Method and apparatus for determining road surface condition

An apparatus for determining a condition of a road surface with which a tire is in contact by detecting tire vibration during vehicular travel, the apparatus comprising:

• a tire vibration detecting unit disposed on an air chamber side of an inner liner portion of a tire tread, and configured to detect the tire vibration during vehicular travel;
• a windowing unit configured to window a time-series waveform of the tire vibration detected by the tire vibration detecting unit at a predetermined time width and extracting time-series waveforms of the tire vibration for respective time windows;
• a feature vector calculating unit configured to calculate feature vectors having as components thereof vibration levels of specific frequencies in the time-series waveforms extracted for the respective time windows or feature vectors having as components thereof functions of the vibration levels;
• a storage unit configured to store road surface feature vectors which are feature vectors for the respective time windows calculated from time-series waveforms of the tire vibration obtained for each of road surface conditions calculated in advance;
• a kernel function calculating unit configured to calculate kernel functions from the feature vectors for the respective time windows calculated by the feature vector calculating unit and the road surface feature vectors stored in the storage unit;
• and
• a road surface condition determining unit configured to determine the road surface condition based on values of discriminant functions using the kernel functions,
• wherein the road surface condition determining unit determines the road surface condition by comparing the values of the discriminant functions obtained for the respective road surface conditions.