The effectiveness of haptic feedback devices highly depends on the perception of tactile stimuli, which differs across body parts and can be affected by movement. In this study, a novel wearable sensory feedback apparatus made of a pair of pressure-sensitive insoles and a belt equipped with vibrotactile units is presented; the device provides time-discrete vibrations around the waist, synchronized with biomechanically-relevant gait events during walking. Experiments with fifteen healthy volunteers were carried out to investigate users’ tactile perception on the waist. Stimuli of different intensities were provided at twelve locations, each time synchronously with one pre-defined gait event (i.e. heel strike, flat foot or toe off), following a pseudo-random stimulation sequence. Reaction time, detection rate and localization accuracy were analyzed as functions of the stimulation level and site and the effect of gait events on perception was investigated. Results revealed that above-threshold stimuli (i.e. vibrations characterized by acceleration amplitudes of 1.92g and 2.13g and frequencies of 100 Hz and 150 Hz, respectively) can be effectively perceived in all the sites and successfully localized when the intertactor spacing is set to 10 cm. Moreover, it was found that perception of time-discrete vibrations was not affected by phase-related gating mechanisms, suggesting that the waist could be considered as a preferred body region for delivering haptic feedback during walking.

中文翻译：

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腰部时敏的触觉反馈对步态的影响是不变的

触觉反馈设备的有效性在很大程度上取决于对触觉刺激的感知，这种感觉在身体各部位之间是不同的，并且会受到运动的影响。在这项研究中，提出了一种新型的可穿戴的感觉反馈设备，该设备由一对压敏鞋垫和一条装有触觉感应带的皮带制成。该设备可在腰部提供随时间变化的振动，并与步行过程中与生物力学相关的步态事件同步。进行了15名健康志愿者的实验，以调查使用者腰部的触觉。按照伪随机刺激顺序，在十二个位置提供不同强度的刺激，每次与一个预先定义的步态事件（即脚后跟撞击，扁平足或脚趾脱落）同步。反应时间，分析检测率和定位精度与刺激水平和部位的关系，并研究步态事件对知觉的影响。结果显示，可以在所有位置有效感知阈值以上的刺激（即，振动振幅分别为1.92g和2.13g以及100 Hz和150 Hz的频率），并且在将间隔器间距设置为10时可以成功定位厘米。此外，还发现，时间离散振动的感知不受相位相关门控机制的影响，这表明腰部可被视为步行过程中传递触觉反馈的首选身体部位。振动间隔设置为10 cm时，可以在所有位置上有效地感知到振动振幅为1.92g和2.13g，频率分别为100 Hz和150 Hz的振动，并成功地将其定位。此外，还发现，时间离散振动的感知不受相位相关门控机制的影响，这表明腰部可被视为步行过程中传递触觉反馈的首选身体部位。振动间隔设置为10 cm时，可以在所有位置上有效地感知到振动振幅为1.92g和2.13g，频率分别为100 Hz和150 Hz的振动，并成功地将其定位。此外，还发现，时间离散振动的感知不受相位相关门控机制的影响，这表明腰部可被视为步行过程中传递触觉反馈的首选身体部位。