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The cylindrical ultrasonic motor, noted for its straightforward design, ease of miniaturization, and high precision, has significant potential in fields such as optics, healthcare, and precision engineering. However, miniaturization presents challenges, including diminished output force and complications in applying preloading stress. To address the reduced output force, this study presents a dual-stator, high-thrust cylindrical linear ultrasonic motor. This innovative motor features two stators, a mover, and a mechanism for applying preloading stress. A key design element is the parallel arrangement of the two stators along a threaded output shaft, separated by elastic components. This setup enables axial preloading via the threads' engagement. Simulations were conducted to refine the stators' parameters, assess their operational modes, and evaluate their in-plane paths. A prototype was subsequently built to test its impedance characteristics and mechanical performance. Test results showed that under a 200 Vpp drive, the single-stator motor generated a maximum force of 4.3 N, while the dual-stator configuration produced 6.8 N. After applying preloading stress, the output force of the dual-stator motor increased to 9.4 N. [ABSTRACT FROM AUTHOR]

The mobile robot is widely used in many cleaning applications. This paper presents the design and implementation of a low-cost smart cleaner wheeled mobile robot for floor cleaning applications. The robot is capable of accurately navigating through various environments and avoiding obstacles. The paper focuses on three main points: interfacing the motion modeling equations with an Android application, designing a differential mobile robot with flexible mobility, and incorporating obstacle avoidance using an Ultrasonic sensor. The results demonstrate that the robot can move with high precision and flexibility, with minimal error. The maximum error on the complex (carpet) floor equals (±1.1500 cm) and it is greater than the maximum error on the flat floor which equals (±0.5800 cm). Additionally, the robot's affordability, priced at 28 $. The designed mobile robot is low cost, for this reason it accessible to anyone seeking a cleaning solution for both flat and rough (complex) floors, whether dry or wet. From these specifications of designed mobile robot, it considered better than related works. [ABSTRACT FROM AUTHOR]

An inertial linear ultrasonic motor with a novel double-stator structure is proposed for achieving higher performance and resolution in this paper. Utilizing a symmetrical structure and single sawtooth wave signal, the prototype is capable of outputting effective linear motion based on inertial movement. The validity and rationality of the prototype are investigated by conducting finite element analyses. The experimental setups are built up to acquire the output characteristics of the motor. The experimental results indicate that the motor can achieve a maximum output velocity of 8.746 mm/s and thrust force of 1.645 N, which is almost twice the output performance of a motor with a single stator. The displacement solution of the motor can be adjusted by changing the amplitude of the voltage, with a resolution of 27 nm. Simultaneously, the relationships between the output characteristics and the input parameters are measured and analyzed during the experiments. Compared to the actuators with complex structures and multi-signal drives, the proposed motor exhibits the merits of higher output performance with the double-stator structure, providing an alternative direction for the further development of the inertial linear ultrasonic motor. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Chongqing University of Technology (Natural Science) is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This research presents the development and evaluation of a miniature autonomous robot inspired by insect locomotion, capable of bidirectional movement. The robot incorporates two piezoelectric bimorph resonators, 3D-printed legs, an electronic power circuit, and a battery-operated microcontroller. Each piezoelectric motor features ceramic plates measuring 15 × 1.5 × 0.6 m m 3 and weighing 0.1 g, with an optimized electrode layout. The bimorphs vibrate at two flexural modes with resonant frequencies of approximately 70 and 100 kHz. The strategic placement of the 3D-printed legs converts out-of-plane motion into effective forward or backward propulsion, depending on the vibration mode. A differential drive configuration, using the two parallel piezoelectric motors and calibrated excitation signals from the microcontroller, allows for arbitrary path navigation. The fully assembled robot measures 29 × 17 × 18 m m 3 and weighs 7.4 g. The robot was tested on a glass surface, reaching a maximum speed of 70 mm/s and a rotational speed of up to 190 deg./s, with power consumption of 50 mW, a cost of transport of 10, and an estimated continuous operation time of approximately 6.7 h. The robot successfully followed pre-programmed paths, demonstrating its precise control and agility in navigating complex environments, marking a significant advancement in insect-scale autonomous robotics. [ABSTRACT FROM AUTHOR]

Piezoelectric ultrasonic motors (USMs) are actuators that use ultrasonic frequency piezoelectric vibration-generated waves to transform electrical energy into rotary or translating motion. USMs receive more attention because they offer distinct qualities over traditional magnet-coil-based motors, such as miniaturization, great accuracy, speed, non-magnetic nature, silent operation, straightforward construction, broad temperature operations, and adaptability. This review study focuses on the principle of USMs and their classifications, characterization, fabrication methods, applications, and future challenges. Firstly, the classifications of USMs, especially, standing-wave, traveling-wave, hybrid-mode, and multi-degree-of-freedom USMs, are summarized, and their respective functioning principles are explained. Secondly, finite element modeling analysis for design and performance predictions, conventional and nano/micro-fabrication methods, and various characterization methods are presented. Thirdly, their advantages, such as high accuracy, small size, and silent operation, and their benefits over conventional motors for the different specific applications are examined. Fourthly, the advantages and disadvantages of USMs are highlighted. In addition, their substantial contributions to a variety of technical fields like surgical robots and industrial, aerospace, and biomedical applications are introduced. Finally, their future prospects and challenges, as well as research directions in USM development, are outlined, with an emphasis on downsizing, increasing efficiency, and new materials. [ABSTRACT FROM AUTHOR]

This study proposes a high-resolution rotation-measuring system for miniaturized MEMS ultrasonic motors using tunneling magnetoresistance (TMR) sensors for the first time. Initially, the architecture and principle of the rotation-measuring system are described in detail. Then, the finite element simulation is implemented to determine the miniaturized permanent magnet's residual magnetization, dimensions, and TMR sensor position. Finally, the experiments are implemented to evaluate the performance. Using calibration based on a high-precision servo motor, it is found that the relationship between the output and rotational angle is highly linear and immune to the rotor's out-of-plane movement. Meanwhile, the angle-detecting resolution is higher than 0.1°. After the calibration, the continuous rotation of the MEMS ultrasonic motor is tested. It is found that the angle testing result varies with a period close to 360°, which indicates that the rotation-measuring system has successfully detected the motor's rotation. [ABSTRACT FROM AUTHOR]

Linear ultrasonic motors can output large thrust stably in a narrow space. In this paper, a plate linear ultrasonic motor is studied. Firstly, the configuration and operating principle of the Π -type linear ultrasonic motor is illustrated. Then, two slotting schemes are put forward for the stator to enlarge the amplitude of the driving foot and improve the output performance of motor. After that, a novel optimization method based on the power flow method is suggested to describe the energy flow of stator, so as to estimate the slotting schemes. Finally, the prototypes are manufactured and tested. The experimental results show that the output performance of both new motors are excellent. The maximum output thrust of the arc slotted motor is 76 N/94 N, and the corresponding maximum no-load speed is 283 mm/s/213 mm/s, while the maximum output thrust of V-slotted motor reaches 90 N/120 N, and the maximum no-load speed reaches 223 mm/s/368 mm/s. [ABSTRACT FROM AUTHOR]

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article introduces a method of enhancing the energy conversion efficiency of a traveling wave rotary ultrasonic motor with a flexible rotor by increasing the friction coefficient at the stator–rotor interface. The increased friction coefficient leads to improvements in energy conversion efficiency by increasing the output power and reducing friction loss power. Experimental verification showed that the friction coefficient in the interface increased from 0.21 to 0.32, the maximum energy conversion efficiency increased from 36.8% to 46.3%, and the interface friction loss was reduced. [ABSTRACT FROM AUTHOR]

In this paper, we present a distal-scanning common path probe for optical coherence tomography (OCT) equipped with a hollow ultrasonic motor and a simple and specially designed beam-splitter. This novel probe proves to be able to effectively circumvent polarization and dispersion mismatch caused by fiber motion and is more robust to a variety of interfering factors during the imaging process, experimentally compared to a conventional noncommon path probe. Furthermore, our design counteracts the attenuation of backscattering with depth and the fall-off of the signal, resulting in a more balanced signal range and greater imaging depth. Spectral-domain OCT imaging of phantom and biological tissue is also demonstrated with a sensitivity of ∼ 1 0 0 dB and a lateral resolution of ∼ 3 μ m. This low-cost probe offers simplified system configuration and excellent robustness, and is therefore particularly suitable for clinical diagnosis as one-off medical apparatus. [ABSTRACT FROM AUTHOR]

BACKGROUND: Prosthetic hands have the potential to replace human hands. Using prosthetic hands can help patients with hand loss to complete the necessary daily living actions. OBJECTIVE: This paper studies the design of a bionic, compact, low-cost, and lightweight 3D printing humanoid hand. The five fingers are underactuated, with a total of 9 degrees of freedom. METHODS: In the design of an underactuated hand, it is a basic element composed of an actuator, spring, rope, and guide system. A single actuator is providing power for five fingers. And the dynamic simulation is carried out to calculate the motion trajectory effect. RESULTS: In this paper, the driving structure of the ultrasonic motor was designed, and the structural size of the ultrasonic motor vibrator was determined by modal and transient simulation analysis, which replace the traditional brake, realize the lightweight design of prosthetic hand, improve the motion accuracy and optimize the driving performance of prosthetic hand. CONCLUSIONS: By replacing traditional actuators with new types of actuators, lightweight design of prosthetic hands can be achieved, improving motion accuracy and optimizing the driving performance of prosthetic hands. [ABSTRACT FROM AUTHOR]

In this study, remote control application of an ultrasonic motor (USM) has been achieved over the power line communication (PLC) system. Fast, practical, affordable and effective operating mode is essential for the USM. This study aimed to develop an original, efficient, effective and economical method. Drive and control of USM control has been succeeded with the developed PLC control system. A two-phase high-frequency inverter, a power line transmitter, and a power line receiver circuits have been designed to drive and control of the ultrasonic motor. Required measurements are acquired from the power line to select the most suitable communication frequency and coupling circuit impedance for the PLC system. For the communication frequency and impedance value measurements the receiver and the transmitter circuits have been designed. The PLC-controlled system has been tested for different operating conditions of the ultrasonic motor. USM control has been accomplished over the existing power line without using extra cables and interfaces for communication. The obtained results show that the PLC-controlled system is practical, reliable, cost-effective, and feasible for the remote control of the USM. This research contributes a new and essential perspective for the PLC-based remote control studies in addition to the USM drive and control strategies. [ABSTRACT FROM AUTHOR]

To reduce harmonic components, balance system impedance, and stabilize driving voltage, an additional matching circuit is required for ultrasonic motors (USMs) driver. However, the performance of inductor or capacitor matching can be seriously weakened with changes in driving frequency. Therefore, this paper presents a simple and effective LC matching method against driving frequency adjustment for USMs. First, the driving scheme of the USM is proposed and the electromechanical coupling model is analyzed. Subsequently, the output characteristics of the full-bridge inverter are derived theoretically when the driving frequency deviates from the mechanical resonant frequency. Then, the impedance circular transform method is proposed, which can intuitively analyze the effect of matching parameters on the voltage amplitude. A matching objective function is established that can consider both the voltage stabilization and harmonic suppression. The matching parameters are solved using random weight particle swarm optimization. Simulations and experiments demonstrate that within the operating frequency of the USM, the proposed matching method can effectively prevent overvoltage and suppress harmonic components. Furthermore, compared with the existing resonant matching method, the proposed matching method can realize more stable driving capability at different frequencies. The proposed method could be useful for USMs' variable-frequency driver design. [ABSTRACT FROM AUTHOR]

A new non-contact ultrasonic motor consisting of a Langevin transducer, an electromagnetic device, and a spherical rotor is presented, and the designed motor is theoretically analysis and experimentally verified. The designed motor is driven by a mixture of near-field acoustic levitation and electromagnetism, and the electromagnetic platform is controlled by three stacked piezoelectric actuators to control the deflection direction, thus driving the spherical rotor to achieve the same angle of deflection and self-propagation. By exciting the Langevin transducer under the rotor, the high-frequency vibration of the stator disc causes the air between the stator disc and the rotor to be squeezed periodically, and when the air pressure in the gap is larger than the external atmospheric pressure, the levitation force generated by the stator is larger than the gravity of the rotor, thus levitating the rotor, and when the rotor deflects, it can still achieve stable levitation because of its special geometry. The proposed new motor is expected to be used in applications requiring high output torque and microdisplacement. [ABSTRACT FROM AUTHOR]

Typically, earthworm-inspired robots consist of N segments and N actuators, each segment having one actuator. However, to reduce the number of actuators, complex mechanisms are often required to activate multiple segments. In this study, we introduce a novel design for an earthworm-inspired robot that reduces the number of actuators from N to N-1, thereby simplifying the mechanical complexity while maintaining high performance. Our proposed robot consists of three segments and two motors embedded between the segments. These two motors share a single flexible shaft and move back and forth along it. By extending or retracting the segments through the movement of the motors, the robot is propelled forward. We evaluated the robot’s performance, achieving a maximum speed of 11.6 mm/s, a payload capacity of 200 g (three times its own weight), and a climbing angle of 20 degrees, demonstrating its superior capabilities in various scenarios. The proposed robot generates significant force through simultaneous motor actuation and exhibits effective steering locomotion with additional actuators. This study introduces a new design approach for earthworm-inspired robots and offers valuable insights into achieving locomotion with fewer actuators.

In this paper, a composite excitation method is used to optimize the design of an existing cantilevered cylindrical ultrasonic motor to avoid vibration interference. Modal and transient simulation analysis of the stator structure was carried out by the finite element method. Optimized stator structure is simpler than the original motor. Simulation analysis results show that the circumferential amplitude is increased by more than 35% with 55.7% reduction in ceramic usage. [ABSTRACT FROM AUTHOR]

Impedance matching circuits are capable of tuning and wave filtering, which is beneficial to performance improvement of piezoelectric ultrasonic motors. At present, impedance matching for piezoelectric ultrasonic motors is usually realized through a series inductance, which has the problem of poor wave filtering effect. Different from the previous series inductance matching method for ultrasonic motors, a series inductance and capacitance matching method is proposed for a radial standing wave piezoelectric ultrasonic motor. The series capacitance is added to adjust the quality factor of the resonance tank so that a desired wave filtering effect can be obtained. The values of the series inductance and capacitance are derived based on the Butterworth–Van Dyke model of the piezoelectric ultrasonic motor. Simulations are conducted to verify the feasibility of the proposed matching method. Finally, the waveforms of voltages and currents as well as torque–speed curves of the motor are measured. The results validate the proposed matching method. In addition, the previous series inductance matching method is compared. The results show that the proposed series inductance and capacitance matching method not only achieves tuning function but also obtains a significantly improved wave filtering effect. Moreover, the torque–speed characteristics of the motor are also improved with the proposed matching method. [ABSTRACT FROM AUTHOR]

Lead-free relaxor ferroelectrics are promising candidates for next-generation piezoelectric high-power devices, such as ultrasonic motors, transformers, and therapeutic ultrasonics. These applications require hard ferroelectrics with a broad operating temperature range. Recently, acceptor Zn2+ doping and composite formation with ZnO were proposed to induce hardening in Na1/2Bi1/2TiO3–BaTiO3 and simultaneously increase the depolarization temperature. Here, these two strategies are compared by studying the temperature dependence of electromechanical properties, ferroelectric loops, and nonlinear polarization harmonics. In the modified compositions, depolarization is associated with the shift of the ferroelectric-to-relaxor transition to higher temperatures, while the depolarization onset remains unchanged. This leads to broadening rather than translation of the depolarization region, accompanied by decoupling of the piezoelectric d 33 and d 31 coefficients. The temperature-dependent electromechanical response is stable for composites, while the Zn2+-doped samples exhibit strong temperature dependence akin to acceptor-doped Pb(Zr,Ti)O3. The thermal evolution of electromechanical coefficients is not related to the thermally induced decrease of the coercive/internal bias fields but instead to the ratio of irreversible-to-reversible nonlinear dynamics arising from displacements of domain walls or similar interfaces. The results demonstrate that mechanical stress-based hardening in the composites exhibits superior thermal stability, which can considerably improve the operational range of lead-free piezoelectric materials. [ABSTRACT FROM AUTHOR]

To compensate for the influence of temperature on the efficiency of an ultrasonic motor (USM), this paper proposed a maximum efficiency point tracking control method for temperature drift by analysing the relationships between the maximum efficiency point and the voltage and frequency of the driving circuit. The method first calculates the frequency update step of the driving circuit by the polynomial surface fitting method, considers the influence of temperature rise on the voltage‐efficiency‐frequency characteristics, and then adjusts the frequency in real time to compensate for temperature effects. Simulation and experimental results show that our method can improve the USM performance at the maximum efficiency point under changing temperature. Maximum efficiency point tracking algorithm with temperature compensation algorithm achieves maximum efficiency in experiment. [ABSTRACT FROM AUTHOR]

Motors driven by surface acoustic waves (SAWs) have been extensively investigated due to their potential applications in various environments. One of the problems we are confronted with is the lifetime of the substrate which supports SAWs since it becomes fragile when large-amplitude SAWs are excited on the substrate. In order to prolong the lifetime of the substrate, we propose to apply modulated driving voltage with a duty ratio to the interdigital transducers. With the implementation of such a proposal, we found an intriguing phenomenon which is out of expectation, i.e., when the driving voltage is high, the slider speed under modulated driving with a suitable duty ratio might be larger than that with the continuous driving. [ABSTRACT FROM AUTHOR]

To fulfill high-reliability requirements for aerospace applications, a novel traveling wave rotary ultrasonic motor with a piezoelectric backup function (Backup motor) is proposed in this paper. The backup function is enabled by the addition of a set of piezoelectric ceramics (PZT). Based on the ultrasonic motor of the CSX-60, a cantilever-tooth backup motor (CTBM) is designed and fabricated. This backup motor can operate in three working modes according to the excitation settings of PZTs, namely normal mode, backup mode, and enhanced mode. The relationships between three working modes' performances are analyzed by finite element (FE) analysis and prototype tests. The results show that backup mode, as the substitution, can nearly reach normal mode's performance, while enhanced mode is obviously higher than others. Furthermore, a modified backup motor with straight-tooth (STBM) and different sizes of PZT is designed and tested as a supplement to verify the feasibility of the proposal. In addition, the effect of stress reduction on PZT damage is verified by extreme working experiments. The comparison between the two types of motors indicates that STBM can provide better frictional drive performance. This proposal can provide a new reference for the subsequent reliability study of ultrasonic motors. [ABSTRACT FROM AUTHOR]

Currently, the driving motor used in a dexterous prosthetic hand is limited by the driving principle, and it has the characteristics of a complex structure, slow response, low positioning accuracy, and excessive volume. There are special requirements in terms of quality and quality, and traditional motor drives have greatly affected the progress of prosthetic robots. A motor (ultrasonic motor) has been developed over more than 30 years. It has the advantages of a small size, small mass, simple structure, accurate positioning, high power density, and fast response time, which is enough to improve the driving mechanism performance of the prosthetic hand with a connecting rod. In this paper, the structural characteristics of the prosthetic hand will be analyzed, and the modal analysis, harmonic response analysis, and transient analysis simulation of the longitudinal vibration linear motor stator used in the prosthetic hand with a connecting rod will be carried out in order to provide preliminary preparation for the feasible design and manufacture of the size of the ultrasonic driver structure used for the prosthetic hand with a connecting rod. [ABSTRACT FROM AUTHOR]

Frequency tracking and amplitude control are essential for piezoelectric transducers. Frequency tracking ensures the piezoelectric transducer operates at the resonant frequency for maximum power output, and amplitude control regulates the mechanical motion of the output. This paper presents a novel driver based on a push–pull inverter for piezoelectric transducers. The proposed driver realizes the frequency tracking and amplitude control scheme by a voltage sensing bridge in the case of transformer secondary matching, guaranteeing automatic frequency tracking and precise mechanical functions regardless of environmental and load variations. The proposed scheme is verified by the ultrasonic scalpel and the ultrasonic motor (USM). The experimental results show that this scheme reduces the build-up time from 10 ms to 3 ms and loaded frequency variations from 250 Hz to 200 Hz. In addition, the amplitude control performance was further observed on USM for various loads. The overshoot is less than 5.4% under different load torques. Therefore, the proposed scheme improves the load adaptability and stability of piezoelectric transducers and promotes the application of piezoelectric transducers under various conditions. [ABSTRACT FROM AUTHOR]

This paper proposed a double-sided staggered conical teeth traveling wave rotating ultrasonic motor based on in-plane bending mode, which reduces the difficulty of rotor preload application and improves the output characteristics of in-plane bending mode traveling wave rotating ultrasonic motor. The motor has four sets of drive teeth alternately distributed on both the inner and outer sides of the vibrator, with the drive teeth gap dedicated to accommodate the piezoelectric ceramic piece, and the staggered drive teeth on both sides of the vibrator are used to drive the rotor rotation. The motor operates in two in-plane third-order bending modes with the same frequency and orthogonal to each other, and is excited by four sets of piezoelectric ceramic disks spaced 90 degrees apart from the inner and outer sides. After the prototype was completed, its vibration characteristics and output performance were experimentally tested, and the actual effects of the three excitation schemes were compared. The experimental results show that the motor can provide a maximum output torque of 1.82N-mm and a maximum no-load speed of 96.4 rpm when the excitation voltage is 300 V and the excitation frequency is 20.60 kHz. [ABSTRACT FROM AUTHOR]

Rotor speed and position detection are integral parts of the closed-loop control system for multi-degree-of-freedom (multi-DOF) ultrasonic motors. The non-contact speed detection method is important for the high-precision control of the spherical rotor. This paper proposes a closed-loop control method based on an optical flow sensor for the velocity–position control of a multi-DOF clamping-type ultrasonic motor. The optical flow information is analyzed using the conical L–K optical flow algorithm to obtain the rotor speed and position. An incremental PID control method is used to perform dual closed-loop positioning control of the motor regarding speed and position. An experimental platform for the optical flow sensor is designed, and the method's feasibility is verified experimentally. [ABSTRACT FROM AUTHOR]

A high-performance servo control system is the basis for realizing high-precision photoelectric tracking. With high position resolution and power-off self-locking, ultrasonic motors have a wide range of applications for high-precision positioning control. An optoelectronic tracking platform driven by two ultrasonic motors is proposed in this study. The shaft structure of the tracking platform is designed and modeled. The shaft structure is simplified, and a dynamic model is established to analyze the motion characteristics. The parameters of the limit mechanism are optimized based on the analysis. The shaft structure is built to verify the response characteristics of the tracking platform at different velocities. The results show that the proposed design can fully utilize the self-locking of ultrasonic motors for rapid automatic alignment of the axis system. The maximum response time is less than 55 ms. When the operating velocity is less than 70°/s, the positioning error is less than 0.055°, and the lower the speed, the smaller the positioning error. [ABSTRACT FROM AUTHOR]

A new level of freedom is made possible by orbital angular momentum (OAM), which can be used to create twisted ultrasonic motors for particle manipulation and control. For steady and free‐flowing particle management, it is essential to produce acoustic OAM beams of high order and high quality. However, this task is difficult due to the phased array's fundamental restriction of insufficient resolution or aperture. Herein, a generic approach is presented to inverse design that may be used to improve the OAM beam quality and produce twisted ultrasonic motors in free space. In comparison to the previous direct‐design method, up to a 14% improvement in amplitude uniformity and a 12 dB improvement in signal‐to‐noise ratio (SNR) of OAM modes are achieved. These notable benefits enable the ultrasonic motor to operate with a straightforward and compact system while enabling steady particle rotation in free space with an undersampled phased array, which is not possible with the conventional technique. This study paves the way for effective particle control, high‐fidelity communication, and other OAM‐based technologies by providing an inverse‐design framework for optimizing OAM. [ABSTRACT FROM AUTHOR]

The traveling-wave rotary ultrasonic motor (TRUM) technique has become increasingly mature deepening of related research and development of related technology. The unique friction drive mode of a TRUM provides the advantages of a low speed, large torque, fast response, and a self-locking feature for power failure but also suffers from a relatively low efficiency. Regarding speed control, the commonly used approach of combining frequency modulation and speed regulation has provided the advantages of high precision and a wide range. Still, the load-carrying capacity of a TRUM is reduced when the driving frequency deviates from the resonant point, which is not conducive to the characteristics of low speed and large torque of the TRUM. To address this limitation, this study uses the pre-pressure and designs an electromagnetic clutch-type variable pre-pressure self-adjusting ultrasonic motor based on the TRUM-70 hollow ultrasonic motor. In addition, the force and motion analyses are conducted on the core components, and the basic parameters of the electromagnetic mechanism are calculated according to the specific design requirements. Furthermore, the Maxwell equation is used to simulate the designed magnetic circuit, and a prototype is fabricated and assembled. The feasibility of the proposed motor design is verified through experimental study, and the performance of the motor is compared with those of conventional ultrasonic motors. The experimental results show that the proposed electromagnetic clutch-type variable pre-pressure ultrasonic motor can effectively improve the output efficiency of the motor, especially when the load varies significantly. [ABSTRACT FROM AUTHOR]

Cylindrical multi-degree-of-freedom (multi-DOF) ultrasonic motors have the potential to significantly reduce motor size compared to other ultrasonic motors. They find applications in various systems, including micro-robot joints and space probes. This paper proposes a 3-DOF cylindrical ultrasonic motor with hybrid vibration modes. Hybrid vibration modes encompass non-standard longitudinal and bending vibrations. The structure and operating principle of the motor are described first. COMSOL Multiphysics models the stator's vibration modes, frequency response, and 3-DOF motion. A motor prototype is manufactured and characterized to demonstrate the output characteristics of the motor. The results indicate that the motor has a no-load speed of 37 rpm along the x- and y-axes and up to 77 rpm along the z-axis. The maximum output torque of the motor is 25 Nm. The motor is low in height and compact, providing a method for further reducing the stator length of motors of the same type. [ABSTRACT FROM AUTHOR]

Lead zirconia titanate (PZT) is the most often used piezoelectric material in various electronic applications like energy harvesters, ultrasonic capacitors and motors. It is true that PZT has a lot of significant drawbacks due to its 60% lead content, despite its outstanding ferroelectric, dielectric and piezoelectric properties which influenced by PZT's morphotropic phase boundary. The recently found potassium sodium niobate (KNN) is one of the most promising candidates for a new lead-free piezoelectric material. For the purpose of providing a resource and shedding light on the future, this paper provides a summary of the historical development of different phase boundaries in KNN materials and provides some guidance on how to achieve piezoelectric activity on par with PZT through a thorough examination and critical analysis of relevant articles by providing insight and perspective of KNN, which consists of detailed evaluation of the design, construction of phase boundaries and engineering for applications. [ABSTRACT FROM AUTHOR]

PI (proportional integral) controller is widely utilized in ultrasonic motor control systems. However, PI controllers which use fixed parameters is often difficult to ensure that the control performance meets the expectations. Based on the idea of iterative learning control (ILC), a new online adaptive adjustment method for PI control parameters is proposed. Simple P (proportional) type and PD (proportional differential) type iterative learning controllers are designed to adjust the proportional and integral coefficients of PI controller online. Using this method, the coefficients of PI controller are adaptively adjusted with the change of motor characteristics to ensure the control performance meets expectations. This method can improve the nonlinear expression ability of the controller, so that its input–output relationship can better match the characteristics of the controlled object, thereby improving the control performance. Results of comparative experiments indicate the validity of the proposed control strategy. • A new method is given for online modification of the control coefficients of PI controller using iterative learning controller. • The control performance and adaptability of the proposed strategy have been substantiated by experiments. • The proposed control strategy is simple, and has strong robustness to make timely and effective response to various disturbances. [ABSTRACT FROM AUTHOR]

In order to facilitate the widespread application of ultrasonic motors, it is essential to conduct a quantitative study aimed at enhancing their performance. The present paper provides a comprehensive theoretical analysis of an ultrasonic motor equipped with dual vibrators, enabling operation in both the single-driven and dual-driven modes, thereby enhancing versatility in terms of performance adjustment. This study provides a detailed examination of the motor's unique performance characteristics and its varying output responses to different driving signals. Experimental investigations are conducted in both the single-driven and dual-driven modes to validate theoretical predictions. The results demonstrate that the motor exhibits a maximum speed, torque, and power that are 1.59, 1.28, and 1.62 times higher than those of the single-driven stator, respectively. A conclusion can be drawn that the motor will attain the desired performance when operated in the appropriate driven mode. [ABSTRACT FROM AUTHOR]

The present study introduces a multi-degree-of-freedom (MDOF) ultrasonic motor, which is capable of driving a spherical rotor using spiral wire stators and a piezoelectric stack actuator. Wire stators and piezoelectric stack actuators enable the proposed motor to be smaller and simpler, lower in power consumption, and have different modes at different frequencies. In this motor, two wire stators are used to drive the spherical rotor and rotate it in different directions. The eigenfrequency and frequency domain analyses were carried out using the finite element method (FEM) to evaluate the MDOF capability of the motor in different vibration modes. It has been demonstrated that the piezoelectric stack actuator can provide MDOF motions through its vibration modes. The resonant frequency obtained by the frequency domain approach agreed with the impedance analyzer test. Rotational speed, torque, and preload force were experimentally investigated. Using shear stress caused by viscous fluid in contact with the spherical rotor, a new torque calculation method was developed. Based on the buoyancy force exerted on the immersed rotor, the preload force was measured. The experimental results indicated that the maximum rotational speed of the spherical rotor was 306 rpm, and the maximum torque was 4.7 μN m. [ABSTRACT FROM AUTHOR]

In order to improve the output torque of an in-plane bending mode traveling wave rotary ultrasonic motor, a double-sided tapered teeth traveling wave rotary ultrasonic motor was proposed. The motor is designed with three types of adaptive rotors that can be used for replacement in different output environments. Simulation analysis was conducted using ANSYS, and prototype production and experimental testing were conducted. The experimental results show that when the excitation voltage is 300 V and the excitation frequency is 22.665 kHz, the maximum output torque that the motor provide is 3.087 N·mm, and the maximum no-load speed is 295 rpm. [ABSTRACT FROM AUTHOR]

In order to simplify the motor structure, to reduce the difficulty of rotor pre-pressure application and to obtain better output performance, a new internal cone type rotating traveling wave ultrasonic motor is proposed. The parametric model of the internal cone type ultrasonic motor was established by the ANSYS finite element software. The ultrasonic motor consists of an internal cone type vibrator and a tapered rotor. The dynamic analysis of the motor vibrator is carried out, and two in-plane third-order bending modes with the same frequency and orthogonality are selected as the working modes. The other advantages of this motor are that pre-pressure can be imposed by the weight of the rotor. The prototype was trial-manufactured and experimentally tested for its vibration characteristics and output performance. When the excitation frequency is 22260.0 Hz, the pre-pressure is 0.1 N and the peak-to-peak excitation voltage is 300 V, the maximum output torque of the prototype is 1.06 N·mm, and the maximum no-load speed can reach 441.2 rpm. The optimal pre-pressure force under different loads is studied, and the influence of the pre-pressure force on the mechanical properties of the ultrasonic motor is analyzed. It is instructive in the practical application of this ultrasonic motor. [ABSTRACT FROM AUTHOR]

Magnetic anchor and guidance system has been widely used in laparoendoscopic single-site surgery with the benefit of small wound, wide field of vision (FoV), and convenience for repeated positioning. This paper introduces a novel three DoF laparoscopic surgical robot (LSR) based on double-leg ultrasonic motor (DUM) which features small dimension, fast response, and high positional precision. Piezoelectric ceramic (PZT) plates can excite longitudinal and bending coupled vibration of DUM and the two phase in-plane three order bending vibration can form traveling wave to drive DUM rotor. DUM stator is optimized by non-dominated sorting genetic algorithm-II for good consistency of two working mode frequencies and negligible influence of adjacent interference modes on working modes, which improves motion stability and driving efficiency. The mechanical characteristic of DUM under different chamfer parameters has been studied through comparative experiments and the design of robot prototype is completed further. For clockwise and counterclockwise rotation, the maximum no-load rotary speeds are 333.75 and 335.77 rpm, and the maximum output torques are 2 and 1.6 N mm. The experimental platform for FoV measurement is built to verify that LSR can adjust the posture to obtain suitable surgical FoV, indicating that the application of DUM in LSR has significant advantages and great potential. [ABSTRACT FROM AUTHOR]

Microactuators are an essential technology to revolutionize existing micromachines, but making them closed-loop controlled with an internal sensor is a great challenge due to the limited size of the components. In this paper, we build a micro-ultrasonic motor in the 2–3 mm scale, combine it with a tunneling magneto resistance (TMR) sensor with dimensions of 1.4 mm $\times1$ mm, and construct a closed-loop system with a control algorithm. It is currently the smallest rotary actuator-sensor system assembled into a size with a height of 3.2 mm, a width of 3.2 mm, and a length of 5 mm. In the system, we attempt to solve a steady-state error problem for the micro-ultrasonic motor’s internal parameter changes, such as a temperature rise and the resonant frequency variation. A model-free, real-time-adaptive extremum seeking controller (ESC) that continuously tracks and localizes the optimum driving frequency is implemented into the system for the desired rotation with minimum steady-state error. Although the controller is simply designed, experiments show a good accordance between the resulting angular velocity and the reference.

For a traveling wave rotary ultrasonic motor, matching the stator with a proper flexible rotor can be challenging because of the actual contact mechanism's complexity. Due to the lack of effective evaluation and prediction means in the rotor design process, the prototype test is usually needed to truly measure how well it performs, leading to high cost and long design cycle. In order to solve this problem, an efficient performance evaluation method of the flexible rotor based on equivalent contact pressure is proposed. By the key parameters of the flexible rotor's contact surface (area and pressure), an equivalent pressure model of the contact surface is established, which reveals the influence law of the flexible rotor's structural parameters on the motor's output performance. It is doubly verified by dynamics simulation and experiments. The advantage of this method is that without dynamics computation and prototype test, only statics analysis can evaluate the matching score of flexible rotor and target stator quickly and accurately. This study is expected to provide support for the structure design and performance prediction of the traveling wave rotary ultrasonic motor's rotor, in which significant time and cost savings can be achieved. [ABSTRACT FROM AUTHOR]

In order to solve the problem that the preload of a travelling wave type rotary ultrasonic motor cannot be continuously and precisely adjusted to the optimal value, we designed a novel preload adjustable device based on a multi-link mechanism. Firstly, the mathematical model of the multi-link parallel mechanism is established, the spatial position and attitude of the mechanism are deduced, and its motion transformation characteristics are obtained. Secondly, the dynamic transfer path of the device was studied to obtain the relationship between pressure and deformation of the rotor convex platform. The transfer function of the device is derived based on the relationship between the motion conversion characteristics and the pressure and deformation. Then, to verify the accuracy of the transfer function, a test platform was set up to measure the strain variables of rotor convex platform and web under different pressures through pressure sensor and strain gauge sensors. Finally, the preload force was set to 310 N. The stall torque, no-load speed, standard deviation of speed and maximum efficiency of the common ultrasonic motor were measured and compared with those of the ultrasonic motor used an adjustable device. The results show the difference of stalling torque is 2.9%, maximum efficiency is 2.2%, standard deviation of speed is 16.6%, and the difference of no-load speed is 2.9%, and the error of the test results meets the expected requirements. Therefore, this design scheme is feasible. It has the advantages of large transmission ratio, continuous and high precision adjustment. [ABSTRACT FROM AUTHOR]

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Inspired by the double crank planar hinged five bar mechanism, a longitudinal–bending hybrid linear ultrasonic motor with compact miniature is proposed and tested. In order to realize miniaturization, it adopts a bonded-type structure. Four lead zirconate titanate (PZT) piezoelectric ceramics are distributed equally into two groups and bonded to the two ends of the metal frame, and then, two voltages with a phase difference of 90° are applied to each of the two groups of PZT ceramics. Subsequently, the first-order longitudinal vibration and second-order bending vibration generated by the motor combine with each other at the tip of the driving foot to form an elliptical motion trajectory. According to the theoretical kinematic analysis of the free beam, the initial structural dimensions of the motor were designed. Then, the initial dimensions of the motor were optimized, and the zero-order optimization algorithm was used to achieve the purpose of longitudinal and bending resonance of the motor, and finally, the optimal dimensions of the motor were obtained. A prototype of the designed motor was made, followed by experimental tests on the performance of the prototype, including mechanical output. The maximum motor speed without load at 69.4 kHz is 134.57 mm s−1. Under 200 Vpp voltage and 6 N preload, the output thrust of the motor is about 0.4 N at the maximum. The actual mass of the motor is about 1.6 g; therefore, the thrust-to-weight ratio was calculated as 25. [ABSTRACT FROM AUTHOR]

A rabbit shaped block, single-phase, linear, ultrasonic motor is proposed. The motor is 17.7 × 9.1 × 6 mm3 in size, and the overall mass is 2.3 g. The motor is designed by referring to the rabbit running mode and the principle of a Langevin vibrator concentrator. It can realize bidirectional driving without changing the constraint position. First, the basic structure of the motor is introduced, and the working principle of the motor is discussed. Then, the motion trajectory and driving force of the motor driving foot are theoretically deduced and simulated, and the simulation results are verified by the modal impedance characteristic test. Finally, the mechanical characteristics of the motor prototype are tested. The results show that under the excitation voltage of 5 N preload and 200 Vpp, the motor is driven to the right in B1 mode, the no-load speed is 42.3 mm/s, the maximum driving force is 0.28 N, and the stall torque is 0.27 Nm. Correspondingly, the motor is driven in reverse in B2 mode, the no-load speed is 118 mm/s, the maximum driving force is 1.48 N, and the stall torque is 1.41 Nm. [ABSTRACT FROM AUTHOR]

In recent decades, various single-phase drive ultrasonic motors have emerged, and only a single excitation signal is used in their working states. Single-phase driven ultrasonic motors have the benefits of most ultrasonic motors, as well as the advantages of a simple driving circuit construction, low cost, high design flexibility, and high reliability, among others. According to the working principles, they are divided into three types: the vibration mode alternating type, the vibration mode coupling type, the vibration mode converting type. This paper summarizes various types of single-phase ultrasonic motors. The three types of the working principles and its representative structures are explained; output performances of the single-phase ultrasonic motors are described; then, practical and potential applications of the single-phase ultrasonic motors are introduced; finally, the research of single-phase ultrasonic motors are reviewed, and its development prospect is prospected. This review is helpful for a comprehensive understanding of single-phase drive ultrasonic motors. This paper offers the groundwork for the development of a novel single-phase driven ultrasonic motor with improved mechanical output. [ABSTRACT FROM AUTHOR]

A novel thin single-phase drive linear ultrasonic motor is proposed and tested in this paper. The proposed motor exhibits bidirectional driving via switching between the right-driving vibration mode (RD mode) and the left-driving vibration mode (LD mode). The structure and working principle of the motor are analyzed. Next, the finite element model of the motor is established and the dynamic performance is analyzed. A prototype motor is then fabricated, and its vibration characteristics are established via impedance testing. Finally, an experimental platform is built and the mechanical characteristics of the motor are experimentally investigated. The maximum no-load speed of the motor is ∼159.7 mm/s. With 8 N preload and 200 V voltage, the maximum thrust force of the motor in the RD and LD modes are ∼2.5 and 2.1 N, respectively. The motor possesses the advantages of being light in weight and thin structure and exhibiting an excellent performance. This work presents a new concept for the construction of ultrasonic actuators with bidirectional driving capacity. [ABSTRACT FROM AUTHOR]