therefore, interface devices are required to complete the process

40、ing of data conversion, to sendthe status of physical device and the real-time simulation data to subsystems of management and control,and to transfer the simulation control commands into the control instrument of the hardware meanwhile.(2) Functions for coordination and management of the simulation

41、 time: the physical hardware system isphysical simulation time increasing, and each component in the simulation system increases its time by itsmeans, while the time is not controllable and irreversible. RTI manages the time ofevery member in HLAcentralized to ensure the event s logic correction at

42、federationlevel. In the case ofhardware in HLAsimulation loop, the time uniform is needed among HLA system time and federatemembers withindependent time promotion. In other words, the events triggered by hardwaresystem should be ensured tobe triggered to correct place on the timeline of a member of

43、HLA Federation, and theevents for a memberof HLA federation is ensured to correct place on the physics timeline of hardwaresystem. Xue Sheng et al. / Procedia Engineering 31 (2012) 801806 805SOC RS232 UART Interface Unit Other systemPhysical device data sampleData conversionData distribution managem

44、entTime managementEventmanagementFPGAManagementFig. 2. Block scheme of interface unit4. Simulation and verificationTaking advantage of presented semi-physical simulation system of micro-satellitebased on HLA, takingcertain satellite model s parameters as input conditions, an orbital period of thesem

45、i-physical simulationhas been completed. The simulation results are shown in Figure 3. Figure 3(a)shows the execution resultsof status display federate in the micro-satellite semi-physical simulation using STKdisplay program. Figure3(b) shows the result data of flywheel model in the dynamic federati

46、on and the speedand control momentcurve of history data. The curves will be updated real-timely during the simulation.Control momentFig. 3. (a) status of micro-satellite;(b) curves offlywheel speed, the control torque and power5. ConclusionAccording to the real requirements of a micro-satellite, the hardwire-in-loop simulation system designingbased on HLA is done. The interfa