1976-02-01

Objective Ride Quality Measurement 760360

This paper describes the use of a measurement and data reduction system for objective ride quality assessment which can be used in all types of transportation systems. The basis of the data handling is the use of the absorbed power criteria developed by Pradko and Lee, modified by using the Amplitude Frequency Distribution (AFD) method, and incorporating a human simulator to obtain the objective parameters used in the ride calculations. The AFD method was originally developed by the authors as a better description of road roughness than commonly used random data descriptions. The method is a joint probability density of amplitude and frequency and therefore maintains both spectrum data and amplitude distribution.The human simulator was developed to eliminate the need for extensive subjective testing. The study showed that in the frequency range of interest to ride quality work, a two-degree-of-freedom simulator adequately modeled human response. The device was built to simulate the response of a 170-lb man and the necessary instrumentation was installed. The complete system was placed in a motor home and comparison data was obtained from both the simulator and a similar human over a wide range of roads varying from very smooth to very rough. The acceleration from both the human subject and the simulator were recorded simultaneously. The analog signals from this test show excellent agreement and samples are presented. The analog data was reduced to absorbed power levels using AFD format and these values obtained from both the subject and simulator show good agreement. The absorbed power information is tabulated.In conclusion, the data reduction method used with the human simulator can be employed for ride quality evaluation of any transportation system be it ground, air, or water. In addition, it can be used in prototype development, redesign, maintenance, vehicle manufacturing, or by guideway designers.

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