V.Yu. Bukin – Master Student, Department “Medical and Technical Information Technology” (BMT-2),  Bauman Moscow State Technical University

E-mail: vladislav_bukin@mail.ru

A.A. Dogadov – Ph.D. Degree in Human Movement and Rehabilitation Sciences, Grenoble Alps University (France), 

E-mail: anton.dogadov@grenoble-inp.fr

M.E. Emelin – Master Student, Bauman Moscow State University; RWTH Aachen University

E-mail: maksemelin@yandex.ru

A.N. Briko – Assistant, Department “Medical and Technical Information Technology” (BMT-2),  Bauman Moscow State Technical University

E-mail: briko@bmstu.ru

S.I. Shchukin – Dr. Sc., Professor, Head of Department “Medical and technical information technology” (BMT-2), Bauman Moscow State Technical University

E-mail: schookin@mx.bmstu.ru

Mechanotactile stimulation is a promising technique, which may implemented in hand prostheses to provide a user feedback. To ensure an adequate feedback perception by a user, an attention must be paid to a choice of a stimulus form used for mechanotactile stimulation.

The aim of the work was to study the influence of the stimulus form on user perception. Two experiments were carried on seven healthy volunteers. During both experiments, to type of stimuli were compared: a cylindrical tip and a hemispherical one. In the first experiment, the stimulus, which was initially out of contact with the subject's skin, was slowly moving towards the subject's forearm, fixed in a setup. The subject was asked to push a button as soon as he notice the touch. At the moment when the subject pushed a button, the stimulus displacement with reference to the skin surface and the forearm reaction force were measured. In the second experiment, the stimulus, which was initially immobile in contact with the skin, stared slowly pressing the forearm. The subject was asked to push a button as soon as he notice the stimulus displacement. The stimulus displacement with reference to initial position and the forearm reaction force were measured.

In first experiment, it was shown that cylindrical stimulus requires 2.42 higher force and 1.72 higher displacement to be noticed by a subject. Moreover, the data from one subject had a smaller variance for a hemispherical stimulus. In the second experiment, it was shown that cylindrical stimulus requires 1.2 higher force to create a displacement, detectable by a subject, than a hemispherical one. This study demonstrates that the shape of the stimulus can affect the dynamic range of the mechanotactile feedback. It was shown that the hemispherical stimulus can be detectable by subjects for smaller displacement; therefore, it provides higher resolution and wider dynamic range. The results of this study can be applied to design mechanotactile feedback in prostheses.

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