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 course of “Applied Optics” is professional and foundational for the specialty of photo-electric information and engineering. According to the characteristics of the specialty, the teaching contents, teaching means, innovations and appraisal methods are mainly discussed in this paper. Firstly, one of the most difficult part to comprehend, the Fermat principle is taken as an example in the teaching content. By using the development history of optics and interesting natural phenomenon, students' understanding of the optical knowledge can be enhanced. Secondly, in various means of teaching art, ZEMAX provides students with a platform of training innovative consciousness and engineering capacity, and it make high cohesion in teaching and scientific research. Thirdly, in the teaching innovation, photoelectric contest can stimulate students' innovative thinking, innovation awareness, and cultivate undergraduate students’ optics, mechanics, electricity, numerology integrated design capabilities. Lastly, the reform in the appraisal methods guide students from focusing on the examination results to pay attention to the learning process. Eventually, students' study interest has improved, demand of the engineering practice has adapted, and the well teaching effect has realized.
A high-resolution transducer of linear displacements is presented. The system is based on semiconductor laser illumination and a diffraction grating applied as a length master. The theory of the optical method is formulated using Doppler description. The relationship model among the interference strips, measurement errors, grating deflection around the X, Y and Z axes and translation along the Z axis is built. The grating interference strips' direction and space is not changed with movement along the X (direction of grating movement), Y (direction of grating line), Z axis, and the direction and space has a great effect when rotating around the X axis. Moreover the space is little affected by deflection around the Z axis however the direction is changed dramatically. In addition, the strips' position shifted rightward or downwards respectively for deflection around the X or Y axis. Because the emitted beams are separated on the grating plane, the tilt around the X axis error of the stage during motion will lead to the optical path difference of the two beams resulting in phase shift. This study investigates the influence of the tilt around the X axis error. Experiments show that after yaw error compensation, the high-resolution diffraction grating interferometric transducer readings can be significantly improved. The error can be reduced from ±80 nm to ±30 nm in maximum.
QR code encodes many kinds of information because of its advantages: large storage capacity, high reliability, full arrange of utter-high-speed reading, small printing size and high-efficient representation of Chinese characters, etc. In order to obtain the clearer binarization image from complex background, and improve the recognition rate of QR code, this paper researches on pre-processing methods of QR code (Quick Response Code), and shows algorithms and results of image pre-processing for QR code recognition. Improve the conventional method by changing the Souvola’s adaptive text recognition method. Additionally, introduce the QR code Extraction which adapts to different image size, flexible image correction approach, and improve the efficiency and accuracy of QR code image processing.
Planar cross diffraction grating can be adopted to measure displacement as scale. In this paper, Planar grating
interferometer configuration for precise displacement measurements is introduced, and the principle of interferometer
based on polarization optics is deduced. According to 2-D grating interferometer structure, error sources are analyzed,
and the pitch and yaw of 2-D grating guide caused by planar guide's non-linearity is the main factors to decrease the
measurement system's accuracy. With grating interferometer error sources analysis, precise planar stage is proposed to
integrate with the gating interferometer, the stage is compact and can minimize abbe error in structure. The methods of
calibration and error compensation are employed to improve the position accuracy of the stage. As experiments show,
the stage position repeatability is less than 0.1um.
2-D grating interferometer configuration for high resolution displacement measurements is introduced, and the interferometer uses one cross grating as the scale to achieve planar displacement measurement. According to 2-D grating interferometer structure, error sources are analyzed, and the pitch and yaw of 2-D grating guide caused by planar guide's non-linearity is the main factors to decrease the measurement system's accuracy. The theoretical analysis of the three spatial axes guide error is carried out and the related errors are evaluated separately. According to the analysis, the measurement accuracy is sensitive to 2-D grating movement's pitch and yaw, the grating's location deflections are only systematic error and can be compensated by calibration experiments and software, some methods of system error correction and system mount are given. In order to decrease the system sensitivity to the errors of the grating plane movement, the improved configuration is proposed.
This paper has researched signal processing methods of grating measurement system, and has come out a method to subdivide grating signals based on BP neural network. This measuring method focuses on the special property of the obtained grating signal. The method also decreases the precision requirement of the signal. When the measuring system changes, subdivision models can be altered automatically by software. BP neural networks can subdivide grating signals with few sampling points but high magnitude. This subdivide-method combines software and hardware, has simple structure, does not require complex circuit, and has a strong adaptive system.