This study demonstrates a new approach for constructing a rotary piezoelectric motor that utilizes an asymmetric stator driven by a single-phase signal. An asymmetric stator with four driving feet is proposed on the basis of the idea of generating asymmetric action on the rotor. This new motor consists of one piezoelectric transducer with two anchors and four driving feet placed in a parallelogram and internally connected to a circular rotor. The four feet vibrate asymmetrically to push the rotor into motion in one direction when a preload is applied. The proposed motor is designed, analyzed, and tested by using a finite element method (FEM). The vibration and impedance characteristics of the stator are measured after fabricating a prototype, and the test results are consistent with the FEM analysis results. The typical output of the prototype is a no-load speed of 176.5 rpm and a maximum torque of 29.4 N mm at an excitation voltage of 274 Vp-p.

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A number of common issues related to the process of flexible tactile sensor calibration are discussed in this paper, and an estimate of the accuracy of classical calibration methods, as represented by a weight-pulley device, is presented. A flexible tactile sensor calibration method that is based on a six-dimensional force measurement is proposed on the basis of a theoretical analysis. A high-accuracy flexible tactile sensor calibration bench based on the air-bearing six-dimensional force measurement principle was developed to achieve a technically challenging measurement accuracy of 2% full scale (FS) for three-dimensional (3D) flexible tactile sensor calibration. The experimental results demonstrate that the accuracy of the air-bearing six-dimensional force measurement platform can reach 0.2% FS. Thus, the system satisfies the 3D flexible tactile sensor calibration requirement of 2% FS.

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This study presents a novel impact piezoelectric motor that excites double stators through a sinusoidal signal. A sawtooth signal drives the traditional impact piezoelectric actuator, and its working frequency is limited by the resonant frequency. This study uses sine signals to drive the double stators to produce a sinusoidal vibration. The sinusoidal vibration of different frequencies and amplitudes are synthesised into a sawtooth vibration on the stage plate. The directional movement of the slider is realised using the vibration of the stage plate to drive the slider. This structure reduces the space required for the piezoelectric actuator to work. The working principle of the motor is discussed, and the structure is constructed. The dynamics model of the whole system is established on the based of the dynamics model of the actuator and the LuGre friction model. Moreover, the dynamics model was simulated and analysed through MATLAB/Simulink. The prototype is fabricated and tested. Experimental results confirm the effectiveness of using sinusoidal signals to drive the piezoelectric actuator, and the motion process of the piezoelectric motor is consistent with the theoretical analysis. The maximum speed of the piezoelectric actuator is 5.54 mm/s, and the resolution is 0.72 μm. This study provides an effective driving method for the quasi-static piezoelectric motor to improve the working frequency.

This study designs, fabricates and tests a piezoelectric pump with the structure of a polystyrene ball check valve. The structure of the check valve consists of three layers of specially designed polymethylmethacrylate plates and six polystyrene balls, which forms a particular three-layer constraint mechanism to limit the lateral and vertical displacement of the balls. The assembly of the ball valve can be completed with a simple placing operation, which simplifies the assembly process of the entire pump. The balls are lightweight, which is beneficial for working at high frequencies. The current design adopts two compressible spaces, and the equivalent analogue circuit of compressible spaces is established and analysed. Experimental results indicate that compressible spaces can alleviate the burden in the actuator and smoothen the flow rate pulsation in the long flow channel. The theoretical analysis and experimental tests reveal that this new piezoelectric pump is self-priming. A high flow rate of 99.6 mL/min and the maximum back pressure of 15.3 kPa are obtained when the pump is driven with a sinusoidal voltage of 448 Vpp at the resonant frequency of 790 Hz.

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