Vibration Propagation on the Skin of the Arm

Abstract

Vibrotactile interfaces are an inexpensive and non-invasive way to provide performance feedback to body-machine interface users. Interfaces for the upper extremity have utilized a multi-channel approach using an array of vibration motors placed on the upper extremity. However, for successful perception of multi-channel vibrotactile feedback on the arm, we need to account for vibration propagation across the skin. If two stimuli are delivered within a small distance, mechanical propagation of vibration can lead to inaccurate perception of the distinct vibrotactile stimuli. This study sought to characterize vibration propagation across the hairy skin of the forearm. We characterized vibration propagation by measuring accelerations at various distances from a source vibration of variable intensities (100–240 Hz). Our results showed that acceleration from the source vibration was present at a distance of 4 cm at intensities >150 Hz. At distances greater than 8 cm from the source, accelerations were reduced to values substantially below vibrotactile discrimination thresholds for all vibration intensities. We conclude that in future applications of vibrotactile interfaces, stimulation sites should be separated by a distance of at least 8 cm to avoid potential interference in vibration perception caused by propagating vibrations.

Effect of Mechanical Stimulation Applied to the Lower-Limb Musculature on Stability and Function of Stair Climbing

“…Therefore, a difference occurs in the signal transmitted to the sensorimotor cortex according to vibration frequency, while a difference in the mu rhythm reduction rate occurs in response to changes in the vibration frequency. This is in line with the previous study, which reported that the somatosensory response to vibrotactile stimuli is frequency-dependent [27]. In addition, Barbara Marconi et al [28] have confirmed that vibrations that were repeatedly applied to the flexor carpi radialis muscles during voluntary contractions can induce excitatory changes in the primary motor cortex.…”

Tactile spatial discrimination on the torso using vibrotactile and force stimulation

“…Thus, it is not known whether force stimuli are characterized by improved tactile performance (compared to vibrotactile stimuli) in spatial discrimination tasks on the torso. Indeed, force and vibrotactile stimuli present some distinct features; for instance, vibrotactile stimuli are known to spread beyond the limits of the contact area (Cholewiak and Collins 2003 ; Sofia and Jones 2013 ; Shah et al 2019b ), while force stimuli are more focal, and this might lead to better accuracy in spatial discrimination. Here, we measured performance in LOC and DIR tasks and investigated the spatial accuracy of focal force and vibrotactile stimuli on the torso.…”

An Investigation into the Dissipation of Vibrations Using Electromyography towards the Development of Self-Adapting Robotic Prosthesis

“…Additionally, the vibration sensors placed on the skin surface were not accurate enough to be able to distinguish how these physiological differences would affect propagation. The information gathered was primarily used to identify the best placement for vibration sources that alleviates the misperceptions associated from simultaneously applied stimuli [14] [15].…”