AdapTics: A Toolkit for Creative Design and Integration of Real-Time Adaptive Mid-Air Ultrasound Tactons

TL;DR

AdapTics introduces an open-source toolkit for designing and real-time rendering adaptive mid-air ultrasound tactons, addressing the limitation of fixed tactons in XR interactions. The system combines the AdapTics Designer (web-based GUI) with the AdapTics Engine (Rust core and API), plus a Unity package, to enable parametric adaptations driven by external parameters and conditional triggers. It defines a five-dimensional design space for adaptive tactons and demonstrates that adaptive features improve Creativity Support Index scores for Exploration and Expressiveness in a study with 12 XR/haptics designers. The work suggests significant potential for expressive, context-aware haptic feedback in VR/AR, while outlining limitations and avenues for extending adaptive design to other technologies and cross-modal orchestration with adaptive audio.

Abstract

Mid-air ultrasound haptic technology can enhance user interaction and immersion in extended reality (XR) applications through contactless touch feedback. Yet, existing design tools for mid-air haptics primarily support creating tactile sensations (i.e., tactons) which cannot change at runtime. These tactons lack expressiveness in interactive scenarios where a continuous closed-loop response to user movement or environmental states is desirable. This paper introduces AdapTics, a toolkit featuring a graphical interface for rapid prototyping of adaptive tactons-dynamic sensations that can adjust at runtime based on user interactions, environmental changes, or other inputs. A software library and a Unity package accompany the graphical interface to enable integration of adaptive tactons in existing applications. We present the design space offered by AdapTics for creating adaptive mid-air ultrasound tactons and show the design tool can improve Creativity Support Index ratings for Exploration and Expressiveness in a user study with 12 XR and haptic designers.

Figures (7)

• Figure 1: The design space of adaptive mid-air ultrasound tactons in AdapTics with five dimensions and their possible values. An adaptive tacton can have multiple values on each dimension such as adaptations to both size and rotation under spatial configuration (D3).
• Figure 2: The AdapTics Designer's web interface showing the Design Library, Pattern Design Canvas, Keyframe Editor Tab, External Parameters Panel, Timeline Pane, and the Post Processing Tab.
• Figure 3: AdapTics Designer's integrated 3D simulation environment showcases the testing of an adaptive tacton for a button. The Button scene uses hand tracking to update the values of the external parameters in real-time, visible in the External Parameters Panel. Also, the Keyframe Editor showcases using the parameters both within formulas and in conditional jumps.
• Figure 4: Example usage of the AdapTics Engine API in C showcasing functions for (1) loading and playing the tacton, and (2) updating the tacton with the "progress" external parameter.
• Figure 5: Results of a synthetic benchmark profiling the maximum update rate achievable by the AdapTics Engine when evaluating adaptive tactons. Starting from the beginning of each tacton, 1000 batches of 40 samples were evaluated as quickly as possible, giving a theoretical maximum update rate for the focal point. The tactons had between 1 (Baseline) and 124 keyframes (RainBench2x). The RainBenchF tacton has the same number of keyframes as RainBench, but has $\sim$9 times more formula computations.