Open Access
PhantomFields: fast time and spatial multiplexation of acoustic fields for generation of superresolution patterns
(2021) Elizondo Martínez, Sonia; Goñi Carnicero, Jaime; Galar Idoate, Mikel; Marzo Pérez, Asier; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika
Ultrasonic fields generated by phased arrays can be tailored to obtain a custom pattern of acoustic radiation forces. These force fields can pattern particles as well as be felt by the human hand, enabling applications for bioprinting and contactless haptic devices. The forcé fields can be switched orders of magnitude faster than the reaction time of the particles that it pushes or the human mechanoreceptors of touch. Therefore, a quick multiplexation in time or in space of different acoustic fields will be perceived as the average field. In this paper, we optimise the non-linear problem of decomposing a target force field into several multiplexed acoustic fields. We create averaged fields, PhantomFields, that cannot be created by a regular (unique) emission of an acoustic field. We improve accuracy by time multiplexation and spatial multiplexation, i.e. quick rotation of the emitters. These processes improve the resolution and strength of the obtained fields without the requirement of new hardware, opening up applications in haptic devices and 3D printing.
Open Access
Comparing a mid-air two-hand pinching point-and-click technique with mouse, keyboard and touchfree
(Association for Computing Machinery, 2024-01-18) Lafuente Duque, Melchor; Elizondo Martínez, Sonia; Fernández Ortega, Unai Javier; Marzo Pérez, Asier; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika
Some of our daily activities are performed by interacting with public touchscreens, such as food kiosks, bank tellers and newsstands. Nonetheless, the physical contact with these screens that are used by different people may be considered unhygienic. To avoid contact, some screens already integrate one-hand contactless interaction technologies, i.e. Leap Motion Controller, though they may lead to arm fatigue and slow performance. We present LeapPointer, a mid-Air two-hand pinching point-And-click technique. Specifically, this technique relies on a Leap Motion device to track both hands, and proposes a new software tool that allows bimanual selection through pointing and pinching gestures. A user study was performed to compare LeapPointer with two other techniques: The common mouse/keyboard and the current UltraLeap's TouchFree technique. Task completion time and accuracy as well as subjective data were gathered. The analysis of these data suggested that LeapPointer is significantly faster than the other touchless technique although less accurate. Self-reported fatigue was less with LeapPointer than with TouchFree.
Open Access
Mental workload of guiding devices: directional pulling forces, vibrotactile stimuli and audio cues
(ACM, 2024-06-19) Donkov Bogdanov, Stefan; Elizondo Martínez, Sonia; Ezcurdia Aguirre, Íñigo Fermín; Sarasate Azcona, Iosune; Marzo Pérez, Asier; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika
Asymmetric vibrations are known to produce a pulling sensation when stimulating the human hand. This effect has been exploited as a means of guidance. We conducted a user study to compare asymmetric vibrations, simple vibration, and sound cues for guidance in terms of task completion time and mental workload. Mental workload was evaluated (N=22) using the dual-task paradigm with a Stroop test and arithmetic operations test as secondary tasks. Audio cues improved significantly the task completion time for baseline and stroop tasks compared to the other methods. No significant differences were found for the reaction time for the guiding task. The use of audio cues was evaluated as the less mentally demanding guiding method on the NASA-TLX questionnaire.
Open Access
Enhancing user experience in immersive virtual environments: advances in multiple object selection and affective interaction
(2025) Elizondo Martínez, Sonia; Marzo Pérez, Asier; Ortiz Nicolás, Amalia; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika
Los Entornos Virtuales Inmersivos (EVI) se utilizan para el entretenimiento, la educación, la atención sanitaria y la colaboración remota. Los EVI permiten a los usuarios participar e interactuar con contenido digital tridimensional de manera segura, consistente y controlada. Tres aspectos relevantes para lograr interacciones adecuadas entre los usuarios y los EVI son: 1) diseñar técnicas de interacción semejantes a las acciones del mundo real; 2) integrar tanto capacidades técnicas como emocionales; y 3) realizar evaluaciones exhaustivas de la experiencia de usuario para permitir una mejora constante de las capacidades de los EVI. Esta tesis doctoral ofrece una introducción detallada a los tres aspectos mencionados anteriormente: las técnicas de interacción (con un enfoque en la selección); el campo de la Computación Afectiva y cómo puede mejorar la experiencia de usuario en los EVIs; y los métodos implícitos y explícitos para evaluar tanto necesidades técnicas como emocionales con el fin de lograr una experiencia de usuario completa. Esta tesis también destaca las actuales limitaciones en la implementación de estos aspectos en los entornos virtuales y propone una nueva técnica de selección multiobjeto para los EVIs, así como un marco de diseño para guiar el desarrollo de EVIs con capacidades emocionales.
Open Access
LevPet: a magnetic levitating spherical pet with affective reactions
(ACM, 2022) Sorbet Molina, Josune; Elizondo Martínez, Sonia; Iriarte Cárdenas, Naroa; Ortiz Nicolás, Amalia; Marzo Pérez, Asier; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika
LevPet combines affective computing and magnetic levitation to create an artificial levitating pet with affective responses and novel ways of moving to express emotions. Our interactive pet can recognise the user's emotional status using computer vision, and respond to it with a low-level empathy system based on mirroring behaviour. For example, if you approach it with a happy face, the pet will greet you and move in a nimble way. A repulsive magnetic levitator is attached to a mechanical stage controlled by a computer system. On top of it, there is the pet playground, where a house, a ping-pong ball,a xylophone and other accessories are placed. Two cameras allow to capture the user's face and the objects placed on the playground, so that the pet can interact with them. LevPet is an exploration of how to communicate internal state with only a levitating sphere; it is a platform for experimentation and an interactive demo that brings together an outer-worldly levitating metallic sphere with familiar things like emotions and a playground made of traditional items.
Open Access
TipTrap: a co-located direct manipulation technique for acoustically levitated content
(ACM, 2022) Jankauskis, Eimontas; Elizondo Martínez, Sonia; Montano Murillo, Roberto; Marzo Pérez, Asier; Martinez Plasencia, Diego; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika
Acoustic levitation has emerged as a promising approach for mid-air displays, by using multiple levitated particles as 3D voxels, cloth and thread props, or high-speed tracer particles, under the promise of creating 3D displays that users can see, hear and feel with their bare eyes, ears and hands. However, interaction with this mid-air content always occurred at a distance, since external objects in the display volume (e.g. user’s hands) can disturb the acoustic fields and make the particles fall. This paper proposes TipTrap, a co-located direct manipulation technique for acoustically levitated particles. TipTrap leverages the reflection of ultrasound on the users’ skin and employs a closed-loop system to create functional acoustic traps 2.1 mm below the fingertips, and addresses its 3 basic stages: selection, manipulation and deselection. We use Finite-Differences Time Domain (FDTD) simulations to explain the principles enabling TipTrap, and explore how finger reflections and user strategies influence the quality of the traps (e.g. approaching direction, orientation and tracking errors), and use these results to design our technique. We then implement the technique, characterizing its performance with a robotic hand setup and finish with an exploration of the ability of TipTrap to manipulate different types of levitated content.
Open Access
Contactless electrostatic piloerection for haptic sensations
(IEEE, 2023) Iriarte Cárdenas, Naroa; Ezcurdia Aguirre, Íñigo Fermín; Elizondo Martínez, Sonia; Irisarri Erviti, Josu; Hemmerling, Daria; Ortiz Nicolás, Amalia; Marzo Pérez, Asier; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika
In this project, we create artificial piloerection using contactless electrostatics to induce tactile sensations in a contactless way. Firstly, we design various high-voltage generators and evaluate them in terms of their static charge, safety and frequency response with different electrodes as well as grounding strategies. Secondly, a psychophysics user study revealed which parts of the upper body are more sensitive to electrostatic piloerection and what adjectives are associated with them. Finally, we combine an electrostatic generator to produce artificial piloerection on the nape with a head-mounted display, this device provides an augmented virtual experience related to fear. We hope that work encourages designers to explore contactless piloerection for enhancing experiences such as music, short movies, video games, or exhibitions.
Open Access
Design of an immersive virtual reality framework to enhance the sense of agency using affective computing technologies
(MDPI, 2023) Ortiz Nicolás, Amalia; Elizondo Martínez, Sonia; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika
Virtual Reality is expanding its use to several fields of application, including health and education. The continuous growth of this technology comes with new challenges related to the ways in which users feel inside these virtual environments. There are various guidelines on ways to enhance users’ virtual experience in terms of immersion or presence. Nonetheless, there is no extensive research on enhancing the sense of agency (SoA), a phenomenon which refers to the self-awareness of initiating, executing, and controlling one’s actions in the world. After reviewing the state of the art of technologies developed in the field of Affective Computing (AC), we propose a framework for designing immersive virtual environments (IVE) to enhance the users’ SoA. The framework defines the flow of interaction between users and the virtual world, as well as the AC technologies required for each interactive component to recognise, interpret and respond coherently within the IVE in order to enhance the SoA.
Open Access
A multi-object grasp technique for placement of objects in virtual reality
(MDPI, 2022) Fernández Ortega, Unai Javier; Elizondo Martínez, Sonia; Iriarte Cárdenas, Naroa; Morales, Rafael; Ortiz Nicolás, Amalia; Marichalar Baraibar, Sebastian Roberto; Ardaiz Villanueva, Óscar; Marzo Pérez, Asier; Institute of Smart Cities - ISC; Universidad Pública de Navarra / Nafarroako Unibertsitate Publikoa
Some daily tasks involve grasping multiple objects in one hand and releasing them in a determined order, for example laying out a surgical table or distributing items on shelves. For training these tasks in Virtual Reality (VR), there is no technique for allowing users to grasp multiple objects in one hand in a realistic way, and it is not known if such a technique would benefit user experience. Here, we design a multi-object grasp technique that enables users to grasp multiple objects in one hand and release them in a controlled way. We tested an object placement task under three conditions: real life, VR with single-object grasp and VR with multi-object grasp. Task completion time, distance travelled by the hands and subjective experience were measured in three scenarios: sitting in front of a desktop table, standing up in front of shelves and a room-size scenario where walking was required. Results show that the performance in a real environment is better than in Virtual Reality, both for single-object and multi-object grasping. The single-object technique performs better than the multi-object, except for the room scenario, where multi-object leads to less distance travelled and reported physical demand. For use cases where the distances are small (i.e., desktop scenario), single-object grasp is simpler and easier to understand. For larger scenarios, the multi-object grasp technique represents a good option that can be considered by other application designers.
Open Access
Enhancing the quality of amplitude patterns using time-multiplexed virtual acoustic fields
(American Institute of Physics, 2023) Elizondo Martínez, Sonia; Ezcurdia Aguirre, Íñigo Fermín; Goñi Carnicero, Jaime; Galar Idoate, Mikel; Marzo Pérez, Asier; Estadística, Informática y Matemáticas; Estatistika, Informatika eta Matematika
Ultrasonic fields can push and levitate particles, heat up materials, induce contactless tactile stimuli, or affect the blood-brain barrier. Current phased-arrays can create dynamic amplitude patterns, but their quality may be insufficient due to the limited density of emitters. On the other hand, passive modulators can provide high quality, but only static patterns can be generated. Here, we show and evaluate how the average of multiple time-multiplexed amplitude fields improves the resolution of the obtained patterns when compared with the traditional single-emission method. We optimize the non-linear problem of decomposing a target amplitude field into multiple fields considering the limitations of the phased-array. The presented technique improves the quality for existing setups without modifying the equipment, having the potential to improve bio-printing, haptic devices, or ultrasonic medical treatments.