Accurate assessment of human trust in driver assistance systems is crucial for enhancing user acceptance and system safety. While prior research has explored physiological signals like skin conductance and heart rate to gauge trust, the link between these signals and trust remains insufficiently understood. Here, we present a novel approach to interpreting driver trust in intelligent warning systems by integrating subjective measures from questionnaires with objective electroencephalography (EEG) data. We develop TrustNet, a model leveraging separable convolution to capture the spatiotemporal dynamics of EEG signals and class activation mapping (CAM) to identify trust-relevant features. TrustNet achieves superior performance in trust assessment and classification, with accuracy and F1 score both exceeding 87%. CAM analysis reveals that EEG beta- and gamma-wave changes in the occipital and frontal regions are strongly associated with trust dynamics. Misclassification analysis highlights sensor noise and individual differences in response variability as key factors affecting performance. These findings demonstrate the feasibility of EEG-based trust assessment, offering new avenues for adaptive driver assistance systems responsive to human trust.

Planning in unstructured narrow environments with perception errors is of great challenge, as inaccurately perceived obstacle positions may lead planners to generate collision-prone trajectories. Typically, constraints are applied on the collision probability of the potential trajectory to ensure safety. However, due to the oversimplified modeling of vehicles or obstacles in estimating collision probabilities, these methods are often unsuitable for unstructured environments. To address this issue, we propose a computationally efficient risk zone generation method and introduce a Gaussian error function-based evaluation method to the collision risk assessment. The resulting risk-aware cost term is integrated into a trajectory optimization framework based on optimal control theory, effectively enabling obstacle avoidance by explicitly penalizing collision risk along the trajectory. Additionally, to address the inherent limitations of penalty based obstacle avoidance, we introduce a geometric safety constraint rigorously derived with duality principles. In the simulation scenarios of the Trajectory Planning Competition for Automated Parking organized by the IEEE Intelligent Transportation Systems Conference 2022, we introduce perception uncertainty to better reflect real-world conditions. The results demonstrate that our algorithm significantly improves trajectory safety while maintaining an effective balance between safety and efficiency.

The Partially Observable Monte Carlo Planning (POMCP) leverages Monte Carlo Tree Search (MCTS) and Particle Filtering (PF) to enhance the computational efficiency in solving large-scale Partially Observable Markov Decision Processes (POMDPs), allowing for updates of the belief state and effective adaptation to evolving uncertainties, which has been widely studied in autonomous driving. However, this approach faces two limitations when applied to planning for autonomous vehicles: chaotic branch expansion in the belief tree reduces computational efficiency, and particle deprivation hinders the accurate estimation of the dynamic intentions of surrounding vehicles. To this end, an intention-guided Partially Observable Monte Carlo Planning with a Heuristic-based Double Progressive Widening (POMCP-HDPW) approach is proposed to facilitate efficient decision-making for autonomous vehicles. We propose an enhance resampling method of PF that accounts for the driving intentions of surrounding vehicles, maintaining particle diversity and thereby improving estimation accuracy. Additionally, we prune the action and observation spaces by leveraging human driving experience and collision risk assessment, enabling the expansion and exploration of high-value belief nodes and preventing chaotic expansion. Three different methods are employed to drive the motion of surrounding vehicles, validating the robustness of the proposed model: intelligent driving model control, offline driving using the exiD trajectories, and driver-in-the-loop validation. Notably, experimental results on the exiD dataset demonstrate a success rate of 96.88% in off-ramp scenarios.

Effective driving style analysis is critical to developing human-centered intelligent driving systems that consider drivers’ preferences. However, the approaches and conclusions of most related studies are diverse and inconsistent because no unified datasets tagged with driving styles exist as a reliable benchmark. The absence of explicit driving style labels makes verifying different approaches and algorithms difficult. This paper provides a new benchmark by constructing a natural dataset of Driving Style (100-DrivingStyle) tagged with the subjective evaluation of 100 drivers’ driving styles. In this dataset, the subjective quantification of each driver’s driving style is from themselves and an expert according to the Likert-scale questionnaire. The testing routes are selected to cover various driving scenarios, including highways, urban, highway ramps, and signalized traffic. The collected driving data consists of lateral and longitudinal manipulation information, including steering angle, steering speed, lateral acceleration, throttle position, throttle rate, brake pressure, etc. This dataset is the first to provide detailed manipulation data with driving-style tags, and we demonstrate its benchmark function using six classifiers. The 100-DrivingStyle dataset is available via https://github.com/chaopengzhang/100-DrivingStyle-Dataset

Driving style is usually used to characterize driving behavior for a driverora group of drivers. However, it remains unclear how one individual’s driving style shares certain common grounds with other drivers. Our insight is that driving behavior is a sequence of responses to the weighted mixture of latent driving styles that are shareablewithinandbetweenindividuals. To this end, this paper develops a hierarchical latent model to learn the relationship between driving behavior and driving styles. We first propose a fragment-based approach to represent complex sequential driving behavior in a low-dimension feature space. Then, we provide an analytical formulation for the interaction of driving behavior and shareable driving styles through a hierarchical latent model. This model successfully extracts latent driving styles from extensive driving behavior data without the need for manual labeling, offering an interpretable statistical structure. Through real-world testing involving 100 drivers, our developed model is validated, demonstrating a subjective-objective consistency exceeding 90%, outperforming the benchmark method. Experimental results reveal that individuals share driving styles within and between them. We also found that individuals inclined towards aggressiveness only exhibit a higher proportion of such behavior rather than persisting consistently to be aggressive.

Accurate speed prediction is practically critical to eco-safe driving for intelligent vehicles. Existing research only makes vehicles adapt to the dynamic driving environment while rarely considering the influence of human driving preferences. This paper proposes a learning-based model to leverage human driving preferences into speed prediction. We first designed an Oriented Hidden Semi-Markov Model (Oriented-HSMM) to learn and predict the driver’s driving preference sequences while considering traffic flow influence. Then, we developed an optimal speed prediction algorithm to retrieve the smooth speed trajectories with maximal likelihood based on the estimated driving preferences. Finally, we evaluated the proposed model using the Next Generation Simulation (NGSIM) data compared to its counterparts that do not consider driving preferences. Experimental results demonstrate that our proposed Oriented-HSMM method reaches the best results and achieves a satisfying performance with a low mean absolute error (4.16 km/h) and root mean square error (5.08 km/h) at a 200 m prediction horizon.

Interpretation of common-yet-challenging inter- action scenarios can benefit well-founded decisions for autonomous vehicles. Previous research achieved this using their prior knowledge of specific scenarios with predefined models, limiting their adaptive capabilities. This paper describes a Bayesian nonparametric approach that leverages continuous (i.e., Gaussian processes) and discrete (i.e., Dirichlet processes) stochastic processes to reveal underlying interaction patterns of the ego vehicle with other nearby vehicles. Our model relaxes dependency on the number of surrounding vehicles by developing an acceleration-sensitive velocity field based on Gaussian processes. The experiment results demonstrate that the velocity field can represent thespatialinteractions between the ego vehicle and its surroundings. A discrete Bayesian nonparametric model, integrating Dirichlet processes and hidden Markov models, is developed to learn the interaction patterns over thetemporalspace by segmenting and clustering the sequential interaction data into interpretable granular patterns automatically. We then evaluate our approach in the highway discretionary lane-change scenarios using the highD dataset collected from real-world settings. Results demonstrate that our proposed Bayesian nonparametric approach provides an insight into the complicated discretionary lane-change interactions of the ego vehicle with multiple surrounding traffic participants based on the interpretable interaction patterns and their transition properties in temporal relationships. Our proposed approach sheds light on efficiently analyzing other kinds of multi-agent interactions, such as vehicle-pedestrian interactions. View associated demos via:https://chengyuan-zhang.github.io/Multivehicle-Interaction.

The information of the road grade plays an important role in improving the ride comfort and fuel consumption. This paper proposes a Quaternion Unscented Kalman Filter (QUKF) to estimate the road grade accurately, which needs only measurements from low-cost Inertial Measurement Unit (IMU). The model is built based on the data from accelerometer and gyroscope. The quaternion, which represents orientations and rotations, is chosen to be the state variables, while the three-axle acceleration is set as measurement vector. The proposed observer is tested and verified using the simulation software CarSim and MATLAB Simulink under several scenarios. To compare the performance of the algorithm, the Kalman filter and complementary filter are also implemented under the same simulation conditions. The results illustrate that the presented observer improves the accuracy and stability. Finally, the results of experiments are delivered and the performance of the filter is assessed against the output of a complete GPS/INS available in the same real-world dataset.

Fast recognition of a driver's decision-making style when changing lanes plays a pivotal role in a safety-oriented and personalized vehicle control system design. This article presents a time-efficient recognition method by integrating k-means clustering (k-MC) with the K-nearest neighbor (KNN) algorithm, called kMC-KNN. Mathematical morphology is implemented to automatically label the decision-making data into three styles (moderate, vague, and aggressive), while the integration of k-MC and the KNN algorithm helps to improve the recognition speed and accuracy. Our developed mathematical-morphology-based clustering algorithm is then validated by a comparison with agglomerative hierarchical clustering. Experimental results demonstrate that the developed kMC-KNN method, in comparison with the traditional KNN algorithm, can shorten the recognition time by more than 72.67% with a recognition accuracy of 90-98%. In addition, our developed kMCKNN method also outperforms a support vector machine in terms of recognition accuracy and stability. The developed time-efficient recognition approach would have great application potential for in-vehicle embedded solutions with restricted design specifications.

Driving style analysis plays a pivotal role in intelligent vehicle design. This paper presents a novel framework for driving style analysis based on primitive driving patterns. To this end, a Bayesian nonparametric approach based on a hidden semi-Markov model (HSMM) is introduced to extract the primitive driving patterns from muti-dimensional time-series driving data without prior knowledge of these driving patterns. For the Bayesian nonparametric approach, a hierarchical Dirichlet process (HDP) is applied to learn the unknown smooth dynamical modes in the HSMM, called primitive driving patterns. Two other types of Bayesian nonparametric approaches (HDP-HMM and sticky HDP-HMM) are developed as comparatives in order to show the advantages of the HDP-HSMM. The naturalistic car-following data of 18 drivers are collected from the University of Michigan Safety Pilot Model Deployment database. For each driver, 75 primitive driving patterns are semantically predefined according to their physical and psychological perception thresholds. The individual driving styles are then semantically analyzed based on the distribution over primitive driving patterns, and the similarity of driving styles among drivers is then evaluated. Experimental results demonstrate that the utilization of driving primitive pattern provides a semantically interpretable way to analyze driver's behavior and driving style.

Supervised learning approaches are widely used for driving style classification; however, they often require a large amount of labeled training data, which is usually scarce in a real-world setting. Moreover, it is time-consuming to manually label huge amounts of driving data due to uncertainties of driver behavior and variances among the data analysts. To address this problem, a semisupervised approach, a semisupervised support vector machine (S3VM), is employed to classify drivers into aggressive and normal styles based on a few labeled data points. First, a few data clusters are selected and manually labeled using a k-means clustering method. Then, a specific differentiable surrogate of a loss function is developed, which makes it feasible to use standard optimization tools to solve the nonconvex optimization problem. One of the most popular quasi-Newton algorithms is then used to assign the optimal label to all of the training data. Finally, we compare the S3VM method with a support vector machine method for classifying driving styles from different amounts of labeled data. Experiments show that the S3VM method can improve the classification accuracy by about 10% and reduce the labeling effort by using only a few labeled data clusters among huge amounts of unlabeled data.

To improve vehicle path-following performance and to reduce driver workload, a human-centered feed-forward control (HCFC) system for a vehicle steering system is proposed. To be specific, a novel dynamic control strategy for the steering ratio of vehicle steering systems that treats vehicle speed, lateral deviation, yaw error, and steering angle as the inputs and a driver's expected steering ratio as the output is developed. To determine the parameters of the proposed dynamic control strategy, drivers are classified into three types according to the level of sensitivity to errors, i.e., low, middle, and high. The proposed HCFC system offers a human-centered steering system (HCSS) with a tunable steering gain, which can assist drivers in tracking a given path with smaller steering wheel angles and change rate of the angle by adaptively adjusting steering ratio according to driver's path-following characteristics, reducing the driver's workload. A series of experiments of tracking the centerline of double lane change (DLC) are conducted in CarSim and three different types of drivers are subsequently selected to test in a portable driving simulator under a fixed-speed condition. The simulation and experiment results show that the proposed HCSS with the dynamic control strategy, as compared with the classical control strategy of steering ratio, can improve task performance by about 7% and reduce the driver's physical workload and mental workload by about 35% and 50%, respectively, when following the given path.

The performance of energy management in hybrid electric vehicles is highly dependent on the forecasted velocity. To this end, a new velocity-prediction approach utilizing the concept of chaining neural network (CNN) is introduced. This velocity forecasting approach is subsequently used as the basis for an equivalent consumption minimization strategy (ECMS). The CNN is used to predict the velocity over different temporal horizons, exploiting the information provided through vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communication channels. In addition, a new adaptation law for the so-called equivalent factor (EF) in ECMS is devised to investigate the effects of future velocity on fuel economy and to impose charge sustainability. Compared with traditional adaptation law, this paper considers the impact of predicted velocity on EF. The control objective is to improve the fuel economy relative to the ECMS without considering predicted velocity. Finally, simulations are conducted in three cases over different prediction horizons to demonstrate the performance of the proposed velocity-prediction method and ECMS with adaptation law. Simulation results confirm that ECMS with EF adjusted by the proposed adaptation law produces between 0.2% and 5% improvements in fuel economy relative to ECMS with traditional adaptation law. In addition, better charge sustainability is achieved as well.

This paper proposes a new energy management based on equivalent consumption minimization strategy (ECMS) for hybrid electric vehicles. The aim is to impose SoC charge-sustainability and enhance the fuel economy. First, the equivalent factor (EF) of ECMS is derived from Pontryagin's Minimum Principle. Second, a new adaptation law using Fuzzy Proportional plus Integral (PI) controller is developed to adjust EF in real-time. Finally, simulations for two driving cycles using ECMS are compared with rule-based (RB) control strategy, indicating that the proposed adaptation law can provide a promising blend in terms of fuel economy and charge-sustainability. The results show that ECMS with Fuzzy PI adaptation of EF achieves significant improvement compared with RB in terms of fuel economy and is more robust than ECMS with constant EF.

In this paper, an optimization method of gear shift schedule for electric buses equipped with 4-AMT is proposed based on Dynamic Programming (DP) to improve the energy economy of the vehicle. A gear shift schedule that can be used in real-vehicle is extracted based on analysis of the obtained optimal gear shift points by DP approach in Chinese typical urban driving-cycles. Compared to the traditional two-parameter gear shift schedule in both simulation and real vehicle platform, the extracted gear shift schedule is proved to improve the energy economy of the electric vehicles (EVs) obviously.

In our previous work, we reported a system that monitors an intersection using a network of horizontal laser scanners. This paper focuses on an algorithm for moving-object detection and tracking, given a sequence of distributed laser scan data of an intersection. The goal is to detect each moving object that enters the intersection; estimate state parameters such as size; and track its location, speed, and direction while it passes through the intersection. This work is unique, to the best of the authors' knowledge, in that the data is novel, which provides new possibilities but with great challenges; the algorithm is the first proposal that uses such data in detecting and tracking all moving objects that pass through a large crowded intersection with focus on achieving robustness to partial observations, some of which result from occlusions, and on performing correct data associations in crowded situations. Promising results are demonstrated using experimental data from real intersections, whereby, for 1063 objects moving through an intersection over 20 min, 988 are perfectly tracked from entrance to exit with an excellent tracking ratio of 92.9%. System advantages, limitations, and future work are discussed.

Many people die each year in the world in single vehicle roadway departure crashes caused by driver inattention, especially on the freeway. Lane Departure Warning System (LDWS) is a useful system to avoid those accident, in which, the lane detection is a key issue. In this paper, after a brief overview of existing methods, we present a robust lane detection algorithm based on geometrical model and Gabor filter. This algorithm is based on two assumptions: the road in front of vehicle is approximately planar and marked which are often correct on the highway and freeway where most lane departure accidents happen. The lane geometrical model we build in this paper contains four parameters which are starting position, lane original orientation, lane width and lane curvature. The algorithm is composed of three stages: the first stage is called off-line calibration which just runs once after the camera is mounted and fixed in the vehicle. The parameters of camera used for lane detection is accurately estimated by the 2D calibration method; The second stage is called lane model parameters estimation and lane model candidates construction, the first three parameters, starting position, lane original orientation and lane width will be estimated using dominant orientation estimation and local Hough transform. Then the construction of lane model candidates is implemented for the final lane model matching; the third stage is model matching. The proposed lane module matching algorithm is implemented to match the best fitted lane model. The combination of these modules can overcome the universal lane detection problems due to inaccuracies in edge detection such as shadow of tree and passengers on the road. Experimental results on real road will be presented to prove the effectiveness of the proposed lane detection algorithm.