![]() Various of stepping piezoelectric actuators can be further classified into three motion types, involving inchworm type, friction-inertia type, and parasitic type. Hence, stepping principle has attracted much attention in the piezoelectric actuator development in the recent decades. By this way, high-precision positioning accuracy can be achieved in long working stroke. ![]() Stepping principle realizes the long working stroke by step displacement accumulation. However, the interfacial wear and heat generation are lack of adequate solution to date, especially in high-speed & full-load motion. Ultrasonic principle utilizes the resonance of stators to drive the slider/rotor. Therefore, the direct-driven principle gradually loses its popularity in the recent years. However, it is still not long enough for most of the applications, and furthermore complicated flexure hinge-based compliant mechanisms deteriorate the static and dynamic characteristics of the piezoelectric actuators, reducing structural stiffness and intrinsic resonant frequency. The maximum working stroke is extended to tens of micrometers. With the assistance of flexure hinge-based compliant mechanisms, it is found that the working stroke can be amplified up to several times of the original displacement of a single piezoelectric element. Direct-driven principle is the initial application in piezoelectric actuators. In order to extend the working stroke of piezoelectric elements, several methods have been proposed and investigated, which can be classified according to the motion principle into the direct-driven principle, ultrasonic principle, and stepping principle. The applications of such positioning stages are only employed within limited scopes due to micro-scale working stroke. Generally, restricted by the inverse piezoelectric effect of current piezoelectric materials, the displacement of a single piezoelectric element is limited within tens of nanometers to several micrometers. ![]() ![]() Up to now, various of piezoelectric-driven positioning systems with flexure hinge-based compliant mechanisms have been developed and widely applied in many scientific and industrial applications, such as atomic force microscopy (AFM), fast tool servo (FTS) single-point diamond turning and optical adaptive mirror, et al. The piezoelectric actuator is one of the potential alternatives for high-resolution precision positioning systems. Most of the conventional actuators can hardly satisfy the requirements on positioning resolution for precision positioning systems, such as hydro-motors, direct/alternating current motors, pneumatic elements, et al., even with the merits of large output capability, fast response, and long working stroke. Nowadays, long working stroke precision positioning systems with micro-to-nano resolution are significantly demanded in many scientific studies and industrial fields. It is expected that this chapter can assist relevant researchers to understand the basic principle and recent development of PMP piezoelectric actuators. Finally, the current existing issues and some potential research topics in the future are discussed. ![]() The emphasis of this chapter includes three key points, the structural optimization, output characteristic analysis and performance enhancement. This chapter is aimed to introduce the basic definition and typical features of the parasitic motion principle (PMP), followed by summarizing the recent developments and achievements of PMP piezoelectric actuators. Among them, inchworm type, friction-inertia type, and parasitic type are three main types of stepping piezoelectric actuators. Stepping piezoelectric actuators have achieved significant improvements to satisfy the urgent demands on precision positioning with the capability of long working stroke, high accuracy and micro/nano-scale resolution, coupled with the merits of fast response and high stiffness. ![]()
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