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

• VerfasserIn: Kuslits, Márton,
• Place / Publishing House: Berlin, Germany : : Logos Verlag Berlin GmbH,, 2022.
• Year of Publication: 2022
• Language: English
• Physical Description: 1 online resource (147 pages) :; illustrations

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.

Table of 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.