Fundamentals of Vehicle Dynamics and Modelling

A Textbook for Engineers With Illustrations and Examples

Bruce P. Minaker

• Publisher: Wiley
• Year: 2019
• ISBN:
  9781118980088
• Edition: 1
• Topic: Tecnologia e ingegneria
• Subtopic: Ingegneria meccanica

An introduction to vehicle dynamics and the fundamentals of mathematical modeling

Fundamentals of Vehicle Dynamics and Modeling is a student-focused textbook providing an introduction to vehicle dynamics, and covers the fundamentals of vehicle model development. It illustrates the process for construction of a mathematical model through the application of the equations of motion. The text describes techniques for solution of the model, and demonstrates how to conduct an analysis and interpret the results. A significant portion of the book is devoted to the classical linear dynamic models, and provides a foundation for understanding and predicting vehicle behaviour as a consequence of the design parameters.

Modeling the pneumatic tire is also covered, along with methods for solving the suspension kinematics problem, and prediction of acceleration and braking performance. The book introduces the concept of multibody dynamics as applied to vehicles and provides insight into how large and high fidelity models can be constructed. It includes the development of a method suitable for computer implementation, which can automatically generate and solve the linear equations of motion for large complex models.

Key features:

? Accompanied by a website hosting MATLAB® code.

? Supported by the Global Education Delivery channels.

Fundamentals of Vehicle Dynamics and Modeling is an ideal textbook for senior undergraduate and graduate courses on vehicle dynamics.

1
Introduction

The subject of vehicle dynamics is very broad, but it can be loosely defined as an analysis of the motion of passenger vehicles, with an intent to characterize the various behaviours, and understand their causes. In this text, the focus will be on four‐wheeled road vehicles, but the topic is often expanded to include the study of multi‐axle trucks and trailers, bicycles and motorcycles, rail vehicles, and even boats and aircraft, as many of the principles used are the same. If the focus is restricted to road vehicles, the topic can be broken into sections:

• Tires The development of mathematical models to predict tire forces, often based on empirical or semi‐empirical techniques, i.e., not derived from first principles, but rather measurements of tire properties and data from experiments
• Longitudinal dynamics Acceleration and braking capability, coupling between engine and vehicle through the drivetrain, and weight transfer effects on tire traction
• Ride quality A study of vertical dynamics and the ability of the vehicle's suspension to accommodate varying terrain while maintaining passenger comfort
• Handling The behaviour of the vehicle with respect to its motion in the plane of the road, particularly its directional stability and its response to steering inputs
• Suspension kinematics The geometry of the suspension and steering components, and its effects on vehicle motion; sometimes expanded to include elastokinematics, the small changes in the geometry due to deflection under load

This text will attempt to introduce the reader to each of these topics, but they are organized slightly differently than in the list above. Chapter 2 will introduce the topic of tire behaviour, and Chapter 3 will cover longitudinal dynamics. Chapter 4 will discuss both ride quality and handling, and focus on the application of linear dynamic modelling to these problems. Chapter 5 expands the models to cover the full vehicle, and discusses the effects of suspension geometry, and the solution of the suspension kinematics problem. Chapter 6 focuses on the application of multibody dynamics to vehicle problems, and how the previously developed models can be expanded using computer based techniques. Finally, Chapter 7 is an overview of the mathematics that is required for the many analyses in the text. The current chapter provides a brief list of some of the notable contributors to the field, and a general overview of the topic of vehicle dynamics as a whole.

1.1 Past, Present, and Future

The study of vehicle dynamics has developed along essentially the same timeline as the automobile itself, with the first papers on the subject appearing in the early 1900s, and significant contributions beginning around the 1930s. There have been a number of significant researchers in vehicle dynamics. Without a doubt, the author's work has been influenced by these pioneers, and any similarity in notation or technique is no coincidence. A few of them, along with a brief description of their work, are mentioned below.

• Maurice Olley An outstanding engineer, his numerous accomplishments during his work for Rolls‐Royce, General Motors and others are detailed in the book Chassis Design: Principles and Analysis Based on Maurice Olley's Technical Notes [11]. The results of his experiments in ride quality are still cited as the Olley ‘Flat Ride’ guidelines. Credited with the introduction of independent suspension in American cars, he was twice awarded the Crompton Medal, the highest award of the Institution of Automobile Engineers.
• Leonard Segel In 1956, he published the landmark paper ‘Theoretical prediction and experimental substantiation of the responses of the automobile to steering control’ [2]. His work was instrumental in understanding the motion and behaviour of road vehicles.
• J.R. Ellis Author of the classic 1969 text Vehicle Dynamics [3], and its follow‐up Vehicle Handling Dynamics [9] in 1994.
• Robin Sharp In addition to his numerous papers on automobile dynamics, he was a pioneer on the study of motorcycle dynamics. He wrote the 1971 paper ‘The stability and control of motorcycles’ [4].
• David Crolla An expert in both road and off‐road vehicle dynamics, his publication record includes some two hundred journal and conference papers. He served on the editorial boards of several journals, including Proceedings of the IMechE Part D, Heavy Vehicle Systems, and the International Journal of Automotive Technology.
• Carol Smith Well known for his extensive hands‐on experience and love of motorsport. He wrote the widely acclaimed Tune to Win [5] series of handbooks, which have motivated thousands of motor racing enthusiasts to study vehicle dynamics and engineering.
• JY Wong An expert in terramechanics and off‐road vehicles, and author of the widely cited text Theory of Ground Vehicles [6].
• Hans Pacejka Developer of the now widely used ‘magic’ tire model, introduced in the 1987 paper ‘Tire modelling for use in vehicle dynamics studies’ [7], and further expanded in his text Tire and Vehicle Dynamics [12].
• T.D. Gillespie The author of the text Fundamentals of Vehicle Dynamics [8], which was published by SAE and was a staple in the US auto industry for many years.
• Bill Milliken The developer of the Milliken Moment Method, some say he invented the science of automobile handling. He's the co‐author of the widely used text Race Car Vehicle Dynamics [10], and his own autobiography is given in Equations of Motion: Adventure, Risk and Innovation [13].

At this point, the author would be remiss not to make any mention of Ron Anderson, professor of Mechanical Engineering at Queen's University in Kingston, Ontario. While perhaps not as widely recognized as those listed above, his A'GEM (Automatic Generation of the Equations of Motion) software was instrumental in initiating the author's own research interest in the application of multibody dynamics techniques to the study of vehicle motion.

A review of the material produced by the authors listed above shows that initially the focus was on developing mathematical models to predict vehicle motion, and that those models were small enough that they could be manipulated on paper to determine the fundamental characteristics; most had from two to six degrees of freedom. As time passed, the models became more sophisticated, increasing in size and incorporating nonlinearities. The arrival of consumer‐grade digital computing has had a profound effect, as multibody dynamics (MBD) has been applied to the vehicle problem in a number of ways. In the last decade or two, with the widespread availability of commercial MBD tools, the use of vehicle dynamics models in the auto industry has broadened considerably.

The ways in which modern automakers are using vehicle dynamics modelling tools has expanded to include many different design objectives, and has even influenced the vehicle development process. The principle of model‐based design, in which system performance is predicted early enough in the design process to affect design choices, has seen application to th...