Dither Based Precise Position Control of Piezo Actuated MicroNano Manipulator Saikat Kumar Shome Scientist, E & I Group CSIRCMERI, Durgapur, India Saikatkshome[a]cmeri.res.in Sourav Pradhan Dept of Electrical Engg National Institute of Technology  Durgapur, India souravpradhan.sp[a]gmail.com Arpita Mukherjee Sr Scientist, E & I Group CSIRCMERI, Durgapur, India ee.arpita[a]gmail.com Uma Datta Chief Scientist, E & I Group CSIRCMERI, Durgapur, India uma_datta58[a]yahoo.in                                                                                                              !     !     "                 #    $       %                  I. INTRODUCTION Users of modern communication gadgets generally want to eliminate any source of background noise as it degrades system performance. Under certain specified conditions, however, an extra dose of noise can enhance rather than deteriorate the operation of the device. This interesting actuality has in fact now been termed as “dithering” which is presently creating a buzz in major fields of science, such as biomedical science, chemistry, physics and even in other branches of engineering. Dithering refers to the phenomenon that manifests in non linear systems whereby processing of a generally weaker input information can be optimized by the assistance of noise. There are three basic ingredients required for this effect, a) an energy activation barrier in the form of threshold, b) a weak coherent input such as a periodic signal, and c) a noise source that can either be added externally or is inherent within the system [1]. Having these features, the system undergoes a resonance like behavior as a function of noise (disturbance) level which is termed as stochastic resonance. Dithering can be framed as the process of intentionally adding noise to an otherwise uncorrupted signal, basically to enhance the performance of the overall system. The theoretical explanation of the concept of dithering where a resonance can be imbibed into a nonlinear system by introducing small external perturbations is elaborated in [2]. Though one of the most common applications of dither has been in reducing quantization error for analogtodigital conversions [3], stochastic resonance has been observed for a wide variety of systems, that includes, semiconductor devices, chemical reactions, bistable ring lasers, climate change and even in mechanoreceptor cells in the parlance of neurophysiology [46]. Dithering can thus prove to be a control methodology parexcellence for non linear hysteresis compensation targeted at precise nanopositioning. However, the effect of stochastic resonance has not been explored in this genre. In this paper, stochastic resonance has been studied for piezo actuated micronano manipulators and dithering has been used as a control strategy for efficient input tracking using a second order Dahl model. For applications based on control engineering, especially micronano positioning, piezoelectric ceramics (PZT) are recently gaining widespread acceptance. Micronano manipulators have oflate become a topic of active global research as it is a primary component of a wide array of mechanisms used in nanotechnology. Some of the prominent applications in this genre range from Scanning Probe Microscope (SPM), integrated chip circuit assembly line, desktop nanofactory to niche biological cell operators. PZT has almost become a flagship linear actuator employed in the industry owing to its advantages like large blocking force, quick response characteristics, high brittleness and the most important, the capacity to attain subnanometer level positioning accuracy. However, hysteresis is a major drawback of piezoceramics which inadvertently attenuates the positional accuracy of the manipulator, if not tackled properly. This dominant nonlinearity which manifests itself between the input voltage and output displacement is generally taken care of in two stages  first, by capturing it through a subtle mathematical model and second, developing suitable control algorithms for hysteresis compensation. The importance for devising a suitable model to encapsulate hysteresis is the accuracy with which the non linearity is captured with. This is because the more closer we get to the physical system behavior, a finer performance is expected. Some of the commonly used hysteresis models available in literature are the Bouc Wen model, Preisach model, Maxwell model, Duhem model, Dahl model, etc. ＹＷＸＭＱＭＴＷＹＹＭＰＲＲＴＭＸＯＱＳＯＤＳＱＮＰＰ＠ﾩＲＰＱＳ＠ｉｅｅｅ ＳＴＸＶ