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Introduction 15
The best multibody system codes now include, specifically for the vehicle
handling task, a ‘concept level’ model that has no literal detail but instead
a ‘wheel trajectory map’. In the near future, it seems that reverse engineering
tools for deducing the required wheel trajectory map will become available.
Crolla (1995) identifies the main types of computer-based tools which can
be used for vehicle dynamic simulation and categorizes these as:
(i) Purpose-designed simulation codes
(ii) Multibody simulation packages that are numerical
(iii) Multibody simulation packages that are algebraic (symbolic)
(iv) Toolkits such as MATLAB
One of the major conclusions that Crolla draws is that it is still generally the
case that the ride and handling performance of a vehicle will be developed
and refined mainly through subjective assessments. Most importantly he
suggests that in concentrating on sophistication and precision in modelling,
practising vehicle dynamicists may have got the balance wrong. This is an
important issue that reinforces the main approach in this book, which is to
encourage the application of models that lead to positive decisions and
inputs to the vehicle design process.
Crolla’s paper also provides an interesting historical review that highlights
an important meeting at IMechE headquarters in 1956, ‘Research in automobile
stability and control and tyre performance’. The author states that
in the field of vehicle dynamics the papers presented at this meeting are
now regarded as seminal and are referred to in the USA as simply ‘The
IME Papers’.
One of the authors at that meeting, Segel, can be considered to be a pioneer
in the field of vehicle dynamics. His paper (Segel, 1956) is one of the first
examples where classical mechanics has been applied to an automobile in
the study of lateral rigid body motion resulting from steering inputs. The
paper describes work carried out on a Buick vehicle for General Motors
and is based on transferable experience of aircraft stability gained at the
Flight Research Department, Cornell Aeronautical Laboratory (CAL). The
main thrust of the project was the development of a mathematical vehicle
model that included the formulation of lateral tyre forces and the experimental
verification using instrumented vehicle tests. Another author at the
meeting, Milliken (Milliken and Whitcomb, 1956), has also continued to
make a significant contribution to the discipline.
In 1993, almost 40 years after embarking on this early work in vehicle
dynamics, Segel again visited the IMechE to present a comprehensive
review paper (Segel, 1993), ‘An overview of developments in road vehicle
dynamics: past, present and future’.
This paper provides a historical review that considers the development of
vehicle dynamics theory in three distinct phases:
Period 1 – Invention of the car to early 1930s
Period 2 – Early 1930s to 1953
Period 3 – 1953 to present