Research And Application Of Laser Triangulation Sensing Technology

Based on the project of National 04 Special Demonstration Project--"High Efficiency Flexible Unit for Crankshaft Grinding of Automobile Engine",our task group undertook the automatic measurement task of the concentricity of main shaft and the position of main shaft and connecting shaft.At present,the above indicators which rely on high-precision detection equipment in the measurement area can get a good evaluation,but it can't meet the industrial field rapid on-line automated measurement requirements,especially the 100% product testing requirements.The measurement of the concentricity and the measurement of the position between the shaft diameters are to obtain the multi-section center,and then give the relevant evaluation.In this paper,the main research contents are as follows:1.Based on the analysis of the advantages and disadvantages of the existing measurement methods of the center coordinates,this paper presents a method for obtaining the non-contact center of the standard circular cross section based on the laser triangulation displacement sensor.The feasibility of the method is verified by experiment.2.A new calibration method based on coordinate machine is proposed to implement the above method.The calibration of the intrinsic parameters of the measuring system is accomplished by the alternating measurement of the standard parts and the standard parts by the coordinate machine.The measurement errors of the two-sensor measurement system and the three-sensor measurement system are obtained through experiments.The selection of calibration points is proposed by processing a large amount of data.The advantages and disadvantages of these two methods and the influence of sensor accuracy on the whole measurement system are analyzed.And through experimental verification,the maximum measurement error of measurement system which is formed by higher accuracy sensors is significantly reduced.The error influencing factors of the whole measuring system and the research direction are analyzed.3.For the commercial sensor's defects--expanding the measuring range,reducing the measurement accuracy and high cost,the paper has carried on the independent research and development work of the sensor.The accuracy of the sensor can influence the accuracy of the measurement system that is proved by experiments.The cost of the sensor based on industrial field considerations,confirmed the need for self-developed sensor.The CCD-based laser triangular displacement sensor is completed by FPGA + DSP as the main core chip.Through the analysis of the sensor principle,the basic composition,mechanical structure,selection factors,hardware structure and calibration methods,the interpolation method is used to complete the interpolation of the full range,to achieve the measurement range of 10 mm laser triangular displacement sensor whose maximum measurement error is10 microns.The error factors of the self-made laser triangulation displacement sensor and the direction of the research are also analyzed.