The authors regret that one of the funding grant numbers is published wrongly. The funding grant number should be No. 52105015 instead of the previous No. 5210051275. The authors would like to apologise for any inconvenience caused. © 2024 Elsevier Ltd

The three-dimensional (3-D) vibration-assisted turning (VAT) has attracted increasing attention for its merits in microstructure sculpturing and ultraprecision machining. However, most current 3-D VAT tools adopt complex structures and it is still difficult to implement high frequency and large amplitude simultaneously on a simple integrated tool. In this article, a 3-D VAT tool with high frequency and large amplitude adjustment capability is proposed for the first time, which adopts a more stable and compact single sandwich piezoelectric transducer structure. High frequency and large amplitude adjustment capabilities improve the machining efficiency and the range of machinable microstructures. The structure of the tool is simplified by using the sandwich-type single transducer structure, which is convenient to reduce cost and improve machining stability. Surface microstructures with variable inclination angles and distribution ratios are first sculptured by the proposed 3-D VAT tool, which provides a new idea for surface modification. In addition, surface microstructures with different depths and high-precision microgrooves are machined, and better machining results are obtained. The texture depth and machining efficiency of the microstructure are increased with the increase of amplitude and frequency. Microgrooves with a surface roughness of Sa 29 nm, minimized burrs and defects, and a specific cutting force reduction of 54.8% are obtained.

随着深空探测技术的发展,空间相机需要集光面积更大、分辨率更高的大口径光学主镜。传统整体式光学主镜受镜体加工工艺、支撑结构以及运载能力的限制,难以满足人类对更大口径空间相机的应用需求。多子镜拼接技术突破了整体式主镜的口径限制,解决了大口径单镜体加工难和成本高的问题,但冲击或振动等外力作用,及在轨运行时压力和微重力等因素的变化,均会引起拼接子镜位姿的改变(维度变化范围为一维～六维;直线位姿变化范围为nm级～mm级,转动位姿变化范围为亚μrad级～rad级),导致相机成像质量下降。本文从拼接子镜灵活高精度调姿的需求出发,基于压电驱动技术优势,围绕驱动原理、构型规划、结构优化、性能提升、测试系统搭建及光学调姿实验等内容展开研究,研制了一种兼备六自由度和跨尺度(mm级直线/rad级旋转位移大行程和nm级直线/亚μrad级旋转位移高分辨力)调姿能力的压电平台,解决光学调姿平台面临的兼具跨尺度与多自由度的难题,实现拼接子镜的独立灵活高精度调姿和光学共焦-共相调节。以四分区弯弯复合压电驱动器作为基本驱动单元,确定了旋转-旋转、直线-旋转和直线-直线运动的自由度组合方案。结合十字交叉轴、直线轴承导向和直...

Inertial positioning platforms driven by piezoelectric actuators have been employed in many precision applications. However, challenges including unstable pose keeping and intractable displacement backward still exist. In this study, a locking device is designed and embedded in a piezoelectric inertial rotary platform to achieve the functions of power-off locking and 2-degree of freedom (DOF) backward motion suppression. The vertical output displacement of the locking end is converted from the horizontal elongation of the lead zirconate titanate (PZT) stack by the flexible hinge mechanisms of the locking device, which is used to lock the rotor of the rotary platform. Theoretical and simulation analyses of the locking mechanism are performed and its dominant parameters are optimized. A prototype is fabricated and a series of experiments are performed. Compared with the inertial rotary platform without the locking device, the locking ability is increased by 4.55 times and the backward ratio is reduced from over 60% to below 12%. The application of locking device not only improves the pose keeping ability of the inertial positioning platform, but also improves its displacement output characteristics through backward motion suppression.

Piezoelectric ultrasonic-assisted precision machining (PUAPM) technology is considered to be an efficient and environmentally friendly machining strategy by virtue of cutting force reduction, ductile cutting promotion, tool wear and machining noise reduction. Piezoelectric ultrasonic transducer (PUT) provides ultrasonic energy for PUAPM system, which is the core component to ensure the normal operation of the system. PUTs for PUAPM devices have emerged endlessly in recent decades and have been successfully applied in many fields, such as MEMS, biomedicine, optoelectronics, aerospace, etc. However, there is no comprehensive classification and analysis of the basic configurations, excitation principles, typical structures, performance analyses and control strategies for PUT. This work gives a critical review of research on PUT in recent years, especially the structural optimization, application expansion and ultrasonic energy stabilization in PUAPM. The influence mechanism of excitation mode, modal type, modal combination, horn structure and ceramic arrangement on the optimization of PUT structure is summarized. The improvement effect and mechanism of PUT vibration dimension, amplitude, frequency and structural characteristics on surface roughness, surface texture and cutting force are discussed. In addition, the causes of PUT amplitude fluctuation, and the influence of sensing and control methods on PUT amplitude regulation and system integration are analyzed. This review will help in understanding the current development and diversified applications of PUT and will promote the application of ultrasonic technology in more fields. © 2023 Elsevier B.V.

Piezoelectric actuators are widely utilized in the precision industry field, but the existing piezoelectric actuators are difficult to achieve high displacement smoothness at low speed, which limits the practical application of the piezoelectric actuators. This work proposes a piezoelectric actuator that can achieve high displacement smoothness through a multi-leg coordinated actuation principle. A multi-objective optimized method based on adaptive mutation genetic algorithm is utilized to design the driving leg by comprehensively considering five design variables. The design goal of the maximum displacement of the driving foot and the minimum size of the driving leg are achieved. A prototype is fabricated and the characteristics are tested. The experimental results demonstrate the effectiveness of the optimized method. High displacement smoothness at low speed is also achieved. The output displacements of the proposed actuator at different driving voltages and frequencies show no regression and intermittent motion. The linearity R 2 could reach 0.9978, and the low output speed of the actuator could reach 22.69 µrad s−1 at voltage of 100 Vp-p and frequency of 1 Hz. © 2023 IOP Publishing Ltd

Vertical piezoelectric platform is the key equipment in precision engineering fields, however, the characteristics of carrying load capacity and the smoothness of cross-scale motion in the vertical direction restrict their applications. In this work, an alternate drive method for a vertical piezoelectric platform is proposed to solve these challenges, and the characteristics of cross-scale motion, large carrying load capacity and smooth displacement output are achieved simultaneously. The working principle of the vertical positioning platform and the theoretical analysis for the alternate drive mode are introduced in detail. A series of experiments are performed, and the results show that the motion of the vertical piezoelectric platform has good smoothness in the cross-scale motion and carrying load capacity based on the alternate drive mode. The maximum upward and downward velocities are 4.44 and 7.43 mm/s under the voltage of 600 Vp-p and the frequency of 850 and 925 Hz, respectively. Finally, the point positioning, oblique and sine trajectory tracking experiments are performed, which demonstrate that the vertical piezoelectric platform has the capacity of automated precision positioning and tracking target. Therefore, the alternate drive-based vertical positioning platform has huge potential in precise applications, such as micro/nano machining and complex biological manipulation. © 2023 Elsevier Ltd

Piezoelectric hydraulic actuators, instead of electromagnetic actuators, have a wide application prospect in the field of aerospace due to the merits of light weight, compact structure, non-magnetic interference, etc. Many researches have been devoted to boosting output powers of actuators with the help of large-scale piezoelectric stacks. However, the existing actuator operates at a relatively low frequency, limiting the output power improvement and the application. In this work, a high bandwidth piezo-hydraulic actuator (PHA) is proposed based on a resonant active valve piezoelectric pump with sandwich bending transducers (SBTs). The configuration and principle of the PHA are presented and analyzed. A tested setup of the PHA is established, and the maximum output velocity and thrust are measured to be 30.5 mm/s and 53.2 N under 1.6 kHz, and the output power reaches up to 294 mW under the load of 30 N. In addition, a variable swept wing (VSW) driven by the PHA is studied. The composition and deformation process of the PHA-Based VSW are discussed; the dynamic model of the PHA-Based VSW is derived; the tested results indicate that the maximum angular velocity and torque of the PHA-Based VSW are 1.135 rad/s and 1.701 N.m, and the swept angle range is 15.9 degrees similar to 64.1 degrees

Achieving agile steering motion without auxiliary forward velocity is difficult for autonomous underwater vehicle (AUV) driven by rudders. Although installing vectored thrusters and more propellers can adjust AUV's posture in situ, the system complexity, cost and volume are multiplied due to the assembled sealing and anti-pressure devices. It is inaccessible to operate in deep-sea unstructured regions. Hence, a novel micro 3.2 cm-diameter piezoelectric jet thruster suitable for high-pressure environment is proposed, which realizes dual-drive system integration without increment in volume and structure complexity after a simple gluing insulation. The high-frequency micron-level deformation of piezoelectric vibrator directly acts on the cavity to form a m/s-level jet with no transmission structure. To achieve high-efficient propulsion of the thruster, the vibration characteristic of vibrator, the flow field and pressure variation and the driving enhancement mechanism are numerically investigated. Then, the exciting waveform parameters, the cavity and nozzle shapes are optimized, and the corresponding fluid flowing state behind is analyzed. The findings indicate that the opposite positions of maximum suction and ejection velocities, and their final values synergistically dominate driving force improving. And the largest average driving force occurs in the thruster with contractive hyperbolic-shaped cavity and nozzle. Reducing the suction velocity and time by changing the duty ratio and falling edge of the square wave is incapable of enhancing the driving performance. In addition, the consistent motion velocity without attenuation below 20 MPa water pressure proves the propulsion feasibility in deep sea. The AUV with body length (BL) of 32 cm can achieve agile steering motion directly driven by the integrated thruster without influencing the original streamlined structure, and the needed steering radius is only 0.42 times as long as its length. This work presents an effective solution for maneuvering deep-sea underwater vehicle in the narrow regions such as the seabed slit and gully. © 2023 Elsevier Ltd