A new model-based system calibration approach to achieve optimal parameters of fringe projective 3D profile sensor is proposed, by modeling the projector as an inverse camera. The whole calibration procedure is divided into two steps: camera calibration and projector calibration. Jointly considering the relations among cameras and projector, a method of bundle adjustment suitable for the system is described. Not only the feature parameters described as homologous pairs of corresponding image points, but also the intrinsic parameters of projector and cameras shared by all views are considered for constructing the cost function. The lack of interaction among parameters for different features in multiple views results in underlying normal equations exhibiting a sparse block structure, which is exploited to obtain considerable computational benefits. The sparse Levenberg-Marquardt method is used as the last minimization means of bundle adjustment. Experiments are carried out for testing the convergence, efficiency and accuracy of the approach. The results show that within reasonable confidence interval the calibration accuracy is higher than that of the linear method. Even with the loss of feature information, the approach still works well and the results remain nearly the same.
In order to get the edge message of a target, a laser scanning system was established. The laser scanning system steers a
beam of laser energy which is dithered in two directions to scan the surface of the object. A laser energy detector detects
laser energy reflected from the target. The reflected information is filtered to distinguish dither frequencies for signal in
both directions. The signals are independently analyzed to determine the edge of the target by detecting the change of
reflected laser energy.
In order to get the fantastic point of echo signal, wavelet transform is used. Based on invariability of the quality factor of
wavelet transform, combined with proper wavelet group, this paper discusses the application of wavelet transform for the
detection of echo signal. On the basis of algorithm analysis, from aspects of detecting principle, detecting steps and
computer emulation, the authors expatiate how to use wavelet transform to find the fantastic point of echo signal, finally
to find the edge of the target being detected. Wavelet transform has the ability of denoting local signal characteristics, so
it is fit to analyzing instantaneous and fantastic phenomena and can lay out signal components. The method in this paper
will supply an algorithm gist and a reference for signal processing for the detection of edge message of target. The results are demonstrated by using Matlab programme. By the measure, the noise can be eliminated, and effective signals can be picked up. When applying the wavelet transform to experimentation, a satisfactory result was obtained. When using this method, the ability of edge detection can be greatly improved.
The horizontal or X-Y tracking gimbal of photoelectric system has spatial blind region because of themselves framework limit, In order to solve the problem of blind region and also track object with high-precision and speediness, a new three-axis photoelectric theodolite system with collimation axis eccentricity is brought forward, It can achieve large-scale space tracking by means of mutual conversion of tracking modes.
There is dynamics and inertia coupling in the three-axis photoelectric tracking system, the kind of coupling will directly affect the static state, dynamic state characteristics and indeed system stability. To get high performance photoelectric tracking system, dynamics coupling must be took into account in three-axis photoelectric tracking system. The matrix transformation of angle velocity and moment can be derived from the reference frame relation of three-axis photoelectric tracking system with collimation axis eccentricity; the kinematics property is analyzed by momentum theorem and angular momentum theorem. Through the analysis of inertia coupling in axes, their object differential equation is gained. In the last, the system nonlinear coupling dynamics model is built using multi-body system theory and Lagrange-Eula equation. From the analysis of dynamic equation, it is evident that the photoelectric tracking system with three input and three output contain complicated nonlinear coupling factor, the study of decoupling control must be carried through in order to get high-precision control system. By importing the geometry coordinate transformation, dynamic compensation and nonlinear state feedback, the nonlinear factor can get accurate elimination on base of the system reversibility of input and output, the three-axis photoelectric tracking system control differential equation can be got nonlinear decoupling by static state feedback, several variable photoelectric tracking system turn into three respective self-governed singularity input and output control system to achieve state or output tracking control.
The coupling and decoupling control system is respectively simulated using MATLAB's simulink toolbox. Simulation results have proved that the decoupling control method proposed and the decoupling controller designed for system are effective.
This paper describes an optical voltage transducer(OVT) for a 35kV system based on Pockels effect in a BGO(Bi<sub>4</sub>Ge<sub>3</sub>O<sub>12</sub>) crystal. OVT used to measure the voltage of power are superior to conventional electromagnet-induced voltage transducer in many aspects, thus it has great potential to applications. It has some advantages. These advantages are: 1)Optics provides total galvanic separation between the measuring point at high voltage (HV) potential and the measuring equipment at ground potential. 2)Transmission of measuring signals in optical fibers is immune to induced electromagnetic noise even in EMI-environment of switchyards and other high voltage installations. 3)Optics and especially optical fibers make the insulation costs independent of voltage levels thus giving an economical advantage at voltage levels above 100kV. 4)The use of optics is expected to reduce the weight of the transducers. 5)Optical transducers are expected to have a large bandwidth than conventional transducers. 6)The output-signals from an optical transducer are easily interfaced with computers and electronically operated equipment such as digital relays. New techniques developed in electronics and optical field including fiber optic technology bring new contributions to the measurement of voltage and electric field. A Pockels voltage sensor has been widely introduced to electrical power transmission and distribution systems and some advantage of the optical voltage measuring techniques are reported. In this paper, a brief summary of electro-optic effects and the principle of OVT is proposed. The signal processing schemes of different optical path and features are analyzed. The basic principle of OVT is to modulate the irradiance of the light-directed to OVT by an optical fiber-according to the potential difference between the HV-line and the ground potential. The modulation of the light is accomplished by placing a material-that has an optical property (the birefringence), which is sensitive to the electrical field strength (Pockels effect)-inside the OVT.