CHS: Small: Realistic Navigation in the Third Dimension Using Low Cost, Portable, Wearable Immersive Environment Systems

我们周围的自然世界以丘陵和山谷为特征。人造建筑通常由多层组成，由楼梯、坡道或梯子连接。坡度帮助我们在导航时保持方向，并对人们选择前往目的地的路线有很大影响。然而，到目前为止，在沉浸式环境（IEs）中，坡度和海拔变化的模拟在很大程度上被忽视了，导致在3D世界中进行2D导航。这种情况的缺点是，沉浸式用户获得的体验不太真实，无法学会利用现实世界中典型的垂直信息；此外，当用户能够毫不费力地滑上可能需要绕道的斜坡时，路线学习和导航可能会变得行为不准确。以往解决这一问题的方法通常是使用昂贵、笨重且复杂的硬件，如倾斜跑步机或主动机械系绳；这样的系统需要在设计上进行权衡，可能擅长于模拟一种运动（例如，倾斜），而忽略了其他运动（例如，转弯），而且专用硬件通常还没有在实验室之外成熟。PI先前的研究旨在创建低成本、高保真度和便携式IE系统，该系统将渲染单元和头戴式显示器结合在一起，具有自然运动界面，允许用户通过正常行走和转弯在虚拟世界中导航。在这个项目中，PI将通过实现坡度和高程变化的现实模拟来建立和扩展这项工作。项目成果将有利于人类空间记忆和学习的认知和行为研究，以及涉及路线选择、一般导航、多级旅行和坡度感知等任务的IE培训。最近的研究表明，基于软件的重定向行走技术可以巧妙地扭曲IE（例如，通过不知不觉地旋转用户周围的虚拟世界或缩放用户移动），从而在受限的跟踪区域内实现公里级导航。PI将以这些技术为基础，用简单廉价的硬件模拟坡度。向上或向下行走所需的努力取决于诸如体重、步幅、运动效率、速度、倾斜度和距离等因素，正如人们在自然界中所期望的那样，这些可以很容易地在IE中测量出来。尽管在可穿戴的IE系统中，用户身下的物理表面不能倾斜，但可以调整用户的移动以施加适当的物理努力。此外，PI和他的团队还开发了一种独特的高精度运动接口，该接口由低成本的足部惯性/磁传感器组成，可以精确跟踪用户的步态和行走模式，以测量力的大小和方向，并可以检测非典型的行走动作，例如与楼梯或梯子相关的动作。系统验证将通过一系列行为研究进行，在这些研究中，受试者在相应的真实和沉浸式环境中完成空间感知和导航任务，这些环境包括坡度和/或导致海拔变化的各种人工因素。

The natural world around us is characterized by hills and valleys. Man-made structures are often composed of multiple levels connected by stairways, ramps, or ladders. Slope helps us remain oriented when navigating, and has a strong influence on the routes people elect to follow towards their destinations. To date, however, the simulation of incline and elevation changes has largely been neglected in immersive environments (IEs), resulting in 2D navigation through a 3D world. The downside of this situation is that immersed users receive a less than realistic experience and do not learn to take advantage of vertical information typical of real world situations; moreover, route learning and navigation can become behaviorally inaccurate when users are able to effortlessly glide up inclines that might otherwise require a detour. Historical solutions to this problem are typically comprised of expensive, heavy, and complex hardware such as a tilting treadmill or active mechanical tether; such systems require design tradeoffs that may excel at simulating one type of motion (e.g., an incline) while neglecting others (e.g., turning), and the specialized hardware has generally not matured beyond the lab. The PI's prior research has been aimed at creating low-cost, high-fidelity, and portable IE systems that incorporate a rendering unit and a head-mounted display with a natural locomotion interface that allows users to navigate through virtual worlds by walking and turning normally. In this project the PI will build upon and extend that work by implementing realistic simulations of slope and changing elevation. Project outcomes will benefit cognitive and behavioral research on human spatial memory and learning, as well as IE training for tasks involving route selection, general navigation, multi-level travel, and slope perception. Recent research has demonstrated that software-based redirected walking techniques can subtly distort an IE (e.g., by imperceptibly rotating the virtual world about the user or scaling user movement), to enable kilometer-scale navigation in a confined tracking area. The PI will build on these techniques to simulate slope with simple inexpensive hardware. The effort required to walk up or downhill will depend upon factors such as weight, stride length, motion efficiency, speed, incline, and distance, as one would expect in the natural world and which can easily be measured in an IE. Although the physical surface under the user cannot be tilted in a wearable IE system, it is possible to scale user movement to enforce an appropriate amount of physical effort. Moreover, the PI and his team have developed a unique high-precision locomotion interface comprised of low cost foot-mounted inertial/magnetic sensors that can precisely track a user's gait and stepping pattern to measure the amount and direction of force, and can detect atypical stepping actions such as those associated with stairs or ladders. System validation will be carried out through a series of behavioral studies, in which subjects complete spatial perception and navigation tasks in corresponding real and immersive environments that include slope and/or various artefacts that lead to changes in elevation.