USE OF VEHICLE DYNAMICS SIMULATION IN

A FORMULA STUDENT TEAM

CONTENT.

1.

2.

3.

INTRODUCTION FORMULASTUDENT

INTRODUCTIONKA-RACEING

SIMULATION MODELS3.

4.

5.

6.

SIMULATION MODELS

CONCEPT DECISIONS

SUSPENSION TUNING

CONTROL SYSTEMVERIFICATION

INTRODUCTION FORMULA STUDENT

• Design competition with an

race car theme

• 11 events in 10 countries

and on 5 continents per

year

• Formula Student teams in

INTRODUCTION FORMULA STUDENT

• Formula Student teams in

over 50 different countries

• Over 70 teams in Germany

• 8 disciplines in an event

– 5 dynamic disciplines

– 3 static disciplines

• Goal is to score 1000 points

INTRODUCTION FORMULA STUDENT

INTRODUCTION KA-RACEING

INTRODUCTION KA-RACEING

7

• Formula Student Team of the Karlsruhe Institute of Technology (KIT)

• Founded in 2006, first car in 2007

• Since 2010 every year one electric and one combustion car

One team, two cars!

INTRODUCTION KA-RACEING

• In 2014:– 55 Students

– 2 cars

– 5 events

KIT14c

INTRODUCTION KA-RACEING

• 199 kg

• Self-developed combustion engine

• Drag Reduction System

• 10“ tires on CFRP rims

• Hybrid Chassis

KIT14e

INTRODUCTION KA-RACEING

• 211 kg

• Self-developed electric engines

• Drag Reduction System

• Monocoque

• 10“ tires on CFRP rims

• „Active Yaw Control“ and „Traction Control“

SIMULATION MODELS

Tire Model

• 2007 – 2013: Magic Formula

– Pro:

• very good for steady-state analysis

• low computing time

SIMULATION MODELS

• low computing time

• available Fitting Software

– Contra:

• over 160 parameters

• often problems with oscillations

• hard to properly fit transient

coefficients

• no road uneveness

• no thermal model

SIMULATION MODELS

Tire Model

• Since 2014: KA-RaceTireWheel Load

Model

1. Order

Model

1. Order

Dynamics

Model

Fz

Camber

Slip Vel.

SlipScale Factor

13

TMEasy Camber Model

Fx Fy

Output

Fx Fy

• Electric Powertrain• Simulink Model of Electric Powertrain containing:

– Engine model with efficiency map

– Battery model with efficiency factors

– Recuperation considered

– Control Systems embedded

SIMULATION MODELS

– Control Systems embedded

SIMULATION MODELS

• Aerodynamics• Aerodynamic coefficients as function of ride height, roll and

pitch angle

• Model for DRS actuation

CONCEPT DECISIONS

• Lap-Time Simulation

• Lap-Time Simulation suitable for basic concept decisions

• Driver handling the car close to its physical limits

• Comparison of lap-times sensitivy of lap-time on different

parameters

CONCEPT DECISIONS

parameters

• Powertrain Concept

• Concepts different in:

– Mass

– Intertia

– Number of driven wheels

CONCEPT DECISIONS

Concept 1 Concept 2 Concept 3

2WD, very

light car

4WD, high

inertia,

medium

weight

4WD, high

weight,

medium

inertia, high

torque

Acceleration 100 % 81 % 78 %– Number of driven wheels

– Center of Gravity

– Engine Power

Acceleration 100 % 81 % 78 %

Skid-Pad 100 % 104 % 106 %

Autocross 100 % 88 % 87 %

Endurance 100 % 88 % 87 %

• Aerodynamics Concept

• Aerodynamics in general

CONCEPT DECISIONS

Without Aero With Aero

Cz - 0,2 % 100 %

Cx 31,3 % 100 %

Lap-Time Skid-Pad 103 % 100 %

Lap-Time Autocross 114,2 % 100 %

• Aerodynamics Concept• DRS Concept

CONCEPT DECISIONS

SUSPENSION TUNING

• Sensitivity Studies with Open-Loop-Maneuvers

– Steady-State Cornering

– Steer-Step

– Sinus-Sweep

– Accelerating

SUSPENSION TUNING

• Parameter Studies to:

– Learn about influences of parameters on vehicle dynamics

– Know which parameter to change

– Save Test Time!

SUSPENSION TUNING

CONTROL SYSTEMS VERIFICATION

• Control Systems on electric since KIT12e

– KIT12e: Traction Control

– KIT13e & KIT14e: Traction Control and Active Yaw Control

CONTROL SYSTEMS VERIFICATION

• Verification of Control Systems in CarMaker:

– Do the Control Systems work?

– How is the interaction?

– Is there any strange behaviour in certain maneuvers?

– Do the Control Systems work in all disciplines?

CONTROL SYSTEMS VERIFICATION

• Validation and Parameter Tuning on track!

Thank you!