Mr. Yulong Liu Profile

Yulong Liu

at Changchun Univ of Science and Technology

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Author

Publications (2)

Proceedings Article | 19 September 2013 Paper

The design of infrared laser radar for vehicle initiative safety

Ping Gong, Xi-ping Xu, Xiao-yu Li, Tian-zhi Li, Yu-long Liu, Jia-hui Wu

Proceedings Volume 8905, 89051O (2013) https://doi.org/10.1117/12.2034481

KEYWORDS: Infrared lasers, LIDAR, Sensors, Safety, Radar, Avalanche photodetectors, Distance measurement, Infrared sensors, Signal detection, Image resolution

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Laser radar for vehicle is mainly used in advanced vehicle on-board active safety systems, such as forward anti-collision systems, active collision warning systems and adaptive cruise control systems, etc. Laser radar for vehicle plays an important role in the improvement of vehicle active safety and the reduction of traffic accidents. The stability of vehicle active anti-collision system in dynamic environment is still one of the most difficult problems to break through nowadays. According to people’s driving habit and the existed detecting technique of sensor, combining the infrared laser range and galvanometer scanning technique , design a 3-D infrared laser radar which can be used to assist navigation, obstacle avoidance and the vehicle’s speed control for the vehicle initiative safety. The device is fixed to the head of vehicle. Then if an accident happened, the device could give an alarm to remind the driver timely to decelerate or brake down, by which way can people get the purpose of preventing the collision accidents effectively. To accomplish the design, first of all, select the core components. Then apply Zemax to design the transmitting and receiving optical system. Adopt 1550 nm infrared laser transmitter as emission unit in the device, a galvanometer scanning as laser scanning unit and an InGaAs-APD detector as laser echo signal receiving unit. Perform the construction of experimental system using FPGA and ARM as the core controller. The system designed in this paper can not only detect obstacle in front of the vehicle and make the control subsystem to execute command, but also transfer laser data to PC in real time. Lots of experiments using the infrared laser radar prototype are made, and main performance of it is under tested. The results of these experiments show that the imaging speed of the laser radar can reach up to 25 frames per second, the frame resolution of each image can reach 30×30 pixels, the horizontal angle resolution is about 6. 98mrad, the vertical angle resolution is about 3. 49mrad, the maximum value of range error is 0. 5m, minimum value is 0. 07m at the detectable distance range 10-200m and the detection probability is more than 99. 9%.

Proceedings Article | 21 August 2013 Paper

Design of laser monitoring and sound localization system

Yu-long Liu, Xi-ping Xu, Yu-ming Dai, Yang Qiao

Proceedings Volume 8906, 890614 (2013) https://doi.org/10.1117/12.2033141

KEYWORDS: Sensors, Glasses, Signal processing, Laser development, Photodiodes, Laser applications, Phototransistors, Receivers, Filtering (signal processing), Stray light

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In this paper, a novel design of laser monitoring and sound localization system is proposed. It utilizes laser to monitor and locate the position of the indoor conversation. In China most of the laser monitors no matter used in labor in an instrument uses photodiode or phototransistor as a detector at present. At the laser receivers of those facilities, light beams are adjusted to ensure that only part of the window in photodiodes or phototransistors received the beams. The reflection would deviate from its original path because of the vibration of the detected window, which would cause the changing of imaging spots in photodiode or phototransistor. However, such method is limited not only because it could bring in much stray light in receivers but also merely single output of photocurrent could be obtained. Therefore a new method based on quadrant detector is proposed. It utilizes the relation of the optical integral among quadrants to locate the position of imaging spots. This method could eliminate background disturbance and acquired two-dimensional spots vibrating data pacifically. The principle of this whole system could be described as follows. Collimated laser beams are reflected from vibrate-window caused by the vibration of sound source. Therefore reflected beams are modulated by vibration source. Such optical signals are collected by quadrant detectors and then are processed by photoelectric converters and corresponding circuits. Speech signals are eventually reconstructed. In addition, sound source localization is implemented by the means of detecting three different reflected light sources simultaneously. Indoor mathematical models based on the principle of Time Difference Of Arrival (TDOA) are established to calculate the twodimensional coordinate of sound source. Experiments showed that this system is able to monitor the indoor sound source beyond 15 meters with a high quality of speech reconstruction and to locate the sound source position accurately.

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