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system for hardware-in-the-loop simulation.² RTSS is also connected through a 1.25 Gbit/sGiganet to a similar facility to share data andresources.This real-time computing facility is suitable forour proposed distributed real-time simulation of thebenchmark aircraft model.Fig. 1GARTEUR Benchmark Model (RCAM)Distributed ModellingThe research objective of this project is to runreal-time distributed simulations on the RCAM modelwith di®erent robust °ight controllers, and to conducta comparative analysis.The interface software that interprets the Matlab/Simulinkmodels and runs them on the real-timenodes is RT-LAB, developed by OPAL-RT Technologies.4 The original RCAM model was created usingMatlab (version 4.2) and Simulink (version 1.3), neitherof which is supported by RT-LAB. Therefore, aninitial task is to upgrade the models and their correspondingcodes. This section details the changes thatwere made in order to prepare this model for real-timedistributed simulation.Model Sub-System SeparationThe original RCAM model (see Figure 1) was regroupedinto sub-systems as illustrated in Figure 3.Fig. 2UTIAS RTSS Facility² Three host computers each having dual-Pentiumprocessorsrunning Windows 2000 operating system.² Four real-time computers each having dual-Pentium-processors running Neutrino (QNX6)real-time operating system.² The real-time nodes are directly connected by400Mbit/sec FireWire and communicate with thehosts over a dedicated 100Mbit/s Ethernet network.² The system consists of 108 multiple channel IOFig. 3New RCAM Block DiagramThe model was grouped into the depicted subsystemsin a manner that best resembled a real aircraft,for the purposes of running distributed simulations.Each sub-system is described below:2 of 9American Institute of Aeronautics and Astronautics Paper 2002-4473
1. The trajectory generator is the ¯rst subsystemand it is a Matlab S-function which outputs aset of reference signals that the virtual aircraftmodel is to follow, as shown in Figure 4. The°ight is broken down into four segments (markedby A,B,C and D in Figure 4). The ¯rst segment(A) consists of a level °ight with a track angle of-90 degrees (west). An engine failure is simulatedpart way through this segment to investigate thelateral features of the robust controllers. The secondsegment (B) is a controlled 90 degree turn,to a track angle of zero degrees (north). Thethird segment (C) is a two-phase approach, ¯rstwith a commanded °ight path angle of -6 degreesfollowed by a commanded °ight path angle of -3degrees. Finally, in the last segment (D), the -3degrees °ight path angle is to be maintained duringa wind shear. The wind shear model is twodimensional and derived from. 52. The wind inputs and aircraft actuators aregrouped into a separate subsystem and are thoroughlyoutlined in the technical report TP-088-3of GARTEUR (AG08). 1 All system actuators areassumed to have ¯rst order system dynamics withrate limits and saturations. As well, all sensorsare assumed to be perfect.3. The next subsystem contains the nonlinear aircraftmodel. This is also a Matlab S-function andrepresents the aircraft's dynamic behavior as a setof equations.4. The controller is the next subsystem to be separated.The separation of the controller from therest of the model allows the incorporation of differentrobust controllers to be quite easy. The restof the model can remain constant while only thecontroller algorithms are changed.5. The ¯nal subsystem is known as the console. Itconsists of all the outputs from the nonlinear aircraftmodel subsystem as well as the simulationclock. This subsystem is necessary for user interfacewhen implementing the model into RT-LABand simulating in real-time.Controller ModelThe original RCAM model incorporated a robustcontroller that GARTEUR designed; it is outlined inthe technical report TP-088-9 of GARTEUR (AG08). 6This controller was used in our simulations solely forthe reason that the results of the original RCAM model(using this controller) are well documented. Theseresults provide a basis of comparison to verify the validityof our o²ine simulation results of the upgradedRCAM model. The design approach of the controlleris based on loop shaping using normalized coprimeFig. 4 Trajectory for the Landing Approach of theRCAMfactorization. This method is based on H 1 synthesisand uses an uncertainty structure that does notrequire explicit uncertainty description. 7 Both the lateraland longitudinal controllers are broken down intoinner and outer loops. The purposes of the inner loopsare to stabilize and augment the handling qualities ofthe aircraft while the outer loop guides the aircraftalong the generated trajectory.Remodeling of RCAMAs mentioned earlier, some modi¯cations had to bemade to the original RCAM model in order for it tobe used in the RT-LAB real-time environment.S-functionsThe purpose of an S-function is to provide acomputer language description of a dynamic system.Two S-functions exist in the RCAM: the trajectorygenerator and the nonlinear aircraft dynamics block.Both of these were originally written in C-code forSimulink (Version 1.3).The upgrading of these S-functions took place in twophases. The ¯rst phase was to reprogram them as Matlabscript ¯les (¯le extension .m). The second phasewas to reprogram the original RCAM S-functions in C-code in accordance with the upgraded stipulations ofSimulink (Version 3). 8 The C-code S-functions werethen converted into Matlab executable ¯les (CMEX¯les) which are recognized by Simulink.RT-LAB Model Con¯gurationFigure 3 illustrates the proper format for which aSimulink model must be grouped in order for RT-LABto acknowledge it. The RT-LAB software groupsmodels into three di®erent categories: slave blocks3 of 9American Institute of Aeronautics and Astronautics Paper 2002-4473
Page 1: AIAA Modeling and Simulation Techno
Page 6 and 7: (4) time delay case where the °igh
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