Advanced Materials Research Vols. 139-141

Abstract: In this paper, a new measurement method is presented, This method is to use a three-coordinate measuring machine (CMM) to test the symmetry error of double keyway in a wheel hub bore. According to the minimum condition criterion of form and position error evaluation, and making use of the minimum tolerance zone of position error evaluation, two symmetry error formulas of double keyway in a wheel hub bore are deduced by geometric analysis. The problems may be encountered when using the formulas in the practical application are discussed. These formulas solve the measurement principle problem of double keyway in the engineering practice. In the end an example is put forward to verify this method and the formulas.

Abstract: Thermal deformation of welding structure is inevitable in welding process. The deformation will not only change the appearance, shape and geometry size of the welding structure, reduce assembly quality but also may reduce the bearing capacity. On this basis, a welding deformation measurement based on visual method was proposed for the problem of the thermal deformation measurement in welding process. Theoretical calculations were carried out and an image processing and measurement algorithm based on MATLAB was also put forward. Then welding deformation measurement experiment was carried out and the results show that the welding deformation obtained by actual measurement is consistent with the theoretical analysis, proving the feasibility of welding deformation measurement based on vision. The welding deformation measurement based on visual method lays a foundation for automatic measurement of welding deformation.

Abstract: According to the demands that calibration organizations need to calibrate various instruments and calibration requirements are complex, a kind of remote calibration system oriented to multiple objects and complex requirements is developed. The system architecture is designed. It’s based on B/S mode, and has the advantage that calibration operation can be done anywhere having Internet access. Then the requirement of remote control is realized. The objects and functions of the system are analyzed in detail, and the object models are built by using object-oriented idea and these models are realized by relation model whose related theories are mature. Then the operation commands can be defined flexibly and the problem that calibration requirements are complex is solved. The theory and experiment shows that the system can be used to calibrate various instruments, its operation command definition is flexible and calibration operation can be done anywhere having Internet access by using the system.

Abstract: The contact and non-contact measuring methods were adopted to measure the twisted blades of the turbine in a casting torque converter. The curves were reconstructed using the B-spline and Bezier curve. Then the blade parameters were extracted based on the conformal transformation. Compared with the original data of the designed blades, measuring results of both methods were effective, while errors existed during both measuring processes including data missing error, measurement error and fitting error. Compared with the contact measuring method, the non-contact measuring method needed improvement because of its larger errors, which is mainly caused by the shrink and distortion of silicone rubber. But non-contact measuring method will be a trend in measurement system because of its own advantages such as expeditiousness, automation and the ability of acquiring relatively comprehensive information.

Abstract: In this paper, a novel algorithm is proposed to detect linear edge. Image gradient is acquired by Sobel or Prewitt filters. Logical addition is applied to enhance image contrast. Statistical method is employed to cope with gradient data—gradient projection in the horizontal and vertical direction to compute the average gradient value. Multi-level B-Spline interpolation is employed to smooth gradient data. At last, edge coordinates can be computed precisely by the number and interval of extreme points. The experiment results are presented to show validity of the algorithm, which precision and accuracy can reach to sub-pixel. The proposed approach puts merits of zero crossing method and threshold method together, which is very robust, convenient and efficient to detect linear edge in industrial environment.

Abstract: In offset printing system, presensitized plate (PS plate) is one of the key factors that influences the quality of printing products. In this paper, we suggest an application of image processing techniques to improve the accuracy of quality detection of PS plate. We use median filtering to get rid of noises and grayscale stretch to enhance image. An improved adaptive threshold selection method for defect segmentation is proposed based on the characteristic of grads-histogram of PS plate image, and a fast scanning algorithm is put forward to extract features of defects for classification and recognition. The experimental results show that the above methods can obtain the accuracy of 96.7% for defect detection of PS plate and the minimum detectable diameter of defects is 0.2mm, which has reached the enterprise standard for quality detection.

Abstract: This paper analyses the method of denoising surface roughness profile signal using self-adaptive filtering technique.The working principle of self-adaptive denoising has been introduced.Method of combining of self-adaptive filter and least square error(LMS) algorithm has been designed.Results obtained from sin-wave with noise are validated using the LMS algorithm to eliminate noise.Comparison of caculating surface roughness mean line between self-adaptive Gaussian filtering meanline and ordinary Gaussian filtering meanline has been presented.From the simulation of self-adaptive denoising it is observed that the designed method can be used as a denoising method in the surface roughness measuring.

Abstract: The tractor-trailer mobile robot (TTMR) is composed of a tractor and multiple trailers. It belongs to a typical nonholonomic, underactuated system. The general control theory can hardly be applied to this system. Because of the multi-body tractor-trailer mobile robot existence, the moving trajectory control is very complicated, especially backward path control becomes a difficult problem for this kind of robot control. This paper takes parking trajectory generation for example, makes tentativeness on tractor-trailer mobile robot to generate the trajectory based on Repeatedly Direct Kinematics (RDK) method. The feasible forward and backward trajectory generations algorithm for tractor-trailer mobile robot are proposed. The design complexity and existing singularity for tractor-trailer mobile robot system are solved. Simulations show the effectiveness of the proposed method.

Abstract: For highly complex embedded control systems, the use of traditional methods of design is very difficult to achieve satisfactory results. In a cooperative project of national 863 plans, the Matlab-based scheme in TDE (Total Development Environment) way was made to design the control system of free-flying space robot, an in-obit service satellite. It can overcome the shortcomings of traditional design to make greater system stability, improve the life of the equipment, speed up development and reduce development costs. In this paper, a development platform was built on Matlab for embedded control system of the manipulator onboard the free-flying space robot. The controller design and simulation was implemented on it. The entire development process is divided into algorithm design, system simulation, and automatic code generation. A test harness was created to test and verify the unit-under-test. The results of experiment show that Control accuracy of the simulation was satisfied with the practical requirements.

Abstract: The paper proposes a new BSS algorithm based on the second-order statistics. By jointly diagonalizing the time delay correlation matrix of the observed signals and using the improved new non-orthogonal joint diagonalization (NOJD) method, a better solution is achieved. The proposed algorithm can successfully separate communication signals under SNR as low as 10dB and the over-determined mode regardless of the signals’ modulation methods. Signal to Interference Noise Ratio (SINR) is used to prove the superiority of the proposed algorithm over the classical Second-Order Blind Identification (SOBI).