Visualization of driving behavior using Deep Sparse Autoencoder

Driving behavioral data is too high-dimensional for people to review their driving behavior. It includes accelerator opening rate, steering angle, brake Master-Cylinder pressure and other various information. The high-dimensional data is not very intuitive for drivers to understand their driving behavior when they take a look back on their recorded driving behavior. We used a deep sparse autoencoder to extract the low-dimensional high-level representation from high-dimensional raw driving behavioral data obtained from a control area network. Based on this low-dimensional representation, we propose two visualization methods called Driving Cube and Driving Color Map. Driving Cube is a cubic representation displaying extracted three-dimensional features. Driving Color Map is a colored trajectory shown on a road map representing the extracted features. The trajectory is colored using the RGB color space, which corresponds to the extracted three-dimensional features. To evaluate the proposed method for extracting low-dimensional feature, we conducted an experiment and found several differences with recorded driving behavior by viewing the visualized Driving Color Map and that our visualization methods can help people to recognize different driving behavior. To evaluate the effectiveness of low-dimensional representation, we compared deep sparse autoencoder with other conventional methods from the viewpoint of linear separability of elemental driving behavior. As a result, our methods outperformed other conventional methods.