Developments in Vehicle Center of Gravity and Inertial Parameter Estimation and Measurement

For some vehicle dynamics applications, an estimate of a vehicle's center of gravity (cg) height and mass moments of inertia can suffice. For other applications, such as vehicle models and simulations used for vehicle development, these values should be as accurate as possible. This paper presents several topics related to inertial parameter estimation and measurement. The first is a simple but reliable method of estimating vehicle mass moment of inertia values from data such as the center of gravity height, roof height, track width, and other easily measurable values of any light road vehicle. The second is an error analysis showing the effect, during a simple static cg height test, of vehicle motion (relative to the support system) on the vehicle's calculated cg height. A method of accounting for this motion is presented. Similarly, the effects of vehicle motion are analyzed for subsequent mass moment of inertia tests. The third topic is a method of measuring the ratio of the sprung mass to the unsprung mass of any light vehicle without disassembly. Knowledge of this ratio is also important for vehicle development. As an addendum, cg heights and mass moments of inertia measured on the Vehicle Inertia Measurement Facility are presented for several vehicles.