3553. Vehicle Inertia Measurement Machine (VIMM)

Paper

Abstract

For the design of modern vehicles the knowledge of mass and moments of inertia is of great importance in terms of their vibration behaviour. Next to the type of incitation the inertia tensor (mass, position of centre of gravity, moments of inertia and products of inertia) is crucial for the translational and rotational vibration behaviour.
In vehicle development simulation models are used increasingly to investigate the dynamic behaviour of motor vehicles. These models are indispensable in the development of modern vehicle controls (e.g. ESP, antilock brake system). The knowledge of the inertia parameters of a vehicle is an important requirement to be able to represent a realistic driving behaviour in the simulation model.
Moreover, the inertia parameters of a vehicle are used for the evaluation of the rollover stability. The National Highway Traffic Safety Administration (NHTSA) awards ‘stars’ for classification of the roll over stability.
Because of this, the identification of parameters by measurement is of great importance and increasingly moves in the centre of interest of producers and public institutions.
Traditional test methods for the determination of vehicle parameters split the investigation in several processing steps, whereas for each inertia parameter a separate test is required. This leads to disadvantages with regard to the reproducibility of the measurement and the required time. Newer test benches use an active movement mechanism as well as a sensor system to detect the movement and the forces and moments, which affects the body. Therefore the technical burden on the active movement mechanism and the sensory is high.
A representative of those test benches is the VIMM (Vehicle Inertia Measuring Machine), which has been developed at ika. It is able to measure all inertia parameters and consists of a spherically seated platform, which can be moved by servo-hydraulic actuators around the three axes. The vehicle, whose inertia parameters are to be measured, is adapted on the platform. During the measurement the angular positions and the forces affecting the platform are measured. Afterwards the inertia parameters are calculated with these values.