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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]

A series elastic actuator (SEA) using an ultrasonic motor (USM) and an elastic element has attracted attention as a compact actuator with high torque-weight ratio and high force control performance. However, an elastic element in a SEA often causes mechanical vibrations. To suppress these vibrations, studies implemented the state feedback of the motor- and load-side angles. However, as the controller has many integrators, the control system becomes unstable when the angular-velocity of the USM is saturated. Therefore, in this study, integrators in the controller were reduced in number. Furthermore, a limit error feedback controller was designed to suppress the windup phenomenon caused by the integrators. The frequency analysis using a describing function showed that stability is guaranteed even if the angular-velocity is saturated. In addition, the experimental results indicate that an overshoot of the torque response is suppressed. [ABSTRACT FROM AUTHOR]

A cantilever ultrasonic motor with nanometer resolution is designed, fabricated, and tested in this article. Two orthogonal first bending vibration modes are used to form elliptical movements on driving tip to move slider. The structure of this motor is depicted, and its geometric dimensions are determined by modal analysis. The total size of this motor is 30 × 30 × 34.2 mm along the X-, Y-, and Z-direction. The working principle of the proposed motor is illustrated, and the motion characteristics of the driving tip are studied by transient analysis. A prototype of this motor is manufactured to investigate its vibration performances and mechanical characteristics. The tested results denote that this motor generates an output speed of 344.35 mm/s when the frequency and voltage are 22.7 kHz and 200 Vp-p, respectively. The maximum output force is tested as about 8 N under the voltage and preload of 100 Vp-p and 50 N, respectively. Furthermore, the proposed ultrasonic motor obtains a high displacement resolution of 48 nm under the resonant working state. [ABSTRACT FROM AUTHOR]

The authors are developing multi degree of freedom micro spherical ultrasonic motor using wire stator for vascular endoscope. Spherical ultrasonic motor with 20 times model is used to confirm the driving characteristics as experimental equipment. Wire stator is designed by assuming the introduction to a vascular endoscope and transient response analysis is performed by the finite element method compared with 20 times model. In this study, the authors improve new support structure on waveguide and investigate new influence of the attenuation of the traveling wave transmitted on the wire stator by analyzing and changing the condition of the model. In the future, the authors will measure the amplitude of the wire stator by experiment and verify the accuracy of the simulation. [ABSTRACT FROM AUTHOR]

A novel single-mode linear piezoelectric ultrasonic motor based on asymmetric structure is proposed. The motor adopts the combination of the first longitudinal vibration and the asymmetric mechanical structure to produce the oblique movement on the driving foot; then, the linear output motion is obtained under the friction coupling between the driving foot and the runner. The motor is designed and its operation principle is illustrated in detail. The transient analysis is developed to verify the formed movement on the driving foot. A prototype is manufactured and its vibration characteristics are measured by a scanning laser Doppler vibrometer. An experimental system is established and the output performances of the motor are tested and discussed. The results indicate that the maximal no-load velocity of the motor is about 127.31 mm/s under the voltage of 150 V p-p and the preload of 30 N. The maximum thrust force is about 2.8 N when the voltage and preload are 150 V p-p and 40 N. The related works in this paper has verified the feasibility of the proposed single-mode ultrasonic motor based on asymmetric structure. [ABSTRACT FROM AUTHOR]

A linear ultrasonic motor (LUSM) with an elliptical-shaped metallic stator and two orthogonal vibration modes is presented in this research. The driving tip’s desired vibration is generated by the excitation of two piezoelectric actuators installed inside the stator by two sinusoidal voltages with ± π 2 phase difference. The working principle of the motor is described and mathematically formulated. Furthermore, finite element analysis and parametric optimization are performed to finalize the motor design. A prototype of the motor is fabricated and evaluated by identification and operation tests. The experimental and numerical characteristic curves of the motor are presented and compared. Based on the experimental results, the prototype has a no-load speed of 40 mm/s and maximum thrust force of 1.55 N under excitation voltage of 70 V p and preload of 12 N. [ABSTRACT FROM AUTHOR]

This article specially designed and demonstrated a new ultrasonic motor and its control system based on the dynamic model of the 2-degree-of-freedom gyro-stabilized platform. The factors such as mechanical resonance, torque and moment inertia coupling, and nonlinearity of the driver were also taken into account during the optimization of the robust proportional-integral-differential control system. Finally, the controller was implemented by an ultrasonic motor and an embedded microcontroller. Experimental results showed that, comparing with the traditional electromagnetic motor controller, the proposed ultrasonic motor controller had the better control performances in dynamic response, static accuracy, isolation, and so on. A practical prototype of the gyro-stabilized platform with stronger robustness was also developed at the same time. [ABSTRACT FROM AUTHOR]

Generally, the modal degeneration problem existed in the design of ultrasonic motors using composite vibration modes can be overcome by adopting the same-order orthogonal-bending composite vibrations. The conventional excitation and the modified hybrid one of sandwich type orthogonal-bending composite vibrations with the same order are compared and analyzed in this paper. Compared with the conventional one, the modified hybrid excitation favors that two groups of ceramics exciting two orthogonal-bending modes are placed in the optimum excitation position. Moreover, the modified hybrid excitation can achieve larger vibration amplitude than the conventional one, while the amount of the ceramics adopted and the exciting voltages applied are the same. The first-order orthogonal-bending composite vibrations are chosen to analyze the advantage of the modified hybrid excitation. Finite-element method is adopted to compare the amplitudes of the models with the same sizes but different excitations. The prototypes corresponding to two excitations are fabricated and tested to verify the results of the theory and simulation. It is proved that the modified hybrid excitation can improve the performance of the sandwich type ultrasonic motors using bending composite vibrations. [ABSTRACT FROM PUBLISHER]

The purpose of this study is to develop a stent motor for medical blood vessel treatment. The stent motor is a movable stent. It has functions of removing plaque and expanding blood vessels. It consists of two parts; ultrasonic receivers and vibration transmitting coil (stator). In this study, the authors have focused to the vibration analysis of the receiver. In the first design stage, the authors have evaluated resonant phenomenon using finite element method. When driving it in water, the resonant frequency of the air use is shifted due to mass effect of water around the receiver. The frequency analysis of the receiver shows that extremely high precision of dimensions is required because the resonant frequency in water depends not only the size but also the amplitude of the vibration. It is very difficult to design an optimal receiver resonating in water. In order to solve this problem, the authors have tried a new receiver with wide plate receiving ultrasound effectively and requiring no resonant. The authors have succeeded in driving this type of motor in water. [ABSTRACT FROM AUTHOR]

The ultrasonic motor is an uncertain time-varying nonlinear system because of the nonlinearity of the piezoelectric material, the friction and the temperature. For example, the operating time of the mechanical switch actuated by the ultrasonic motor in regular stroke is highly dispersed. Unfortunately, it is difficult to establish accurate mathematical model. In this paper, an analytical autoregressive process model (AR) is employed to identify and control the ultrasonic motor. First of all, dispersed operating time of the mechanical switch actuated by the ultrasonic motor is investigated. Then, the AR model is established to predict the operating time of the ultrasonic motor on the basis of the statistical data to reduce the nonlinear behavior of the ultrasonic motor, and to improve the accuracy and obtain a good time response of the switch. The simulation results are agreed with experimental results, confirming the effectiveness of proposed model. Furthermore, we adopt the predicted result of the AR model to control the mechanical switch actuated by the ultrasonic motor. The analytical investigation is fulfilled with two target operating time ranges, namely 12 ms and 24 ms. Comparison of the results obtained from the AR model and the experimentation reveal that the standard deviations are less than 95.3 μs and 102.7 μs with maximum errors equal to 0.41 % and 0.44 % respectively. Thereby, the proposed dispersed operating time control is performed. Findings indicate that the maximum errors for the operating time of the mechanical switch are less than 140 μs and 110 μs with ±0.85 % and ±0.42 % respectively. [ABSTRACT FROM AUTHOR]

Elastic wave quality determines the operating performance of traveling wave ultrasonic motor (TWUM). The time-variant circumferential force from the shrink of piezoelectric ceramic is one of the factors that distort the elastic wave. The distorted waveshape deviates from the ideal standard sinusoidal fashion and affects the contact mechanics and driving performance. An analytical dynamic model of ring ultrasonic motor is developed. Based on this model, the piezoelectric parametric effects on the wave distortion and contact mechanics are examined. Multi-scale method is employed to obtain unstable regions and distorted wave response. The unstable region is verified by Floquét theory. Since the waveshape affects the contact mechanism, a contact model involving the distorted waveshape and normal stiffness of the contact layer is established. The contact model is solved by numerical calculation. The results verify that the deformation of the contact layer deviates from sinusoidal waveshape and the pressure distribution is changed, which influences the output characteristics directly. The surface speed within the contact region is averaged such that the rotor speed decreases for lower torque and increases for larger torque. The effects from different parametric strengths, excitation frequencies and pre-pressures on pressure distribution and torque-speed relation are compared. [ABSTRACT FROM AUTHOR]

The authors have developed Multi degree-of-freedom micro spherical ultrasonic motor using multiple spiral wire stators in previous research. In this research, the authors have developed the new spherical ultrasonic motor using single spiral wire stators. At the beginning, single spiral type wire stator was made. Next, rotational direction was controlled by duty ratio of traveling wave and standing wave. Then the drive properties of rotational speed and starting torque were clarified in this research. In the future, fixing method of wire stators without damping the vibration is needed to be planed. These results contribute to development of blood vessel endoscope which can move camera in any direction. [ABSTRACT FROM AUTHOR]

Optimal vibration-based energy harvesting from the axially functionally graded non-prismatic piezolaminated cantilever beam using finite element and genetic algorithm has been proposed in this article. The functionally graded material (i.e. non-homogeneous) in the axial direction is considered, where the cross section is varied (continuously decreasing from root to tip of such cantilever beam) using a proposed power law formula. The shape variations of piezolaminated cantilever (such as linear, parabolic and cubic) have been modelled using the Euler-Bernoulli beam theory. Hamilton's principle is used in order to derive the governing equation of motion. The governing equation is solved by considering two-noded beam element with 2 degrees of freedom at each node. The responses (such as frequency, voltage and output power) are compared between uniform and the axially functionally graded beam with arbitrary power gradient index. The effects of taper (both in the width and height directions) on output power along with frequency and voltage are analysed for axially functionally graded beam. In order to maximise the output power within the allowable limits of voltage and stresses, a real-coded genetic algorithm-based constrained optimisation technique has been proposed. [ABSTRACT FROM AUTHOR]

Based on vibration of four side panels, a type of dual-rotor hybrid ultrasonic motor without using the torsional piezoelectric ceramics polarized along the circumferential direction is presented. The first longitudinal and the first bending vibration modes of the four side panels are used to indirectly excite the first longitudinal and the second torsional vibration modes of the stator cylinder. There are rectangle piezoelectric ceramics bonded on both sides of the four side panels, which are uniformly distributed along the circumference of the stator cylinder. One pair of panels on the opposite side is used to indirectly excite the first longitudinal vibration mode of the stator cylinder, and the other pair is used to indirectly excite the second torsional vibration mode. The simulation results, using finite element method software Workbench, reveal the operating principles, and the optimal structure is proposed. The appearance size of the prototype is 27.2 mm × 27.2 mm × 70 mm, while the outer diameter of the stator cylinder is 20 mm. The working frequency of the prototype measured in experiment is 44.7 KHz, which is consistent with the numerical results. According to the major mechanical measurement at 450 Vp-p operating voltage and 3.46 N preload, the stalling torque of the prototype is 8 mN·m and the no-load speed is 140 r/min. The experimental results indicate that the motor can operate in the first longitudinal and the second torsional coupled vibration modes transformed from the first longitudinal and the first bending vibration modes of four side panels. [ABSTRACT FROM AUTHOR]

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A novel large thrust-weight ratio V-shaped linear ultrasonic motor with a flexible joint is proposed in this paper. The motor is comprised of a V-shaped transducer, a slider, a clamp, and a base. The V-shaped transducer consists of two piezoelectric beams connected through a flexible joint to form an appropriate coupling angle. The V-shaped motor is operated in the coupled longitudinal-bending mode. Longitudinal and bending movements are transferred by the flexible joint between the two beams. Compared with the coupled longitudinal-bending mode of the single piezoelectric beam or the symmetrical and asymmetrical modes of the previous V-shaped transducer, the coupled longitudinalbending mode of the V-shaped transducer with a flexible joint provides higher vibration efficiency and more convenient mode conformance adjustment. A finite element model of the V-shaped transducer is created to numerically study the influence of geometrical parameters and to determine the final geometrical parameters. In this paper, three prototypes were then fabricated and experimentally investigated. The modal test results match well with the finite element analysis. The motor mechanical output characteristics of three different coupling angles θ indicate that V-90 (θ = 90°) is the optimal angle. The mechanical output experiments conducted using the V-90 prototype (Size: 59.4 mm × 30.7 mm × 4 mm) demonstrate that the maximum unloaded speed is 1.2 m/s under a voltage of 350 Vpp, and the maximum output force is 15 N under a voltage of 300 Vpp. The proposed novel V-shaped linear ultrasonic motor has a compact size and a simple structure with a large thrust-weight ratio (0.75 N/g) and high speed. [ABSTRACT FROM AUTHOR]

Ultrasonic motor (USM) is an electromechanical coupling system with ultrasonic vibration, which is driven by the frictional contact force between the stator (vibrating body) and the rotor/slider (driven body). Stick-slip motion can occur at the contact interface when USM is operating, which may affect the performance of the motor. This paper develops a physically-based model to investigate the complex stick-slip-separation dynamics in a bimodal standing wave ultrasonic motor. The model includes both friction nonlinearity and intermittent separation nonlinearity of the system. Utilizing Hamilton׳s principle and assumed mode method, the dynamic equations of the stator are deduced. Based on the dynamics of the stator and the slider, sticking force during the stick phase is derived, which is used to examine the stick-to-slip transition. Furthermore, the stick-slip-separation kinematics is analyzed by establishing analytical criteria that predict the transition between stick, slip and separation of the interface. Stick-slip-separation motion is observed in the resulting model, and numerical simulations are performed to study the influence of parameters on the range of possible motions. Results show that stick-slip motion can occur with greater preload and smaller voltage amplitude. Furthermore, a dimensionless parameter is proposed to predict the occurrence of stick-slip versus slip-separation motions, and its role in designing ultrasonic motors is discussed. It is shown that slip-separation motion is favorable for the slider velocity. [ABSTRACT FROM AUTHOR]

This paper presents a novel 2-DOF planar linear ultrasonic motor. The stator of the motor can be divided as two transducers and two isosceles triangular beams. The bending vibration modes and longitudinal vibration modes of the stator are superposed as three operation modes and generate elliptical trajectories of the driving foot in two planes to provide the thrust force along two dimensions. The operating principle of the motor and the formation of the elliptical trajectory of the driving foot are analyzed, and the variable mode excitation method is illustrated. A prototype was made and experiment investigation of the motor characteristics is presented. Testing results of the prototype shows that this motor can gain a maximum speed of 211.3 mm/s and its thrust force can reach 3.15 N under an exciting voltage of 400 VP-P. The major feature of the motor is that the 2-DOF driving function can be achieved by using the method of variable mode excitation. [ABSTRACT FROM AUTHOR]

This paper presents a new-type linear ultrasonic motor which takes advantage of the combination of two orthogonal bending vibration modes. The proposed ultrasonic motor consists of eight pieces of PZT ceramic plates and a metal beam that includes two cone-shaped horns and a cylindrical driving foot. The finite element analyses were finished to verify the working principle of the proposed motor. The mode shapes of the motor were obtained by modal analysis; the elliptical trajectories of nodes on the driving foot were obtained by time-domain analysis. Based on the analyses, a prototype of the proposed motor was fabricated and measured. The mechanical output characteristics were obtained by experiments. The maximal velocity of the proposed motor is 735 mm/s and the maximal thrust is 1.1 N. [ABSTRACT FROM AUTHOR]

This paper aims to clarify the sphere forming mechanisms in vibration-assisted ball centreless grinding, a new technique for effectively processing balls using ultrasonic vibrations. Based on a comprehensive analysis of the ball rotation motion, geometrical arrangement and stiffness of the whole grinding system, a reliable mechanics model was successfully developed for predicting the sphere forming process. Relevant experiments conducted showed that the model had captured the mechanics and the major sphere forming mechanisms in ball centreless grinding. It was found that the ball whole surface can be well ground with a high accuracy, while efficiency is much enhanced compared with that in the traditional methods. The ball rotational speed which is controlled by the ultrasonic regulator has a great impact on final sphericity, and the speed controlled by the ultrasonic shoe dominates the whole processing time. To achieve a stable and high precision grinding, the ball needs to rotate rhythmically, and the wheel feed per step and the ball location angle should be controlled in a critical range. [ABSTRACT FROM AUTHOR]

In the work is presented the modeling of ultrasonic motor with three degrees of freedom. The basic and operating diagram of ultrasonic motor with piezoceramic active elements. The presentation of all vibration modes discovered by computer is make it and the possibility of being accomplished from practical viewpoint. From viewpoint all vibration modes presented are briefly described and as for the features of the useful are exhibited more to length. [ABSTRACT FROM AUTHOR]

Most screw-thread-type ultrasonic motors are designed to be two-phase driven. This paper aims to present a novel single phase driven design that generates the required wobble motion, thus significantly simplifying the driving circuit of the ultrasonic motor. The proposed single-phase driven screw-thread-type ultrasonic motor works with two orthogonal bending modes generated by an asymmetric stator design. The novel stator design can improve the vibration displacement and further enhance the performance of the single phase driven motor. The vibration characteristics of the asymmetric stator structure were analyzed by ANSYS finite element analysis software. Based on the design and analysis processes, a prototype of the desired screw-thread-type ultrasonic motor was fabricated and tested. When the operating voltage is 200 Vpp, the obtained main characteristics of the proposed motor are as follows: the working frequency is between 28.3 and 29.5 kHz; the maximum no-load velocity is approximately 4.1 mm s-1; and the thrust force is 1.6 N. [ABSTRACT FROM AUTHOR]

The purpose of this research is to develop the spherical ultrasonic motor (SUSM) for space. The SUSM is a small multi-DOF motor. The various performances are requested of the motor for space. The experiments under the high temperature environment were carried out to check the durability to the radiant heat from the sun this time. Our experimental results showed that SUSM for space also maintains the drive performance under the high temperature environment. The material of piezoelectric elements and adhesives which influence the performances of SUSM for space will be reported in detail. [ABSTRACT FROM AUTHOR]

A vibro-impact system is proposed to investigate the normal motion and impact of the driving foot of the linear ultrasonic motors based on longitudinal and bending modes. Using coefficient of restitution (CoR) method a dynamical model is developed to simulate the normal impacts between the stator and mover taking into account the preload and vibration of barycenter of the stator. Furthermore, the sticking motions that can occur are simulated when the stator impacts the mover via a Lagrange multiplier. It is shown that the sticking motions occurring in the system are affected by some factors like CoR, preload and stiffness of the preload spring in clamping parts. Results indicate that a friction material with a higher hardness, modest preload and stiffness of the preload spring can weaken sticking motion in the system. [ABSTRACT FROM AUTHOR]

A Langevin transducer can provide longitudinal vibration with larger amplitude while also possessing a greater fatigue life than other types of piezoelectric vibrators. A novel rotary Ultrasonic Motor (USM) was proposed based on the use of a longitudinal transducer (acting as the stator) and a spiral fin rotor: the front cover of the Langevin transducer was designed as a double-layer cup-shaped structure, with the rotor sustained by the inner-layer, and the bearing cover fixed to the outer-layer; the rotor consisted of a shaft and spiral fins which acted as the elastic coupler. It is different from a traditional traveling USM, because the stator provides longitudinal vibration and the rotor generates the elliptical motion. This paper analyzed the motion locus equation of the fin contact points. Additionally, a theoretical analysis was performed in regards to the mechanism and the motor’s rotor motion characteristics, which demonstrates the relationships among the motor’s driving force, the torque, the revolution speed, and the motor structure parameters. A motor prototype has been manufactured and surveyed to demonstrate the motor performance. The relationships between the amplitude and the preload on the rotor, the free revolution speed, and the torque of the motor have also been studied. [ABSTRACT FROM AUTHOR]

A high order longitudinal and bending hybrid ultrasonic motor with new excitation is proposed in this study. In the new type motor, the locations of two sets of piezoelectric ceramics are the loops of bending vibration mode. By applying two alternating voltages to the ceramics, the second longitudinal and the fifth bending vibrations will be superimposed, that make the points of the driving feet to move elliptically. The finite element method is adopted to realise two phase vibration frequency degeneration. The vibration locus of the driving feet is obtained by means of transient analysis; elliptical trajectories are observed, which verify the driving principle of the new type motor. The impedance characteristics, the vibration modes and mechanical ability of the new motor are verified by prototype tests. When the excitation voltage is 450 Vp-p, the maximum no-load speed and the maximum output force of the prototype are 439 mm s−1 and 37 N respectively. [ABSTRACT FROM AUTHOR]

In this paper, a new omnidirectional driving system is proposed that is composed of an ultrasonic motor, a sphere wheel, and ball bearings. The sphere wheel is driven by an ultrasonic motor, which is a Λ-type motor developed in the previous research. If the piezo-ceramic plates of the ultrasonic motor vibrate at the resonant frequency, the displacement of the ellipse orbit is generated at a sharp end of Λ-type. Modal analysis and time domain analysis were performed. The proposed omnidirectional driving system was validated by analyzing its motion characteristics. [ABSTRACT FROM AUTHOR]

Highlights: [•] A novel linear ultrasonic motor based on in-plane bending and longitudinal mode vibration is presented in this paper. [•] The stator of the motor is designed and optimized for the longitudinal and bending mode coupling. [•] Experimental results based on the prototype are evaluated. [ABSTRACT FROM AUTHOR]

To simplify the design of the linear ultrasonic motor (LUSM) and improve its output performance, a method of modal decoupling for LUSMs is proposed in this paper. The specific embodiment of this method is decoupling of the traditional LUSM stator's complex vibration into two simple vibrations, with each vibration implemented by one vibrator. Because the two vibrators are designed independently, their frequencies can be tuned independently and frequency consistency is easy to achieve. Thus, the method can simplify the design of the LUSM. Based on this method, a prototype modal-independent LUSM is designed and fabricated. The motor reaches its maximum thrust force of 47 N, maximum unloaded speed of 0.43 m/s, and maximum power of 7.85 W at applied voltage of 200 Vpp. The motor's structure is then optimized by controlling the difference between the two vibrators' resonance frequencies to reach larger output speed, thrust, and power. The optimized results show that when the frequency difference is 73 Hz, the output force, speed, and power reach their maximum values. At the input voltage of 200 Vpp, the motor reaches its maximum thrust force of 64.2 N, maximum unloaded speed of 0.76 m/s, maximum power of 17.4 W, maximum thrust-weight ratio of 23.7, and maximum efficiency of 39.6%. [ABSTRACT FROM AUTHOR]

Longitudinally vibration ultrasonic motor (LV-USM), a canonical nonlinear system, utilizes the inverse piezoelectric effect of piezoelectric ceramic to generate the mechanical vibration within the scope of ultrasonic frequency. However, it is very difficult to establish a strict and accurate mathematical model. Hence seeking a dynamic identifier and controller for LV-USM avoiding the accurate mathematical model becomes a feasible approach. In this paper, a novel learning algorithm for dynamic recurrent Elman neural networks is present based on a particle swarm optimization (PSO) to identify and control an LV-USM. To overcome the PSO's global search ability, Lévy flights, a kind of random walks, are imported to improve the ability of exploration rather than Brownian motion or Gauss disturbance based on Cooperative Quantum-behaved PSO (CQPSO). Thereafter, a controller is designed to perform speed control for LV-USM along with the nonlinear identification also using this kind of neural network. By discrete Lyapunov stability approach, the controller is proven to be stable theoretically and the latter trial shows its robustness of anti-noise performance. In the experiments, the numerical results illustrate that the designed identifier and controller can achieve both higher convergence precision and speed, relative to current state-of-the-art other methods. Moreover, this controller shows lower control error than other approaches while the displacement of the rotor disc in LV-USM appears more smooth and uniform. [ABSTRACT FROM AUTHOR]

For the intelligent and smart requirements of fuze safety system, a linear ultrasonic motor is proposed based on the eximious characteristics of the ultrasonic motor, such as non-electromagnetic interference, fast response, self-locking, simple structure, and flexible design, etc. The initial structure size of motor is determined according to the structure of fuze safety system. The sensitivity of structural parameters to the two-phase modal frequency consistency is analyzed by finite element software ANSYS, and the motor structure size is optimized. Frequency sweep test and vibration modal test are carried out, indicating that the motor can generate required two-phase oscillation modes, and two-phase frequency are quite close each other. The mechanical performance of motor is tested. The test results show that the speed and maximum output force of motor are 88. 2 mm/s and 2. 3 N, respectively, under the excitation of sinusoidal voltage signal with 90° phase difference, Upp = 80 V and f = 86 540 Hz. The fuze safety system with linear ultrasonic motor presented in this paper introduces new ideas for the traditional fuze design. [ABSTRACT FROM AUTHOR]

Abstract: Vibro-impacts are essential for many ultrasonic applications like ultrasonic welding or ultrasonic motors. These systems are described with a piezoelectric equivalent circuit, that is extended by an impact and a static deflection. As long as the movement of the system is mainly sinusoidal, the method of harmonic balance gives a good approximation of the vibration behaviour. It is known, that the mounting situation has a great influence on the characteristic of a vibro impact system. Therefore the analytical solution of the equivalent circuit is given and discussed for a constant pressing force, a constant gap and an arbitrary foundation stiffness. It turns out that, the dependency of static and harmonic deflection gives a good explanation and deeper understanding of vibro-impact systems. Finally the model is compared to measurements with a constant pressing force. [Copyright &y& Elsevier]

While “vibrational noise” induced by rotating components of machinery is a common problem constantly faced by engineers, the controlled conversion of translational into rotational motion or vice-versa is a desirable goal in many scenarios ranging from internal combustion engines to ultrasonic motors. In this work, we describe the underlying physics after isolating a single degree of freedom, focusing on devices that convert a vibration along the vertical axis into a rotation around this axis. A typical Vibrot (as we label these devices) consists of a rigid body with three or more cantilevered elastic legs attached to its bottom at an angle. We show that these legs are capable of transforming vibration into rotation by a “ratchet effect”, which is caused by the anisotropic stick-slip-flight motion of the leg tips against the ground. Drawing an analogy with the Froude number used to classify the locomotion dynamics of legged animals, we discuss the walking regime of these robots. We are able to control the rotation frequency of the Vibrot by manipulating the shaking amplitude, frequency or waveform. Furthermore, we have been able to excite Vibrots with acoustic waves, which allows speculating about the possibility of reducing the size of the devices so they can perform tasks into the human body, excited by ultrasound waves from the outside. [ABSTRACT FROM AUTHOR]

Based on the concept of forming elliptical movements on the two leading ends of a beam by the superimposing of two orthogonal first-order bending modes, a high power linear ultrasonic motor using a bending bolt-clamped transducer is proposed in this study. Two groups of bending PZT located at the wave loop of the bending vibration are excited by alternating voltages with the transducer's bending resonance frequency to accomplish the generations of the two orthogonal bending vibrations. The symmetrical setting of the PZT elements makes the two driving feet have the same elliptical movement trajectory. Elastic supporting is accomplished by thin beams machined on the two sides of each horn. The electromechanical coupling factors of the motor are calculated; the movement trajectories of the diving feet are simulated. After the fabrication of a prototype, its vibration characteristics and mechanical ability are tested. The proposed motor achieves a maximum speed of 1309 mm/s and a maximum thrust force of 45 N. [ABSTRACT FROM PUBLISHER]

Abstract: In systems with rotational symmetry, bending modes occur in doubly-degenerate pairs with two independent vibration modes for each repeated natural frequency. In circular plates, the standing waves of two such degenerate bending modes can be superposed with a 1/4 period separation in time to yield a traveling wave response. This is the principle of a traveling wave ultrasonic motor (TWUM), in which a traveling bending wave in a stator drives the rotor through a friction contact. The stator contains teeth to increase the speed at the contact region, and these affect the rotational symmetry of the plate. When systems with rotational symmetry are modified either in their geometry, or by spatially varying their properties or boundary conditions, some mode-pairs split into singlet modes having distinct frequencies. In addition, coupling between some pairs of distinct unperturbed modes also causes quasi-degeneracies in the perturbed modes, which leads their frequency curves to approach and veer away in some regions of the parameter space. This paper discusses the effects of tooth geometry on the behavior of plate modes under free vibration. It investigates mode splitting and quasi-degeneracies and derives analytic expressions to predict these phenomena, using variational methods and a degenerate perturbation scheme for the solution to the plate’s discrete eigenvalue problem; these expressions are confirmed by solving the discrete eigenvalue problem of the plate with teeth. [Copyright &y& Elsevier]

We report a miniature piezoelectric ultrasonic linear motor that is made of four Pb(Zr,Ti)O3 (PZT) piezoelectric ceramic layers for low-voltage work. The 4-layer piezoelectric laminate works in two orthogonal first-bending modes for producing elliptical oscillations, which are then used to drive a contacting slider into continuous linear motion. Experimental results show that the miniature linear motor (size: 4 ? 4 ? 12 mm, weight: 1.7 g) can generate a large driving force of 0.48 N and a linear motion speed of up to 160 mm/s, using a 40 Vpp/mm voltage drive at its resonance frequency of 64.5 kHz. The maximum efficiency of the linear motor is 30%. [ABSTRACT FROM PUBLISHER]

Abstract: This paper presents and verifies a new idea for constructing rotary ultrasonic motor that may effectively make use of the longitudinal vibrations of the bolt-clamped transducers. Based on the idea of generating elliptical motion on the driving tip by superimposing longitudinal vibrations, a square-type rotary ultrasonic motor with four driving feet is proposed. This new motor consists of four longitudinal vibration transducers, which are located in square-type and form an enclosed construction. The longitudinal vibrations of the four transducers are superimposed to produce the same circular movements on the four feet, which can push the rotor into motion when a preload is applied. By using FEM method, the proposed motor is designed and analyzed, and circular trajectories on the driving feet are gained. The vibration and input impedance characteristics of the motor are measured after the fabricating of a prototype, and the test results are in good agreement with the FEM analysis results. Typical output of the prototype is no-load speed of 71r/min and maximum torque of 12.3Nm at an exciting voltage of 200Vrms. [Copyright &y& Elsevier]

Abstract: Speed improvements of plate ultrasonic motors could be achieved by choosing suitable excitation frequencies; however, the combination of these two frequencies is hard to be determined. Based on the linear superposition of vibrations at two independent mode frequencies, the rotation angles and amplitudes of modal vibrations are proposed to select the possible dual-frequency excitation combinations in this paper. Experimental prototype is a plate ultrasonic motor using single-phase asymmetric excitation, which can work under a single vibration or multiple vibration modes. The speed characteristics of prototype driven by dual-mode coupling are used to verify the coupling effects of dual-mode drive, in which each rotation angle of two modal vibrations is not close to vertical phase, and the two modal vibrations with larger amplitudes and closer rotation angles could improve the rotation speed of motor. [Copyright &y& Elsevier]

Abstract: This paper describes a motion-visualization technique for an ultrasonic motor (USM) by using a stroboscopic oblique-incidence interferometer. Characteristics of USM depend on a vibration mode of a stator which is one of main component of USM. Though there are some visualization techniques of its vibrated mode, it is difficult to visualization. Because the surface of the stator is rough for a light. For visualization such a surface, we focused on an oblique-incidence interferometer. The interferometer is well suited to analyze the rough surface because a scattering at the rough surface is reduced by using an oblique-incidence light. Furthermore, for detecting a vibrated surface, a pulsed light synchronized with stator was used as light source. We have succeeded to detect a periodically movement of fringe patterns of the vibrated stator. [Copyright &y& Elsevier]

In this paper, we develop a meal assistance robot for people with disabilities of upper limbs and pacemakers in the body. In the robot, ultrasonic motors are used because the motors do not generate an electromagnetic field. The robot is handled using acts of user's eyes so that the people can use it. Moreover, the vibration is small because the arms of our robot move independently of each other. In this paper, we introduce structure of our robot and show the advantage with experiment results. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, heat problem and temperature distribution of a piezoelectric plate-type ultrasonic motor, which is operated at not only steady state conditions but also unsteady state conditions, are analyzed based on finite element analysis and finite difference method. Mechanical vibration losses, dielectric losses and friction heat were considered as the heat source of ultrasonic motor and were calculated using three-dimensional finite element method. Gauss–Seidel iteration method was used to calculate the temperature field based on finite difference method. The calculated temperature field distribution and the calculated temperature increase with time are verified at different pre-presses by comparison with experimental results obtained using an infrared imager. The results show a good agreement between experiment and calculation. It shows that the presented method for the temperature field distribution of piezoelectric ultrasonic motor is feasible. [Copyright &y& Elsevier]

A high-power linear ultrasonic motor using longitudinal vibration transducers with single foot was proposed in this paper. The stator of proposed motor contains a horizontal transducer and a vertical transducer. Longitudinal vibrations are superimposed in the stator and generate an elliptical trajectory at the driving foot. The sensitivity analysis of structural parameters to the resonance frequencies of two working modes of the stator was performed using the finite element method. The resonance frequencies of two working modes were degenerated by adjusting the structural parameters. The vibration characteristics of stator were studied and discussed. A prototype motor was fabricated and measured. Typical output of the prototype is a no-load speed of 1160 mm/s and maximum thrust force of 20 N at a voltage of 200 Vrms. [ABSTRACT FROM AUTHOR]

Abstract: The electromechanical coupled dynamic model of the stator of the bar-type ultrasonic motor is derived based on the finite element method. The dynamical behavior of the stator is analyzed via this model and the theoretical result agrees with the experimental result of the stator of the prototype motor very well. Both the structural design principles and the approaches to meet the requirements for the mode of the stator are discussed. Based on the pattern search algorithm, an optimal model to meet the design requirements is established. The numerical simulation results show that this optimal model is effective for the structural design of the stator. [Copyright &y& Elsevier]

Abstract: This paper presents an analysis and measurement method for studying lateral elliptic motion effect of an asymmetric disc-type ultrasonic motor whose stator is a circular disc with a bonded PZT plate serving as a drive. At the edge of the stator with a simple, fixed three-point support of a 120°–90°–150° configuration, there exists a coupled vibration wave with lateral elliptical motion so as to generate a driving force between the stator and the rotor. The equations of the lateral elliptic motion and the driving force are analytically formulated based on the wave equation on the circular plate, thereby obtaining the driving frequency and the revolution speed of the motor. The relationship between the ultrasonic stator and its boundary condition is investigated as well. The analysis shows that the circumferential edge with a 90° included angle is an optimal contact section for the placement of the rotor. Experiments using the laser vibrometer and photodetector are used to show the validity of the proposed analysis method. [Copyright &y& Elsevier]

Piezoelectric ceramics, constituting an active element, make a stator vibrate generating a rotational force in ultrasonic motors. In the drive of ultrasonic motors, many factors exist that can affect the resonance characteristics of piezoelectric ceramics. For example, those factors are the bonding conditions with the elastic body, the magnitude of the electric field, the normal force for the frictional drive, the emission of heat due to vibration and friction, and so on. Therefore, it is important to properly research the inclination for variation of piezoelectric ceramics in the circumstance where complex elements are involved. In this paper, we focus on the analysis of the resonance characteristics of an ultrasonic motor due to the magnitude of the input voltage and normal force. [ABSTRACT FROM AUTHOR]

Abstract: A novel multi-degree-of-freedom (MDOF) ultrasonic motor was presented in this paper. The in-plane deformation of planar piezoelectric elements was used to generate the vibrations in the single stator. The working principle was elaborated; an initial prototype was fabricated and tested. The elliptical motion at the tip of the stator was demonstrated by measuring the vibration characteristics. And the load characteristic of the motor was also obtained. The results confirm that the motor successfully provides the desired MDOF motion around orthogonal axes with a single stator using in-plane deformation of planar piezoelectric elements. [Copyright &y& Elsevier]

Abstract: A finite element is presented to analyze the three-dimensional (3-D) vibration of piezoelectric coupled circular and annular plates. The proposed finite element is a modification of a conventional axisymmetric finite element and is capable of conducting both axisymmetric and nonaxisymmetric vibration analysis of circular and annular laminated plates, with piezoelectric layers therein. The present formulation, a two-dimensional model itself, can investigate 3-D vibration of those plates for a preselected number of nodal diameters, and is therefore more economical than the conventional 3-D finite element analysis, yet still has almost the same accuracy and versatility as the 3-D analysis. In cases such as analysis of stators of traveling wave ultrasonic motors where only vibration modes with particular numbers of nodal diameters are of interest, the proposed approach is very convenient and useful. [Copyright &y& Elsevier]

In this paper, disk-type ultrasonic motor using a combination of radial and bending vibration modes is newly designed and fabricated. The characteristics of the test motor are also measured. By means of traveling elastic wave induced at the surface of circumference of the elastic disk, a steel bar in contact with the surface of circumference of elastic disk bonded onto the piezoelectric ceramic disks is driven in both directions by changing the sine and cosine voltage inputs. The stator of the motor is composed of two sheets of piezoelectric ceramic disk to bond onto both surfaces of a elastic disk, respectively. As the results, the diameter of elastic body is increased, the resonant frequency is decreased. The resonant frequency of the stator is about 92 kHz, which is composed with piezoelectric ceramic disks of 28 mm in diameter and 2 mm in thickness, and an elastic body of 32 mm in diameter and 2 mm in thickness. A driving voltage of 20 Vpp produces 200 rpm with a torque of 1 Nm and an efficiency of about 10%. [ABSTRACT FROM AUTHOR]