Co-simulation environment for
vehicle-powertrain-tire on/off-road analysis
Dan Negrut
Simulation-Based Engineering Lab
University of Wisconsin, Madison
Acknowledgements
• Joint work with:
– Makarand Datar, University of Wisconsin, Madison
– Andrew Dyer, MSC.Software
– Ilinca Stanciulescu, University of Illinois, Urbana-Champaign
• Financial support
– US Army through Resilient Technologies
– BAE Systems
• Technical support
– Anthony Sajdak (MSC Software)
– Sylvain Pagerit (Argonne National Lab)
– Brian Anderson, Resilient Technologies, WI
Overview
• Simulation Based Engineering Lab
• Building vehicle models in ADAMS/Car
– Templates Subsystems Assembly
– HMMWV
– Powertrain system in ADAMS/Car
• PSAT
– Powertrain Systems Analysis Toolkit
• Co-simulation
– Vehicle – Powertrain
– Vehicle – Tire
• Future work
[1] Modeling
[2] Numerical Solution
[3] Validation and UQ
•
Modeling
–
Start with a physical problem that needs to be investigated, and produce an abstraction (a model)
whose response, behavior, performance, resembles that of the physical system
[1] Modeling
[2] Numerical Solution
[3] Validation and UQ
• Equation formulation and solution
– Once a model is available, formulate the equations associated with
the time evolution of the model and solve them
– Focus:
• Simulation of frictional contact
• Co-simulation approaches to enable cross discipline simulation
• Parallel methods for multibody dynamics simulation
[1] Modeling
[2] Numerical Solution
[3] Validation and UQ
• Model Validation and Uncertainty Quantification [UQ]
– Important question in virtual prototyping:
• How do you know whether the model adequately captures reality?
– UQ - statistical approach needed to assess model performance
– Data assimilation (compare experimental and simulation results)
– System identification - calibrate certain parameters (damping coefficients,
bushing stiffness coefficient, etc.)
– Surrogate modeling
End Introduction
On to High Fidelity Vehicle Modeling
HMMWV Model
• High Mobility Multipurpose Wheeled Vehicle
(HMMWV)
– Modeled in ADAMS/Car
– Four Wheeled Drive
– CAD geometry applied to Chassis and Wheels
• Focus on
– Vehicle topology
– Vehicle Powertrain
– Tire Models
Powertrain Systems in ADAMS/Car
• Simplified Topology of the Elements in Powertrain
System
Engine
Differential
Clutch
Transmission
Tire
Powertrain Systems in ADAMS/Car
• The dynamics are modeled using differential and
algebraic equations
• Limitations
–
–
–
–
Only conventional powertrain systems
The fuel economy can not be predicted
Not very sophisticated
Not validated extensively
PSAT
• Powertrain System Analysis Toolkit
• Sophisticated powertrain models
•
•
•
•
Conventional
Electric
Fuel cell
Several varieties of hybrid powertrain
– Parallel, series, power split, series-parallel
– For light and heavy duty vehicles
• Validated within 1%-5% for both fuel economy and battery state-of-charge on
several driving cycles
– Conventional and mild hybrid within 2% (Honda Insight, Ford P2000)
– Full hybrid vehicles within 5% (Toyota Prius)
• Modeled using MATLAB, Simulink and Stateflow
PSAT – Integrated Development Environment
Build and compare
large number of
powertrain
configurations
Easy selection of data,
models, control
strategies or drive cycles
Analyze and
compare test and
simulation data
Ensure simulation
traceability
Easy implementation
of data, models,
control strategies or
drive cycles
Run batch mode
Ensure model
compatibility
Use models and
controls for HIL/RCP
Forward Modeling
Accelerator/Brake pedal
Controller Commands
Motor command
Engine command
Clutch command
Shift command
Brake command
Co-simulation ADAMS-PSAT
• ADAMS vehicle model handles chassis, suspension, steering,
road definition
• PSAT handles powertrain system
• MATLAB/Simulink used as common co-simulation platform
Co-simulation ADAMS-PSAT
• Simulink S-Function to co-simulate with ADAMS/Car vehicle generated
using ADAMS/Controls
• Simulink model of vehicle in PSAT
• The vehicle + wheels + road blocks in PSAT model replaced by
ADAMS/Car model
• Co-simulation based on data exchange
Driveline speed, longitudinal velocity
ADAMS
PSAT
Driveline torque, brake demand
Co-simulation ADAMS-PSAT-FTire
PSAT vehicle
block is removed
ADAMS vehicle
block is inserted in
Simulink to work with
PSAT
FTire used in
ADAMS
vehicle
ADAMS-PSAT
Interface
Double click
A Word on Tire Models
• Tire models supported
– Fiala
– Pacejka
– FTire
• Other tire models not used yet in ADAMS-PSAT context:
– Flex tire model
– Nonlinear tire model
Flexible Tire
• Component Mode Synthesis (CMS)
approach:
– Relies on modal analysis of tire in ABAQUS
– Tire element is subsequently imported in
ADAMS as a flexible body
• Limitation: small defs. only
• Advantage: fast simulation
Flexible Tire (Cntd.)
• The MNF file used has 125 mode shapes and 6 rigid body modes
• Flexible tire model relevant in durability and fatigue analysis studies
• Craig-Bampton method: superposition of
– Constraint modes
– Fixed-boundary normal modes
Nonlinear Tire model (FEAP)
• Collaboration with professor from UIUC
• Formulation uses 3D, 8 node finite elements (bricks)
• Contact with sliding – Coulomb friction law
• Sources of nonlinearity
– Large deformations (geometric nonlinearities)
– Rubber Material (composite): constitutive law used is Mooney-Rivlin
• Incompressibility handled through Q1P0 approach
– Pressure loading (based on Simo et al, 1991)
– Exact integration
– Consistent Newton-Raphson linearization
Future Work
• Automate the ADAMS-PSAT co-simulation interfacing
– There is still busy legwork that needs to be done for enabling co-simulation
• Simulation of off-road vehicles with deformable terrain
– Developing co-simulation capability for simulating non-linear finite element
models of tire with ADAMS/Car
• Other research projects in our lab
–
–
–
–
Dynamics of granular flow
Fast methods for frictional contact in mechanical system simulation
Real-time simulation
Surrogate modeling and model validation (Uncertainty Quantification)
ADAMS at University of Wisconsin
• Simulation-Based Engineering Lab
– Car modeling
– Track modeling
– Co-simulation mode (ongoing projects for interfacing with DEM
and nonlinear FE codes)
• Kinematics and Dynamics Class
– Senior level undergrads and first year grad students
• Future Truck team
• SAE Formula Team
– 2007 National Champions
Technical Report Available
• July 2007
– http://sbel.wisc.edu/documents/Tr-2007-03.pdf
Dr. Dan Negrut
Email: [email protected]
Tel. +001 608 890 0914