Ontology-based framework for risk assessment in road scenes using videos

Recent advances in autonomous vehicle technology pose an important problem of automatic risk assessment in road scenes. This article addresses the problem by proposing a novel ontology tool for assessment of risk in unpredictable road traffic environment, as it does not assume that the road users always obey the traffic rules. A framework for video-based assessment of the risk in a road scene encompassing the above ontology is also presented in the paper. The framework uses as input the video from a monocular video camera only, avoiding the need for additional sometimes expensive sensors. The key entities in the road scene (vehicles, pedestrians, environment objects etc.) are organised into an ontology which encodes their hierarchy, relations and interactions. The ontology tool infers the degree of risk in a given scene using as knowledge video-based features, related to the key entities. The evaluation of the proposed framework focuses on scenarios in which risk results from pedestrian behaviour. A dataset consisting of real-world videos illustrating pedestrian movement is built. Features related to the key entities in the road scene are extracted and fed to the ontology, which evaluates the degree of risk in the scene. The experimental results indicate that the proposed framework is capable of assessing risk resulting from pedestrian behaviour in various road scenes accurately

DSRC-based rear-end collision warning system – An error-component safety distance model and field test

Dedicated short-range communication (DSRC) technology can provide drivers with information about other vehicles that are beyond the normal range of vision and enables the development of driving support systems such as the rear-end collision warning system (ReCWS). However, technology constraints such as communication delays and GPS error affect the accuracy of a DSRC-based ReCWS. This paper proposes a ReCWS design that explicitly represents functional specifications of DSRC technology, including transmission delay specifications that describe the information transmission process and an error-component safety distance specification used to represent the effect of GPS error and the information propagation delay. We propose three collision warning strategies each with different deceleration requirements. The system is assembled with off-the-shelf DSRC and mobile technology that can be readily installed into test vehicles. To test the effectiveness of the proposed ReCWS, we ran a variety of controlled scenarios on a test track. The results show a high degree of warning accuracy. These field test results also provide calibrated system parameter values for future studies and designs of DSRC-based ReCWSs