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.
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.
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.
Vehicle dynamics describes the behavior of a vehicle, using dynamic analysis tools. Therefore, to understand vehicle behavior, one must have a sufficient background in dynamics. These dynamics may be linear, as in case of nonextreme behavior, or nonlinear, as in a situation when tires are near saturation (i.e., when the vehicle is about to skid at front or rear tires.). Hence, the tires play a critical role in vehicle handling performance.
The theory of linear system dynamics is well established and many tools related to state space format are available; this includes local stability analysis that refers to the eigenvalues of the linear vehicle system. Therefore, once the handling problem is formulated in (state space) mathematical terms, as follows,
However, a mathematical background in system dynamics alone is not sufficient for solving vehicle dynamics problems. The experience in lecturing on vehicle dynamics shows that there is room for improvement in the mathematical background of the students, with reference to multivariate analysis, Laplace transformation, and differential equations. For this reason, we included a number of necessary commonly used tools in the appendices for further reference. These tools will help the researcher to interpret model output in physical terms. The strength of the simple linear models is the application and therefore, the interpretation to understanding real vehicle behavior. The researcher should answer questions such as:
When vehicle speed is relatively low and/or tires experience loading frequencies beyond 4 Hz (as in case of road disturbances or certain control measures), the steady-state assumption on tire performance (tire belt follows rim motions instantaneously) is no longer valid. A first step to include dynamics is to consider the tire as a first order (relaxation) system. Higher order dynamics require the belt oscillation to be incorporated in the tire model. 781b155fdc