Design of a tribometer for investigating tactile perception

The understanding of the tactile perception mechanism implies the reproduction and measurement of friction forces and vibrations induced by the contact between the skin of human fingers and object surfaces. When a finger moves to scan the surface of an object, it activates the receptors located under the skin allowing the brain to identify surfaces and information about their properties. The information concerning the object surface is affected by the forces and vibrations induced by the friction between the skin and the rubbed object. The vibrations propagate in the finger skin and are converted into electric impulses sent to the brain by the mechanoreceptors. Because of the low amplitude of the induced vibrations, it results quite hard to reproduce the tactile surface scanning and measuring it without affecting measurements by external noise coming from the experimental test-bench. In fact the reproduction of the sliding contact between two surfaces implies the relative motion between them, which is obtained by appropriate mechanisms having a more or less complicated kinematics and including several sliding surfaces (bearings, sliders, etc.). It results quite difficult to distinguish between the vibrations coming from the reproduced sliding and the parasitic noise coming from the other sliding contact pairs. This paper presents the design and validation of a tribometer, named TRIBOTOUCH, allowing for reproducing and measuring friction forces and friction induced vibrations that are basilar for a clear understanding of the mechanisms of the tactile sense.