![]() For example, lead zirconate titanate crystals will generate measurable piezoelectricity when their static structure is deformed by about 0.1% of the original dimension. The piezoelectric effect is a reversible process: materials exhibiting the piezoelectric effect also exhibit the reverse piezoelectric effect, the internal generation of a mechanical strain resulting from an applied electric field. The piezoelectric effect results from the linear electromechanical interaction between the mechanical and electrical states in crystalline materials with no inversion symmetry. It is derived from Ancient Greek πιέζω ( piézō) 'to squeeze or press', and ἤλεκτρον ( ḗlektron) ' amber' (an ancient source of electric current). The word piezoelectricity means electricity resulting from pressure and latent heat. ![]() Piezoelectricity ( / ˌ p iː z oʊ-, ˌ p iː t s oʊ-, p aɪ ˌ iː z oʊ-/, US: / p i ˌ eɪ z oʊ-, p i ˌ eɪ t s oʊ-/) is the electric charge that accumulates in certain solid materials-such as crystals, certain ceramics, and biological matter such as bone, DNA, and various proteins-in response to applied mechanical stress. The proposed inertial motor features simple mechanical and electrical design, which makes it ideal for miniature electro-mechanical device applications.Electric charge generated in certain solids due to mechanical stress Piezoelectric balance presented by Pierre Curie to Lord Kelvin, Hunterian Museum, Glasgow The maximum efficiency of the motor is 2.1%, which is higher than that of the previously reported piezoelectric inertial rotary motors. Using a preload of 1.07 N, stall torque reaches 1220 Nm driven at 80 Vpp and 35.3 kHz. The maximum no-load angular speed reaches 300 rpm with driving voltage of 60 Vpp at the fundamental resonant frequency of 35.3 kHz in both directions. The rotation direction of the rotor can be reversed by changing the duty ratio. Experiments show that with optimized duty ratios, both the rotation speed and stall torque can be enhanced. It is composed of an aluminum plate (20 mm × 4 mm × 2 mm) sandwiched between two piezoelectric plates (10 mm × 4 mm × 0.73 mm). A bending stator with second harmonics at its double fundamental resonant frequency is designed to generate saw-tooth type displacements under a rectangular pulse. ![]() The rectangular pulse drive methodology is explained and its influence on output displacement of the stator is discussed in relation to four factors: frequency ratio, duty ratio, vibration amplitude ratio, and phase difference. In this paper, a resonant-type piezoelectric inertial motor driven by rectangular pulse is developed. It was shown that the proposed method can be used to generate single-frequency motions with wide range of nanometric sizes with average errors less than 5% of the targeted motion amplitudes. The effectiveness of the presented control method is demonstrated through a set of evaluation tests on two different three-axis piezo-stack actuators, where a set of motion-error metrics were defined and quantified. For the higher-order response terms, a compensation approach based on an iterative experimental technique is proposed. The fundamental and the first-order compensatory excitation components are determined analytically using the inverse hFRFs. To obtain the desired motions at a given frequency, the actuator is excited at both the fundamental (motion) frequency and its harmonics, latter of which aiming to compensate for the unwanted higher-harmonic response components that arise due to non-linear dynamic behavior. ![]() In this approach, the dynamic behavior of piezo-stack actuators is represented by the harmonic frequency response functions (hFRFs) that are obtained through an laser Doppler vibrometry (LDV)-based experimental characterization method. In this paper, an open-loop technique to control the three-dimensional single-frequency motions of multi-axis piezo-stack actuators is presented. Precision control of three-dimensional dynamic motions of piezoelectric actuators is crucial for many applications of nanotechnology and precision engineering. ![]()
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