Vehicle behavior prediction in complex urban scenarios with traffic signals and interactive agents is an important yet complicated task for autonomous vehicles (AVs). In this work, a hierarchical vehicle behavior prediction framework is proposed to incorporate the traffic signal information and model the interaction between vehicles. The framework predicts vehicle behaviors in two stages, discrete intention prediction and continuous trajectory prediction. In the discrete intention prediction stage, Bayesian network is adopted to provide a high-level behavior prediction of the principle other vehicle. The discrete prediction results are forwarded to the second stage, where a continuous trajectory is predicted with maximum entropy inverse reinforcement learning and potential game. The framework is designed to be able to capture the difference among human drivers with parameterized driver characteristics. The proposed predictor is validated in two scenarios: the yellow light running scenario and the right-turn scenario. The trajectory prediction average displacement error of the yellow light running scenario is 0.695m for a 3-second prediction interval, and the prediction accuracy of the right-turn vehicle in the right-turn scenario is 0.51m for a 2-second prediction interval.

To assure the successful operation of connected and automated vehicles, it is critical to detect and isolate anomalous and/or faulty information in a timely manner. To do so, anomaly detection techniques should be implemented in real-time where if the probability of anomalous information exceeds a certain threshold, the information is dealt with accordingly. Traditionally, the threshold for judging whether the data is anomalous is fixed and determined a priori. However, not only does this approach fail to account for the feedback obtained during a trip on the performance of the algorithms, but it also fails to respond to potential changes in rates of anomalies. Hence, it is important to develop an approach that can dynamically alter this threshold in response to exogenous factors to assure reliable and robust system operation. We develop a mathematical framework which utilizes a dynamic threshold for an anomaly classification algorithm in order to maximize the safety of a trip. Specifically, we develop and pair an anomaly classification algorithm based on convolutional neural networks (CNN), with a partially observable Markov decision process (POMDP) model. We solve the resulting POMDP model using the asynchronous advantage actor critic (A3C) deep reinforcement learning algorithm. The prescribed policy determines the anomaly classification threshold in real-time that maximizes the performance. Our numerical experiments show that the POMDP model outperforms state-of-the-art benchmarks, especially under more difficult to detect anomaly profiles.

In this paper we propose an unsupervised learning framework to predict risky driving at intersections in a connected vehicle environment. The proposed framework uses time series k-means to categorize multi-dimensional time series trajectories into several context-aware driving patterns. Dynamic time warping (DTW) is implemented within the time series k-means algorithm for measuring the similarity between trajectories. DTW is adopted to make the framework robust to temporal distortions and missing data points. We train an isolation forest (iForest) model on the trajectory dataset to identify anomalous trajectories, and apply this model to clusters to provide Risky Driving Prediction (RDP) scores for each driving pattern. We provide a real-time online assessment approach to predict the risk score of driving trajectories that travel toward a signalized intersection. We use real-world connected vehicle trajectories collected by a road-side unit (RSU) in Ann Arbor, Michigan to implement our framework. We use several quantitative measures as well as illustrations to validate our model. We further discuss how the RDP framework can be used to develop network-level and individual vehicle-level insurance and safety focused applications.

In this paper we propose a novel observer-based method to improve the safety and security of connected and automated vehicle (CAV) transportation. The proposed method combines model-based signal filtering and anomaly detection methods. Specifically, we use adaptive extended Kalman filter (AEKF) to smooth sensor readings of a CAV based on a nonlinear car-following model. Using the car-following model the subject vehicle (i.e., the following vehicle) utilizes the leading vehicle's information to detect sensor anomalies by employing previously-trained One Class Support Vector Machine (OCSVM) models. This approach allows the AEKF to estimate the state of a vehicle not only based on the vehicle's location and speed, but also by taking into account the state of the surrounding traffic. A communication time delay factor is considered in the car-following model to make it more suitable for real-world applications. Our experiments show that compared with the AEKF with a traditional x2-detector, our proposed method achieves a better anomaly detection performance. We also demonstrate that a larger time delay factor has a negative impact on the overall detection performance.

Automated vehicles are envisioned to be an integral part of the next generation of transportation systems. Whether it is striving for full autonomy or incorporating more advanced driver assistance systems, high-accuracy vehicle localization is essential for automated vehicles to navigate the transportation network safely. In this paper, we propose a reinforcement learning framework to increase GPS localization accuracy. The framework does not make rigid assumptions on the GPS device hardware parameters or motion models, nor does it require infrastructure-based reference locations. The proposed reinforcement learning model learns an optimal strategy to make “corrections” on raw GPS observations. The model uses an efficient confidence-based reward mechanism, which is independent of geolocation, thereby enabling the model to be generalized. We incorporate a map matching-based regularization term to reduce the variance of the reward return. The reinforcement learning model is constructed using the asynchronous advantage actor-critic (A3C) algorithm. A3C provides a parallel training protocol to train the proposed model. The asynchronous reinforcement learning strategy facilitates short training sessions and provides more robust performance. The performance of the proposed model is assessed by comparing it with an extended Kalman filter algorithm as a benchmark model. Our experiments indicate that the proposed reinforcement learning model converges fast, has less prediction variance, and can localize vehicles with 50% less error compared to the benchmark Extended Kalman Filter model.

Autonomous vehicles (AVs) are expected to be an integral part of the next generation of transportation systems, where they will share the transportation network with human-driven vehicles during the transition period. In this work, we model the interactions between vehicles (two AVs or an AV and a human-driven vehicle) in a lane changing process by leveraging the Stackelberg game. We explicitly model driving attitudes for both vehicles involved in lane changing. We design five cases, in which the two vehicles have different levels of knowledge, and make different assumptions, about the driving attitude of the rival. We conduct theoretical analysis and simulations for different cases in two lane changing scenarios, namely changing lanes from a higher-speed lane to a lower-speed lane, and from a lower-speed lane to a higher-speed lane. We use four metrics (fuel consumption, discomfort, minimum distance gap and lane change success rate) to investigate how the performance of a single vehicle and that of the system will be influenced by the level of information sharing, and whether a vehicle trajectory optimized based on selfish criteria can provide system-level benefits.

Connected and automated vehicles (CAVs) are expected to revolutionize the transportation industry, mainly through allowing for a real-time and seamless exchange of information between vehicles and roadside infrastructure. Although connectivity and automation are projected to bring about a vast number of benefits, they can give rise to new challenges in terms of safety, security, and privacy. To navigate roadways, CAVs need to heavily rely on their sensor readings and the information received from other vehicles and roadside units. Hence, anomalous sensor readings caused by either malicious cyber attacks or faulty vehicle sensors can result in disruptive consequences and possibly lead to fatal crashes. As a result, before the mass implementation of CAVs, it is important to develop methodologies that can detect anomalies and identify their sources seamlessly and in real time. In this paper, we develop an anomaly detection approach through combining a deep learning method, namely convolutional neural network (CNN), with a well-established anomaly detection method, and Kalman filtering with a χ2-detector, to detect and identify anomalous behavior in CAVs. Our numerical experiments demonstrate that the developed approach can detect anomalies and identify their sources with high accuracy, sensitivity, and F1 score. In addition, this developed approach outperforms the anomaly detection and identification capabilities of both CNNs and Kalman filtering with a χ2-detector method alone. It is envisioned that this research will contribute to the development of safer and more resilient CAV systems that implement a holistic view toward intelligent transportation system (ITS) concepts.