Open Access
Power converter for ultra low-frequency and low-voltage energy harvesters
(SpringerOpen, 2025-05-29) Hualde Otamendi, Mikel; Cruz Blas, Carlos Aristóteles de la; Castellano Aldave, Jesús Carlos; Carlosena García, Alfonso; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Institute of Smart Cities - ISC
Energy conversion mechanisms present in some harvesters are only able to provide very low voltage (mV) and fre‑ quency (few Hz) electrical signals, which may also have a bipolar nature (AC). These characteristics make unusable most conventional power converters to extract from them a DC voltage. This letter describes an autonomous selfstarting ultra-low voltage and frequency AC-DC converter that can start the operation for AC signals around 25 mV, and below 10 Hz. The converter has been designed with ultra-low vibration harvesters in mind, but is also of appli‑ cation to, for instance, thermoelectric generators (TEG). The circuit is basically an oscillator driven by the harvester output, which therefore converts a low-frequency and low-voltage signal into large signal oscillation amenable for further DC conversion. The proposed circuit is based on the classical Hartley oscillator, which is modifed in a non‑ trivial confguration, and optimized to be able to operate with bipolar, low frequency and voltage driving signals. This is achieved with a minimum number of passive components and a single JFET transistor. A practical prototype has been fabricated, and measurement results are obtained, demonstrating the feasibility of the approach. Moreover, a vibration harvester with the power converter proposed has been tested in real conditions in a wind turbine.
Open Access
Dataset for the identification of a ultra-low frequency multidirectional energy harvester for wind turbines
(Elsevier, 2024-11-20) Bacaicoa Díaz, Julen; Hualde Otamendi, Mikel; Merino Olagüe, Mikel; Plaza Puértolas, Aitor; Iriarte Goñi, Xabier; Castellano Aldave, Jesús Carlos; Carlosena García, Alfonso; Ingeniería Eléctrica, Electrónica y de Comunicación; Ingeniaritza Elektrikoa, Elektronikoa eta Telekomunikazio Ingeniaritza; Ingeniería; Ingeniaritza; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
This paper presents a publicly available dataset designed to support the identification (characterization) and performance optimization of an ultra-low-frequency multidirectional vibration energy harvester. The dataset includes detailed measurements from experiments performed to fully characterize its dynamic behaviour. The experimental data encompasses both input (acceleration)-output (energy) relationships, as well as internal system dynamics, measured using a synchronized image processing and signal acquisition system. In addition to the raw input-output data, the dataset also provides post-processed information, such as the angular positions of the moving masses, their velocities and accelerations, derived from recorded high-speed videos at 240 Hz. The dataset also includes the measured power output generated in the coils. This dataset is intended to enable further research on vibration energy harvesters by providing experimental data for identification, model validation, and performance optimization, particularly in the context of energy harvesting in low-frequency and multidirectional environments, such as those encountered in wind turbines.
Open Access
Modelado multiplataforma para el control de un sistema articulado
(UNED, 2023) Ibarrola Chamizo, Javier; Merino Olagüe, Mikel; Iriarte Goñi, Xabier; Hualde Otamendi, Mikel; Ingeniería; Ingeniaritza; Institute of Smart Cities - ISC
En el presente artículo se ha trabajado con las herramientas de simulación de sistemas mecánicos Gazebo y Simulink, realizando una interconexión entre ambos con el fin de desglosar la parte dinámica y cinemática de la parte de control, obtención y tratamiento de datos. La vía de enlace entre ambos programas se realiza mediante otro software de comunicación, ROS. Con todo ello, se ha conseguido la cosimulación de un mecanismo articulado en la cual, Simulink comanda trayectorias a Gazebo a través de pares en articulaciones, Gazebo envía los valores de posición articular de la simulación a Simulink, y mediante el control multiarticular de pares realimentados diseñado en este último programa, se minimiza el error entre la trayectoria simulada y la ideal. La obtención de los parámetros del modelo dinámico requeridos en el control se ha realizado mediante una librería de Matlab (Lib_3D_MEC_Matlab) de análisis de sistemas multicuerpo desarrollada por la UPNA.
Open Access
AI training for application to industrial robotics: trajectory generation for neural network tuning
(Springer, 2023) Merino Olagüe, Mikel; Ibarrola Chamizo, Javier; Aginaga García, Jokin; Hualde Otamendi, Mikel; Ingeniería; Ingeniaritza; Institute of Smart Cities - ISC
In the present work robot trajectories are generated and kinematically simulated. Different data (joint coordinates, end effector position and orientation, images, etc.) are obtained in order to train a neural network suited for applications in robotics. The neural network has the goal of automatically generating trajectories based on a set of images and coordinates. For this purpose, trajectories are designed in two separate sections which are conveniently connected using Bezier curves, ensuring continuity up to accelerations. In addition, among the possible trajectories that can be carried out due to the different configurations of the robot, the most suitable ones have been selected avoiding collisions and singularities. The designed algorithm can be used in multiple applications by adapting its different parameters.
Open Access
LMR-based optical sensor for ethylene detection at visible and mid-infrared regions
(IEEE, 2023) Gallego Martínez, Elieser Ernesto; Hualde Otamendi, Mikel; Ruiz Zamarreño, Carlos; Matías Maestro, Ignacio; Ingeniería Eléctrica, Electrónica y de Comunicación; Institute of Smart Cities - ISC; Ingeniaritza Elektrikoa, Elektronikoaren eta Telekomunikazio Ingeniaritzaren; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Ethylene monitoring has long been a method of controlling the ripening of climacteric fruits, but it turns out that this gas is an important biomarker in biomedical applications. This work presents an optical gas sensor based on the lossy mode resonance (LMR) effect for ethylene detection in planar waveguide configuration. Two different approaches have been explored: one in the visible (VIS) spectral region and the second one in the mid infrared (MIR) region. Optical resonances have been achieved, in all cases, by means of sputtered tin oxide thin films. Response and recovery times were 54 and 246 s, respectively, for the sensor with the resonance in the VIS region, while the device operating in the MIR obtained response and recovery times of 19 and 47 s, respectively. The sensitivity during ethylene detection varied from 93.8 to 187.5 pm/ppm with the devices working in the VIS and MIR regions, respectively. According to the calibration curve, devices show an ethylene limit of detection (LOD) of 4.0058 and 0.6532 ppm in the VIS and MIR spectral regions, respectively, which finds applications in climacteric fruit ripening assessment as well as hemodialysis control. Cross sensitivity with humidity was also characterized for both devices.