Papers by Keyword: Distance Measurement

Abstract: Distance measurement technology of binocular stereo vision has the advantages of wide-range detection, simplicity and reliability. The method is widely applied to robot obstacle avoidance and path planning. Binocular stereo vision can only measure the distance of images feature points generally. However, more information about distance of non-feature points is also needed to acquire in practical applications. This paper proposes a stereo distance measurement method, which can measure distance of points whether it is a feature point or not based on a dense matching method. A dense parallax map is obtained by the graph-cuts algorithm. On the basis of the calibration parameters of binocular camera and the left and right image dense parallax map, the three-dimensional coordinates of the any points and their distance will be gotten. The true image experiment has proved the feasibility of this algorithm with high accuracy and maneuverability.

Abstract: This paper aims to detect cracks on the rail head via eddy current and show their locations. The combination with mechanical and electronic devices is approached by modeling and analysis. Based on eddy current technology, voltage difference replaces phase shift and the amplification is gained by a triode differential amplifier. It realizes inspection of cracks. Being operated with an incremental optical encoder, Peripheral Interface Controllers and the Liquid Crystal Display, the distance measurement module records the defects. It is applied with a small section of rail tracks.

Abstract: The concept of information entropy is applied to evaluation for anti-interference performance of velocity and distance measurement in DS/FH hybrid spread spectrum TT&C (Tracking, Telemetry & Command) system, establishing an evaluation model where the entropy loss degree is used as an index under the rule of information, and analyzing the impact on the index from the changing of interference parameters. The feasibility of using entropy loss degree as an evaluation index was verified by simulation.

Abstract: In computer graphics, Stereo Vision has been a research hotspot for many years, and it is been widely used in many areas. Stereo Vision is a technique which utilizes computer to simulate human eye system. In order to achieve this simulation, two main problems need to be solved: camera calibration and stereo matching. We focus on stereo matching in this paper. After years of development some achievements have been made in stereo matching, but some problems remain unsolved. The two most important things concerned in stereo vision trend to be contradictory: accuracy and efficiency. This paper presents a method called Advanced-Census which is a good combination of SAD and Census. When finding corresponding pixel in left and right image, SAD can get high accuracy with low speed and Census have the opposite result. Advanced-Census has advantages of both SAD and Census. It retains the speed of Census while having the accuracy of SAD. Although it has the speed of Census but not enough for practical applications, so we speed up Advanced-Census using multi-thread technique and edge detection. After speeding up, Advanced-Census gets nearly real-time performance.

Abstract: Current approaches for opening door usually focus on the recognition of door handle in a fixed position, but in the process of door opening, a manipulator with a mobile platform is very important under real-world scenarios, which brings significance to the location and distance measurement of a door handle when the mobile platform is moving. In this paper, a method for location of a door handle in HSI color space is presented. The image of the door handle is captured by the kinect for Xbox360, and is processed in HSI color space, resulting in a rectangle frame fitted to the door handle to be displayed in real time. The distance value of the door handle is obtained from the depth image. Experiment results show the efficiency of the proposed method.

Abstract: In this article, discussed the traditional method of ultrasonic distance measurement , analyzed the main factors that restrict to impove the precision, and according to the energy attenuation of ultrasonic transmission, designed a measurement method based on rebuilding the digital signal waveform, this method solved the measurement precision problem caused by the traditional threshold method, the accuracy is no longer affected by the attenuation of ultrasonic energy, achieved the consistency precision in full range, makes the measuring accuracy is nearly one hundred times higher than the threshold method.

Abstract: This paper deals with the development of an alternative approach for sonic distance measurement. A linear frequency modulated signal (chirp signal) is regarded as a template signal. The sonic distance measurement system transmits the template signal and receives the echo signal, then calculate the correlation between template and echo signal. The time of flight is determined according to the position of the peak in the correlation result, then the distance is calculated. The major advantage of this approach is that it can detect weak echo signals among noises and increase measurement range significantly.

Abstract: In theory, FMCW radar has very high distance measuring accuracy. While in practical system, the accuracy of FMCW radar is decreased due to the firm frequency sampling interval caused by using FFT to do signal processing. To solve this problem, basing on traditional FFT processing, this paper takes advantage of Chirp-Z transformation to partially detailing the main-lobe of echo wave distance frequency spectrum. Therefore, under the circumstance of smaller calculation, this method greatly has promoted the distance measuring accuracy and met the actual requirements of high accuracy distance measurement.

Abstract: With the improvement of precision in various fields, we present a new method for the measurement of the absolute distance of a remote target based on the laser interferometry technique. In this paper, we obtain the interference fringes change information (the distance information) with the help of laser scanning with different frequency. It does not require the target to move in the direction of measurement. We have done experiments to compare this new methods results with the results of RENISHAW interferometer. Its improved that the accuracy of distance measurement is 10^-4~10^-5 relatively.

Abstract: The principle of an ultrasonic distance measurement system is introduced. The system adopts non-contact measurement method and it consists of signal generator, echo receiver circuit, microcontroller, time sequential logic control circuit, target distance detection circuit, temperature measurement circuit, RS-485 serial interface circuit, ultrasonic sensor and its driver circuit, etc. The results show that the system has high precision within measuring range from 20cm to 15m.