Comparative analysis of traditional and modern controller for piezoelectric actuated nanopositioner

Abstract

Nanopositioning, Precise control and manipulation of devices and materials at nanoscale is the most important constraint of nanotechnology. Nanopositioning stage consisting of piezoelectric actuator has widespread use in applications requiring positioning with precision at nanoscale. In this paper, open loop characteristics of the non minimum phase nanopositioning system are investigated. To guarantee high precision positioning and improvement in the system characteristics demands different types of feedback controllers. The main aim of the controller is to design a closed loop system with good dynamic characteristics and to maintain the desired stability margins. PID controller is a generic closed loop controller widely used for industrial control applications. This paper presents design of PID controller using Ziegler Nichols tuning method. This paper analyzes time and frequency response of traditional PID controller. Non minimum phase system can be stabilized more effectively by modern controller such as pole placement controller, Linear Quadratic Regulator (LQR) and H infinity controllers. This paper develops a methodology for the design of full state feedback controller using pole placement and LQR control techniques. Step response and frequency responses under variety of conditions are plotted and analyzed to verify the effectiveness of the proposed controllers. Closed loop system is analyzed in both time and frequency domain for different dynamic characteristics such as rise time, settling time, maximum overshot and stability margins. A comparative assessment based upon the system’s response characteristics of traditional PID controller, pole placement controller and LQR controller is presented. Simulation results for the performance analysis are carried out on MATLAB and demonstrate effectiveness and adaptability of controller for precise control of piezoelectric actuated nanopositioning system.