59 research outputs found
Transfusor: Transformer Diffusor for Controllable Human-like Generation of Vehicle Lane Changing Trajectories
With ongoing development of autonomous driving systems and increasing desire
for deployment, researchers continue to seek reliable approaches for ADS
systems. The virtual simulation test (VST) has become a prominent approach for
testing autonomous driving systems (ADS) and advanced driver assistance systems
(ADAS) due to its advantages of fast execution, low cost, and high
repeatability. However, the success of these simulation-based experiments
heavily relies on the realism of the testing scenarios. It is needed to create
more flexible and high-fidelity testing scenarios in VST in order to increase
the safety and reliabilityof ADS and ADAS.To address this challenge, this paper
introduces the "Transfusor" model, which leverages the transformer and diffusor
models (two cutting-edge deep learning generative technologies). The primary
objective of the Transfusor model is to generate highly realistic and
controllable human-like lane-changing trajectories in highway scenarios.
Extensive experiments were carried out, and the results demonstrate that the
proposed model effectively learns the spatiotemporal characteristics of humans'
lane-changing behaviors and successfully generates trajectories that closely
mimic real-world human driving. As such, the proposed model can play a critical
role of creating more flexible and high-fidelity testing scenarios in the VST,
ultimately leading to safer and more reliable ADS and ADAS.Comment: Submitted for presentation only at the 2024 Annual Meeting of the
Transportation Research Boar
PFL-LSTR: A privacy-preserving framework for driver intention inference based on in-vehicle and out-vehicle information
Intelligent vehicle anticipation of the movement intentions of other drivers
can reduce collisions. Typically, when a human driver of another vehicle
(referred to as the target vehicle) engages in specific behaviors such as
checking the rearview mirror prior to lane change, a valuable clue is therein
provided on the intentions of the target vehicle's driver. Furthermore, the
target driver's intentions can be influenced and shaped by their driving
environment. For example, if the target vehicle is too close to a leading
vehicle, it may renege the lane change decision. On the other hand, a following
vehicle in the target lane is too close to the target vehicle could lead to its
reversal of the decision to change lanes. Knowledge of such intentions of all
vehicles in a traffic stream can help enhance traffic safety. Unfortunately,
such information is often captured in the form of images/videos. Utilization of
personally identifiable data to train a general model could violate user
privacy. Federated Learning (FL) is a promising tool to resolve this conundrum.
FL efficiently trains models without exposing the underlying data. This paper
introduces a Personalized Federated Learning (PFL) model embedded a long
short-term transformer (LSTR) framework. The framework predicts drivers'
intentions by leveraging in-vehicle videos (of driver movement, gestures, and
expressions) and out-of-vehicle videos (of the vehicle's surroundings -
frontal/rear areas). The proposed PFL-LSTR framework is trained and tested
through real-world driving data collected from human drivers at Interstate 65
in Indiana. The results suggest that the PFL-LSTR exhibits high adaptability
and high precision, and that out-of-vehicle information (particularly, the
driver's rear-mirror viewing actions) is important because it helps reduce
false positives and thereby enhances the precision of driver intention
inference.Comment: Submitted for presentation only at the 2024 Annual Meeting of the
Transportation Research Boar
Tradeoffs between safe/comfortable headways versus mobility-enhancing headways in an automated driving environment: preliminary insights using a driving simulator experiment
Purpose – The anticipated benefits of connected and autonomous vehicles (CAVs) include safety and mobility enhancement. Small headways between successive vehicles, on one hand, can cause increased capacity and throughput and thereby improve overall mobility. On the other hand, small headways can cause vehicle occupant discomfort and unsafety. Therefore, in a CAV environment, it is important to determine appropriate headways that offer a good balance between mobility and user safety/comfort. Design/methodology/approach – In addressing this research question, this study carried out a pilot experiment using a driving simulator equipped with a Level-3 automated driving system, to measure the threshold headways. The Method of Constant Stimuli (MCS) procedure was modified to enable the estimation of two comfort thresholds. The participants (drivers) were placed in three categories (“Cautious,” “Neutral” and “Confident”) and 250 driving tests were carried out for each category. Probit analysis was then used to estimate the threshold headways that differentiate drivers' discomfort and their intention to re-engage the driving tasks. Findings – The results indicate that “Cautious” drivers tend to be more sensitive to the decrease in headways, and therefore exhibit greater propensity to deactivate the automated driving mode under a longer headway relative to other driver groups. Also, there seems to exist no driver discomfort when the CAV maintains headway up to 5%–9% shorter than the headways they typically adopt. Further reduction in headways tends to cause discomfort to drivers and trigger take over control maneuver. Research limitations/implications – In future studies, the number of observations could be increased further. Practical implications – The study findings can help guide specification of user-friendly headways specified in the algorithms used for CAV control, by vehicle manufacturers and technology companies. By measuring and learning from a human driver's perception, AV manufacturers can produce personalized AVs to suit the user's preferences regarding headway. Also, the identified headway thresholds could be applied by practitioners and researchers to update highway lane capacities and passenger-car-equivalents in the autonomous mobility era. Originality/value – The study represents a pioneering effort and preliminary pilot driving simulator experiment to assess the tradeoffs between comfortable headways versus mobility-enhancing headways in an automated driving environment
Large network multi-level control for CAV and Smart Infrastructure: AI-based Fog-Cloud collaboration
Effects of Bridge Surface and Pavement Maintenance Activities on Asset Rating
This study provides and demonstrates a methodology to quantify the impact of INDOT’s standard maintenance treatments on state highway pavements and bridge deck surfaces, in terms of their condition ratings. Of the specific objectives, the first is to generate requisite reset values that INDOT’s asset manager can use in the agency’s PMS and BMS software packages. The second is to measure the longer-term effectiveness of specific maintenance treatments in terms of the extension to asset life. The third specific objective is to use this information to assess the cost-effectiveness of the treatments.
The research product from this project is a set of averages or models that represent the impacts (performance jump, post-treatment performance vs. age relationship, and cost) of each treatment type typically applied to INDOT’s assets. The performance impacts are expressed in terms of the requisite performance indicators. The performance jump models showed that the asset’s functional class and pre-treatment condition, and the treatment type were major significant predictors of the performance jump and post-treatment performance loss. The first deliverable from this project is the average (mean) impact for each treatment type under investigation. The second is the overall statistical description of the impact, namely, the minimum and maximum impact, and range and standard deviation of impact; a statistical model that predicts the impact as a function of asset and treatment attributes. The third is a set of charts that describe the sensitivity of the treatment impact to factors related to the asset or the treatment. The study also developed cost models for each of the pavement and bridge treatments and used these results to assess the long-term cost-effectiveness of the treatments
The diagnostic value of blood metagenomic next-generation sequencing in patients with acute hematogenous osteomyelitis
AimsThis study aims to evaluate the diagnostic value of blood metagenomic next-generation sequencing (mNGS) in detecting pathogens from patients clinically diagnosed as acute hematogenous osteomyelitis (AHO).MethodsThis retrospective study enrolled 66 patients with AHO. The test results of mNGS and bacterial culture on different samples, including blood and puncture fluid samples, from patients with AHO were compared to explore the diagnostic value of blood mNGS. Besides, this study also explored the efficacy of blood mNGS in decision making for antibiotic administration and analyzed the factors associated with the positive result of blood mNGS.ResultsThe most common causative pathogens were Staphylococcus and Streptococcus. The sensitivity of blood mNGS (77.3%) was higher than that of blood culture (42.4%) (P<0.001), while the turnaround time of blood mNGS (2.1 ± 0.4 d) is much less than that of blood culture (6.0 ± 2.1 d) (P<0.001). Besides, the sensitivity of blood mNGS tests (77.3%) was slightly lower than that of puncture fluid mNGS (89.4%). Furthermore, detection comparison at pathogen level unravels that blood mNGS might be suitable for diagnosing AHO caused by common pathogens, while puncture fluid mNGS could be considered as preferred examination in diagnosing AHO caused by uncommon pathogens. Finally, three independent factors associated with the true positive result of blood mNGS in patients with AHO were identified, including Gram-positive pathogens (OR=24.4, 95% CI = 1.4-421.0 for Staphylococcus; OR=14.9, 95%CI= 1.6-136.1 for other Gram-positive bacteria), body temperature at sampling time (OR=8.2, 95% CI = 0.6-107.3 for body temperature of >38.5°C; OR=17.2, 95% CI = 2.0-149.1 for patients who were chilling), and no use of antibiotics before sampling (OR=8.9, 95% CI =1.4-59.0).ConclusionThis is the first report on evaluating and emphasizing the importance of blood mNGS in diagnosing AHO. Blood sample might be an alternative sample for puncture fluid for mNGS, and its extensive application in diagnosing AHO could be expected
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