A two-degrees-of-freedom (two-DOF) ultrasonic motor, which could output linear motions with two-DOF by using only one longitudinal–bending hybrid sandwich transducer, is proposed and tested in this paper. The motion in the horizontal ( X ) direction is achieved by the hybrid of the second longitudinal and fifth bending vibrations of the motor, while the motion in the vertical ( Y ) direction is gained by the composition of two orthogonal fifth bending vibrations. The proposed ultrasonic motor is designed and the principles for the two-DOF driving were analyzed. Then, the simulation analyses of the motor are accomplished to verify the described principles. Finally, a prototype is fabricated and its mechanical output characteristics are tested. The results indicate that the maximum no-load velocities of the motor in horizontal and vertical directions are 572 and 543 mm/s under the preload of 100 N and the voltage of 300 Vp-p, respectively. The maximum output forces in horizontal and vertical directions are 24 and 22 N when the preload is 200 N. The simulation and experiment results verify the feasibility of the proposed two-DOF ultrasonic motor.

A Two-DOF Ultrasonic Motor Using a Longitudinal–Bending Hybrid Sandwich Transducer

A trapezoid-type stick–slip piezoelectric linear actuator using a right circular flexure hinge mechanism was proposed, designed, fabricated, and tested with the aim of accomplishing linear driving based on stick–slip motion. The angle adjustment of the trapezoid beam was used for generating lateral motion on the driving foot of the flexure hinge mechanism. A method of tuning the lateral motion of the flexure hinge mechanism was discussed. Based on the finite-element method, a proper angle of the trapezoid beam was obtained. The analysis results proved that asymmetrical flexure hinge mechanism can increase static friction force in slow extension stage and decrease kinetic friction force in quick contraction stage by lateral motion of the driving foot. A prototype was fabricated and its experimental system was established. The mechanical output experiments showed that the prototype achieved maximum output velocity and load of 5.96 mm/s and 3 N at a voltage of 100 V $p-p$ and a frequency of 500 Hz, respectively.

A Novel Trapezoid-Type Stick–Slip Piezoelectric Linear Actuator Using Right Circular Flexure Hinge Mechanism

A single-foot linear piezoelectric actuator is proposed in this paper, and a new exciting method for the stepping motion is discussed The proposed actuator works in the hybrid modes of the second horizontal bending vibration and the second vertical bending vibration Two intermittent sinusoidal signals with a phase difference of 90° are applied on the horizontal and vertical PZT elements, respectively, to obtain a discontinuous elliptical motion at the driving foot, which can move the runner linearly step by step The structure of a single-foot linear piezoelectric actuator is designed and the mechanism for the linear driving is clarified Then, modal and transient analyses are carried out by using ANSYS software to get the resonance frequencies of the bending modes and the movement trajectory of the driving foot Finally, a prototype of the piezoelectric actuator is fabricated, and experiments are carried out The experiment results show that the displacement resolution, the maximum velocity, and the maximum thrust of the proposed piezoelectric actuator are about 021 μm, 8275 mm/s, and 27 N, respectively

Design and Experiments of a Single-Foot Linear Piezoelectric Actuator Operated in a Stepping Mode

To overcome the modal degeneration problem that commonly exists in the design of ultrasonic motors (USMs) using composite vibration modes, a high-power linear USM using a bending vibration transducer is proposed in this paper. In this new design, two orthogonal bending vibration modes with the same order are superimposed in the motor and generate elliptical motions at the two driving feet. Square cross-section structure is adopted by the motor to ensure that the two bending modes have the same resonance frequency. After the introduction of the working principle, the motor is analyzed by using finite-element method. A prototype motor is fabricated and measured. Typical output of the prototype is a no-load speed of 1527 mm/s and a maximum thrust force of 50 N at a voltage of 200 Vrms. This study verifies the feasibility of the proposed design and provides a way to improve the output power of USMs.

A High-Power Linear Ultrasonic Motor Using Bending Vibration Transducer

A review of recent studies on non-resonant piezoelectric actuators

A hybrid transducer type ultrasonic linear motor using the 1st longitudinal and the 2nd bending vibration modes of a bolt-clamped Langevin type transducer has been proposed and studied for accomplishing high mechanical output The longitudinal vibration generates the mechanical driving force and the bending vibration controls the frictional force To obtain large vibration amplitude and large mechanical output, a method of tuning the longitudinal resonance frequency to the bending one was investigated using finite element simulations, and demonstrated experimentally To avoid magnetic interaction, we employed phosphor bronze for the bolt of the transducer The prototype motor achieved the no-load velocity of 047 m/s and the maximum output mechanical force of 92 N

https://iopscience.iop.org/article/10.1143/JJAP.40.3773/pdf

A High Power Ultrasonic Linear Motor Using a Longitudinal and Bending Hybrid Bolt-Clamped Langevin Type Transducer

A novel ultrasonic micro linear motor that uses 1st longitudinal and 2nd bending modes, derived from a bartype stator with a rectangular slot cut through the stator length, has been proposed and designed for end-effect devices of microrobotics and bio-medical applications. The slot structure plays an important role in the motor design, and can be used not only to tune the resonance frequency of the two vibration modes but also to reduce the undesirable longitudinal coupling displacement caused by bending vibration at the end of the stator. By using finite element analysis, the optimal slot dimension to improve the driving tip motion was determined, resulting in the improvement of the motor performance. The trial linear motor, with a weight of 1.6 g, gave a maximum driving velocity of 1.12 m/s and a maximum driving force of 3.4 N. A maximum mechanical output power of 1.1 W was obtained at force of 1.63 N and velocity of 0.68 m/s. The output mechanical power per unit weight was 688 W/kg.

/pdf/a-piezoelectric-ultrasonic-linear-micromotor-using-a-slotted-w4w0b1mv8w.pdf

A piezoelectric ultrasonic linear micromotor using a slotted stator

Three types of support mechanism for the ball rotor of a three-degree-of-freedom ultrasonic motor with a single stator have been proposed and studied in order to achieve a large output torque. These support mechanisms could apply a sufficient preload to the ball rotor, and the three-degree-of-freedom rotational movements of the ball rotor were possible. The output torque were 1.7 kgf(.)cm for the z-axis rotation and 2.8 kgf(.)cm for the x-axis rotation at a preload of 4 kgf. The no-load maximum rotation speeds were 5 rps for the z-axis rotation and 4.3 rps for the x-axis rotation

Support Mechanism for the Ball Rotor in the Three-Degree-of-Freedom Ultrasonic Motor

A new ultrasonic suction pump is described in this paper. The pump uses the suction force of a rigid cylinder tube vibrating at an ultrasonic frequency and has no physically moving parts. The pump consists of a longitudinal bolt-clamped Langevin transducer (BLT) combined with a stepped horn working at a resonance frequency of 24 kHz. A glass tube with the length of the half-wavelength-resonance is glued at the tip of the horn. To enhance pump performance, we introduced a reflection plate and a thin rod installed to the end of the glass tube with a small gap. Maximum pressures of 7.2 kPa and 23.5 kPa were recorded using the reflection plate and the thin rod, respectively. In this study, we experimentally investigate the characteristics of the pump and the operating physics. The maximum pressure is a function of the vibration velocity of the end surface of the glass tube and of the gap.

https://iopscience.iop.org/article/10.1143/JJAP.43.2864/pdf

An Ultrasonic Suction Pump with No Physically Moving Parts

To improve the operating stability and controllability of a high-power ultrasonic linear motor, the authors propose a mechanism to hold the vibrator using the resonance of stepped horns. The new holding system can support the motor firmly, without affecting the longitudinal and bending vibration modes. The resonance frequency of the supporting system is designed to be very near to that of the motor. By using the proposed system, the residual vibrations and the settling time in the transient state have been reduced markedly. When supported by the resonance support mechanism, the no-load speed and the maximum thrust force of the motor were not changed even after 8000 complete back-and-forth cycles, while with the one-point support system, the no-load speed fell rapidly and the motor failed after 20 to 30 cycles.

https://iopscience.iop.org/article/10.1143/JJAP.41.3261/pdf

Cheol-Ho Yun

Papers

A High Power Ultrasonic Linear Motor Using a Longitudinal and Bending Hybrid Bolt-Clamped Langevin Type Transducer

A piezoelectric ultrasonic linear micromotor using a slotted stator

Support Mechanism for the Ball Rotor in the Three-Degree-of-Freedom Ultrasonic Motor

An Ultrasonic Suction Pump with No Physically Moving Parts

Holding Mechanism Using a Resonance System for a High-Power Ultrasonic Linear Motor