An analysis of automobile handling characteristics and stability

by Gary Karl Sandberg

Institution: Oregon State University
Department: Mechanical and Industrial Engineering
Degree: MS
Year: 1965
Keywords: Automobiles  – Design and construction  – Research
Record ID: 1587656
Full text PDF: http://hdl.handle.net/1957/48196


It is desirable to be able to describe an automobile mathematically because of the large number of variables which affect automobiles' handling characteristics and of the high cost of building prototypes. A mathematical analysis facilitates the construction of a few prototypes whose configurations look most promising. Equations of motion were derived for an automobile composed of a rigid mass connected to four wheels by springs, dampers and rigid, weightless linkages. The resulting system of ten differential equations was intended to estimate the response of an automobile to a rough road. The ten degree of freedom system was then simplified to six degrees of freedom; the resulting equations were limited to smooth road conditions. Several attempts were made to obtain a computer solution for the ten degree of freedom system, but were not successful. Some transient solutions of the six degree of freedom system was obtained on an IBM 1410 computer, and an approximate steady state solution was found by an iterative technique which does not require a computer. Several vehicle configurations were investigated. The following are the most important conclusions. 1. Tire properties, especially the differences in front and rear tire properties, are extremely important in determining an automobile's handling characteristics. 2. An automobile with rear weight bias can be designed with virtually any handling characteristics. 3. Changes in the roll geometry of a suspension system can have significant effects on an automobile's handling characteristics. These effects, however, depend on other characteristics of the vehicle, such as weight distribution and roll steer. Future work of the author will be directed toward a more accurate description of an automobile and further investigation of suspension geometry.