The Design Of A Real-time And High-Precision Laser Triangulation System

Laser Triangulation has been widely used in the current measurement system with the characteristics of high speed, high-precision and non-contact measuring. However, as the rapid development of industrial technology, the requirement of micro displacement detection's performances becomes high. Now, Laser Triangulation trends to high-speed, high-precision, large-scale, small size and automation. In order to overcome the defects on low accuracy and speed, this paper focuses on the sub-pixel positioning algorithms and hardware realization. A high-precision and Real-time Laser Triangulation System, which is based on linear CCD, is successfully designed.First, the current development of Laser Triangulation system is widely investigated, and the principles of the distance measuring and characteristics of the CCD array are also thoroughly studied.Then, several sub-pixel CCD array subdivision algorithms, which make the full use of the information in the vicinity of the spot, are introduced. These algorithms are used to process the Spot Images, and this is helpful for us to find the best method by analyzing and comparing the results. Eventually, an optimal algorithm, which can be called "multi frequency inserting value and centre of gray" algorithm, is proposed with merits on high precision and easy realization by hardware. Based on this optimal algorithm, the accuracy of the positioning and the stability of system are improved significantly.Next, the design of the system's hardware platforms and the sub-pixel algorithms' hardware realization are introduced in detail. FPGA rich logical resources and ARM fast data processing capability are made full use to achieve high-speed real-time detection.Finally, some experiment is done to give the indexes of the system, including system stability, system precision and system scaling. Experimental results show that: the system is high in stability and accuracy with a largest range of 135 mm, and the measuring speed of the system is adjustable from 1K/s to 36K/s.The accuracy and speed of laser ranging has been greatly improved by the research in this paper, which is conducive to make the system become small, intelligent and own a strong practical application value.