BMW Driver Assistance Systems & Active Safety Systems

BMW Driver Assistance Systems &Active Safety Systems

Karl-Heinz KustermannEngineering Division (China)

China International Automotive Congress 20082008, Oct. 30th – Nov. 1stShenyang, China

Dr. Heinz Leffler, Dr. Joachim Steinle Vehicle Dynamics Development

Driver Assistance Systems & Active Safety Content

Driver Assistance & Active Safety SystemsK-H KustermannBMW GroupSeite 2

Overview

BMW xDrive

Torque Vectoring: Dynamic Performance Control (DPC)

BMW Active Steering

System Integration: BMW Integrated Chassis Management (ICM)

Predictive Active Safety: Adaptive Brake Assistant

Further Driver Assistant Systems to– improve perception & interaction–facilitate driving tasks–optimal driver information


Driver Assistance SystemsLevel of Safety and Comfort Functions

DPC

DXC

DSCACC

ACC S&G

LDW

PMA

LDW

NiVi

Coll.-Mit.WarningColl.-Mit.

Braking

RFT

Airbags

ACN

Safetybelt-Systems

AFS

Environment: weather, traffic guidance, traffic density

Driver: condition, perception, operation

Vehicle: handling characteristics

Active Safety

(Collision Avoidance)

Passive Safety

(Collision Mitigation)

Vehicle Guidance

active

passive

ComfortSafety

Driver Instruction/-Information/-Warning


Chassis Control and Driver Assistance SystemsEnhancement of Driver and Car

Deceleration

Steer-ability Agility

VehicleStability

VehicleTraction

Acceleration

Physical LimitVehicleEnhancement

Vehicle PotentialDriverEnhancement

VehicleGuidance

Driver Potential

Chassis Design. Vehicle Genes.


Additional importantparameters

- Drivetrain Concept- Engine Characteristic- Axle Kinemtics/Steering

Wheelbase

FZ V FZ H

Axle LoadDistribution

y

x

x Moment of Inertia Jz

Heightof CG

Track

z

y

= Centre of Gravity (CG)

z Cz,hCz,vAerodyn. Lift

- Seat- MMI

- Weight- Unsprung Masses- Body Stiffness

Aerodynamic

Driver Assistance Systems & Active SafetyDriver Assistance & Active Safety SystemsK-H KustermannBMW GroupSeite 6

Overview

BMW xDrive


BMW Active Steering




Stability Control: xDriveInnovative Transfer Gear Box


Quelle: Fa. Robert Bosch

EBMx DXC


Stability Control: xDrivexDrive Drive Train Concept


FL

FS FS

FL

Fmax

10

2

FL0

FS0

FL2

FS2

FL1

FS1FS1

FL1

Forces at the Wheel:Kamm‘s Circle.


Oversteer

Situation Oversteer:Torque Distribution Front-Rear


Understeer

Situation Understeer:Torque Distribution Front-Rear


Handling Course with Low-Friction (Snow track)

-80 -60 -40 -20 0 20 40 60 80 -80 -60 -40 -20 0 20 40 60 80

500

300

100

0

-100

-300

-500

Steering Angle Steering Angle

Permanent 4WDVehicle Stability Control System

not active

xDrive aktiveVehicle Stability Control System

not active

DriftAngle

Grad [°] Grad [°]

Stability Control: xDriveReduced Steering Effort

DriftAngle

xDrive vs. 4WD-DSC:Comparison System Dynamics


xDrive

TorqueFront Axle = 38 %

t = ca. 0,1 s t = ca. 0,5 s

4x4 with Brake Actuation

xDrive

100 %

DSC 4x4 BA

38 %62 %

Torque Front Axle = 100 %


Vehicle Stability Control and All-Wheel Drive:BMW Application Philosophy

Per

form

ance

DSC Actuation Threshold

Lateral Dynamics

DSC

Engine ControlBrake Control

Per

form

ance

DSC ActuationThreshold

xDrive + DSC in 3 Series Coupé

Lateral Dynamics

Engine ControlBrake Control

xDrive Control


Overview

BMW xDrive


BMW Active Steering




Torque Vectoring:BMW Dynamic Performance Control.


Planetary gear(3 planetary gears)

Multi-discbrake

Ball ramp(Two-stage pitch)

Asynchronousmotor

Separation of oilchambers

Breather

BMW Dynamic Performance Control.Layout of Final Drive Unit.


Multi-discbrake

Planetarygear

Torquevectoring

unit“left”

Torquevectoring

unit“right”

Basic gearbox

BMW Dynamic Performance Control.Torque Flow (I).


WITHOUT torque transferMleft = Mright

1000 Nm1000 Nm

2000

BMW Dynamic Performance Control.Torque Flow (II).


WITH torque transferWITH drive torqueMleft < Mright

1400 Nm500 Nm

2000

500 500

1000

100900

BMW Dynamic Performance Control.Torque Flow without Engine Torque.


WITH torque transferWITHOUT drive torqueMleft < Mright

400 Nm500 Nm 500 500

1000

100900

BMW Dynamic Performance Control.Summary Torque Flow.


Planetary gear opens second load path

Force transferindependentof drive torque

Same behaviour as with conventional final driveDriving straight-ahead:Planetary gear circulates “in a block“In a bend:Planetary gear rolls without load

WITHOUT torque transferMleft = Mright

WITH torque transferMleft < Mright

Mleft < Mright

BMW Dynamic Performance Control:Mode of Operation


Benefits:

• improvedresponsiveness

• optimized traction in bends and fromstandstill

• increased yawdamping

• reduced understeer

conventionalrear axle differential

Rear axle differential with torque vectoring

BMW Dynamic Performance Control.Function: Avoiding Understeer.


Dynamic Performance Control xDrive

1

23

4

5

BMW Dynamic Performance Control.Function: Avoiding Understeer.


Requiredsteering angle

Steering precision and stability in bends with BMW Dynamic Performance Control.

Steering precision and stablity in bends withoutBMW Dynamic Performance Control.

Understeering without BMW Dynamic Performance Control.

Stable driving in a bend with turn in yaw moment through BMW Dynamic Performance Control.

BMW Dynamic Performance Control.ISO Lane Change.


x-coordinate [m]60 80 100 120 140 160

Vehicle speed

Veh

icle

spee

d[k

m/h

] 115.2

113.4

111.6

109.8

108.0

106.2

x-coordinate [m]60 80 100 120 140 160

Mean difference in speed of car: 3.3 [km/h]

withwithout

Dynamic Performance Control

Higher speed at entry

Higher average speed

Improvement byBMW DynamicPerformance Control

No counter-steeringin the second lane

Less counter-steeringin the third lane

Lower steering forces

150

100

50

0

-50

-100

-150

Steering angleS

teer

ing

angl

e [°

]

Mean difference in steering angle effort: 20.6 [°]


Overview

BMW xDrive


BMW Active Steering




BMW Active SteeringBasic Construction


Electric Motor

PlanetaryGear

Components of aMechatronic System:

• one or severalelectrical / mechanicalenergy converters,(i. e. electric motorsor generators),

• electronic control unit,

• additional mechanicalequipment, e. g. gears, connecting rods.


Superposition GearingBasic Function

complete form-fitmechanical connectionSteering angle superpositionreal feedback torqueinherent fail-safe

to powersteering

fromsteering wheel

z1

z2

z3

z4

Zworm gear

BMW Active Steering:Variable Steering Ratio


System Function: Variable Steering Ratio

speed [km/h]

stee

ring

ratio

conventional cars

Active Steering

Optimal control at high vehicle speed

Improvedcontrollabilityin dynamicmanoeuvres

Improved comfort in parkingand taxiing

Improved handling and agility at low and medium vehicle speeds

System Function: Vehicle Stabilization

BMW Active Steering:Vehicle Control together with DSC


Less dominant braking activities, improved drivingdynamics

Maximum vehicle stability via combined steering and braking control

Support of the driver for vehiclestabilization

BMW Active Steering.Yaw Rate Control.


Conventional Steering + DSC

Active Steering + DSC

Stabilising Brake Control (DSC)Engine Torque ControlStabilising Steering Control (Active Steering)

BMW Active Steering.Yaw Moment Compensation.


Low µ

High µ

Lane change

w/o steering

control

Wheel Brake ForceVehicle Speed

Yaw MomentStabilising Steering Control


Overview

BMW xDrive


BMW Active Steering




BMW Integrated Chassis Management (ICM)Master Control Unit DSC


DSC

BrakexDrive Electro-MechanicParking Brake Actuator

Active SteeringHigh level controlsoftware of DSC, xDrive, and parkingbrake implementedin DSC ECU, interface to ActiveSteering ECU via CAN bus.

Integrated Chassis Management.New Potentials for Active Safety.


ICMIntegrated Chassis

Management

SupervisionControl Systems

SteeringControl Systems

BrakeControl Systems

AssistanceControl Systems

RideControl Systems


Overview

BMW xDrive


BMW Active Steering




Predictive Active Safety: Adaptive Brake AssistReduction of Stopping Distance


30m

pressure rise

60m

Maximum pedal force

100m

stop

0

100 km/h

potential for reductionof stopping distance

28m

Reaction time

Adaptive Brake Assist.In Case of Inattention …


Hesitating driver recognizes unexpectedobstacle on the street

Reduces stopping distance in case of

Prefill

Prefill and Brake Assist

WithoutAssistance

40m 30m

2m due to prefill time

2m

unexpected braking of leading vehicle orclosing up on slow vehicles

Reduced stopping distance due to maximum deceleration

100km/h

100km/h

100km/h

40m 30m

40m

Collision Warning.In Case of Inattention …


Reduces overall stopping distance using an additional driver warning

Prefill

Prefill and Brake Assist

WithoutAssistance

2m due to prefill time

2mWarning Reaction

40m 30m

40m 30m

40m

40m

Reduced overall stopping distance because of faster reaction due tocollision warning


Overview

BMW xDrive


BMW Active Steering





Comfortable and fast input of e.g.:- destinations into navigation system - telephone calls by number or by name- radio stations or CD-Titlesthrough extremely reliable whole-word voice recognition.

Whole-Word Voice recognition:Keeps the hands on the steering wheeland the eyes on the road


Head-Up Display:Driver has all the important information whilestill paying attention to traffic


60km/h60km/h

Distance control in flowing traffic and when driving dead slow.

0km/h

Aktive Cruise Control with Stop&Go FunctionAutomated speed and distance control in exhausting traffic situations


Intuitive warning:Steering wheel vibrates lightly on unintentional lane deviations.

Lane Departure WarningAlways safe on course


Automatic switching off of headlights in the event of oncoming traffic, vehicle ahead and in lit built-up areas.

High-Beam AssistantUnique feature for automated headlamp dimming


Thermal image camera

Thermal image cameraidentifies persons, animals and objects at the roadside up to a distance of 300 meters.

BMW Night Vision:Highest degree of safety when driving at night

Vision:Enhanced Network/Integration of all Systems


Active Safety

Stability Control

Driver Assistance

to keep the vehiclesafely on track


Active SafetyConclusion

Active Safety is real teamwork:

A precisely designed layout of

chassis components and premium stability control systems plus an array of predictive active safety systems

keep the vehicle safely on track - even in the mostdemanding situations.

BMW Driver Assistance Systems &Active Safety Systems

Karl-Heinz KustermannEngineering Division (China)

China International Automotive Congress 20082008, Oct. 30th – Nov. 1stShenyang, China

Dr. Heinz Leffler, Dr. Joachim Steinle Vehicle Dynamics Development

Thank you for your attention!

BMW Driver Assistance Systems & Active Safety Systems

Documents

Transcript of BMW Driver Assistance Systems & Active Safety Systems