| High-precision measurement and positioning for two-dimensional platforms are required in CMM,high-precision CNC and other industrial measurement systems.This paper introduces a plane absolute position sensing system based on pseudo-random sequence.The system employed pseudo-random sequence to achieve 2-D absolute coding,and the image processing methods are used to subdivide the coded image for the better accuracy and resolution.The system has the advantages of high precision,large measurement range and low environmental requirements.Experiments show that the resolution can reach 1μm.The main contents of this paper are as follows:1.The paper summarized and analyzed the absolute coding measurement theory,proposed a plane absolute coding and decoding method based on pseudo-random code,the developed 2-D sensor system can reduce the problem of Abbe errors during two-dimensional platform measurement with two sets of 1-D gratings sensors.2.With the developed 2-D coding measuring method,the processing circuit of image acquisition and signal processing was designed based on FPGA technology.3.The 2-D absolute position sensing system was setup,and the system mainly include annularity light source,two-dimensional absolute position code palte,two-dimensional platform,imaging lens,image acquisition module and FPGA signal processing system.The image acquisition module reads the code pattern image containing the two-dimensional absolute position information,transfers the pattern information to the FPGA signal processing system through the DVP communication protocol,and obtains the position information can be acquired with the code identification and decoding algorithm. |
