Proc. of the 2019 IEEE 6th International Conference on Smart Instrumentation, Measurement and Applications (ICSIMA 2019) 27-29 August 2019, Kuala Lumpur, Malaysia Hybrid PSO-Tuned PID and Hysteresis-Observer Based Control for Piezoelectric Micropositioning Stages Marwan Nafea #1 , Zaharuddin Mohamed *2 , Mohamed Sultan Mohamed Ali *3 , Kamyar Mehranzamir #4 , Tariq Rehman *5 # Department of Electrical and Electronic Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia 43500 Semenyih, Selangor, Malaysia * School of Electrical Engineering, Faculty of Engineering, Universiti Teknologi Malaysia 81310 Skudai, Johor, Malaysia 1 marwan.nafea@nottingham.edu.my (Corresponding author), 2 zahar@fke.utm.my, 3 sultan_ali@fke.utm.my, 4 kamyar.mehranzamir@nottingham.edu.my, 5 rtariq2@live.utm.my Abstract—Piezo-actuated micropositioning stages consist of a piezoelectric actuator that operates a positioning system. Hysteresis nonlinearity is one of the significant variables limiting the positioning precision of these stages. This paper introduces a technique of developing a hybrid controller for a precise positioning tracking of a piezoelectric micropositioning system. Bouc-Wen nonlinear hysteresis model is utilized to denote the hysteresis nonlinear phenomenon of the piezo-actuated system. A hysteresis observer-based feedforward controller is designed based on Luenberger observer. This feedforward controller is then coupled with a particle swarm optimization (PSO)-based proportional-integral-derivative (PID) feedback controller to form a hybrid controller. A new fitness function is used to compute the optimal PID gains. This fitness function is intended to reduce the overshoot, steady-state error, and the rise and settling times. The findings of this work indicate that using the developed controller structure can significantly decrease the hysteresis effect. In addition, the proposed structure shows the ability to reduce the error is to 0.046% of the maximum displacement range. Such performance demonstrates that the proposed hybrid control structure is efficient for precise micropositioning applications. Keywords—PSO; PID; piezoelectric; Bouc-Wen; feedback; feedforward I. INTRODUCTION Micropositioning stages have been extensively implemented in various applications apps, including imaging tunneling microscopy, atomic force microscopy, optical bridge connections, and parallel test-based data storage systems. Various micropositioning stages with different actuation mechanisms and structures have been developed. Such actuating mechanisms include electrostatic [1], shape-memory- alloy [2], electromagnetic [3], electrothermal [4], and piezoelectric actuators [5]. The choice of the suitable type of microactuators depends on the specifications of the actuator and the system, the ability of the integration with the fabrication process, and the economic feasibility. One of the most important factors that should be taken in account to satisfy these conditions is the efficiency of the microactuator, which is the ratio of the mechanical work output to the energy input of the actuator during a complete operation cycle. Electrostatic microactuators are high efficient actuators, but their stroke is small, require very high voltage over narrow gaps between electrodes, and have a short lifetime, which limit the applications of the device [6]. Electromagnetic microactuators possess high efficiency, but they have limitations in terms of operation and material compatibility, as well as the integration of the magnetic materials into the overall fabrication process. Thermal and shape-memory-alloy microactuators have low efficiency and slower cycle rates than other types of microactuators [7]. Piezoelectric microactuators have the highest efficiency among other types of actuators. Furthermore, they have the advantages of and high stiffness, fast response, and high resolution in the nanometer range, which make them favorable to be used in micropositioning stages. The primary shortcomings of piezoelectric actuators are nonlinearity induced by the creep phenomenon, high-frequency vibrations, and hysteresis [8]. Creep is a slight shift in the position after the required displacement when a steady voltage is applied to the terminals of the piezoelectric actuator. This behavior leads to a poor precision when positioning is required for a long time. Creep can be reduced by operating the piezoelectric actuator over a short duration of time. This phenomenon is often represented by a nonlinear logarithmic model of time and input voltage [9], or a linear dynamic model. On the other side, when a piezoelectric actuator is operated at frequencies near to its first resonant frequency, unwanted vibrations occur. This limits the operating frequencies of the piezoelectric actuator to less than 1% to 10% of the first resonant frequency [10]. These vibrations are usually simulated and compensated depending on the identified dynamics of the piezoelectric actuator [11]. While hysteresis produces severe nonlinear effects on the movement of piezoelectric actuator, the nonlinear effects of creep and near-resonant vibrations are comparatively low. The nonlinear relationship that relates the applied voltage and the produced displacement creates problems in regulating the displacement of the piezoelectric actuator [12]. Charge-driven method was utilized by several This work was supported by the University of Nottingham Malaysia, Prototype Research Grant Scheme (PRGS) 4L690 by the Ministry of Education Malaysia, and UTM Shine 04G75 by Universiti Teknologi Malaysia. Authorized licensed use limited to: UNIVERSITY TEKNOLOGI MALAYSIA. Downloaded on July 21,2021 at 04:44:56 UTC from IEEE Xplore. Restrictions apply. brought to you by CORE View metadata, citation and similar papers at core.ac.uk provided by Universiti Teknologi Malaysia Institutional Repository