The document discusses the significance of multibody dynamics (MBD) in vehicle dynamics and real-time simulation, encompassing its applications in analyzing vehicle behavior under different forces. It highlights the role of MBD in automotive development processes, including testing methods such as Software in the Loop and Hardware in the Loop for improving control systems and integrating supplier models. The use of driving simulators for safe testing and subjective analysis of vehicle dynamics is also emphasized for enhancing development cycles.

1. THE ROLE OF MULTIBODY DYNAMICS IN VEHICLE DYNAMICS:
REAL TIME SIMULATION
JEGA SRISKANTHA
DIRECTOR, CERYNEIAN
© 2017

2. THE ROLE OF MULTIBODY DYNAMICS IN VEHICLE DYNAMICS :
REALTIME SIMULATION
 What is Multibody Dynamics ?
 The study or analysis of the effect of forces on a mechanical system made
up of bodies connected together
 Vehicle dynamics analysis : The study of vehicle behavior due to a force or
multiple forces acting on a vehicle
1 DOF 2 DOF n DOF
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3. THE ROLE OF MULTIBODY DYNAMICS IN VEHICLE DYNAMICS :
REALTIME SIMULATION
 Using Multibody Dynamics for Vehicle Dynamics Analysis
Time domain solution for the equations of motion
 Full Vehicle Vehicle Dynamics Simulations
 Kinematics and Compliance test rigs
 Measured road input ride simulations
 Constant Radius
 J Turn
 Double lane change
 Sine with dwell
and many more…
Image courtesy of Simpack
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4.  Multibody Simulation (MBS)
 Over 40 years of MBS methodologies
 Over 20 years of mainstream use of MBS
 MBS is now integral in the vehicle development process
THE ROLE OF MULTIBODY DYNAMICS IN VEHICLE DYNAMICS :
REALTIME SIMULATION
Benchmarking
Target Setting
Concept Analysis Component Testing
System Testing
Vehicle Sign-Off
Synthesis Current MBS
Integrated
Processes
Future MBS
Integrated
Process
Vehicle Testing
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5. THE ROLE OF MULTIBODY DYNAMICS IN VEHICLE DYNAMICS :
REALTIME SIMULATION
 Very Fast Analysis Tools vs Virtual Prototypes
Increasing number of car segments
and crossovers to support new
markets, requires OEM’s to output
more vehicles in order to stay
competitive
Very Fast
Analysis Tools
Virtual
Prototypes
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6.  Embedding MBS into Automotive Development
THE ROLE OF MULTIBODY DYNAMICS IN VEHICLE DYNAMICS :
REALTIME SIMULATION
MBS Experts
Vehicle
Dynamics
Analysts
Image courtesy of Simpack
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7.  Realtime Simulation
THE ROLE OF MULTIBODY DYNAMICS IN VEHICLE DYNAMICS :
REALTIME SIMULATION
 Realtime Simulations:
 must ensure a response within a specified
time
 that don’t complete or fail within that
specified time may no longer be considered
realtime
Traditional
Simulation
targets
accuracy
Realtime
Simulation
targets time
deadlines Actual Time : Simulation Time <= 1
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8. THE ROLE OF MULTIBODY DYNAMICS IN VEHICLE DYNAMICS :
REALTIME SIMULATION
 Realtime Simulation for Vehicle Dynamics
Parameterized
Model
Code Export
Full MBS
Realtime
Simulation
for Vehicle
Dynamics
 Often dedicated application specific software
optimized for realtime applications
 Easy model population, limited parameters
but still representative
 Very fast models ( faster than realtime )
 Very easy integration of control systems
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9. THE ROLE OF MULTIBODY DYNAMICS IN VEHICLE DYNAMICS :
REALTIME SIMULATION
 Realtime Simulation for Vehicle Dynamics
 Export as a FMU or S-function from a known
modelling environment
 Use model in many different simulation
environments
 Black box exchange between suppliers and
OEM’s
 Easy integration with realtime Hardware and
Software
Parameterized
Model
Code Export
Full MBS
Realtime
Simulation
for Vehicle
Dynamics
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10. THE ROLE OF MULTIBODY DYNAMICS IN VEHICLE DYNAMICS :
REALTIME SIMULATION
 Realtime Simulation for Vehicle Dynamics
Realtime
Simulation
for Vehicle
Dynamics
 Run ‘normal’ offline models directly in realtime
 Ability to truly stay in the same modelling
environment
 Run on standard realtime-enabled operating
systems
 Fully parameterized models
 Instant model changes
Parameterized
Model
Code Export
Full MBS
Realtime
Simulation
for Vehicle
Dynamics
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11.  Utilizing Realtime Simulation
THE ROLE OF MULTIBODY DYNAMICS IN VEHICLE DYNAMICS :
REALTIME SIMULATION
Realtime
Simulation
Software in the
Loop
Hardware in
the Loop
Driver in the
Loop
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12.  Software In The Loop (SiL)
THE ROLE OF MULTIBODY DYNAMICS IN VEHICLE DYNAMICS :
REALTIME SIMULATION
 Testing executable code embedded into another
simulation environment
 Allows for rapid control system prototyping early
in the development process
 Integration of Supplier Models ( e.g. EPAS, CVD)
 Increase maturity of the complex integration of
control algorithms (e.g. ABS, ACC, ESP, Torque
Vectoring)
Realtime MBS
Simulation
Software-in-
the-loop
(e.g. ABS, ESP)
Vehicle Dynamics behavior
Brake System Inputs
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13.  Hardware in the Loop (HiL)
THE ROLE OF MULTIBODY DYNAMICS IN VEHICLE DYNAMICS :
REALTIME SIMULATION
Realtime MBS
Simulation
Hardware-in-
the-loop
(e.g. ECUs)
Vehicle Dynamics behavior
Controller Outputs
 Testing hardware embedded into a simulation
environment
 ECU testing and component test rigs
 Obtain realistic vehicle dynamics outputs for
accurate representative testing
 CCP and XCP Integration
 ESC Homologation
 Testing of autonomous vehicle hardware
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14.  Driver in the Loop (DiL)
THE ROLE OF MULTIBODY DYNAMICS IN VEHICLE DYNAMICS :
REALTIME SIMULATION
 Testing model behavior (model data) based on
real driver inputs
 Safer Human Machine Interaction testing of ADAS
 Laptime Simulation
 Testing complex ’real world’ scenarios involving
driver interactions, in a controlled environment
Vehicle Dynamics
behavior
Vehicle path and
control modifiers
Vehicle Dynamics
Feedback
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15.  Driving Simulators
THE ROLE OF MULTIBODY DYNAMICS IN VEHICLE DYNAMICS :
REALTIME SIMULATION
Realtime MBS
Simulation
Hardware-in-the-
loop
(e.g. Steering
Wheel)
Driver-in-the-loop
(e.g. SWA)
 A safe testing environment, to test driver
interactions with new systems
 Capturing physiological behavior and responses of
drivers
 Safe exploration of vehicle limits
 All year testing, simulating various environmental
conditions
 Subjective vehicle assessment early in the
development cycle
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Vehicle Dynamics
behavior
Vehicle path and
control modifiers
Vehicle Dynamics
Feedback

16.  Driving Simulator Hardware and Technology
THE ROLE OF MULTIBODY DYNAMICS IN VEHICLE DYNAMICS :
REALTIME SIMULATION
Mercedes-Benz Driving Simulator Center:
Image Source: [www.mercedes-benz.com/en/mercedes-benz/innovation/the-mercedes-
benz-driving-simulation-center/]
 Driving Simulators allow for interactions between
driver and a virtual model
 Different hardware setups
 Static Simulators
 Hexapods ( Stewart Platform)
 Multi – DOF platforms
 Using hardware requirements to limit model
fidelity
 Hardware latency and bandwidth
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17.  Subjective Analysis of MBS Models
THE ROLE OF MULTIBODY DYNAMICS IN VEHICLE DYNAMICS :
REALTIME SIMULATION
 Vehicle Dynamics sign-off is based on subjective
analysis
 Understanding relative performance, mapping
virtual and physical vehicle's
 Motion cueing
 Sensory cues that mimic real driving
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18.  Unifying Vehicle Dynamics Analysis
THE ROLE OF MULTIBODY DYNAMICS IN VEHICLE DYNAMICS :
REALTIME SIMULATION
Practical
Vehicle
Dynamics
Experts
Theoretical
Vehicle
Dynamics
Experts
DiL
Objective Vehicle
Dynamics
Analysis
Often CAE driven
engineering decisions
Subjective Vehicle
Dynamics
Analysis
Hardware driven
engineering decisions
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