Jankauskis, EimontasElizondo Martínez, SoniaMontano Murillo, RobertoMarzo Pérez, AsierMartinez Plasencia, Diego2023-06-162023-06-162022Jankauskis, E., Elizondo, S., Montano Murillo, R., Marzo, A., & Martinez Plasencia, D. (2022). Tiptrap: A co-located direct manipulation technique for acoustically levitated content. Proceedings of the 35th Annual ACM Symposium on User Interface Software and Technology, 1-11. https://doi.org/10.1145/3526113.3545675978-1-4503-9320-110.1145/3526113.3545675https://academica-e.unavarra.es/handle/2454/45517Acoustic 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.application/pdfeng© 2023 Association for Computing Machinery. This is the author's version of the work. It is posted here for your personal use. Not for redistribution. The definitive Version of Record was published in UIST '22: Proceedings of the 35th Annual ACM Symposium on User Interface Software and Technology. October 2022. Article No. 60. Pages 1-11 https://doi.org/10.1145/3526113.3545675Acoustic levitationCo-located direct manipulationInteraction techniquesSpatial interactioninfo:eu-repo/semantics/conferenceObject2023-06-16info:eu-repo/semantics/openAccess