Preface

Demand for manufacturing has increased with the development and progress of science and technology. In this regard, piezoelectric actuators and transducers are attracting attention because of characteristics such as millisecond response speed, nanoscale accuracy, power-off self-locking, absence of electromagnetic interference, and no generation of a magnetic field. Owing to their advantages over traditional electromagnetic actuators, piezoelectric actuators and transducers have been used in aerospace engineering, biomedical engineering, artificial intelligence, micro-nano processing, 3D printing, and more. Researchers have developed many novel types of precision piezoelectric actuators and transducers to improve output performance, including velocity, load capacity, and accuracy. This book comprehensively summarizes the latest progress in precision piezoelectric actuators and transducers, such as piezoelectric bionic actuators, piezoelectric stick-slip actuators, piezoelectric direct-driving actuators, and piezoelectric pumps. It also discusses corresponding working principles, excitation signals, design theoretical framework, novel structure, and control methods. This book is a useful reference that provides guidance for the development of piezoelectric actuators and transducers.

Chapter 1 introduces piezoelectric actuators based on different operating principles, including direct-driving piezoelectric actuators, ultrasonic piezoelectric actuators, friction-inertia piezoelectric actuators, and bionic piezoelectric actuators.

Chapter 2 presents an intriguing case where domain walls (DWs) exhibit enhanced electrical conductivity with respect to bulk conductivity. By combining experimental data and modeling, it will be shown that local conductivity, related to the accumulation of charged point defects at DWs, not only affects DW dynamics through DW-defect pinning interactions but also affects the macroscopic nonlinearity and hysteresis in a more complex manner. The chapter also reviews and discusses the major characteristics and implications of the underlying nonlinear Maxwell–Wagner piezoelectric relaxation, triggered by the presence and dynamics of conducting DWs, in the framework of systematic multiscale analyses on BiFeO3 ceramics.

Chapter 3 introduces bionic-type piezoelectric actuators with long-range outputs. First, the chapter discusses commonly used piezoelectric materials and piezoelectric effects, including positive piezoelectric effect and inverse piezoelectric effect. Second, it elaborates on inchworm-type actuators and seal-type actuators, which are classified into the walker type, the pusher type, and the mixed type. Finally, it examines the characteristics of bionic actuators, such as their configurations, classifications, principles, connections, and distinctions.

Chapter 4 introduces a piezoelectric tool actuator used in elliptical vibration cutting, which offers tertiary cutting operations with quick response and flexible modulated ability. The chapter covers the working principles of piezoelectric tool actuators, compliant mechanism design, static modeling, kinematic and dynamic modeling, structure optimization, and offline testing.

Chapter 5 briefly presents three distinctive concepts of micropump actuator driving modules, each with its waveform specifics and impact on micropump performance. The first presented concept is based on two mutually exclusive boost switched-mode power supply modules. Characterization of this module identified output voltage asymmetry to be the limiting factor of micropump performance. To assure driving symmetry, an alternative driving module based on independent high-voltage stages and optocouplers was implemented. Moreover, the design is based on an embedded arbitrary waveform generator, which offers an efficient trade-off between high pumping performance and low current consumption.

Chapter 6 introduces the development of topology optimization and summarizes the design and research of the compliant mechanism of the piezoelectric actuator. The experiments show that the topology optimization method has guiding significance for the design of piezoelectric actuators. The chapter ends by proposing future research directions and challenges of topology optimization design for flexure hinge-type piezoelectric actuators.

Chapter 7 studies the active vibration suppression of an active-passive composite vibration suppression system based on piezoelectric actuators. On the basis of fully analyzing the characteristics of the piezoelectric actuator and displacement amplifying mechanism and the dynamic model of the vibration suppression system, an active composite control strategy based on IFF feedback and RLS adaptive feedforward for vibration suppression on the piezoelectric system is discussed.

Chapter 8 introduces the modeling and control of piezoelectric stick-slip actuators. In the aspect of modeling, the existing mathematical models describing the hysteresis characteristics of piezoelectric stick-slip actuators and the mathematical models of complex friction relationships in the structure are introduced. In terms of control, according to open-loop control and closed-loop control, this chapter summarizes and studies the efforts made to make up for control accuracy, and summarizes many control cases, such as feedforward control, sliding mode control, PID control, neural network control, and others.

We are very grateful for the help of our colleagues who contributed to this book.

**Tinghai Cheng** Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing, China

> **Jianping Li** College of Engineering, Zhejiang Normal University, Jinhua, China

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Section 1

Introduction

Section 1 Introduction
