Online road profile estimation in automotive vehicles

The road profile is one of the most important factors that determines the automotive vehicle performance; specially, when it is used to adapt the suspension features. Direct measurements of the road represent expensive solutions and are susceptible to be contaminated. This paper proposes a novel road profile estimation method based on classic vehicle measurements to online compute the road roughness and an ISO 8608 classification; all suspension variables used in the road estimation algorithm are obtained by an H _∞ robust observer. The method of road profile estimation is based on the frequency and amplitude estimation of the road irregularities using a Fourier analysis. Experimental results on the rear-left corner of a 1:5 scale vehicle have been used to validate the proposed road estimation method. Different ISO road classes online evaluate the performance of the road identification algorithm, whose results show that any road can be identified at least 70% of success with a false alarm rate lower than 5%; the average error of road identification is 17.5%. A second test with variable vehicle velocity shows the importance of the online frequency estimation to adapt the road estimation algorithm to any driving velocity, the road is correctly estimated with an error of 17%).