Electrical and Electronic Engineering, Industrial and Manufacturing Engineering
53
Scopus Publications
Scopus Publications
Resolution of a positioning system with signal conditioning, based on a PSD optical sensor. Influence of system noise José Luis Lázaro-Galilea, Álvaro De-La-Llana-Calvo, Carlos Andrés Luna-Vázquez, Rubén Gil-Vera, Marina Hernández-Grau Measurement Journal of the International Measurement Confederation, 2026 This paper presents an analysis of the influence of electronic noise from sensors and electronic conditioning circuits on the resolution of measurement in a system based on a PSD (Position Sensitive Device) optical sensor. In a previous study, the authors proposed the design of signal conditioning circuits for optical sensors, which generally supply currents of tens of nA that must be suitably managed before the analogue-to-digital conversion process (total gain close to 20M). The present work comprises an analysis of resolution influenced by the noise of the proposed circuit, considering different choices for retrieving the desired information and taking into account the equivalent noise bandwidth (ENBW) used in each one. Shot noise, thermal noise and flicker noise have been considered for the different stages, as well as how next stages amplified noise of previous ones. Once the global expression of noise and its influence on resolution have been obtained, sensitivity from different parameters and the result of resolution were calculated and discussed. Some of the main results of this work indicate that the resolution on the sensor surface, depending on the method of information retrieval, is between 3 and 12 μ m . This value translated to resolution in space, at a distance of 3.5 m and with a lens on the sensor of focal f=8 mm is from 1.3 to 5.2 mm. • The study addresses how system noise affects the resolution of a light beam’s impact on a PSD photodetector and its measurement projection. This is crucial for applications requiring precise spatial measurements. • The analysis focuses on obtaining the noise expression at the output of a three-stage conditioning system. This expression is vital for determining resolution, as signal increments smaller than the noise level cannot be detected. • The input voltage noise density of the first stage’s operational amplifier (OA) contributes to over 50% of the output noise. Given the amplification value of 20M, it is essential to use OAs with the lowest possible noise, provided their gain-bandwidth product (GBP) supports the necessary frequencies. • The resistor used for biasing the PSD photodiode significantly influences noise. Its value must be carefully balanced to maintain a linear response while minimizing noise. A small resistor value prevents variation in the polarization point due to the PSD’s continuous current component, but increases noise. Conversely, a large resistor value risks non-linear response. • Sensitivity analysis of different parameters revealed their contributions to the noise power spectral density at the output. This analysis helps identify which parameters most significantly affect resolution, guiding improvements in system design.
Feasibility of PSD-Based Indoor Positioning in Smoke-Filled Environments Using Building Luminaires Álvaro De-La-Llana-Calvo, José-Luis Lázaro-Galilea, María-Cristina Rodríguez-Sánchez, Rubén Gil-Vera, Héctor Chinchero-Villacis, Santiago Murano IEEE Sensors Journal, 2025 This paper investigates the feasibility of a visible light-based indoor positioning system (IPS) using Position-Sensitive Detectors (PSDs) and commercial luminaires in smoke-filled environments. A dataset comprising 285 measurements was collected over 79 minutes in a controlled test room, with visibility levels ranging from 3 to 300 meters. The system was evaluated under varying smoke densities using visibility as the principal metric, calculated via the Beer-Lambert law and Koschmieder equation. Experimental results show that positioning accuracy degrades with increasing smoke levels, with errors remaining below 270 mm even under extreme conditions (visibility ≈ 3 m). Notably, the system detects signals from emitters outside the nominal field of view (FoV) via multipath reflections, with received power increasing under moderate smoke due to enhanced diffusion. In a challenging scenario—receiver placed 3 meters away, behind an obstacle, and under dense smoke—the system maintained signal detection, enabling reliable room-level localization. These findings demonstrate the robustness of PSD-based IPSs in adverse environments and highlight their potential for emergency response applications, such as firefighter tracking and evacuation support, where coarse localization is critical.
Performance-driven visible light sensor for indoor georeferenced positioning Rubén Gil Vera, Álvaro De-La-Llana-Calvo, José Luis Lázaro Galilea, Ignacio Bravo Muñoz, Alfredo Gardel Vicente Sensors and Actuators A Physical, 2025 This paper presents the design and performance evaluation of a visible light sensor tailored for transmitting georeferenced information from light-emitting lamps. A detailed analysis of the IEEE 802.15.7 visible light communication (VLC) standard protocol is carried out, followed by the design and description of a novel custom communication protocol specifically optimized for this application. Unlike existing solutions, which often rely on external databases for georeferenced data retrieval, the proposed protocol enables real-time transmission and localization of information directly through the VLC channel, eliminating the need for additional infrastructure and reducing system complexity. A comparative analysis of theoretical simulations for widely used modulation schemes, including On-Off Keying (OOK), Orthogonal Frequency Division Multiplexing (OFDM), Binary Phase Shift Keying (BPSK), and Frequency Shift Keying (FSK), was conducted in terms of Bit Error Rate (BER) across varying CNR conditions. The findings indicate that BPSK and FSK offer the best trade-off between implementation simplicity and noise resilience, with BPSK demonstrating superior performance, particularly in scenarios with high noise levels. Conversely, FSK emerges as a viable, low-cost alternative for moderate-noise environments. Experimental tests with light-emitting diodes (LEDs) of different wattage ratings provided insights into the system’s practical performance under real-world conditions, validating theoretical and simulation results. By integrating LEDs of varying wattages into the evaluation process, this study highlights the system’s adaptability to different light sources and noise conditions. • Tailored VLP sensor system for georeferenced positioning in indoor applications. • System locates users providing emitter georeferenced data and communication exchange. • Protocol ensures robust sync, precise detection and reusability in low-complexity apps. • Adaptable, low-cost sensor system with low computational demands for wide applications.
Electronic Circuit for the Signal Conditioning of PSD Optical Sensors José Luis Lázaro-Galilea, Álvaro De-La-Llana-Calvo, Carlos Andrés Luna-Vázquez, Alfredo Gardel-Vicente, Ignacio Bravo-Muñoz, Carlos Cruz-De-La-Torre IEEE Transactions on Instrumentation and Measurement, 2025 This article presents the methodological process to be followed in the design of signal conditioning circuits for optical sensors (position sensitive detector (PSD) or photodiodes), which generally supply currents of nanoamperes that must be suitably managed before the analog-to-digital conversion process. The first step is to define the requirements for the signal supplied by the sensors and the signal to be sent to the analog-to-digital converter (ADC), taking into account the operating conditions and the configuration of the sensors. The various aspects to be taken into account in the design stages are presented below. In the first stage of the conditioning circuit, the output of the sensors is adapted with a high-gain transimpedance stage and low-pass filtering. In the next stages, the gain is increased to the values required to make maximum use of the dynamic range of the ADC (total gain close to 20M). Two alternatives are studied, one of first order and the other of second order. In both cases, high-pass filtering is performed to eliminate low-frequency optical signal noise, the noise bandwidth is reduced to obtain a flat response in the passband, and the output offset is limited. In the third stage, a gain adjustment is introduced and the appropriate bias is added to the signal to be delivered to the ADC. The design methodology is analyzed using SPICE to verify that the necessary requirements are met. The circuits are then implemented to verify that they behave as required.
Vehicle-to-Vehicle VLC Based on PSD Sensor: System Modeling and Effects of Multipath in Unfavorable Situations Fatima Zahra Raissouni, Álvaro De-La-Llana-Calvo, José Luis Lázaro-Galilea, Alfredo Gardel-Vicente, Abdeljabbar Cherkaoui IEEE Sensors Journal, 2024 Vehicular communication based visible light presents an excellent solution to ensure road safety and transportation efficiency in critical environments like tunnels, underground garages, or covered parking lots where traditionally RF solutions cannot provide an efficient communication. In this paper, we propose a new multipath channel model for V2V-VLC in unfavorable situations like in tunnels by using a PSD sensor. The performance of the derived channel model is evaluated using statistical measures based on numerical simulations in terms of channel impulse response, channel DC gain and RMS delay spread to quantify the effects of multipath propagation. Monte Carlo simulation is also used to explore the statistical model obtained for different transmission scenarios. Additionally, we evaluate the influence of various model parameters, such as road width and inter-vehicular distance, on the performance of the V2V channel. The main results are compared with typical Lambertian reflector model to confirm the validity of the proposed model.
Seamless Mobile Indoor Navigation with VLP-PDR Aitor Alcázar-Fernández, Álvaro De-La-Llana-Calvo, José Luis Lázaro-Galilea, Antoni Pérez-Navarro, Rubén Gil-Vera, Alfredo Gardel-Vicente IEEE Sensors Journal, 2024 This study unveils a mobile app-based Indoor Positioning System (IPS) tailored for seamless museum navigation. Leveraging smartphone Inertial Measurement Unit (IMU) sensors, it incorporates a Pedestrian Dead Reckoning (PDR) algorithm and a Visible Light Positioning (VLP) beacon-based Angle of Arrival (AoA) algorithm for precise user positioning relative to smart light sources. In standalone mode, the VLP AoA-based algorithm demonstrates reliability with a mean error of 10.64 cm, while the PDR algorithm, operating independently, exhibits mean error of 3 m influenced by environmental factors. Integration of both algorithms proves crucial in mitigating cumulative errors. By updating PDR deviations with the precision provided by the VLP AoA-based solution, the entire system minimizes its mean error to 0.85 m. The user-friendly interface not only enriches visitor experiences with contextual information but also enables intuitive navigation without continuous internet connectivity. This innovative solution caters to the critical demand for precise indoor navigation, particularly in museum environments, fostering increased user acceptance and utilization.
Vehicular Visible Light Positioning System Based on a PSD Detector Fatima Zahra Raissouni, Álvaro De-La-Llana-Calvo, José Luis Lázaro-Galilea, Alfredo Gardel-Vicente, Abdeljabbar Cherkaoui, Ignacio Bravo-Muñoz Sensors, 2024 In this paper, we explore the use of visible light positioning (VLP) technology in vehicles in intelligent transportation systems (ITS), highlighting its potential for maintaining effective line of sight (LOS) and providing high-accuracy positioning between vehicles. The proposed system (V2V-VLP) is based on a position-sensitive detector (PSD) and exploiting car taillights to determine the position and inter-vehicular distance by angle of arrival (AoA) measurements. The integration of the PSD sensor in vehicles promises exceptional positioning accuracy, opening new prospects for navigation and driving safety. The results revealed that the proposed system enables precise measurement of position and distance between vehicles, including lateral distance. We evaluated the impact of different focal lengths on the system performance, achieving cm-level accuracy for distances up to 35 m, with an optimum focal length of 25 mm, and under low signal-to-noise conditions, which meets the standards required for safe and reliable V2V applications. Several experimental tests were carried out to validate the results of the simulations.
Accuracy and Precision of Agents Orientation in an Indoor Positioning System Using Multiple Infrastructure Lighting Spotlights and a PSD Sensor Álvaro De-La-Llana-Calvo, José Luis Lázaro-Galilea, Aitor Alcázar-Fernández, Alfredo Gardel-Vicente, Ignacio Bravo-Muñoz, Andreea Iamnitchi Sensors, 2022 In indoor localization there are applications in which the orientation of the agent to be located is as important as knowing the position. In this paper we present the results of the orientation estimation from a local positioning system based on position-sensitive device (PSD) sensors and the visible light emitted from the illumination of the room in which it is located. The orientation estimation will require that the PSD sensor receives signal from either 2 or 4 light sources simultaneously. As will be shown in the article, the error determining the rotation angle of the agent with the on-board sensor is less than 0.2 degrees for two emitters. On the other hand, by using 4 light sources the three Euler rotation angles are determined, with mean errors in the measurements smaller than 0.35° for the x- and y-axis and 0.16° for the z-axis. The accuracy of the measurement has been evaluated experimentally in a 2.5 m-high ceiling room over an area of 2.2 m2 using geodetic measurement tools to establish the reference ground truth values.
Dynamic insulin basal needs estimation and parameters adjustment in type 1 diabetes Jesús Berián, Ignacio Bravo, Alfredo Gardel-Vicente, José-Luis Lázaro-Galilea, Mercedes Rigla Sensors, 2021 Technology advances have made possible improvements such as Continuous Glucose Monitors, giving the patient a glucose reading every few minutes, or insulin pumps, allowing more personalized therapies. With the increasing number of available closed-loop systems, new challenges appear regarding algorithms and functionalities. Several of the analysed systems in this paper try to adapt to changes in some patients’ conditions and, in several of these systems, other variables such as basal needs are considered fixed from day to day to simplify the control problem. Therefore, these systems require a correct adjustment of the basal needs profile which becomes crucial to obtain good results. In this paper a novel approach tries to dynamically determine the insulin basal needs of the patient and use this information within a closed-loop algorithm, allowing the system to dynamically adjust in situations of illness, exercise, high-fat-content meals or even partially blocked infusion sites and avoiding the need for setting a basal profile that approximately matches the basal needs of the patient. The insulin sensitivity factor and the glycemic target are also dynamically modified according to the situation of the patient. Basal insulin needs are dynamically determined through linear regression via the decomposition of previously dosed insulin and its effect on the patient’s glycemia. Using the obtained value as basal insulin needs and other mechanisms such as basal needs modification through its trend, ISF and glycemic targets modification and low-glucose-suspend threshold, the safety of the algorithm is improved. The dynamic basal insulin needs determination was successfully included in a closed-loop control algorithm and was simulated on 30 virtual patients (10 adults, 10 adolescent and 10 children) using an open-source python implementation of the FDA-approved (Food and Drug Administration) UVa (University of Virginia)/Padova Simulator. Simulations showed that the proposed system dynamically determines the basal needs and can adapt to a partial blockage of the insulin infusion, obtaining similar results in terms of time in range to the case in which no blockage was simulated. The proposed algorithm can be incorporated to other current closed-loop control algorithms to directly estimate the patient’s basal insulin needs or as a monitoring channel to detect situations in which basal needs may differ from the expected ones.
Weak calibration of a visible light positioning system based on a position-sensitive detector: Positioning error assessment Álvaro De-La-Llana-Calvo, José-Luis Lázaro-Galilea, Alfredo Gardel-Vicente, David Salido-Monzú, Ignacio Bravo-Muñoz, Andreea Iamnitchi, Rubén Gil-Vera Sensors, 2021 Reduced deployment and calibration requirements are key for scalable and cost-effective indoor positioning systems. In this work, we propose a low-complexity, weak calibration procedure for an indoor positioning system based on infrastructure lighting and a positioning-sensitive detector. The proposed calibration relies on genetic algorithms to obtain the relevant system parameters in the real positioning environment without a priori information, and requires a low number of simple measurements. The achievable performance of the proposal was assessed by direct comparison with a formal offline calibration method requiring complex dedicated infrastructure and instruments. The comparative error assessment showed that the maximum accuracy reduction compared to the significantly more costly formal calibration was below 25 mm, and the overall absolute positioning error was smaller than 35 mm with orientation errors of around 0.25°. The performance achieved with the proposed weak calibration procedure is sufficient for many indoor positioning applications and largely reduces the cost and complexity of setting up the positioning system in real environments.
Indoor Positioning System Based on LED lighting and PSD Sensor A. De-La-Llana-Calvo, J. L. Lazaro-Galilea, A. Gardel-Vicente, D. Rodriguez-Navarro, I. Bravo-Munoz 2019 International Conference on Indoor Positioning and Indoor Navigation Ipin 2019, 2019
Simplified Calibration Process for a PSD-Based Optical IPS D. Rodriguez-Navarro, J.L. Lazaro-Galilea, F. Espinosa, A. De-La-Llana-Calvo, C. Santos Ipin 2018 9th International Conference on Indoor Positioning and Indoor Navigation, 2018
Indoor positioning system based on PSD sensor David Rodríguez-Navarro, José Luis Lázaro-Galilea, Alfredo Gardel-Vicente, Ignacio Bravo-Muñoz, Álvaro De-La-Llana-Calvo Geographical and Fingerprinting Data for Positioning and Navigation Systems Challenges Experiences and Technology Roadmap, 2018
Modeling the effect of optical signal multipath Álvaro De-La-Llana-Calvo, José Lázaro-Galilea, Alfredo Gardel-Vicente, David Rodríguez-Navarro, Ignacio Bravo-Muñoz, Georgios Tsirigotis, Juan Iglesias-Miguel Sensors Switzerland, 2017
Sensor deployment for motion trajectory tracking with a genetic algorithm Francisco Domingo-Perez, Jose Luis Lazaro-Galilea, Ignacio Bravo, Ernesto Martin-Gorostiza, David Salido-Monzu, Alvaro Llana, Felix Govaers Proceedings of the IEEE International Conference on Industrial Technology, 2015
Infrared local positioning system using phase differences Ernesto Martin-Gorostiza, Francisco Javier Meca-Meca, Jose Luis Lazaro-Galilea, David Salido-Monzu, Eduardo Martos-Naya, Andreas Wieser 2014 Ubiquitous Positioning Indoor Navigation and Location Based Service Upinlbs 2014 Conference Proceedings, 2015
