Hybrid vehicle simulation methods combine physical test articles
(vehicles, suspensions, etc.) with complementary virtual vehicle
components and virtual road and driver inputs to simulate the
actual vehicle operating environment. Using appropriate components,
hybrid simulation offers the possibility to develop more accurate
physical tests earlier, and at lower cost, than possible with
conventional test methods. MTS Systems has developed Hybrid System
Response Convergence (HSRC), a hybrid simulation method that can
utilize existing durability test systems and detailed non-real-time
virtual component models to create an accurate full-vehicle
simulation test without requiring road load data acquisition.
MTS Systems and Audi AG have recently completed a joint
evaluation project for the HSRC hybrid simulation method using an
MTS 329 road simulator at the Audi facility in Ingolstadt, Germany.
The hybrid simulation consisted of an Audi A5 Coupé installed on
laboratory road simulator, combined with virtual vehicle tires
modeled using FTire™ and Audi digital roads running in the
standard ADAMs simulation environment. The scope of the evaluation
included the development of a complete set of 20-channel control
signals for the 329 road simulator for 3 rough-road durability test
profiles representing selected Audi proving ground roads.
The physical spindle loads developed by the A5 + FTire hybrid
simulation were compared to vehicle spindle loads obtained from
three other methods: 1) a road load measurement for the A5, 2) a
road measurement for a different but similar vehicle, and 3)
analytically predicted loads from a complete virtual vehicle system
model. The comparisons indicated that laboratory vehicle test loads
created using accurate tire models and hybrid simulation closely
correlate to fatigue-critical loads from a physical road
measurement, and in overall result in more appropriate loads for
the test vehicle than analytically predicted or
"bookshelf" loads.
This paper describes the HSRC hybrid simulation method, and its
potential advantages for the vehicle durability testing and
development process compared to other laboratory simulation
methods. The paper describes the application of HSRC to create a
full-vehicle laboratory test, and presents detailed simulation
results for rough-road test events, along with comparison of the
results to 3 alternate sources of vehicle loads.
