“Design, Modelling, Simulation and Validation of

Candidate: Tommaso Favilli

[email protected]

Relatore: Prof. Marco Pierini

“Design, Modelling, Simulation and Validation of

Advanced Mechatronic Control Systems for Road

Electric Vehicle’s Stability Performances Improvement”

Accademic Year: 2020-2021

PSPPIProgetto e Sviluppo diProdotti e Processi Industriali

Co-Relatori: Prof. Luca Pugi,

Ing. Lorenzo Berzi

02

Index

Introduction

Research Question

Proposed Approach

Developed Solution

Results & Discussion

Firenze, 11 Ottobre 2021

Design, Modelling, Simulation and Validation of Advanced Mechatronic Control Systems

for Road Electric Vehicle’s Stability Performances Improvement

Summary: Challenges and Opportunities

Introduction

Intent of the research: Challenges

• Improve Electric Vehicle’s stability performance

• Ensure flexibility and portability

Proposed solutions: Tools and Means

• Development of advanced control systems through model-based approach

• Optimization of control strategy and multi-DOF allocation problems

Main output: First Order Sliding Mode Controller

• Exploit coordinated steering and active torque distribution techniques

• Verification according to standardized methodologies respect to commercial ESP solution




03

Introduction


04



What is an ESP systems

Driver Tasks▪ Ensure comfort and safety

▪ Maximize the performances

▪ Optimize consumption

Driving Assistance System

Courtesy of Robert Bosch GmbH

Electronic Stability Program

[1] K. Reif, Ed., Automotive Mechatronics: Automotive Networking, Driving Stability Systems, Electronics. Wiesbaden: Springer Fachmedien Wiesbaden, 2015. doi: 10.1007/978-3-658-03975-2.

ESP assets:▪ Directional stability

▪ Handling and manoeuvrability

▪ Integration with safety CU

Introduction


05



What is an ESP systems Differential Allocation

[1] K. Reif, Ed., Automotive Mechatronics: Automotive Networking, Driving Stability Systems, Electronics. Wiesbaden: Springer Fachmedien Wiesbaden, 2015. doi: 10.1007/978-3-658-03975-2.

Oversteering Understeering

𝑀𝑦𝑎𝑤 = 𝑘𝐸𝑆𝑃(𝑟𝑟𝑒𝑓 − 𝑟 − ∆𝐸𝑆𝑃 ሶ𝑟𝑟𝑒𝑓 − ሶ𝑟

𝑀𝑦𝑎𝑤

Introduction


[2]M. Nuessle, R. Rutz, M. Leucht, M. Nonnenmacher, and H. Volk, ‘OBJECTIVE TEST METHODS TO ASSESS ACTIVE SAFETY BENEFITS OF ESP®’, p. 8.[3] H. Baum, S. Grawenhoff, and T. GEIßLER, ‘Cost-Benefit Analysis of the Electronic Stability Program (ESP)’, p. 35.[4] Koisaari, T., Kari, T., Vahlberg, T., Sihvola, N., & Tervo, T. (2019). Crash risk of ESC-fitted passenger cars. Traffic Injury Prevention, 1–7.

06



Why ESP controllers are so important Euro Commission▪ Halve road kills in 10 year

Introduction

Lateral Stability Control

Vehicle Dynamics Knowledge Robust Control System Design

Lateral Stability Controller

Stability


Non-conventionalControl Strategies• By-wires• E-powertrain

07



Open Problem

Research QuestionHow can the EV’s stability

performances be improved?

Open Problem: EV’s Solutions

Feasibility• Economical cost• Technological trend• Required performances

FWD 4WD

Hybrid Battery

H2

Fuel Cell SuperCap

Powertrain layout

Energy Storage System

Control strategies


08



Research Question

State-of-Arts Investigation

Optimization of Electric Powertrain Management

Coordination of By-Wire Systems

Model-Based Simulation Approach

Proposed Approach


09



StabilityFunctional

SafetyEnergy

[14,15,16] [16,17] [17,18,19,20]

[15] Rauh J., Ammon D. - System dynamics of electrified vehicles - Some facts, thoughts, and challenges (2011)[16] Boerboom M. - Electric Vehicle Blended Braking maximizing energy recovery while maintaining vehicle stability and maneuverability (2012)[17] Oleksowicz S. A. - Regenerative braking strategies vehicle safety and stability control systems critical use case proposals (2013)

How can the EV’s stability performances be improved?

Consulted Materials (1:Book, 2:Paper)

Vehicle Dynamics

Stability Controllers

Electric Powertrain

By-wire Systems

281, 552 2052 121, 642 1192

Brake by-Wire

Steer by-Wire

Model-based Design

Proposed Approach

System Design Process

Environment

Physical Systems

Control Algorithms

Code Generation

C++ HDL FPGA

Implementation V-shape Development Model

Advantages:• Continuous Verification and Validation• Graphical description of the system • Less coding effort • Robustness• Code re-use

Disadvantages:• Difference between prototype and series code• Implementation of special functions• Adapting the toolchain to the target hardware

[21] A. Bergmann, ‘Benefits and Drawbacks of Model-based Design’, KMUTNB: IJAST, Sep. 2014,


10



Why use a Model-Based approach?

Standardization

Multi-layer Structure▪ Scalable

▪ Abstract

▪ Parametrized

▪ Modular

▪ Flexible

▪ RT Capable

Proposed Approach

Autonomous Driving

Portability

Model-based

methods and toolsStandardization


11



How can the EV’s stability performances be improved?

Open Problem: EV’s Solutions

SimRod Kyburz 48V ValeoFIAT 500e

Benchmark Vehicle Use Cases

Variable Value

Mass 1320 [kg]

Front Track 1407 [mm]

Rear Track 1397 [mm]

Front Wheelbase 989 [mm]

Rear Wheelbase 1311 [mm]

E-Motor Power 85 [kW]

Battery Cap 64 [kWh]

Variable Value

Mass 848 [kg]






Battery Cap 12 [kWh]

Variable Value

Mass 1094 [kg]






Battery Cap 42,5 [kWh]

Application of the Approach in 2020 Horizon project


12



In-Wheel Motors Architectures

• High power density

[22] R. de Castro, M. Tanelli, R. E. Araújo, and S. M. Savaresi, ‘Minimum-time manoeuvring in electric vehicles with four wheel-individual-motors (2014)

Indipendent Wheel Motor

• Easy and precise control

• Fast bandwidth response

• Active Torque Distribution

• Four quadrant modes


13



Application of the Approach in 2020 Horizon project

Developed Solution

Coordinated Steering and Torque Vectoring Lateral Stability Sliding Mode Control (SMC)

High-Level Module

Control Objective• Target Side-Slip• Target Yaw Rate

From sensors

𝛽𝑡𝑎𝑟

𝑟𝑡𝑎𝑟+_

𝛽𝑟

Intermediate-Level Module

Sliding Control• Des. Steer Angle• Des. Yaw Moment

+_𝑉𝑥

𝛿 𝛿𝑑𝑒𝑠

𝑀𝑦𝑎𝑤

Low-Level Module

Actuators Reference• Steer Angle Cor.• Torque Vectoring

∆𝛿𝑐𝑜𝑟 𝑇𝑞𝑓𝑙 𝑇𝑞𝑓𝑟 𝑇𝑞𝑟𝑙 𝑇𝑞𝑟𝑟

To steerTo wheel

14




[23] Bartolini, G. A Survey of Applications of Second-Order Sliding Mode Control to Mechanical Systems (2003)[24] Goggia, T. Integral Sliding Mode for the Torque-Vectoring Control of Fully Electric Vehicles: Theoretical Design and Experimental Assessment (2015)[25] Tota, A. On the Experimental Analysis of Integral Sliding Modes for Yaw Rate and Sideslip Control of an Electric Vehicle with Multiple Motors (2018)[26] Canale, M. Vehicle Yaw Control via Second-Order Sliding-Mode Technique (2008)

yawM

1) Steer Control2) Active Torque Distribution

15

High-Level Module: Control Objectives Definition

Assumptions:

a) 𝛽 =𝑉𝑦

𝑉𝑥=

ሶ𝑦

𝑉𝑥(small 𝛿 angles)

b) ሷ𝑦 = 𝑉𝑥 ∙𝑑𝛽

𝑑𝑡(Vx constant)

c) 𝐹𝑦 = 𝐶𝛼 ∙ 𝛼(Small slip angle)

d) 𝐶𝛼 constant




State Space Model

𝑥 =𝛽𝑟; 𝑢 =

𝛿𝑀𝑦𝑎𝑤

ሶ𝑥 =−2

𝐶𝛼𝑓+𝐶𝛼𝑟

𝑚𝑉𝑥−1 − 2

𝑎𝐶𝛼𝑓−𝑏𝐶𝛼𝑟

𝑚𝑉𝑥2

2𝑏𝐶𝛼𝑟−𝑎𝐶𝛼𝑓

𝐼𝑧−2

𝑎2𝐶𝛼𝑓+𝑏2𝐶𝛼𝑟

𝐼𝑧𝑉𝑥

∙ 𝑥 +2𝐶𝛼𝑓

𝑚𝑉𝑥0

2𝐶𝛼𝑓

𝐼𝑧

1

𝐼𝑧

∙ 𝑢= 𝐴 ∙ 𝑥 + 𝐵 ∙ 𝑢

Reference State Space Model (ideal trajectory)

ො𝑥 =መ𝛽Ƹ𝑟; 𝑢 =

𝛿𝑀𝑦𝑎𝑤

ሶ𝑥 =ො𝑥𝑡 − ො𝑥𝑡−1

𝑇𝑠=

1

𝑇𝑠

መ𝛽𝑡 − መ𝛽𝑡−1Ƹ𝑟𝑡 − Ƹ𝑟𝑡−1

=

𝐾𝛽

𝑇𝑠0

𝐾𝑟𝑇𝑠

0

∙ 𝑢 −1

𝑇𝑠

መ𝛽𝑡−1Ƹ𝑟𝑡−1

= 𝐵 ∙ 𝑢 + 𝑔

Developed Solution

High-Level Module

Control Objective• Target Side-Slip• Target Yaw Rate

𝛽𝑡𝑎𝑟

𝑟𝑡𝑎𝑟𝑉𝑥

𝛿

Lyapunov Candidate

𝑉 𝑡 =1

2𝑆2 +න𝜂 𝑆 𝑑𝑡

ሶ𝑉 𝑡 = 𝑆 ሶ𝑆 + 𝜂 𝑆 ≤ 0

Error

𝑥 = 𝑥 − ො𝑥 = 𝛽 − መ𝛽𝑟 − Ƹ𝑟

𝑆 = 𝑒 + 𝜆න𝑒𝑑𝑡

16

Lyapunov Stable: ሶ𝑥 = 𝐴 ∙ 𝑥 + 𝐵 − 𝐵 ∙ ො𝑢𝐿 − 𝑔 ≤ 0

ො𝑢𝐿 =መ𝛿

𝑀𝑦𝑎𝑤= 𝐵 − 𝐵

−1∙ 𝑔 − 𝐴 ∙ 𝑥

𝑓𝑒𝑒𝑑−𝑓𝑜𝑟𝑤𝑎𝑟𝑑

−𝑘𝑃 𝑥 − 𝑘𝐼න 𝑥𝑑𝑡 − 𝑘𝑆 ∙ 𝑠𝑖𝑔𝑛(𝑆)

𝑓𝑒𝑒𝑑−𝑏𝑎𝑐𝑘




Developed Solution

Intermediate-Level Module: First Order Sliding Mode Control (SMC)

𝛽𝑡𝑎𝑟

𝑟𝑡𝑎𝑟+_

𝛽𝑟

Intermediate-Level Module

Sliding Control• Des. Steer Angle• Des. Yaw Moment

+_𝛿𝑑𝑒𝑠

𝑀𝑦𝑎𝑤

Original Contribution

𝜆 = 𝑘𝑃; 𝑘𝐼 > 0 𝑘𝑆 ≥ 𝜂 − 𝑘𝐼න𝑒𝑑𝑡 ∙ 𝑠𝑖𝑔𝑛(𝑆)

17[27] Mangia, A. An Integrated Torque-Vectoring Control Framework for Electric Vehicles Featuring Multiple Handling and Energy-Efficiency Modes Selectable by the Driver (2021)

[28] J. Jin, ‘Modified Pseudoinverse Redistribution Methods for Redundant Controls Allocation’, Journal of Guidance, Control, and Dynamics, vol. 28, no. 5, Art. no. 5, Sep. 2005, doi: 10.2514/1.14992.




Developed Solution

Low-Level Module: Yaw Moment Allocation Problem

Multi-DOF Solutions

Lateral Stability

Driver Intentions

Optimal Trade-offOver-actuated System

In-Wheel Motor Driven

∞4 Combinations Constrains∞2 Combinations

Moore-Penrose pseudo-inverse

Original Contribution

18

1) Yaw Moment: Moore-Penrose torque vectoring

2) Steer Control∆𝛿𝑐𝑜𝑟≤ %𝛿𝑚𝑎𝑥

𝑡 ∙ ∆𝑇𝑞 =−

𝑡𝑓

2𝑅𝑤

𝑡𝑓

2𝑅𝑤

1 1

−𝑡𝑟

2𝑅𝑤

𝑡𝑟

2𝑅𝑤

1 1∙ ∆𝑇𝑞 =

𝑀𝑦𝑎𝑤

0

∆𝑇𝑞 = 𝑇𝑞𝑖𝑗 − 𝑇𝑞𝑖𝑗∗ = 𝑡+ ∙

𝑀𝑦𝑎𝑤

0

𝐽∆𝑇𝑞 2= 𝑇𝑞𝑖𝑗 − 𝑇𝑞𝑖𝑗

∗ 2




Developed Solution

Low-Level Module: Control Effort Allocation

𝛿𝑑𝑒𝑠

𝑀𝑦𝑎𝑤

Low-Level Module

Actuators Reference• Steer Angle Cor.• Torque Vectoring

∆𝛿𝑐𝑜𝑟 𝑇𝑞𝑓𝑙 𝑇𝑞𝑓𝑟 𝑇𝑞𝑟𝑙 𝑇𝑞𝑟𝑟

To steerTo wheel

𝛿

19


Simulation Activities: Performed Tests




• Open-loop Testsobjectively determine steady-state and transient-state vehicle response

• Closed-loop Testssubjectively assess the performances of the lateral stability controller

Driver

Vehicle

Environment

• ESP-Controlled Vehicle

• Non-Controlled Vehicle

20




Preliminary implementation: Model Overview


14-DOF Vehicle Model:• Driver Model• Stability Control Units• Proposed ESP• Actuators Models• Vehicle Body: 6DOF• Vehicle Wheel: 2DOF each

FIAT 500e

21




Preliminary implementation: Simulation Results


Ste

ady-s

tate

circula

r drivin

g T

est

Double

Lane C

hange T

est

Target

45 km/h

80 km/h

45 km/h

22




Preliminary implementation: Simulation Results


No Control Torque Vectoring + Steering Control

+

23




Hardware-in-the-Loop Implementation


ESP Comparative Investigation:

• Sliding Mode Controller SMC (Favilli)

• Linear Quadratic LQR (Montani)

• Commercial Solution (OEM)

RT Simulator

EPSiL Steering Bench

Brake Unit

Human Interface Devices

Fixed step: 1kHz

24




Hardware-in-the-Loop Implementation: Test Conditions


Off-line Test Campaign On-line Test Campaign

Aims:

▪ Tuning of the controller's gain

▪ Identification of tires cornering stiffness

Aims:

▪ Assessment of vehicle stability behaviour

▪ Evaluation of impact on driver perception

Name Standard Purpose

Ramp Steer FVMSS No.126 Calibration

Step Steer ISO 7401:2003 Calibration & Validation

Sine Steer ISO 7401:2003 Validation

Lane-Change ISO 3888:2018 Validation

[25] Hal, M. Is Vehicle Characterization in Accordance With Standard Test Procedures751a Necessary Prerequisite for Validating Computer Models of a Test Vehicle?

25




Hardware-in-the-Loop Implementation: On-line Test Campaign


Step Steer Test Conditions• Vehicle Speed: 150 km/h• Steer Wheel Angle: 90deg

26






Sine Steer Test Conditions• Vehicle Speed: 150 km/h• Steer Wheel Angle: 90deg

Lane-Change Test Conditions• Vehicle Speed: 150 km/h• Lat Displacement: 3m

27






Commercial ESPNo ESP Proposed ESP

28




Modularity of the Low-Level Module

80 km/h 270 deg


Friction ESC Max Vx [km/h] RMSE

1ON 50 0.52

OFF 40 0.78

0.7ON 40 0.40

OFF 30 0.53

0.5ON 30 0.11

OFF 30 0.28

50 km/h

29




Scalability of the Low-Level Module

∆𝛿𝑚𝑎𝑥= 𝑚𝑖𝑛 𝑚𝑎𝑥𝑇𝑖𝑦(𝑚𝑎𝑥) − 𝑇𝑖𝑦

∗

ℎ𝑖𝑦, 0

80 km/h

LateralStability

Min Engaged Adhesion


30





Next Step

➢Improved lateral stability performances of Sliding Mode ESP

➢Optimal trade-off between vehicle stabilization and driver intention

➢Ensured portability properties of the controller

➢Last calibration and validation for the Fiat 500e UC

➢Thesis writing

Conclusions

Candidate: Tommaso Favilli

[email protected]

Relatore: Prof. Marco Pierini

Co-Relatori: Prof. Luca Pugi,

Ing. Lorenzo Berzi

Accademic Year: 2020-2021

PSPPIProgetto e Sviluppo diProdotti e Processi Industriali

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“Design, Modelling, Simulation and Validation of

Advanced Mechatronic Control Systems for Road

Electric Vehicle’s Stability Performances Improvement”

32

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