Finite element analysis of a membrane-type piezoelectric tactile sensor with four sensing elements

This paper focuses on the finite element modeling of a membrane-type piezoelectric tactile sensor with four sensing elements; the membrane is made of polyvinylidene fluoride (PVDF). This tactile sensor, capable of measuring magnitude and position of an applied normal force along with an estimation of the shape of the contacting objects, is an improved version of its already-tested three-element predecessor. It overcomes the problems of crosstalk, complexity, and fragility, which are associated with an array of sensing elements arranged in a matrix form. Difficulties of attaining a closed-form solution are briefly discussed and the results of finite element analysis are presented. Triangulation method is combined with membrane stresses to determine the position and the magnitude of forces. If the force is applied on the membrane by pressing an object on it, then through triangulation an estimation of the shape of the object can be found as well. With this approach the entire area of the tactile sensor becomes active. The sensor is linear, highly sensitive and exhibits high dynamic range. This tactile sensor can potentially be used in robotic and medical applications.