Multi-frequency Stimulation: Spatial Differentiation of Bone-Conducted Tactile Stimulation on the Elbow Bony Landmarks

Sensory feedback in upper limb prostheses is a highly desirable feature and bone conduction as one of the feedback methods has shown promising characteristics. Multiple feedback information is required simultaneously for effective grasping and manipulation and has been recently studied in conjunction with bone conduction. The user’s ability to identify the stimulation in the case of simultaneous stimulation of the same frequency on multiple sites via bone conduction has shown a low performance. However, simultaneous stimulation on multiple sites using different frequencies per site has not been studied yet. In this paper, the psychometric evaluation of multiple frequencies on the multiple physiological bony landmarks on the elbow is investigated. The proposed approach is evaluated on a human-subject experiment with ten able-bodied subjects. The vibrotactile transducers are placed on the bony landmarks of the elbow and the identification rate of the number of active stimulation points determined. The outcomes show an increased identification rate for one and three simultaneous stimulation sites.