Research And Design Of A High-Precision Laser Triangulation Sensor

Based on the project— “Research on automatic measurement technology of large workpiece on machine”,our task group undertook the development of a laser triangulation displacement sensor and to use of this sensor to achieve the task of inner dimension measurement.To achieve high-precision inner dimension measurement,our group proposed a measurement method based on laser triangulation displacement sensor.At present,a measurement system using commercial triangulation sensor should complete the measurement tasks.However,Due to foreign monopolistic behavior,commercial sensors are expensive,and the single forms of measurement makes it hardly to be integrated.While the domestic research on the laser triangulation sensor is still in the exploratory stage.Due to the above reasons,our group carried out the triangular sensor prototype development work.The main work of this paper is as follows:(1)The optical structure of a direct jet laser triangulation sensor is designed according to the laser triangular principle and the actual object surface reflection model.The hardware system of the sensor is completed by ARM + FPGA architecture.Meanwhile.Meanwhile,a host computer procedure is designed for graphic display of the sensor output.(2)In view of the problem that the light intensity distribution of image point is interfered by the surface characteristics of the workpiece,a localization algorithm with dynamic template and normalized cross correlation is studied for image point positioning.The algorithm is used in the laser sensor,and the experiment results shows that this algorithm has higher precision and stability than Centroid method.(3)A piece of calibration equipment is designed for the laser triangulation.A calibration method based on curve fitting is proposed,and the formula of arbitrary start position is derived.After calibrated,the laser sensor is used to measuring the displacement of a gauge block,and the result shows that the sensor with proposed localization algorithm and calibration method achieved the measurement range of 4mm with 10?m accuracy.(4)A combined measurement device with two self-made laser triangulation sensors was designed and used to measuring the distance between two parallel plates.The result shows that the maximum measurement error of the combined device is no great than 10?m.