Virtual environments (VEs) allow safe, repeatable, and controlled evaluations of obstacle avoidance and navigation performance of people with visual impairments using visual aids. Proper simulation of mobility in a VE requires an interface, which allows subjects to set their walking pace. Using conventional treadmills, the subject can change their walking speed by pushing the tread with their feet, while leveraging handrails or ropes (self-propelled mode). We developed a feedback-controlled locomotion interface that allows the VE workstation to control the speed of the treadmill, based on the position of the user. The position and speed information is also used to implement automated safety measures, so that the treadmill can be halted in case of erratic behavior. We compared the feedback-controlled to the self-propelled mode by using speed-matching tasks (follow a moving object or match the speed of an independently moving scene) to measure the efficacy of each mode in maintaining constant subject position, subject control of the treadmill, and subject pulse rates. In addition, we measured the perception of speed in the VE on each mode. The feedback-controlled mode required less physical exertion than self-propelled. The average position of subjects on the feedback-controlled treadmill was always within a centimeter of the desired position. There was a smaller standard deviation in subject position when using the self-propelled mode than when using the feedback-controlled mode, but the difference averaged less than 6 cm across all subjects walking at a constant speed. Although all subjects underestimated the speed of an independently moving scene at higher speeds, their estimates were more accurate when using the feedback-controlled treadmill than the self-propelled.

中文翻译：

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虚拟环境中跑步机运动的反馈控制界面

虚拟环境 (VE) 允许使用视觉辅助设备对视力障碍者的避障和导航性能进行安全、可重复和可控的评估。正确模拟 VE 中的移动性需要一个界面，该界面允许受试者设置他们的步行速度。使用传统的跑步机，受试者可以通过用脚推动踏板来改变他们的步行速度，同时利用扶手或绳索（自行模式）。我们开发了一个反馈控制的运动界面，允许 VE 工作站根据用户的位置控制跑步机的速度。位置和速度信息还用于实施自动安全措施，以便在出现异常行为时停止跑步机。我们通过使用速度匹配任务（跟随移动物体或匹配独立移动场景的速度）将反馈控制模式与自走模式进行比较，以测量每种模式在保持恒定主体位置、主体控制方面的功效跑步机和受试者的脉搏率。此外，我们测量了 VE 在每种模式下的速度感知。反馈控制模式比自走式需要更少的体力消耗。反馈控制跑步机上受试者的平均位置始终在所需位置的一厘米以内。与使用反馈控制模式相比，使用自走模式时受试者位置的标准偏差更小，但所有以恒定速度行走的受试者的差异平均小于 6 厘米。