Mass properties have a profound effect on automotive fuel economy, emissions, safety, ride, acceleration, braking, and maneuver. Because of this fact, it is important to have a reliable and comprehensive methodology for the estimation of key mass property parameters in the conceptual design stage. Also, such a methodology would be important for researchers investigating aspects of automotive dynamics, for programmers creating realistic automotive simulations, and for investigators studying the dynamics of automotive crash scenarios.
There is a scarcity of published information of sufficient accuracy and/or completeness so as to constitute a viable methodology. Published automotive mass property estimation methods seem to be available only in a non-comprehensive fashion through a variety of scattered sources. It is the intent of this paper to systematize the information drawn from published sources and, with the employment of techniques based on those used in the aerospace industry, to augment and improve upon the published information so as to develop a basis for a comprehensive automotive mass properties estimation methodology.
Note the use of the word “basis”; it is not to be imagined that this paper will represent the “last word” in automotive mass properties estimation. What is presented herein is intended to provide a possible overall framework for, and an initial “first cut” at, the development of a comprehensive methodology. Automotive design practitioners working within the established industry may have a far more potent estimation methodology available to them, but in the form of proprietary techniques that they are not at liberty to divulge. Yet even such automotive industry insiders may find an independently derived methodology interesting, and perhaps even useful for comparison with in-house procedures. However, it is the independent designer or researcher that is most likely to find this paper to be of great value, and it is the purpose of this paper to aid such independent efforts through promoting the development of a publicly accessible methodology.
To that end this paper presents the development of a preliminary “top-down” methodology which requires as input only those most basic and common overall parameters as would be available in the earliest of design stages or, for existing designs, from the commonly available literature. This includes such parameters as vehicle dimensions, applicable general legal specification or regulation, general vehicle configuration and category, type of suspension, and level of technology (which is generally time dependent). The desired output consists of the curb weight/c.g. coordinates/inertias, the unsprung weight/c.g. coordinates/inertias, the sprung weight/c.g. coordinates/inertias, and the sprung weight roll moment of inertia (i.e., a rotational inertia about an essentially longitudinal axis, the location of which is determined by the suspension geometry).