Finding an unknown object by using piezeoelectric material: A Finite element approach Aydin Azizi, Laaleh Durali, Shahin Zareie, Farid Parvari Rad Department of mechanical engineering, Sharif University of technology, Kish Island, Iran azizi@kish.sharif.edu, Durali_laaleh@kish.sharif.edu, zareie_shahin@kish.sharif.edu, f.parvarirad@yahoo.com Abstract— this paper presents a method to determine material of an unknown sample object. The main objective of this study is to design a database for specifying material of an object. We produce the database for different materials which is subjected to different forces. For this purpose we use a Polyvinidilene Fluoride (PVDF) sensor which is a piezoelectric material. Also we study the effect of changing place of sensor on our study. The detailed design was performed using finite element method analysis. Furthermore, if we have an object which we do not know its material by use of this database we can find out what this object is and how much its Yanoung's modules is. This study will be suitable for medical purposes especially minimally invasive surgery. Keywords- Piezoelectric material; Polyvinidilene Fluoride sensor; Young's modules of materials; Finite element method; minimally invasive surgery I. INTRODUCTION The advances of industrial automation on the one hand, and the advent of micro-electro-mechanical systems (MEMS) technology in recent years on the other hand, have opened the avenue for the design and fabrication of multifunctional tactile sensors. In many applications these sensors are required to replicate the human finger tactile perception capabilities. Teleoperations, not only in medical surgery but also in many areas such as aerospace programs, require both exact measurement of applied forces and close examination of the touched objects. Tactile sensors could play a key role in these processes by providing valuable information about the magnitude of the applied force and its position on the grasper, slippage, and softness of the touched object [1]. A number of tactile sensors have already been designed, analyzed and manufactured, some of them for MIS applications. However, most of the developed tactile sensors are confined to force sensing. In addition, the proposed tactile sensors either are very complex in structure and operation or difficult to microfabricate. Shikida et al [2], reports on an active tactile sensor able to detect both contact force and hardness of an object. Their system consists of a diaphragm with a mesa (a flat-topped projection) at the center, a piezoresistance displacement sensor at the periphery, and a chamber for pneumatic actuation. To detect the hardness distribution, the contacted mesa element is pneumatically driven towards the object. The contacted region of the object is deformed according to the driving force of the mesa element and the hardness of the object. Then from the relationship between the resultant deformation and the driving force generated by pneumatic pressure, the hardness of the contact object can be evaluated. The proposed tactile sensor is microfabricable, which makes it attractive. In today’s digital world, information of real-world events are usually collected, stored, and analyzed with a computer by numerical data. The computer can automate the data acquisition process, enabling fewer errors in data collection. It can easily record measurements with very small time intervals (i.e., much less than a millisecond), minimizing the difference between the analog signal and its digital representation. Moreover, the information can be easily displayed graphically, analyzed, and/or processed by the computer. Owing to the decreasing cost and increasing functionality of computers in both hardware and software, digital data acquisition and control have superseded the analog technology in both laboratories and the industry. As computers are common in today’s world, implementing a digital data acquisition system is often just a moderate expense of add-in boards and support software. As noted, the real-world signals are analogs, not in a form of binary numbers that can be directly stored by a computer [1]. The limitations of human mind are such that it cannot grasp the behavior of its complex surroundings and creations in one operation. Thus the process of subdividing all systems into individual components or 'elements', whose behavior is readily understood, and then rebuilding the original system from such components to study its behavior is a natural way in which the engineers, the scientist or even the economist proceeds[3]. So the finite element method is a suitable way for our problem. A more sophisticated description of the FE method regards it as piecewise polynomial interpolation. That is, over an element, a filed quantity such as displacement is interpolated from values of the filed quantity at nodes. By connecting elements together, the filed quantity becomes interpolated over the entire structure in piecewise fashion, by as much polynomial expression as there are elements. Matrix symbolism for this set of equation is KD=F, where D is vector of unknown (value of the filed quantity at nodes), F is a vector Aydin Azizi Tel: +98 914 141 6821 E-mail: azizi@kish.sharif.edu