Applied Mechanics and Materials Vols. 226-228

Abstract: Three-dimensional (3D) vision scanning measurement is widely used in industry for its ability to obtain the 3D surface data of the object. Aiming at overcoming the shortcomings of 3D scanning measurement system with single structured-light sensor, such as limited measurement range and blind measurement area, a scanning system based on double structured-light sensors (DSS) is established. The object is scanned from two different directions, and the 3D surface coordinates are unified to the measurement coordinate system to obtain the 3D surface of the measured object. In this paper, the mathematical model of the DSS scanning system is established. Meanwhile, an on-site calibration approach based on planar target is proposed to complete the system calibration task. Finally, experimental results of practical data are given to show the feasibility and validity of the proposed system.

Abstract: The X-ray security inspection systems are widely used in airports, customs, and railway stations now. Their radiation safety is related to the health of public. It is necessary to take radiation safety tests at least once a year. For their energy is usually in the level of keV, the radiation caused by photoelectric effect is the most important. According to the photoelectric effect of X-ray, the methods of testing Micro-dose X-ray radiation include radiography method, ionization testing method, scintillation testing method and semiconductor testing method. Radiography method and ionization testing method can be used to test the stronger X-ray radiation, while scintillation testing method and semiconductor testing method can be used to test the weaker. Geiger counter testing method is not proper to be used when taking the accurate test; however, because of its relative low cost, non-professional technicians can use it to test the Micro-dose X-ray radiation daily.

Abstract: The local quasi-geoid model up to centimeter precision has became the basic requirement for the development of modern surveying and mapping science. There are a variety of models can be used for the quasi-geoid refinement, including the spherical cap harmonic model (SCH). This paper studies the theory of SCH to get the spherical cap harmonic expression to fit the height anomaly in the least squares sense, which is to achieve the transformation between the geodetic height and the normal height. We also discuss the selection of the maximum model degree in local region. The practical case is studied to refine the local quasi-geoid model with SCH using GPS/leveling data at 85 points. The results indicate that the local quasi-geoid model can reach 3 centimeter-level at the internal and external fitting precision.

Abstract: Compared with normal reflecting scanning transform Spectrometry, cube-based Spectrometr is a key component in the time-based modulation interference spectrometer, it have more compact structure ,using less accessory , easy to fix up , more steadily and more practicality . Calculations on optical path difference (OPD) of spectrometry play an important role in analyzing and improving of the structure. Following the law of Malus and the geometrical relationship of model, get the formula of OPD and the affective factors .The calculation results demonstrate that OPD is closely related to the tilted angel of rotating reflector , the size of cube reflector and the refractive index of reflector. And this kind of spectrometry has the character of high resolution, especial in some spectrum.

Abstract: This paper investigates the geo-positioning accuracy of across-track QuickBird stereo imagery in Shanghai, China, where the terrain relief is very low about 3m but with very high buildings up to 380m. The rational function model (RFM) and the bias-compensated RFM with different parameters are employed to do accuracy analysis with different configurations of ground control points (GCPs). The systematic errors in vendor provided RPCs are revealed and discussed. The results of bias-compensated RFM show that different strategies in terms of the number of GCP and different geometric correction methods should be taken into consideration in order for a better and reasonable positioning accuracy in the three directions. The results also show that the best accuracy of 0.6m in horizontal direction and 0.8m in vertical direction can be acquired by the second-order polynomial model when GCPs are more than 8.

Abstract: Based on ESPI experimental principle and finite element theory, this research obtains the law that the shrink of light-cured composite resin leads to deformation. The out-of-plane displacement of light-cured composite is measured by ESPI experimental system, and then the model corresponding to the test that is built in ANSYS and numerical simulation are building, so that solidified deformation and stress of light-cured composite is studied. These results are compared with each other and the differences between the results are small. It is found that ESPI is a feasible testing method which is suitable to deformation measurement of structure surface. Influence factors of drawdown deformation of composite resin are obtained by ESPI experiment and numerical calculation, some basis is provided for clinical treatment, and direction that improve the performance of light-cured composite resin are provided for manufacturer of this resin.

Abstract: This essay study that in magnetic field and current intensity, measurement, work of electric motor regulating speed applied by Hall integrated sensor shows that in electrical machinery electric circuit control and automatic control system, using Hall integrated sensor has stable properties, high reliability, good temperature stable properties, anti-pollution, without touch dot, etc advantages, comparing with traditional automatic control electric circuit has obvious advantages. It attaches importance to many people in practical use.

Abstract: With ability of full-field phase distribution obtained from one grating image by the sampling moiré method, it has potential applications in the dynamic measurement. On the basis of introduction to the basic principle, the sampling moiré method is utilized to characterize the vibration parameters of a shaking stage. A piece of paper with black and white grid lines is pasted on the surface of the measured object as an optical non-contact displacement sensor. Experiment images are recorded by a CCD camera during the translational experiments and vibration experiments. The translation experimental results show that the sampling moiré method has a high measurement accuracy of less than 0.12% of the grating pitch. The vibration experimental results are consistent with the theoretical values. Experimental errors are discussed finally.

Abstract: Binocular and parallel plate structure load cells are very successful designs for strain based measurements of shear loads. In this paper we use finite element methods (FEM) to investigate the suitability of these two load cell designs for use in a force plate and compare the sensitivity of these two force plates to that of the Heglund’s force plate. Each force plate is also sensitive to two moments with axis in the same plane as the force plate. If the force plate is to be used as a two component force-moment sensor, we determine which moment axis is best to use. Finally, a novel six-axis load cell is modelled by assembling three force plates together with rotational symmetry. The sensitivity of the six-axis load cell is calculated using FEM. Analysis of the six axis load cell predicts good measurement sensitivity and isotropy while maintaining low interference between measurement axes. Further benefits of the load cell design are discussed.

Abstract: Monocular vision system for medical robot must have high accuracy. In traditional monocular vision system, localization algorithm is realized by image space transformation, which leads to a trivial calculation process and a complex camera calibration method, therefore, this paper presents a new target characteristics identification method. Through the establishment of an equidistance pseudo binocular image acquisition way, searching the image and space coordinate transformation relation, avoid the complicated space matrix conversion and improve the position precision. Using Pointer method for image processing and customized backtracking boundary conditions for image searching, this paper realizes the curve fitting of target features boundary, and pattern recognition. Finally, an experiment is completed to guide the pharmacy movement of the Staubli TX40 arm, whose software runs within 200 ms and location error is less in 0.2 mm, verifies the validity of the algorithm.