Advanced Stability Control of Electric Vehicle with In-wheel Motor ...

Advanced Stability Control of Electric Vehicle with Advanced Stability Control of Electric Vehicle with InIn--wheel Motor and Active Steering Systemwheel Motor and Active Steering SystemInIn wheel Motor and Active Steering Systemwheel Motor and Active Steering SystemHiroshi Fujimoto (([email protected]@k.u--tokyo.ac.jptokyo.ac.jp))

The University of Tokyo

Slide 1H.FujimotoH.Fujimoto ((Univ.TokyoUniv.Tokyo))http://hflab.k.u-tokyo.ac.jp/

Hori/Fujimoto Lab.

Dept. Advanced Energy Dept. Electrical Eng.Frontier Sciences (Kashiwa) Grad. School of Eng. (Hongo)

Research Field: Control Engineering, Motion Control, Electric Vehicle, Research Field: Control Engineering, Motion Control, Electric Vehicle, Wireless Power Transfer, Wireless Power Transfer, NanoNano--scale Servo, Power Electronics, Robotics, scale Servo, Power Electronics, Robotics,

Lab Members: 8 staffs (P, AP, Assistant P, 2 PDs, Engineer, 2 secretaries) 33 students (9 Ph.D, 19 M.S., 4 B.S., 1 R.S. , including 13 international students)students)

EV Garage (250EV Garage (250㎡㎡) )

ff ㎡㎡EV test field (2600EV test field (2600㎡㎡))

Slide 2H.FujimotoH.Fujimoto ((Univ.TokyoUniv.Tokyo))

Kashiwa New Campus Kashiwa New Campus (40 min from center of Tokyo)(40 min from center of Tokyo)

Motion Control of EVs over ICVs[Y.Hori, TIE ‘04]

Advantages of motors →High Control Perf.f

■ Quick torque response Ｎi

f

Torque of Motors （1ms）

>> Torque of Engines (500ms)Ｓ

iB

>> Torque of Engines (500ms)

→ Anti-slip Controlp

■Measurable torque

→ Estimate of Road Cond.

■I di id l h l t l b IWMSlide 3

H.FujimotoH.Fujimoto ((Univ.TokyoUniv.Tokyo))

■Individual wheel control by IWMs

→ Vehicle Stability Control in 2D

ContentsContents

1.1. IntroductionIntroduction

l d l f ll d l f l2.2. Development and Control of Original EV FPEV2Development and Control of Original EV FPEV2--KanonKanon

3.3. Vehicle Stability Control with Wheel Side Force SensorVehicle Stability Control with Wheel Side Force Sensor

4.4. Range Extension Control SystemRange Extension Control System

55 ConclusionConclusion5.5. ConclusionConclusion


In-wheel motorsOuter rotor type

Big torque generation

F t R

Direct drive systemNo Transmission Loss of GearHi h Effi i d S ll N i Front Rear

Maker Toyo Denki Seizo K.K., Ltd

Motor type Outer rotor type

High Efficiency and Small NoiseQuick responseEstimation by reaction force

Motor type Outer rotor type

Direct drive system

Rated torque 110[Nm] 137[Nm][ ] [ ]Max torque 500[Nm] 340[Nm]Rated power 6.0[kW] 4.3[kW]Max power 20.0[kW] 10.7[kW]Max speed 1113[rpm] 1500[rpm]


Motor mass 32[kg] 26[kg]Cooling Natural air cooling

FPEVFPEV--2(Kanon)2(Kanon)Future Personal Electric Vehicle

FPEVFPEV 2(Kanon)2(Kanon)

Inverter andChopper Li-ion BatteryChopper

ECU

Li ion Battery

ECU

Steer-by-wire and

DD in-wheel motors4WS (Front and Rear Steering Control by

Motors)Slide 6


Motors)Side force sensors

Active Front/Rear Active Front/Rear Stee ing S stemStee ing S stem

• 2 DC Motors (Maxon 250W) for Steering

Steering SystemSteering System •Front steering shaft is removable.→Steer-by-wire


Development of Original EVDevelopment of Original EV


Principle of Driving Force EstimationPrinciple of Driving Force Estimation

mMotion Equation of WheelMotion Equation of Wheel

r

m

dRadius of wheelRadius of wheel

TJdrFTJ

dtd

dtInertia of wheelInertia of wheel

FFdd :Drive.Force:Drive.Force

Angular AccelAngular Accel

Motor torqueMotor torque

→→Measured byMeasured byInertia of wheelInertia of wheel

→→Constant Constant

Angular Accel.Angular Accel.

→→Measured byMeasured by

SensorsSensors

CurrentCurrent

Driving Force FDriving Force Fdd can be estimated by this equation. can be estimated by this equation. I t it i l l t d lti ith 0 1I t it i l l t d lti ith 0 1


In our system, it is calculated realtime with 0.1ms In our system, it is calculated realtime with 0.1ms sampling. sampling.

AntiAnti--slip Control slip Control

+ Wheel Speed

Dynamics of EV

+Accel. Signal Wheel SpeedTorque Command-

Swithc

Inverse Dynamics on Grip+-gain

Slip TorqueToque on adhesionw.r.t wheel speed

ControllerController

Slide 10H.FujimotoH.Fujimoto ((Univ.TokyoUniv.Tokyo))Without controlWithout control With controlWith control

Direct Yaw Control (DYC)Direct Yaw Control (DYC)


Yaw rate

DYC resultsDYC results

Without controlWithout controlWithout controlWithout control

Wi hWi h ll

Counter steering

With With controlcontrol

g


With controlWith controlWithout controlWithout control

SlipSlip--ratio Control with Regenerative Brakingratio Control with Regenerative Braking

Mechanical Braking Only Mechanical Braking Only Electric and Mechanical BrakingElectric and Mechanical Braking


Collaboration with Mitsubishi MotorsCollaboration with Mitsubishi Motors


ContentsContents




i.i. Lateral Force SensorLateral Force Sensor

iiii YawYaw rate Control by IWMs and Active Front/Rearrate Control by IWMs and Active Front/Rearii.ii. YawYaw--rate Control by IWMs and Active Front/Rear rate Control by IWMs and Active Front/Rear SteeringSteering

44 R E i C l SR E i C l S4.4. Range Extension Control SystemRange Extension Control System

5.5. ConclusionConclusion


Research and Development of Yaw ControlResearch and Development of Yaw Control

ESC:Electronic Stability ControlS bili h hi l i b lli b 4 h l b kSystem to stabilize the vehicle motion by controlling yaw-rate by 4 wheel brakeindependently. One of the active safety technologies. ESCs have already been implemented in many commercialize cars.

A study of dynamics performance improvement by rear right and left

implemented in many commercialize cars.

independent drive system [Sugano (Mazda)]Friction circle estimation and integrated control of 4 wheels independent dive

and 4WS [Ono (Toyota CRL)]El t i C t l T S lit 4WDElectric Control Torque Split 4WD [Nissan]Development of 4 wheel driving force control system [Mori (Honda)]Integrated Vehicle Motion Control System“S-AWC” [Miura (Mitsubishi Motors)]Motion Control of Electric Vehicle ith Tire Workload [I (B id t )]Motion Control of Electric Vehicle with Tire Workload [Iwano (Bridgestone)]Effects of Model Response on Model Following Type of Combined Lateral Force

and Yaw Moment Control Performance for Active Vehicle Handling Safety[O.Mokhiamar (Kanagawa U)]


[O o a a ( a aga a U)]Mini-max Optimal Distribution of Lateral and Driving/Braking Forces

[Nishihara (Kyoto Univ)]

Wheel Lateral Force SensorWheel Lateral Force Sensor Slip Angle

• Lateral force detection by sensors in Hub-unit• Possible to measure lateral force under suspension• Possible to measure lateral force under suspension

Velocity

Lateral Force

Normallyunknown

– Expected Big Contribution to Active Safety– Intelligent wheels by these sensors and in-wheel

motors (and steer-by-wire)motors (and steer-by-wire)

• Recent development in Japan– NSK : Sensing by wheel speed sensor and encorders


– NTN : Sensing by strain gauge– J-Tekt

ContentsContents




i.i. Lateral Force SensorLateral Force Sensor

iiii YawYaw rate Control by IWMs and Active Front/Rearrate Control by IWMs and Active Front/Rearii.ii. YawYaw--rate Control by IWMs and Active Front/Rear rate Control by IWMs and Active Front/Rear SteeringSteering

44 R E i C l SR E i C l S4.4. Range Extension Control SystemRange Extension Control System

5.5. ConclusionConclusion


��

Equation of Motion for 4 wheels independent drive/steering

・Longitudinal Motion �� Æ� Æ��

��

・Lateral Motion

�Æ Æ

��

��

�

��

・Yawing Motion

��

Æ� Æ��

��

��

)1( f Yawing Motion

��

(Driving/Braking Force Diff.)

)1,( rf

(Moment by Lateral Force)

Active steering or 4 wheel ・Sum of squares workload minimization (Abe03)


independent vehicles have redundancy in control input.

minimization (Abe03)

・Minimax (Nishihara06)

・Workload equalization (Ono07)

Load change in decelerating turning

Force saturationDecrease of yaw-moment caused by saturation destabilizes vehicle Force saturation

on rear lefty

motion.


Yaw-control of front/rear independent steering and rear IWMs

�

[Ando, Fujimoto, AMC10][Ando, Fujimoto, AMC10]

�� Æ� Æ�

��

��

��

A x

FF 22 ��

Æ� Æ��

��

�

��

z

yx

FFF

η 22

Workload

��

� Æ�

��

��

��

FF Tyijxij 22

Objective function: sum of squares of workload

�

Friction circleFriction circle

��

Æ

WxxF

J T

rljrfi zij

yijxij ,,,

2

O i l di ib i

��

Optimal distribution


Example of force Example of force saturationsaturation

Conventional （YMO）: torque diff. only Optimal method: torque diff. and front/rear steering/ g

Test by decelerating turning

Accelerates to 30km/h →step-type steering ( =0.06rad)fp yp g ( )

Decelerating turning with braking force -800N

C d i l t t t i diSlide 22


Command signals: constant turning radiusfyf l

ValV

2

*,*

Movie of ExperimentspTorque diff and active F/R steerTorque difference only


Red： Force Vector Locus，Blue: wheel load，Blue dashed： Amplitude of force

Control input in experimentsControl input in experiments

Torque diff and active F/R steerTorque difference only

SteeringSteering

TorqueCommand


Experimental results (yawExperimental results (yaw--rate, workload)rate, workload)

Torque diff and active F/R steerTorque difference only

Yawraterate

E li tiEqualizationof each wheelworkload

Workload


ContentsContents




4.4. Range Extension Control SystemRange Extension Control System

55 ConclusionConclusion5.5. ConclusionConclusion


Critical Problem of EVs

Critical issues for EVsCritical issues for EVs Mileage per chargeMileage per chargeCritical issues for EVsCritical issues for EVs Mileage per chargeMileage per charge

Comparison of ICV and electric vehicleComparison of ICV and electric vehicle

mileagemileage capacitycapacity cruising ragecruising rageGasoline vehicleGasoline vehicle ((ii) 21 km/L) 21 km/L （（gasoline 35Lgasoline 35L）） 735km735km

Electric vehicleElectric vehicle（（ii--MiEVMiEV））88 km/kWhkm/kWh （（battery capacity 16 kWhbattery capacity 16 kWh）） 130km130km

[M. [M. KamachiKamachi, AVEC08], AVEC08]

EV’s cruising range is shorter than ICV’s range.EV’s cruising range is shorter than ICV’s range.

・・High efficiency motorHigh efficiency motor・・Novel driving method by two reduction gearNovel driving method by two reduction gear

In order to solve this problemIn order to solve this problem･･････

[K. Sakai, JIASC09][K. Sakai, JIASC09][A Sorniotti AVEC10][A Sorniotti AVEC10]


・・Novel driving method by two reduction gearNovel driving method by two reduction gear [A. Sorniotti, AVEC10][A. Sorniotti, AVEC10]

Range Extension Control System: RECSRange Extension Control System: RECSTry to enhance the cruising range of EV’s by control technologiesTry to enhance the cruising range of EV’s by control technologies

(Assumption: EV has multiple motors)(Assumption: EV has multiple motors)

3 3 types of RECS types of RECS developeddeveloped••RECS I: Optimal torque RECS I: Optimal torque distributiondistribution••RECS II: Minimization the corneringRECS II: Minimization the cornering resistanceresistance

[Fujimoto, [Fujimoto, SumiyaSumiya IECON2011]IECON2011]••RECS II: Minimization the cornering RECS II: Minimization the cornering resistanceresistance••RECS III: Minimization motor output RECS III: Minimization motor output [[EgamiEgami, Fujimoto, IECON2011], Fujimoto, IECON2011]••Total optimization (RECS I + III) [Fujimoto, Total optimization (RECS I + III) [Fujimoto, EgamiEgami, IECON2012], IECON2012]p ( ) [ j ,p ( ) [ j , gg , ], ]

B ttB tt

RECS III RECS III

BatteryBattery(+ (+

Chopper)Chopper)Inv. Inv. 11 MM11

…… ……V hi lV hi l

V

Inv. Inv. 44 MM44…… ……

VehicleVehicle

Slide 28


44 44 RECS IRECS I RECS IIRECS II

RECS I: Optimal torque distributionRECS I: Optimal torque distribution

Assumption: Front and rear independent motors Straight roadAssumption: Front and rear independent motors Straight roadAssumption: Front and rear independent motors. Straight roadAssumption: Front and rear independent motors. Straight roadThe sum of the torque only needs to The sum of the torque only needs to

satisfy the driver demands.satisfy the driver demands.

Torque distribution Torque distribution

Same accelerationSame acceleration

Front Front RearRear


29Efficiency map of motor + inverterEfficiency map of motor + inverter

Optimize overall efficiency by Optimize overall efficiency by distibutiondistibution

Experiment of RECS IExperiment of RECS IExperimental conditionsExperimental conditions

••Speed command:Speed command:••Total torque command:Total torque command:E l i hE l i h h i dh i d••Evaluation on the Evaluation on the chassis dynamometer chassis dynamometer

opt

Extended mileageExtended mileage

••1 kWh1 kWh 500 m500 m••1 kWh 1 kWh 500 m500 m••16kWh 16kWh 8 km8 km


30

Collaboration with Mitsubishi Motors Front MotorFront MotorFront MotorFront Motor

Rear MotorRear Motor

Prototype PHEV with 2 onPrototype PHEV with 2 on--board motorsboard motors・・2 motors has different efficiency map.2 motors has different efficiency map.・・2 differential gears for F/R wheels2 differential gears for F/R wheels

Proposed method Proposed method 1.0[kW]1.0[kW] reductionreduction

・・2 differential gears for F/R wheels2 differential gears for F/R wheels

・・Engine is stopped. Engine is stopped. Evaluate as Battery EVEvaluate as Battery EV

EV cruising range extensionEV cruising range extensionEV cruising range extensionEV cruising range extensionCruising distance [km/kWh]Cruising distance [km/kWh] (at 50km/h constant speed)(at 50km/h constant speed)


1.52km extend per 1kWh1.52km extend per 1kWh24.2km extend per 16kWh 24.2km extend per 16kWh

RECSII: Cornering resistance minimizationRECS on curving road by left and right independent motorsRECS on curving road by left and right independent motors

c p

Mi i i f t t i lMi i i f t t i l bb N

c

Cornering resistanceCornering resistance

Minimize front steering angleMinimize front steering angle by by zN

Cornering resistanceCornering resistanceis reducedis reduced

<Conventional><Conventional> <Proposed><Proposed>

Cornering resistanceCornering resistanceMileage per charge is extended!Mileage per charge is extended!

pc

Cornering resistanceCornering resistance

Driving forceDriving force


: yaw: yaw--moment generated by driving force moment generated by driving force difference between left and right motorsdifference between left and right motors

zN

Cruse distance (km/kWh)Cruse distance (km/kWh)( / )( / )

<Conventional><Conventional> <Proposed><Proposed>


33

••V=15 [km/h]V=15 [km/h]，，R=8 [m]R=8 [m]Input power of Input power of inveterinveter Front Steering AngleFront Steering Angle

Control Technologies of EV Developed in Control Technologies of EV Developed in Hori/Fujimoto Hori/Fujimoto Lab.Lab.

Advanced Safty

•Slip-ratio control•Yaw-rage controlYaw rage control•Slip-angle control•…..

Driving Comfort

Pit hi t l

Range ExtensionControl System

•Pitching control•Roll control •Optimal Distribution

•Minimize Resistance


Minimize Resistance

ConclusionConclusion

1.1. SmallSmall--scale EV “FPEV2scale EV “FPEV2--Kanon” are designed and developed Kanon” are designed and developed with active front/rear steering and direct drive inwith active front/rear steering and direct drive in--wheel wheel motors.motors.

2.2. Control theories developed with FPEV2Control theories developed with FPEV2--Kanon was applied to Kanon was applied to the prototype EVs ofthe prototype EVs of industiresindustires..the prototype EVs of the prototype EVs of industiresindustires..

3.3. Developed technologies are available not only Battery EVs Developed technologies are available not only Battery EVs but also (Plugbut also (Plug--in) hybrid vehicles and FCEVs.in) hybrid vehicles and FCEVs.


New Developing EV (FPEV4 Sawyer) New Developing EV (FPEV4 Sawyer) Main UnitMain Unit

LiLi--ionion BatteryBattery

L/R Individual OnL/R Individual On--board Motorboard Motor(N of Turns:(N of Turns: 42T/21T)42T/21T)

InIn--wheel Motorwheel Motor(N of Turns:(N of Turns: 12T/8T)12T/8T)

SubSub--unitunit(N of Turns: (N of Turns: 42T/21T)42T/21T) (N of Turns: (N of Turns: 12T/8T)12T/8T)

Left/Right Individual OnLeft/Right Individual On--OnOn--board motor / board motor / InIn--wheel motorswheel motorsNonNon--driven Unitdriven Unit

Drive Unit in SubDrive Unit in Sub--unit which is installed both rear and frontunit which is installed both rear and front>M fi ti i d ith f i i>M fi ti i d ith f i i

board Motorboard MotorDifferential Gear Differential Gear

=>Many configurations are examined with fair comparison=>Many configurations are examined with fair comparisonProvide common test platform (e.g. OnProvide common test platform (e.g. On--board motor + board motor + Drive shaft vibration Drive shaft vibration supressionsupression control = IWM?)control = IWM?)Active Front and Rear Steering, Steer by wireActive Front and Rear Steering, Steer by wire


36g, yg, y

Suspension geometry is tunableSuspension geometry is tunableLateral force sensorsLateral force sensors Test driveTest drive＠＠EV test field in KashiwaEV test field in Kashiwa

Advanced Stability Control of Electric Vehicle with In-wheel Motor ...

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