a new approach to steady state and quasi steady state ...· to steady‐state and quasi‐steady...

AnewapproachAnewapproachtosteadytosteadystateandquasistateandquasisteadystatesteadystate
vehiclehandlinganalysisvehiclehandlinganalysis
Presentation By Claude RouelleVehicle
DynamicsExpo
June
16nd -1
8th
2009

Vehicle Dynamics Expo 16-18 May 2009 Stuttgart, Germany
OptimumGOptimumG OverviewOverview
Vehicle Dynamics & Data Acquisition Seminars In-House Seminar Public Seminar
Consulting Track Testing Race Engineering Data Acquisition Mechanical Design ...
Software Development OptimumK Simulation
2

OptimumGOptimumG SeminarsSeminars
Vehicle Dynamics & Data Acquisition Seminars In-House Seminar Public Seminar One-on-One training
From 1 to 12 days Design around customer needs 8900 Power Point Slides to choose from
3

OptimumGOptimumG SeminarsCustomersSeminarsCustomers
312 Seminars / 12 Years Over 6000 Satisfied Customers
Alcon AP Brakes Brembo Bridgestone-Firestone USA Bridgestone Tech. Center Europe BMW Citroen Sport Corrsys-Datron Chrysler Dunlop Ferrari Ford Advanced Vehicle Operations Goodyear Mac Laren
Magneti-Marelli, Michelin Mitsubishi Multimatic MoTeC Nascar Ohlins Oreca Penske Pi Research Pirelli Porsche PSA Peugeot Citroen Toyota ZF-Sachs. 4

OptimumGOptimumG ConsultingConsulting
Mechanical Studies
Chassis Design
Suspension Geometry Design
5

OptimumGOptimumG ConsultingConsulting Race Car Engineering
On Track Engineering
On Track Testing
Lab Testing
Data Acquisition
6

OptimumGOptimumG SoftwareDevelopmentSoftwareDevelopment OptimumK : Kinematics software
7

OptimumGOptimumG SoftwareDevelopmentSoftwareDevelopment OptimumT : Tire Data Fitting and Visualization Software
8

OptimumGOptimumG SoftwareDevelopmentSoftwareDevelopment Computational Vehicle Dynamics
Steady State simulation Quasi-Steady State simulation Yaw Moment Diagram Moment Method
9

PresentationPresentation
About CVD
CVD Presentation Design Motion Setup Analysis
Quasi Steady State Simulation
Pure Steady State Simulation
Steering Simulation
Yaw Moment Diagram Simulation10
COMPUTATIONALOMPUTATIONALVEHICLEEHICLEDYNAMICSYNAMICS

AboutCVDAboutCVD CVD (Computational Vehicle Dynamics) calculates the
behavior of the car in steady state
Steady state: all the forces and moments are balanced in each step of the simulation
No inertiaNo damping
Calculation of lateral and longitudinal gripReaction of both suspended and non suspended massWeight TransferTire Deflection
However, CVD could consider the case where the yaw moment is not equal to zero allowing the user to analyze parameters like understeer or oversteer.
11

CVDCVD DesignDesign
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FrontSuspensionTemplates: DoubleAArm NascarMacPhersonMacPhersonPivotArm
RearSuspensionTemplates: DoubleAArmMacPherson Nascar V8Supercar FiveLink

CVDCVD SetupSetup
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CreateasmanySetupasyouwant
Setupsplitin4:MassesandCG Others(Stiffness,Brake,Diff) TireModel AeroMaps
FastSetupchanges

CVDCVD Setup(2)Setup(2)
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Masses and CG Masses and CG Inputs Inputs
Print
Import - Export
CornersMasses NonSuspendedMasses CGTotalHeight NonSuspendedMassesCG

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Other InputsOther Inputs
SpringStiffness AntiRollBarStiffness(orBellevilleWashersStiffness) BrakeDistribution DrivetrainConfiguration StaticRideHeight NonSuspendedMassCGs ChassisTorsionalStiffness

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Tire ModelTire Model Pacejka Fiala STI Harty
VisualizationTools: 2DGraph 3DGraph TireForcesCalculator

17
Aero MapsAero Maps AeroMapVisualization: 3DGraph IsoLines CzFrontandRear
Cx AeroBalance Efficiency

CVDCVD MotionMotion
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In CVD the inputs are based on forces and speed
3 types of motion can be generated according to the need of the user.
Pure Steady StateQuasi Steady StateYaw Moment vs. Lateral Acceleration diagram

CVDCVD Motion(2)Motion(2)
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PureSteadyState(PSS)PureSteadyState(PSS)
PSS motion: Yaw moment equal to zero Steering wheel angle is calculated in order to maintain the equilibrium.
Skid Pad Simulation
Parameters
Yaw Moment = 0Lateral Acceleration = InputSteering Wheel Angle = OutputBody Slip Angle = Output

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QuasiSteadyState(QSS)QuasiSteadyState(QSS)
QSS motion: the steering angle is an input and therefore the yaw moment is not zero anymore.
Forces, Roll and Pitch Moments are in equilibrium.
Parameters
Yaw Moment = OutputLateral Acceleration = InputSteering Wheel Angle = InputBody Slip Angle = Output

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YawMomentDiagramYawMomentDiagramIn a diagram motion the input is a sweep for both body SA and steering wheel angle. For each point the lateral acceleration and yaw moment are calculated and then a diagram can be generated. This gives a quick visualization of parameters such as control, stability, behavior at the limit.
Parameters
Yaw Moment = OutputLateral Acceleration = OutputSteering Wheel Angle = InputBody Slip Angle = Input

CVDCVD AnalysisToolsAnalysisTools
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YawMomentDiagramYawMomentDiagram PresentationPresentation
23
For a given speed an longitudinal acceleration, the yaw moment diagram covers the full maneuvering envelope and presents the results graphically in one graph.
Graphic analyze of the stability and control of an automobile.
Analogy with aeronautical techniques.
Force/Moment study instead of motion study avoids filtering effects of the inertias and give the ability to isolate results of small changes in the vehicle configuration not discernible in a transient response.

YawMomentDiagramYawMomentDiagram ConstructionConstruction
24
SweepofSteeringWheelAngleSweepofSteeringWheelAngleSweepofBodySlipAngleSweepofBodySlipAngle
VehicleSpeedVehicleSpeedLongitudinalAccelerationLongitudinalAcceleration
VerticalAccelerationVerticalAccelerationIso Body Slip AngleIso Steer Angle

YawMomentDiagramYawMomentDiagram Howtouseit?Howtouseit?
25

YawMomentDiagramYawMomentDiagram Howtouseit?(2)Howtouseit?(2)
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STABILITY: The slope of the zero-steer curve shows the yaw moment (N) for different CG body slip angle (). This is called the directional stability of the car.
The magnitude tells you how much yaw moment is acting on the car with zero steering input. The sign is always the opposite sign as the lateral acceleration sign, thus this yaw moment tends to reduce the body slip angle.
StabilityStability

27
CONTROL: The yaw moment generated at 1 of steering shows the derivative of yaw moment (N) with regard to steering angle. This is a measure of the yaw moment control that the driver has.
Lateral acceleration generated at 1 of steering shows the derivative of lateral acceleration (Y) with regard to steering angle. This is a measure of the lateral-acceleration control that the driver has.
ControlControl

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LIMIT BEHAVIOR: If the tip of the diagram is above the line yaw moment (N) = 0 for positive lateral accelerations, then the car is limit oversteer (spin).
If the tip of the diagram is below the yaw moment (N) = 0 for positive lateral accelerations, the car is limit understeer (plow).
Note that a car can be limit oversteer but understeer in terms of trim behavior.
LimitBehaviorLimitBehavior

YawMomentDiagramYawMomentDiagram OverlayOverlay
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a new approach to steady state and quasi steady state ...· to steady‐state and quasi‐steady...

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