The integration of haptics within Augmented Reality may help to deliver an enriched experience, while facilitating the performance of specific actions (e.g. repositioning or resizin ) that are still dependent on the user's skills. This paper gathers the description of a flexible architecture designed to deploy haptically-enabled AR applications. The haptic feedback may be generated through a variety of devices (e.g., wearable, graspable, or mid-air ones), and the architecture facilitates handling the specificity of each. For this reason, it is discussed how to generate a haptic representation of a 3D digital object depending on the application and the target device. Additionally, it is included an analysis of practical, relevant issues that arise when setting up a system to work with specific devices like Head-Mounted Displays (e.g., HoloLens) and mid-air haptic devices (e.g., Ultrahaptics UHK), such as the alignment between the real world and the virtual one. The architecture applicability is demonstrated through the implementation of two applications: Form Inspector and Simon Game, built for HoloLens and iOS mobile phones for visualization and for UHK for mid-air haptics delivery. These applications have been used by nine users to explore the efficiency, meaningfulness, and usefulness of mid-air haptics for form perception, object resizing, and push interaction tasks. Results show that, although mobile interaction is preferred when this option is available, haptics turn out to be more meaningful in identifying shapes when compared to what users initially expect and in contributing to the execution of resizing tasks. Moreover, this preliminary user study reveals that users may be expecting a tailored interface metaphor, not necessarily inspired in natural interaction.

翻译：在增强现实中集成触觉反馈有助于提供更丰富的体验，同时促进特定操作（如重新定位或调整大小）的执行，这些操作目前仍依赖于用户的技能。本文汇集了一种灵活架构的描述，该架构旨在部署支持触觉的增强现实应用。触觉反馈可通过多种设备（如可穿戴式、手持式或空中设备）生成，该架构便于处理各类设备的特性。为此，本文讨论了如何根据应用和目标设备生成三维数字对象的触觉表征。此外，还分析了在配置使用特定设备（如头戴式显示器（例如HoloLens）和空中触觉设备（例如Ultrahaptics UHK））的系统时出现的实际相关问题，例如真实世界与虚拟世界之间的对齐。该架构的适用性通过两个应用的实现得到验证：为HoloLens和iOS手机（用于可视化）以及UHK（用于空中触觉传递）构建的Form Inspector和Simon Game。九名用户使用这些应用探索了空中触觉在形状感知、对象大小调整和按压交互任务中的效率、意义和实用性。结果表明，尽管在可用时用户更倾向于移动交互，但触觉在识别形状方面比用户最初预期的更有意义，并对执行大小调整任务有所贡献。此外，这项初步用户研究显示，用户可能期望一种定制的界面隐喻，而不一定受自然交互的启发。