Essentials of Vehicle Dynamics

Book Preface

Teaching vehicle dynamics and control for the last 25 years, I have often struggled with the challenge of how to give students a proper understanding of the vehicle as a dynamic system. Many times, students new to the field do not currently have sufficient practice in design and experimental performance assessment, which are required for them to progress in skills and knowledge.

Fortunately, most students in automotive engineering have a minimal (and sometimes much higher) level of practical experience working on vehicles. This practical experience is usually a motivator to choose automotive engineering. However, that experience is not always matched with a sufficient level of practical knowledge of mathematics and dynamics, which is essential in vehicle dynamics and control. Lately, I have seen more and more students with a background in control or electronics who choose to specialize in automotive engineering. This should be strongly supported because future advanced vehicle chassis design requires a multidisciplinary approach and needs engineers who are able to cross borders between these disciplines.

However, these students can often be focused on a small element of the vehicle and lack a complete overview of the entire vehicle system. An overall understanding is important because this system is more complex than a linear system, which can be given any response with appropriate controllers. The tireroad contact and the interface between the vehicle and the driver especially should not be disregarded. At the end of a study, it is always asked whether the vehicle performance has been improved with respect to safety and handling, with or without the driver in the loop. Because drivers do not always respond in the way engineers expect, engineers must always be aware of the overall drivervehicle performance assessment.

I wrote this book with the objective to address vehicle dynamics within a solid mathematical environment and to focus on the essentials in a qualitative way. Based on my experience, I strongly believe that a qualitative understanding of vehicle handling performance, with or without the driver, is the essential starting point in any research and development on chassis design, intelligent chassis management, and advanced driver support. The only way to develop this understanding is to use the appropriate mathematical tools to study dynamical systems. These systems may be highly nonlinear where the tireroad contact plays an important role. Nonlinear dynamical systems require different analysis tools than linear systems, and these tools are discussed in this book.

This book will help the reader become familiar with the essentials of vehicle dynamics, beginning with simple terms and concepts and moving to situations with greater complexity. Indeed, there may be situations that
require a certain model complexity; however, by always beginning a sequence with minimal complexity and gradually increasing it, the engineer is able to explain results in physical and vehicle dynamics terms. A simple approach always improves understanding and an improved understanding makes the project simpler.

My best students always tell me, after completing their thesis project, that with their present knowledge, they could have solved their project must quicker and in a simpler way if they repeated it. This improved understanding they gained is one of the objectives of teaching.

Starting from scratch with too much complexity leads to errors in models and therefore, improper conclusions as a result of virtual prototyping (e.g., using a model approach, and more and more common in the design process). To help reader to evaluate their learning, a separate chapter of exercises is included. Many of these exercises are specially focused on the qualitative aspects of vehicle dynamics. Further, they encourage readers to justify their answers to verify their understanding.

The book is targeted toward vehicle, mechanical, and electrical engineers and engineering students who want to improve their understanding of vehicle dynamics. The content of this book can be taught within a semester. I welcome, and will be grateful for, any reports of errors (typographical and other) from my readers and thank my students who have pointed out such errors thus far. I specifically acknowledge my colleague Saskia Monsma for her critical review in this respect.

Joop Pauwelussen Elst, The Netherlands May 2014