David Fernández-Llorca

Dr. David Fernández-Llorca

orcid

Research Focus & Metrics

Academic Career Length

22Years (2005-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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12 October 2011 in Sensors
Verified
Journal Article
Open access
PDF file
MGMiguel Gavilán
Miguel Gavilán
DBDavid Balcones
David Balcones
OMOscar Marcos
Oscar Marcos
David Fernández-LlorcaDavid Fernández-Llorca
David Fernández-Llorca
MSMiguel Angel Sotelo
Miguel Angel Sotelo
AAAlejandro Amírola
Alejandro Amírola
This paper presents a road distress detection system involving the phases needed to properly deal with fully automatic road distress assessment. A vehicle equipped with line scan cameras, laser illumination and acquisition HW-SW is used to storage the digital images that will be further processed to identify road cracks. Pre-processing is firstly carried out to both smooth the texture and enhance the linear features. Non-crack features detection is then applied to mask areas of the images with joints, sealed cracks and white painting, that usually generate false positive cracking. A seed-based approach is proposed to deal with road crack detection, combining Multiple Directional Non-Minimum Suppression (MDNMS) with a symmetry check. Seeds are linked by computing the paths with the lowest cost that meet the symmetry restrictions. The whole detection process involves the use of several parameters. A correct setting becomes essential to get optimal results without manual intervention. A fully automatic approach by means of a linear SVM-based classifier ensemble able to distinguish between up to 10 different types of pavement that appear in the Spanish roads is proposed. The optimal feature vector includes different texture-based features. The parameters are then tuned depending on the output provided by the classifier. Regarding non-crack features detection, results show that the introduction of such module reduces the impact of false positives due to non-crack features up to a factor of 2. In addition, the observed performance of the crack detection system is significantly boosted by adapting the parameters to the type of pavement.

12 June 2023
Verified
Conference Paper
Open access
CPCecilia Panigutti
Cecilia Panigutti
RHRonan Hamon
Ronan Hamon
IHIsabelle Hupont
Isabelle Hupont
David Fernández-LlorcaDavid Fernández-Llorca
David Fernández-Llorca
DYDelia Fano Yela
Delia Fano Yela
EGEmilia Gómez
Emilia Gómez
The proposed EU regulation for Artificial Intelligence (AI), the AI Act, has sparked some debate about the role of explainable AI (XAI) in high-risk AI systems. Some argue that black-box AI models will have to be replaced with transparent ones, others argue that using XAI techniques might help in achieving compliance. This work aims to bring some clarity as regards XAI in the context of the AI Act and focuses in particular on the AI Act requirements for transparency and human oversight. After outlining key points of the debate and describing the current limitations of XAI techniques, this paper carries out an interdisciplinary analysis of how the AI Act addresses the issue of opaque AI systems. In particular, we argue that neither does the AI Act mandate a requirement for XAI, which is the subject of intense scientific research and is not without technical limitations, nor does it ban the use of black-box AI systems. Instead, the AI Act aims to achieve its stated policy objectives with the focus on transparency (including documentation) and human oversight. Finally, in order to concretely illustrate our findings and conclusions, a use case on AI-based proctoring is presented.

31 May 2018 in IEEE Transactions on Intelligent Transportation Systems
Verified
Journal Article
Closed access
RMRaul Quintero Minguez
Raul Quintero Minguez
IAIgnacio Parra Alonso
Ignacio Parra Alonso
David Fernández-LlorcaDavid Fernández-Llorca
David Fernández-Llorca
MSMiguel Angel Sotelo
Miguel Angel Sotelo
According to several reports published by worldwide organizations, thousands of pedestrians die in road accidents every year. Due to this fact, vehicular technologies have been evolving with the intent of reducing these fatalities. This evolution has not finished yet, since, for instance, the predictions of pedestrian paths could improve the current automatic emergency braking systems. For this reason, this paper proposes a method to predict future pedestrian paths, poses, and intentions up to 1 s in advance. This method is based on balanced Gaussian process dynamical models (B-GPDMs), which reduce the 3-D time-related information extracted from key points or joints placed along pedestrian bodies into low-dimensional spaces. The B-GPDM is also capable of inferring future latent positions and reconstruct their associated observations. However, learning a generic model for all kinds of pedestrian activities normally provides less accurate predictions. For this reason, the proposed method obtains multiple models of four types of activity, i.e., walking, stopping, starting, and standing, and selects the most similar model to estimate future pedestrian states. This method detects starting activities 125 ms after the gait initiation with an accuracy of 80% and recognizes stopping intentions 58.33 ms before the event with an accuracy of 70%. Concerning the path prediction, the mean error for stopping activities at a time-to-event (TTE) of 1 s is 238.01 ± 206.93 mm and, for starting actions, the mean error at a TTE of 0 s is 331.93 ± 254.73 mm.

17 February 2011 in IEEE Transactions on Intelligent Transportation Systems
Verified
Journal Article
Closed access
David Fernández-LlorcaDavid Fernández-Llorca
David Fernández-Llorca
VMVicente Milanes
Vicente Milanes
IAIgnacio Parra Alonso
Ignacio Parra Alonso
MGMiguel Gavilan
Miguel Gavilan
Iván García DazaIván García Daza
Iván García Daza
MSMiguel Angel Sotelo
Miguel Angel Sotelo
Collision avoidance is one of the most difficult and challenging automatic driving operations in the domain of intelligent vehicles. In emergency situations, human drivers are more likely to brake than to steer, although the optimal maneuver would, more frequently, be steering alone. This statement suggests the use of automatic steering as a promising solution to avoid accidents in the future. The objective of this paper is to provide a collision avoidance system (CAS) for autonomous vehicles, focusing on pedestrian collision avoidance. The detection component involves a stereo-vision-based pedestrian detection system that provides suitable measurements of the time to collision. The collision avoidance maneuver is performed using fuzzy controllers for the actuators that mimic human behavior and reactions, along with a high-precision Global Positioning System (GPS), which provides the information needed for the autonomous navigation. The proposed system is evaluated in two steps. First, drivers' behavior and sensor accuracy are studied in experiments carried out by manual driving. This study will be used to define the parameters of the second step, in which automatic pedestrian collision avoidance is carried out at speeds of up to 30 km/h. The performed field tests provided encouraging results and proved the viability of the proposed approach.

4 June 2007 in IEEE Transactions on Intelligent Transportation Systems
Verified
Journal Article
Closed access
IAIgnacio Parra Alonso
Ignacio Parra Alonso
David Fernández-LlorcaDavid Fernández-Llorca
David Fernández-Llorca
MSMiguel Angel Sotelo
Miguel Angel Sotelo
LBLuis M. Bergasa
Luis M. Bergasa
PTPedro Revenga de Toro
Pedro Revenga de Toro
MGMiguel Ángel García-Garrido
Miguel Ángel García-Garrido
This paper describes a comprehensive combination of feature extraction methods for vision-based pedestrian detection in Intelligent Transportation Systems. The basic components of pedestrians are first located in the image and then combined with a support-vector-machine-based classifier. This poses the problem of pedestrian detection in real cluttered road images. Candidate pedestrians are located using a subtractive clustering attention mechanism based on stereo vision. A components-based learning approach is proposed in order to better deal with pedestrian variability, illumination conditions, partial occlusions, and rotations. Extensive comparisons have been carried out using different feature extraction methods as a key to image understanding in real traffic conditions. A database containing thousands of pedestrian samples extracted from real traffic images has been created for learning purposes at either daytime or nighttime. The results achieved to date show interesting conclusions that suggest a combination of feature extraction methods as an essential clue for enhanced detection performance

21 May 2021 in IET Intelligent Transport Systems
Verified
Journal Article
Open access
PDF file
David Fernández-LlorcaDavid Fernández-Llorca
David Fernández-Llorca
AMAntonio Hernández Martínez
Antonio Hernández Martínez
IDIván García Daza
Iván García Daza
The need to accurately estimate the speed of road vehicles is becoming increasingly important for at least two main reasons. First, the number of speed cameras installed worldwide has been growing in recent years, as the introduction and enforcement of appropriate speed limits are considered one of the most effective means to increase the road safety. Second, traffic monitoring and forecasting in road networks plays a fundamental role to enhance traffic, emissions and energy consumption in smart cities, being the speed of the vehicles one of the most relevant parameters of the traffic state. Among the technologies available for the accurate detection of vehicle speed, the use of vision‐based systems brings great challenges to be solved, but also great potential advantages, such as the drastic reduction of costs due to the absence of expensive range sensors, and the possibility of identifying vehicles accurately. This paper provides a review of vision‐based vehicle speed estimation. The terminology and the application domains are described and a complete taxonomy of a large selection of works that categorizes all stages involved is proposed. An overview of performance evaluation metrics and available datasets is provided. Finally, current limitations and future directions are discussed.