Guotian He

Phase unwrapping based on branch cut placing and reliability ordering

A new 2-D quality-guided phase-unwrapping algorithm, based on the placement of the branch cuts, is presented. Its framework consists of branch cut placing guided by an original quality map and reliability ordering performed on a final quality map. To improve the noise immunity of the new algorithm, a new quality map, which is used as the original quality map to guide the placement of the branch cuts, is proposed. After a complete description of the algorithm and the quality map, several wrapped images are used to examine the effectiveness of the algorithm. Computer simulation and experimental results make it clear that the proposed algorithm works effectively even when a wrapped phase map contains error sources, such as phase discontinuities, noise, and undersampling. (c) 2005 Society of Photo-Optical Instrumentation Engineers.

Study of Nonspherical Particle Magnetorheological Greases with Computer Simulation Technology

Based on computer simulation technology, we put forward the shear stress model of nonspherical magnetic particle MRG, and take the hexagon form magnetic particle MRG as an example; this paper deduces hexagon magnetic particle MRG shear stress formula. The model simulate and calculate the relationship between shear yield stress and magnetic field intensity respectively when radius and side length is equal and when the volume is equal also shear yield stress in the zero field condition. The simulation results show that in the same volume condition the shear yield stress of nonspherical magnetic particle MRG is bigger than that of spherical magnetic particle MRG; the shear yield stress of nonspherical magnetic particle MRG cut down with contacting side length’s reducing but also greater than that of spherical magnetic particle MRG and this relationship is also the same in the zero field condition, so spherical magnetic particle MRG is not the best choice. Therefore, this research has an extremely vital significance for the development and application of high-performance MRG.

Study on interferometric measurements of a high accuracy laser-diode interferometer with real-time displacement measurement and its calibration

In view of low precision of existing semiconductor laser micro displacement real-time interference measuring instrument and the difficulty to adjust, this article proposes a normalized technology and demarcation technology, develops one kind of semiconductor laser vibration real-time interference measuring instrument which has the adjustment function, analyzes its real-time surveys principle and demarcation method. This interferometer carries on processing using normalized electric circuit and real-time phase discriminator to process interference signals, and has realized high accuracy real-time examination of micro displacement. Its measurement result has nothing to do with system parameter luminous intensity, initial light path difference, electric circuit enlargement factor, modulation depth and Bessell function value. Demarcation technology has been carried on to the interferometer, which further increases the measuring accuracy of interferometer. Experimental result confirms the feasibility of this interferometer and its measuring accuracy surpasses 3.89nm.The survey time is smaller than 50μs.

The Model and Simulation of Magnetorheological Grease Characteristics

Magneto-rheological grease attracts the attention as a new kind of intelligent material. Under the external magnetic force, it is difficult to use traditional mathematics model to solve and analysis internal structure because of its complexity and polytropy. The modeling and simulation for complex system using computer becomes a good way to investigate complex system. Based on the electromagnetic theory and computer simulation, this paper constructed the model of shear stress to describe the characteristic of magneto-rheological grease that is to use body centered cubic pillars model to analysis the mechanism and characteristics of magneto-rheological grease. Using matlab simulink toolkit to compose the simulation program, simulate and analysis using theoretic model, and plot the shear stress curve of magneto-rheological grease with magnetic strength and particle size, and the shearing force under zero field. The simulation and experimental results indicate that the simulated shear stress curve is coincidence with experimental curve when the density of ferromagnetic particle is low, and it is lower than experimental curve when the density is high (the variation tendency is close), which verified the accuracy of theoretical model. It needs to improve the model by considering the still friction between ferromagnetic particles.

Study on the technology of sinusoidal phase modulating interferometry based on Fourier transform algorithm

Sinusoidal phase modulation interference survey technology is an advanced interference measuring technique in international front. Through introducing the piezoelectric ceramics (PZT) of sinusoidal vibration in Michelson interferometer reference path of light ,we carry on the modulation to the reference light, which produces modulation item along with the time sine change of interference signal. The demodulation is carried on based on Fourier analysis method to obtain the phase of corresponding object to measure the interference signal. This article proposes the algorithm of Fourier analysis method to carry on the solution to the interference signal, discusses the influence of the algorithm on measuring accuracy and compares it with traditional method. Experimental result indicates the sinusoidal phase modulation interference survey technology is an effective interference measuring technique with high accuracy.

A Hybrid Real-Time Visual Tracking Using Compressive RGB-D Features

The online multi-instance learning tracking (MIL) algorithm is known for its ability of alleviating tracking drift by training classifiers with positive and negative bag. However, the increased computational complexity results in time consuming due to the lack of consideration of sampling importance when collecting training samples. Additionally, the MIL method, as a 2D feature-based tracking algorithm, performs unsteadily when the object changes poses or rotates seriously. In this paper, a histogram-based feature similarity measurement is employed as a weighting strategy to select positive samples. Benefited from profitable depth information, the tracking algorithm we proposed achieves higher tracking performance. For computational efficiency, a compressive sensing method is adopted to extract features and reduce dimensionality. Experimental results demonstrate that our algorithm is better in robustness, accuracy, efficiency than three state-of-the-art methods on challenging video sequences.

Study on Adaptive SPM Displacement Measurement

This article designed a sinusoidal phase modulation (SPM) interferometer for the precision measurement of object displacement. By using low-pass filters to deal with interference signals, the sine and cosine values of phase in the measured object displacement were got. Then the sine and cosine values of phase divided each other, got its arctangent, and processed one-dimensional phase unwrapping to get the measured object displacement. The Interferometer had high measurement accuracy and strong anti-jamming ability; every measurement was the ratio of two values got by two filtering, the effects of the amplitude of interference signal AC component, circuit amplification, the light-intensity of interference signal, and attenuation of filter on the signal and other factors on the measurement results need not be considered. The circuit structure of the Interferometer was designed to be simple.

A New Sinusoidal Phase Modulation Interferometry

Sinusoidal phase modulation (SPM) interferometer is a time phase modulation method, which has strong anti-jamming ability and needs higher CCD frame rate, so ordinary CCD do not meet the requirement. This article proposed a new interval sampling based on SPM. When SPM modulating signal frequency was 200 Hz, preset sampling frequency was 2,000 Hz; area array CCD with 182 Hz frame rate only collected an interference image in a modulation cycle, and then, these collected images are processed using 2,000 Hz CCD frame rate, thereby reducing the CCD frame rate. This article processed simulation and extracted phase principle values of interference images with filtering method, and by joining main interference signal in the work environment, the error analysis proved that interval sampling could improve the anti-jamming ability of SPM interferometer in the measurement of object surface topography.

Industrial Robot Simulation Based on OpenGL

In the background of simulation system and industrial robot, this paper described the application features of OpenGL and focused on the design and implementation of simulation system of industrial robot. Then, we need to study the application and key technology of OpenGL in graphical simulation system and to explore the implementation method of the system. Finally, the disadvantages of OpenGL in specific industrial robot simulation system were described, and to achieve good results further improved measures were proposed in this paper.

A Preprocessing Algorithm of Corn Infrared Spectrum Based on MSC and DOSC

To characteristics the near infrared spectrum of corn, we proposed a preprocessing algorithm combining multiplicative scatter correction (MSC) and direct orthogonal signal correction (DOSC). In this article, we compared the SG first derivative correction, MSC, DOSC and the new algorithm. And using partial least squares analysis (PLS) built the quantitative analysis model. The results show that the preprocessing algorithm combining with the MSC and DOSC can improve the prediction accuracy of all components. This work has some practical and scientific value.