128 - Estimation of vehicle inertial properties based on on-road measurements
Rozyn M., Dissanayake G., Zhang N.
Abstract
Improving performance and safety, whilst reducing emissions are desirable qualities sought in an automobile. A method of estimating the current vehicle mass, inertia and centre of gravity would allow more satisfactory operation of systems such as traction control, active suspension and engine management. Vehicle mass and centre of gravity would be particularly useful in larger vehicles where the payload of the vehicle can change by over 50%. This paper presents a method of determining a vehicle’s inertial properties on-line by using modal testing techniques. First, the bounce and pitch motions are measured by a bounce accelerometer and a pitch gyroscope attached rigidly to the vehicle body. The random decrement technique is used to obtain the free vibration responses of the bounce and pitch modes from the measured vehicle motion in response to unknown road conditions. A least square curve fitting technique is then employed to determine the natural frequencies and damping ratios of the bounce and pitch modes from the free vibration responses. Lastly, the vehicle mass and centre of gravity are estimated using modal analysis combined with a least square estimator with the assumption that the vehicles stiffness and damping characteristic curves are known. Simulation using a full car model with random road disturbance has been performed in Matlab, the output of which is a set of simulated bounce and pitch measurements. Using the above mentioned estimation method, combined with the known values of damping and stiffness, shows that the inertial properties can be determined. A number of tests have been performed on a Ford UTE with different payload configurations, with the bounce and pitch vibrations being measured by an inertial measurement unit. Results have shown that estimation of the mass and centre of gravity is possible given linear simplification of the highly non-linear nature of the vehicle suspension.
Citation
Rozyn M.; Dissanayake G.; Zhang N.: Estimation of vehicle inertial properties based on on-road measurements, CD-ROM Proceedings of the Thirtheenth International Congress on Sound and Vibration (ICSV13), July 2-6, 2006, Vienna, Austria, Eds.: Eberhardsteiner, J.; Mang, H.A.; Waubke, H., Publisher: Vienna University of Technology, Austria, ISBN: 3-9501554-5-7
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