Method for determining road surface condition

Abstract

In a method for determining a road surface condition, the speed of calculation is improved by applying an appropriate path limitation. To further improve the accuracy of determination, a time-series waveform of tire vibration detected by an acceleration sensor is windowed at time width T by a windowing means, and time-series waveforms of tire vibration in the respective time windows are extracted before feature vectors Xof the respective time windows are calculated. Then kernel functions K(X, Y) are calculated from the feature vectors Xfor the respective time windows and road surface feature vectors Y, which are feature vectors for the respective time windows calculated from time-series waveforms of tire vibration having been determined in advance for distinctive road surface conditions. In doing so, the kernel functions are calculated after weighting respective paths by weighting parameters ω (i, j) using a time-series waveform length corresponding value in the time-series waveform of tire vibration as measured and a previously determined time-series waveform length corresponding value in the time-series waveform of tire vibration.