Analysis and Optimisation of a New Differential Steering Concept / Márton Kuslits.

Format:

Book

Author/Creator:

Kuslits, Márton, author.

Language:

English

Subjects (All):

Electric vehicles.

Steering-gear.

Physical Description:

1 online resource (147 pages) : illustrations

Place of Publication:

Berlin, Germany : Logos Verlag Berlin GmbH, 2022.

Summary:

The emergence of electric drives opens up new opportunities in vehicle design. For example, powerful in-wheel motors pro -vide unprecedented flexibility in chassis design and are suitable for distributed drive solutions, although implying non-trivial vehicle dynamics control problems. This work aims at a new differential steering concept relying only on passive steering linkages where the necessary steering moment about the kingpins is generated by traction force differences produced by in-wheel motors. For the analysis of the proposed steering concept, a tailored multi-body system model is introduced along with the associated steering control system. In addition, this work explores the general applicability of such a new steering concept by using multi-objective optimisation. For this purpose, various design objectives and constraints are defined with respect to the dynamic, steady-state and low-speed steering performance of the vehicle. The resulting behaviour of the proposed steering concept is investigated by various simulation experiments demonstrating a comparable steering performance to that of conventional passenger cars.

Contents:

List of Symbols and Acronyms IX

1 Introduction 1

1.1 State of the Art in Differential Steering 3

1.2 Motivation and Outline of the Thesis 6

2 Vehicle Model with Differential Steering 9

2.1 Model Definition and Kinematics 10

2.2 Nonlinear Equations of Motion 15

2.3 Tyre Models 18

2.3.1 Modelling Considerations and Tyre Model Selection 18

2.3.2 The Magic Formula Tyre Model 19

2.3.3 Bore Torque Modelling 24

2.3.4 Load Distribution and Load Transfer 27

3 Symbolic Linearisation of Equations of Motion 29

3.1 Symbolic Taylor Expansion 30

3.2 State Reduction 34

3.3 Representation in the Frequency Domain 35

3.4 Application to the Vehicle Model 36

3.4.1 Symbolic Manipulations on the Vehicle Model 36

3.4.2 Validation of the Linearised Model 42

4 Control of the Differential Steering System 45

4.1 Full State Feedback Lateral Control for High-Speed Operation 45

4.1.1 Closed-Loop System 46

4.1.2 Feedback Gain Calculation Using the LQ-Principle 47

4.1.3 Feedforward Gain Calculation 48

4.1.4 Reference Model 49

4.1.5 Gain Scheduling Extension 50

4.2 Angle Tracking Controller for Low-Speed Operation 50

4.2.1 PI Control Rule 51

4.2.2 Control Design with Root Locus Method 51

5 Simulations and Steering Characterisation 55

5.1 Simulation Framework 55

5.2 Simulation Studies 56

5.2.1 Step Steer Simulation 56

5.2.2 Steady-State Cornering 59

5.2.3 Double Lane Change 61

5.2.4 Low-Speed Manoeuvring 62

5.3 Steering Performance Characterisation 63

5.3.1 Dynamic Performance in the Time Domain 64

5.3.2 Tracking Performance in the Frequency Domain 65

5.3.3 Steady-State Cornering Performance 68

5.3.4 Low-Speed Manoeuvring Performance 69

6 Multi-Objective Steering Performance Optimisation 71

6.1 Design Parametrisation 72

6.2 Sensitivity Studies 73

6.2.1 Preselection of Control Parameter τd 73

6.2.2 Identification of the Most Influential Parameters 74

6.3 Optimisation Strategy 79

6.3.1 Formulation of the Optimisation Problem 79

6.3.2 Optimisation Assistance by Response Surfaces 80

6.3.3 Optimisation Procedure 82

6.4 Discussion of Optimisation Results 86

7 Disturbance Rejection of the Differential Steering System 91

7.1 Wheel-Curb Collision Model 92

7.2 Simulation Framework for Collision Investigations 96

7.3 Collision Simulations 98

8 Conclusions and Outlook 101

Appendix: Detailed Results of Model Derivation 103

A.1 Kinematics 103

A.2 Equations of Motion 108

A.3 Constraints 115

List of Figures 117

List of Tables 121

References 123.

Notes:

CC BY-NC-ND

Description based on publisher supplied metadata and other sources.

ISBN:

3-8325-5578-1