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Unsupervised driving style analysis based on driving maneuver intensity

This paper proposes a novel unsupervised clustering framework to identify driving style not in terms of the discrete features of driving behavior data, but rather the time-varying patterns of driving maneuver intensity. This framework can describe the dynamic decision-making process of driving behavior and the continuity of driving data. Driving maneuver intensity is the basic of this paper. Therefore, detection, feature analysis and clustered on intensity of driving maneuvers are carried out using a threshold-based approach, hierarchical feature extraction, and k-means clustering. Then, to analyze fine-grained driving style, dynamic time windows are determined according to road alignment. In dynamic time windows, this paper constructs time-varying patterns based on driving maneuver intensity, which consider the intensity and frequency of driving behavior and preserve the time-varying characteristics of time-series data. However, not all dynamic time windows are equal in maneuvers’ duration and number, which means the time-varying patterns of driving maneuver intensity are curves with various lengths. So that, for clustering time-varying patterns, this paper proposes a novel curve clustering algorithm named Similarity-Based Clustering with Dynamic Time Warping (SBC-DTW) that can cluster curves with various lengths. The empirical results based on real driving data demonstrate that the proposed framework can classify driving style more accurately than the classical method. Moreover, according to this framework, we can have an in-depth understanding of dynamic driving behavior and the composition of drivers’ long-term driving styles.