The damage of noise barriers will highly reduce the transportation safety of the high-speed railway. In this paper, an online inspection system of noise barrier based on laser vision for the safety of high-speed railway is proposed. The inspection system, mainly consisted of a fast camera and a line laser, installed in the first carriage of the high-speed CIT(Composited Inspection Train).A Laser line was projected on the surface of the noise barriers and the images of the light line were received by the camera while the train is running at high speed. The distance between the inspection system and the noise barrier can be obtained based on laser triangulation principle. The results of field tests show that the proposed system can meet the need of high speed and high accuracy to get the contour distortion of the noise barriers.
The damage or lack of the noise barriers is one of the important hidden troubles endangering the safety of high-speed railway. In order to obtain the vibration information of the noise barriers, the online detection systems based on laser vision were proposed. The systems capture images of the laser stripe on the noise barriers and export data files containing distance information between the detection systems on the train and the noise barriers. The vibration status or damage of the noise barriers can be estimated depending on the distance information. In this paper, we focused on the method of separating the area of noise barrier from the background automatically. The test results showed that the proposed method is in good efficiency and accuracy.
Based on 2-D laser sensor, an optimized system for dynamically measuring geomet rical parameters of train wheels is proposed in this paper. The calibrat ion of the system is simplified by combining a 1-D laser sensor and a 2-D laser sensor. Accuracy of the 2-D laser sensor reaches 0.2mm and it ensures that most information of the wheel tread surface is acquired. The geometrical parameters including wheel diameter, flange thickness, flange height, tread wear and rim width can be calculated once the information is processed. In order to improve the measurement accuracy of wheel diameter, a new method for spatial circle fitting is proposed. According to the results acquired in the field, the measurement system can satisfy the requirements of dynamically measuring the geometrical parameters of train wheels.
In order to detect the diameter of a wheel-set online, the diameter was detected by using a laser displacement sensor and two eddy current displacement sensors at a speed of 15km/h. The weight of the wheel -set caused extrusion of the rail and changed the original measuring position, which had severe influence on the measuring results, so the influence of the deformation of the rail is analyzed and a compensation method based on the detection of the settlement of the rail is proposed. After compensation, the errors of the results are within ±0.5mm and the standard deviation is 0.12mm. The measuring results showed that the compensation method satisfied with the need of measuring accuracy.
The dynamic diameter measurement of locomotive wheels is important to ensure the vehicle safety. We propose that the diameter of locomotive wheels can be automatically determined by a one-dimensional displacement sensor and two eddy sensors which are installed on the inside rail. The distance between the laser displacement sensor and the wheels can be detected when the wheels pass through the center of the two eddy sensors. The diameter of wheels can be calculated. The experimental results show that the accuracy and repeatability can meet the need of measurement.
Without dying and fluorescently labeled markers on tissues, Intrinsic optical signals (IOSs) detection technology is a promising method to detect retinal function without influence on normal activities of organism. Slow IOSs of retina reflect the activities in inner retina and the middle layer of retina. In this paper, an IOSs’ detection system was built to detect slow IOSs based clinical instrument, Heidelberg Retina Angiograph 2(HAR2). The retina was illuminated by near infrared light continuously during the experiments. The visible light was presented to stimulate the retina. After image alignment and image processing, the signal-to-noise ratio of the IOSs was improved and the signal changes can be extracted. The experimental results showed that the present detection system is suitable to obtain the slow IOSs in clinic and IOSs detection technology is an effective noninvasive method to study changes of function of retina.
Improvement of absolute phase calibration in phase-measuring profilometry is presented. In order to calculate the absolute phase of calibration plane, linear interpolation of unwrapping phase of reference point is introduced. Accuracy of height calibration and measurement is improved. A novel 3D surface shape measurement system is designed. Experiments of given height plane are presented. The mean of measurement error of conventional algorithm is about 0.5 mm. That of the novel algorithm introduced in this paper is reduced to about 0.2 mm.
For the fast and shade-free shape measurement of 3-D objects with large discontinuous height step, a new 3-D shape measurements based on the function of modulation is proposed. To avoid the shadings we adopt a coaxial optical system for projection and observation. A sinusoidal grating pattern is projected onto the surface of a testing object. Instead of phase information, we use the fringe modulation of the detected fringe pattern to determine the height distribution. Different modulation values correspond to different distances from the point of the object to the projecting system. Established the look-up table of modulation and position, only one frame of projected sinusoidal fringe is obtained and the height distribution of object can be calculated according to the value of modulation for the specified pixel of interest. The measurement result shows that the proposed 3-D shape measurement technique will be a promising method for fast acquiring 3-D data of complex objects.