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System Analysis Using Multiple Expert Tools
DOE Update April 18, 2011
Ram Vijayagopal Argonne National Laboratory
Sponsored by David Anderson & Lee Slezak
This presentation does not contain any proprietary, confidential, or otherwise restricted information
Overview
Need for detailed vehicle models Interconnection of expert tools - Challenges Interface process definition
– Interface architecture – Interface rules
• Examples : GT Power, AMESim, CarSim
Autonomie for system integration Appropriate use of detailed models Case study
2
Need for Detailed Vehicle Models
3
Quick evaluation of new technologies Shortens the design time Expert system tools exist
– Technology exists for linking them
Engine GT-Power
Transmission AMESim
Veh.DynamicsCarSim
DriverEnvironment
Vehicle Controller
Vehicle Propulsion Architecture
Interconnect expert system tools to build detailed vehicle models
Interconnection of Expert Tools
4
Challenges – I/O formats – Unit conversion – Documentation – Path settings, Environment variables – Compiler, solver settings – Supporting files, APIs – Signal name translation, Sign conventions – Other tools specific & even version specific properties
Tools considered – GT-Power, AMESim, CarSim and many more
Technology exists
Solution: Define a common interface process & automate it.
*.dat *.par *.ame *.c
Overview - Interface Process Definition
5
Interface architecture definition – Documentation, Re-usability
Interface rules definition – Tool specific checks – System specific ‘Information exchange’ needs – Simulation specific requirements
Experts can define the process. Entire organization can use it
Matlab scripts Expert tool APIs
A modeling environment to automate & implement the process
Autonomie Used for System Integration
6
Model documentation
Expert 1 : Tool 1
Model documentation
Expert 2 : Tool 2
Model documentation
Expert 3 : Tool 3
System specific information exchange needs
Tool specific checks
Simulation specific requirements
Expert 4 : System integration Automated interface Detailed vehicle model
Common Interface Architecture Definition
7
S-Function
Output signal
formatting
Input signal
formatting
Wrapper built around s-function – Automated for different tools – Supporting files provide information about I/O signals
• *.dat, *.ame, simfile etc.
– Documentation of the model generated automatically
XML
New format, better documentation. Critical for interface & sharing of the models
Interface Rules - 1 Tool Specific Checks
AMESim – Environment variables – Compiler selection
CarSim – Register automation server
GT Power – Version specific changes
Path setting – include all solvers in Matlab path
8
Tool specific checks are done while starting the vehicle simulation tool
eval(['!ameload ',amesim_ame_file]) ……… ameputpaliases(….,…..,…..)
Interface Rules - 2 System Specific Information Exchange Needs CarSim interface model initialization
– Invoke CarSim, Launch CarSim if needed – Generate simfile automatically – Read parameters needed for vehicle control
• vehicle mass, wheel radius, etc.
GT Power
– Parameters can be read from the .dat file.
AMESim
– Use APIs to set gear ratios on the AMESim model
9
h = actxserver('CarSim.Application'); h.Yellow('#ALTPATH',user_dir); ………. h.RunButtonClick(n);
Information exchange
between models
Solver settings Step time Supporting files Result analysis
set_param(veh_mdl, 'SolverType', 'Fixed-step'); set_param(veh_mdl, 'Solver', 'ode4'); set_param(veh_mdl, 'FixedStep', delta_t) copyfile(tmp.source_file,tmp.dest_file)
Interface Rules - 3 Simulation Specific Requirements
Engine GT-Power
Transmission AMESim
Veh.DynamicsCarSim
DriverEnvironment
Vehicle Controller
Vehicle Propulsion Architecture
Build Vehicle Using Systems Defined by Experts
11
dat
init file
ame
init file
sim file
init file
Engine system
Transmission system
Vehicle dynamics system
Appropriate Use of Interface Simplify detailed models for faster simulations
Automated process to run a component on a virtual test bench Detailed model are used to generate steady state maps Maps used to run default Autonomie models
12
Automated component characterization process
initialization data
Case Study: Overview Effect of Steering on Fuel Economy
13
Vehicle dynamics : CarSim – Define the road – Takes in torque from transmission – Speed feedback for driver
Engine – Autonomie model – Fuel data generated from GT Power
Autonomie – GUI for model/system selection – Models rest of the vehicle – Automatic model building – Enforce interface rules – Result analysis capabilities
Case Study: Effect of Steering on Fuel Economy Appropriate Use of Multiple Tools
14
CarSim
Engine initialization data automatically generated
from GT-Power
Autonomie
Build & Run Models Automatically Automatic building saves time and avoid errors Automatic enforcement of interface rules & checks Post processing capabilities
model building
Running external tools
resu
lts
Simulation Results Overview Different steady speeds on straight
& circular roads – Effect of turning – More torque from engine, more fuel
Use expert tools to analyze results – Saves results for all tools involved
16
Autonomie Result analysis
CarSim Result analysis
Conclusion
17
A common interface architecture is developed. This is adaptable to any tool that supports a Simulink interface.
Automated the interface process to ensure that all tool specific requirements are satisfied
Interface automation demonstrated for GT-Power, AMESim, CarSim
Autonomie provided user interface for model/system/process selection and enabled model sharing, and knowledge sharing
Demonstrates a methodology for detailed simulation studies