David Castells-Rufas

Dr. David Castells-Rufas

Universitat Autònoma de Barcelona
orcid

Research Focus & Metrics

Academic Career Length

21Years (2006-Present)

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

Representative Publications

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1 January 2020 in IEEE Access
Verified
Journal Article
Open access
JBJuan Borrego-Carazo
Juan Borrego-Carazo
DCDavid Castells-Rufas
David Castells-Rufas
EBErnesto Biempica
Ernesto Biempica
JCJordi Carrabina
Jordi Carrabina
The advent of machine learning (ML) methods for the industry has opened new possibilities in the automotive domain, especially for Advanced Driver Assistance Systems (ADAS). These methods mainly focus on specific problems ranging from traffic sign and light recognition to pedestrian detection. In most cases, the computational resources and power budget found in ADAS systems are constrained while most machine learning methods are computationally intensive. The usual solution consists in adapting the ML models to comply with the memory and real-time (RT) requirements for inference. Some models are easily adapted to resource-constrained hardware, such as Support Vector Machines, while others, like Neural Networks, need more complex processes to fit into the desired hardware. The ADAS hardware (HW platforms) are diverse, from complex MPSoC CPUs down to classical MCUs, DPSs and application-specific FPGAs and ASICs or specific GPU platforms (such as the NVIDIA families Tegra or Jetson). Therefore, there is a tradeoff between the complexity of the ML model implemented and the selected platform that impacts the performance metrics: function results, energy consumption and speed (latency and throughput). In this paper, a survey in the form of systematic review is conducted to analyze the scope of the published research works that embed ML models into resource-constrained implementations for ADAS applications and what are the achievements regarding the ML performance, energy and speed trade-off.

1 August 2015 in Biomedical Signal Processing and Control
Verified
Journal Article
Open access
DCDavid Castells-Rufas
David Castells-Rufas
JCJordi Carrabina
Jordi Carrabina
Detection of QRS complexes in ECG signals is required to determine heart rate, and it is an important step in the study of cardiac disorders. ECG signals are usually affected by noise of low and high frequency. To improve the accuracy of QRS detectors several methods have been proposed to filter out the noise and detect the characteristic pattern of QRS complex. Most of the existing methods are at a disadvantage from relatively high computational complexity or high resource needs making them less optimized for its implementation on portable embedded systems, wearable devices or ultra-low power chips. We present a new method to detect the QRS signal in a simple way with minimal computational cost and resource needs using a novel non-linear filter

11 November 2022 in Computer Methods and Programs in Biomedicine
Verified
Journal Article
Closed access
JBJuan Borrego-Carazo
Juan Borrego-Carazo
CSCarles Sanchez
Carles Sanchez
DCDavid Castells-Rufas
David Castells-Rufas
JCJordi Carrabina
Jordi Carrabina
DGDebora Gil
Debora Gil

16 December 2022 in IEEE Access
Verified
Journal Article
Open access
DCDavid Castells-Rufas
David Castells-Rufas
VNVinh Ngo
Vinh Ngo
JBJuan Borrego-Carazo
Juan Borrego-Carazo
MCMarc Codina
Marc Codina
CSCarles Sanchez
Carles Sanchez
JCJordi Carrabina
Jordi Carrabina
On the road to making self-driving cars a reality, academic and industrial researchers are working hard to continue to increase safety while meeting technical and regulatory constraints Understanding the surrounding environment is a fundamental task in self-driving cars. It requires combining complex computer vision algorithms. Although state-of-the-art algorithms achieve good accuracy, their implementations often require powerful computing platforms with high power consumption. In some cases, the processing speed does not meet real-time constraints. FPGA platforms are often used to implement a category of latency-critical algorithms that demand maximum performance and energy efficiency. Since self-driving car computer vision functions fall into this category, one could expect to see a wide adoption of FPGAs in autonomous cars. In this paper, we survey the computer vision FPGA-based works from the literature targeting automotive applications over the last decade. Based on the survey, we identify the strengths and weaknesses of FPGAs in this domain and future research opportunities and challenges.

13 June 2022 in IEEE Access
Verified
Journal Article
Open access
QAQuim Aguado-Puig
Quim Aguado-Puig
SMSantiago Marco-Sola
Santiago Marco-Sola
JMJuan Carlos Moure
Juan Carlos Moure
DCDavid Castells-Rufas
David Castells-Rufas
LALluc Alvarez
Lluc Alvarez
MMMiquel Moreto
Miquel Moreto
Sequence alignment remains a fundamental problem with practical applications ranging from pattern recognition to computational biology. Traditional algorithms based on dynamic programming are hard to parallelize, require significant amounts of memory, and fail to scale for large inputs. This work presents eWFA-GPU, a GPU (graphics processing unit)-accelerated tool to compute the exact edit-distance sequence alignment based on the wavefront alignment algorithm (WFA). This approach exploits the similarities between the input sequences to accelerate the alignment process while requiring less memory than other algorithms. Our implementation takes full advantage of the massive parallel capabilities of modern GPUs to accelerate the alignment process. In addition, we propose a succinct representation of the alignment data that successfully reduces the overall amount of memory required, allowing the exploitation of the fast shared memory of a GPU. Our results show that our GPU implementation outperforms by 3- $9\times $ the baseline edit-distance WFA implementation running on a 20 core machine. As a result, eWFA-GPU is up to 265 times faster than state-of-the-art CPU implementation, and up to 56 times faster than state-of-the-art GPU implementations.

3 April 2023 in Parallel Computing
Verified
Journal Article
Open access
DCDavid Castells-Rufas
David Castells-Rufas