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The multidimensional motion ultrasonic motor with a single spherical stator is studied in this paper. It has the characteristics of miniaturization and can be used in precision motion applications. By bonding six identical pieces of piezoelectric ceramic onto the stator and applying the voltage signal of high frequency, the deformation of the inverse piezoelectric effect is used to excite the stator yaw vibration mode. The orthogonal superposition of the modes of the spherical stator on the driving foot produces elliptical trajectory around X, Y, and Z directions by different excitation methods. According to the yaw vibration mode of the spherical stator, 12 driving feet are designed to drive the rotation of the spherical rotor. The structure and mechanical characteristics of the motor are simulated by using simulation software, and the transient response of the stator driving foot was obtained, which proved its feasibility. Finally, the output performance of the motor in actual operation is given through experiments, which provides a new reference scheme in the field of precise multi-degree-of-freedom motion. At a voltage of 100 V and a frequency of 26.7 kHz, the prototype has a no-load speed of 73, 70, and 114 rpm around X, Y, and Z axes, respectively. [ABSTRACT FROM AUTHOR]

A novel spherical multi-degree-of-freedom ultrasonic motor is designed, which can achieve three-degree-of-freedom motion through the cooperative drive of three built-in traveling wave stators. The novel ultrasonic motor has the characteristics of compact structure and high power density. Additionally, in order to solve the problem of impedance mismatch between the ultrasonic motor and the driving power supply, a semi-analytical method of impedance matching based on parallel resonance is proposed according to the impedance characteristics of ultrasonic motor. Through the combination of theoretical derivation and finite element simulation, the ultrasonic motor impedance matching on the impedance circle is analyzed. By this method, the optimum matching inductor of the motor is determined. After matching, the motor obtains a larger vibration amplitude and higher transmission efficiency. Finally, the reliability of the method is verified by simulation and experiment, which provides a reference for further improving the motor performance. [ABSTRACT FROM AUTHOR]

The traditional stick-slip piezoelectric actuator uses a single flexible hinge structure, and the output force of the piezoelectric stack is greater than the clamping force between the driving foot and the slider, resulting in a small working stroke, slow speed, and poor load capacity. A new piezoelectric actuator based on a two-stage flexible hinge structure is proposed. The piezoelectric actuator uses a combination of a lever flexible hinge and a triangular flexible hinge. The working stroke and speed of the actuator are enlarged by the lever flexible hinge, and the output force of the piezoelectric stack is perpendicular to and greater than the clamping force between the driving foot and the slider through the triangular flexible hinge, which enhances the load capacity of the actuator. First, the structure and working principle of the piezoelectric actuator are presented. The lateral output displacement of the piezoelectric ceramic stack is amplified by the lever amplification structure so that the triangular flexible hinge structure is then used to convert the lateral displacement into a coupled motion composed of longitudinal and lateral displacement to drive the slide rail to generate total displacement. Then, the superiority of the piezoelectric actuator was verified through the analysis of displacement amplification and clamping force and finite element analysis. Finally, the performance of the piezoelectric actuator is studied. It can produce an output speed of 354.55 mm/s under a driving voltage of 4.7 kHz and 150 V, and the maximum load can reach 3 kg. This article provides a new design idea for stick-slip piezoelectric actuators. [ABSTRACT FROM AUTHOR]

Cam mechanism is widely applied in industry because it can help achieve various complex motions of the follower via the cam contour design. However, its performance is significantly affected by the wear condition. This study proposes a load distribution measurement instrument to assist the study on friction and wear regularities of oscillating follower cam mechanisms through obtaining the normal pressure (F) and friction force (Ff) distributions along the cam profile. In the instrument, F and Ff are automatically calculated via a MATLAB program based on the geometry and the measured rotary resistance torque and rotary angle of the cam. The latter two parameters are obtained through a static torque sensor and a rotary encoder built in servo motor in real time, respectively. An experimental test was conducted and the cam morphology after service was observed using scanning electron microscopy. Results show that the wear condition of the cam is significantly related to the corresponding F and Ff. Complex load parameters of oscillating follower cam mechanisms can be provided by this instrument, which is crucial in understanding the friction and wear behaviors of cams and finding the vulnerable position. [ABSTRACT FROM AUTHOR]

The response characteristics of a two-stage CuSO[sub 4] solution "tube" resistive divider placed in another CuSO[sub 4] solution "tube" in a concentric cylindrical configuration for measuring highvoltage nanosecond pulses have been studied. The test results showed that it was capable of maintaining pulse rise time tess than 10 ns, and the hold-off voltage for pulses with rise times less than 10 ns was 600 kV. [ABSTRACT FROM AUTHOR]

This paper presents a new biomimetic soft finger joint with elastic ligaments for enhanced restoration capability. A hemisphere-shaped flexible finger joint is designed to secure omnidirectional restoration and guarantee a reliable recovery function. Joint design comparative studies for enhancing restoration are presented with joint mechanisms and potential energy formulation analyses. A ligament design that enables an efficient grasping mode switch from power to pinch grasping is also considered. By using the presented joint and ligament, a tendon-driven robot hand is assembled. For the finger's biomimetic features, the hand provides a reasonably secure grasping operation for various complicated objects with minimum controls. The impact test and grasping experiments confirmed that the fabricated hand has the right amount of passive compliance in all directions as designed, and the restoration to the original state is also stably performed.

Silicon single-photon detectors (SPDs) are the key devices for detecting single photons in the visible wavelength range. Here we present high detection efficiency silicon SPDs dedicated to the generation of multiphoton entanglement based on the technique of high-frequency sine wave gating. The silicon single-photon avalanche diode components are acquired by disassembling 6 commercial single-photon counting modules (SPCMs). Using the new quenching electronics, the average detection efficiency of SPDs is increased from 68.6% to 73.1% at a wavelength of 785 nm. These sine wave gating SPDs are then applied in a four-photon entanglement experiment, and the four-fold coincidence count rate is increased by 30% without degrading its visibility compared with the original SPCMs.

Avalanche transistors have been widely studied and used in nanosecond high voltage pulse generations. However, output power improvement is always limited by the low thermal capacities of avalanche transistors, especially under high repetitive working frequency. Parallel stacked transistors can effectively improve the output current but the controlling of trigger and output synchronism has always been a hard and complex work. In this paper, a novel stereo-symmetrical nanosecond pulsed power generator with high reliability was developed. By analyzing and testing the special performances of the combined Marx circuits, numbers of meaningful conclusions on the pulse amplitude, pulse back edge, and output impedance were drawn. The combining synchronism of the generator was confirmed excellent and lower conducting current through the transistors was realized. Experimental results showed that, on a 50 Ω resistive load, pulses with 1.5-5.2 kV amplitude and 5.3-14.0 ns width could be flexibly generated by adjusting the number of combined modules, the supply voltage, and the module type.

This paper presents a 2-degrees of freedom flexure-based micropositioning stage with a flexible decoupling mechanism. The stage is composed of an upper planar stage and four vertical support links to improve the out-of-plane stiffness. The moving platform is driven by two voice coil motors, and thus it has the capability of large working stroke. The upper stage is connected with the base through six double parallel four-bar linkages mechanisms, which are orthogonally arranged to implement the motion decoupling in the x and y directions. The vertical support links with serially connected hook joints are utilized to guarantee good planar motion with heavy-loads. The static stiffness and the dynamic resonant frequencies are obtained based on the theoretical analyses. Finite element analysis is used to investigate the characteristics of the developed stage. Experiments are carried out to validate the established models and the performance of the developed stage. It is noted that the developed stage has the capability of translational motion stroke of 1.8 mm and 1.78 mm in working axes. The maximum coupling errors in the x and y directions are 0.65% and 0.82%, respectively, and the motion resolution is less than 200 nm. The experimental results show that the developed stage has good capability for trajectory tracking.