The treatment force and moment on the teeth play an important role in orthodontics. However, there are many difficulties to investigate the biomechanical mechanism of tooth movement in vivo. Orthodontic simulation system becomes an acceptable method to reproduce the orthodontic process and measure the mechanical parameters. In this study, an orthodontic mechanics test platform based on a six-axial force/moment sensor is developed to provide a quantitative evaluation of orthodontic forces and moments exerted by the invisible braces. First, the mechanical design and working principle of the test platform are explained. Then, the hardware design and data processing of the six-axial force/moment sensor are illuminated. The calibration of the sensor is described. Finally, the maxillary model of a central incisor with specific displacement are tested and discussed. The experimental results show that the proposed test platform can simulate the position change of the concerned tooth and reflect the magnitude change of their mechanical parameters during the orthodontic treatment. This study provides an effective technical solution for the investigation of the biomechanical mechanism of tooth movement during the orthodontic process.
Adaptive optical systems are originally developed for the field of astronomy to eliminate image blurring aberrations induced by atmospheric disturbance. In some complex applications, such as the contactless thin adaptive mirror for large-aperture ground-based optical telescopes, displacement sensors are needed to measure the deformation of the deformable mirror and construct a local position control loop. In the past adaptive secondary mirrors, capacitive sensors are designed to measure the mirror deformation. However, they suffer problems of manufacturing, maintenance, and environment. In this paper, a high-performance eddy current displacement sensor is proposed for the deformation measurement of adaptive secondary mirrors. Simulation and optimization of the detecting coil and conductive target are carried out. A deliberate signal processing circuit is designed for weak signal detection. Experimental results of the prototype sensor indicate a resolution up to 5 nm and a linearity better than 0.1% within the measuring range of 50 μm and bandwidth of 3 kHz, which meet the basic technical requirements of the adaptive optical systems.
This study presents the design and model of a XY parallel inertial drive mechanism (PIDM) based on piezoelectric bending actuators. Mechanical structure of the PIDM and its working principle are introduced. A dynamic model of the XY PIDM is established with simplification of mechanism and expansion of friction force. With extracted dynamic model parameters, numerical simulations of the XY parallel motions are implemented using software MATLAB/Simulink. Stepping responses of the single DOF motions and cooperative planar motions with various driving parameters are analyzed.
With rapid developments of micro/nano science and technology, precision platforms are widely required in the research and industry fields. This paper presents a 2-DOF parallel linear precision platform utilizing piezoelectric impact drive mechanism. With symmetrical flexible structure and specific piezoelectric driving manner, effective and decoupled actuation of the stator is achieved. FEA simulations are conducted to investigate the characteristics of the stator. With established dynamic model of the platform, motion responses of stator and slider in the two directions are simulated and analyzed. With simultaneous actuation of the 2-DOF motions, a motion interaction phenomenon is raised and discussed.
The large adaptive deformable mirrors were adapted in several large aperture telescopes and has been proved to have great effect in the AO system, however the captive sensors used in the adaptive secondary are very sensitive to the circumstance such as temperature, moisture, dust, So a new adaptive mirror scheme using the Eddy Current Sensors has been proposed in this paper. The technical plan would be discussed in this paper, a number of simulations would be carried out and some experiments result would be posed in this paper.
The segmented mirror active optics technology is one of the key technologies for the extremely large telescope, while edge sensor is one of the essential core components of active optics for the co-phasing maintenance of all segmented mirrors. The main properties of these edge sensors are of high precision of nanometers, high linearity, and low sensitivity to temperature and humidity fluctuations as well as high reliability. This paper presents an eddy current edge sensor design developed cooperatively by Nanjing Institute of Astronomical Optics and Technology and University of Science and Technology of China. The stage work performance results of eddy current sensor prototype under representative operational conditions are also presented.
This paper presents a novel impact piezoelectric linear-rotary motor which is driven by a single piezoceramic tube with two parts of electrodes. From the inner and outer electrodes, longitudinal displacement of the tube is generated and used to actuate the shaft with linear motion ability. From the grooved helical interdigitated electrodes, torsional displacement is generated and used to actuate the shaft with rotary motion ability. Working principle and structural design of the motor are introduced and quasi-static longitudinal and torsional displacements of the tube are estimated. With established kinematics model of the motor, the working behaviors of the motor are investigated numerically with MATLAB/Simulink software. The stepping characteristics of the linear and rotary motions are analyzed, compared, and discussed. With optimized material selection, structural design, and driving parameters, the proposed linear-rotary motor will provide remarkable performances as a miniaturized multi-degree driving device for complex positioning and manipulation applications.
Torsional vibrations of circular tubes, rods, rings, and disks are widely used as operation modes of acoustic wave transducers in various piezoelectric devices. In this paper, a piezoelectric disk with spiral interdigitated electrodes is proposed to generate in-plane torsion in a simple and effective manner. Design and working principle of the torsional transducer are introduced. Vibration characteristics of the transducer with a constant spiral angle are studied. A simplified model is established to investigate the basic dynamic characteristics of torsional vibration accompanying with radial vibration. Electric admittance, resonant frequencies, and mode shapes with different boundary conditions are calculated. Resonant frequencies as functions of several structural parameters are discussed.
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