Analysis of change in motional capacitance of electrical equivalent circuit of quartz-crystal tuning-fork tactile sensor induced by viscoelastic materials in contact with its base

Abstract

We investigated experimentally and theoretically the change in the reciprocal of the motional capacitance Δ(1/Ca) of a quartz-crystal tuning-fork tactile sensor before and after its base comes into contact with neoprene rubbers. We derived the analytical formula for the motional capacitance of the electrical equivalent circuit of the sensor at resonance based on the combination of the L-shaped bar model and viscoelastic foundation model, and the law energy of conservation. We found from both contact experiments and theoretical considerations on the analytical formula that Δ(1/Ca) is intrinsically induced by both the dynamic Young’s modulus and viscosity of neoprene rubbers at 32.5 kHz, which is the actual resonant frequency of the quartz tactile sensor. In this paper, we showed experimentally and theoretically for the first time that the motional capacitance of the tuning fork tactile sensor is affected by the dynamic viscosity of materials in contact with the sensor’s base, except their dynamic Young’s modulus.