Mobile Augmented Reality enhances indoor navigation for wheelchair users

Introduction: Individuals with mobility impairments associated with lower limb disabilities often face enormous challenges to participate in routine activities and to move around various environments. For many, the use of wheelchairs is paramount to provide mobility and social inclusion. Nevertheless, they still face a number of challenges to properly function in our society. Among the many difficulties, one in particular stands out: navigating in complex internal environments (indoors). The main objective of this work is to propose an architecture based on Mobile Augmented Reality to support the development of indoor navigation systems dedicated to wheelchair users, that is also capable of recording CAD drawings of the buildings and dealing with accessibility issues for that population. Methods Overall, five main functional requirements are proposed: the ability to allow for indoor navigation by means of Mobile Augmented Reality techniques; the capacity to register and configure building CAD drawings and the position of fiducial markers, points of interest and obstacles to be avoided by the wheelchair user; the capacity to find the best route for wheelchair indoor navigation, taking stairs and other obstacles into account; allow for the visualization of virtual directional arrows in the smartphone displays; and incorporate touch or voice commands to interact with the application. The architecture is proposed as a combination of four layers: User interface; Control; Service; and Infrastructure. A proof-of-concept application was developed and tests were performed with disable volunteers operating manual and electric wheelchairs. Results The application was implemented in Java for the Android operational system. A local database was used to store the test building CAD drawings and the position of fiducial markers and points of interest. The Android Augmented Reality library was used to implement Augmented Reality and the Blender open source library handled the basis for implementing directional navigation arrows. OpenGL ES provided support for various graphics and mathematical transformations for embedded systems, such as smartphones. Experiments were performed in an academic building with various labs, classrooms and male and female bathrooms. Two disable volunteers using wheelchairs showed no difficulties to interact with the application, either by entering touch or voice commands, and to navigate within the testing environment with the help of the navigational arrows implemented by the augmented reality modules. Conclusion The novel features implemented in the proposed architecture, with special emphasis on the use of Mobile Augmented Reality and the ability to identify the best routes free of potential hazards for wheelchair users, were capable of providing significant benefits for wheelchair indoor navigation when compared to current techniques described in the literature.

引言：下肢残疾导致行动障碍的人群，在参与日常活动与在各类环境中通行时往往面临极大困境。对多数此类人群而言，轮椅是保障其行动能力与社会融入的核心工具。尽管如此，他们仍需克服诸多障碍才能在社会中正常生活。在诸多困难中，尤为突出的一项便是在复杂室内环境中通行。本研究的核心目标是提出一种基于移动增强现实（Mobile Augmented Reality）的架构，用于开发专为轮椅使用者设计的室内导航系统；该架构同时可记录建筑CAD绘图，并能针对该人群解决无障碍通行相关问题。

方法：总体而言，本研究提出五项核心功能需求：其一，可通过移动增强现实技术实现室内导航；其二，可注册并配置建筑CAD绘图、基准标记点、兴趣点以及轮椅使用者需避让的障碍物位置；其三，可规划轮椅室内导航的最优路径，同时将楼梯与其他障碍物纳入考量；其四，可在智能手机屏幕上显示虚拟导航箭头；其五，支持通过触控或语音指令与应用程序交互。该架构由四层结构组合而成：用户界面层、控制层、服务层与基础设施层。本研究开发了一款概念验证应用，并招募使用手动轮椅与电动轮椅的残障志愿者开展测试。

结果：该应用基于Java语言开发，适配安卓（Android）操作系统。本地数据库用于存储测试建筑的CAD绘图、基准标记点与兴趣点的位置信息。本研究采用安卓增强现实库实现增强现实功能，并依托Blender开源库构建定向导航箭头的实现基础。OpenGL ES则为智能手机等嵌入式系统提供各类图形与数学变换支持。实验在一栋包含多个实验室、教室及男女卫生间的学术建筑内开展。两名使用轮椅的残障志愿者均可顺利通过触控或语音指令与应用交互，并借助增强现实模块生成的导航箭头在测试环境中完成通行，未遇到任何困难。

结论：相较于现有文献中记载的技术方案，本研究提出的架构所实现的创新功能——尤其突出移动增强现实的应用，以及为轮椅使用者规划无潜在风险最优路径的能力——可为轮椅室内导航带来显著优势。