Research On Spatial Information Extraction And Calibration Technology For A Dual-Galvanometer-based 3D Image Laser Sensor

3D image laser sensor is one of the most effective techniques for the extraction of the complex surroundings information. Compared with other sensors, 3D image laser sensor has a special superiority that can complete the extraction of target's space information directly, where each extracted pixel contains three-dimension coordinate information. So the 3D image laser sensor has a widely application prospect in deep space detection intelligent robot, road auxiliary driving unmanned vehicles, etc. In this paper, we mainly focus on the spatial information extraction and calibration technology of the double galvanometers-based 3D image laser sensor, and the system modeling, simulation, imaging experiments and correction are carried out. The mainly points are as follows:(1) Though the modeling of 3D image sensor subsystems, the relationship between transmitted power and the receiving laser power is deduced and the way to increase the system detection ability is analyzed; meanwhile, the generation methods of dual galvanometer scanning lissajous figure and the hysteresis effect of scanning field are also analyzed. According to the system modeling and analysis, a scheme of target space information extraction has been proposed successfully.(2) Through the contrastive analysis of the common-used time discrimination technology and measurement technology for ranging system, the time discrimination method and measuring method have been determined. Employing the geometric method and vector method, the scanning track of double galvanometers system were analyzed and simulated, furthermore, the corresponding relationship between the dual-galvanometer scanning angle and position coordinates was determined. Additionally, according to the requirements of imaging system, the unified timing benchmark is also been determined to ensure the temporal synchronicity between subsystems,(3) A 3D imaging experimental system is successfully built up, and for ranging lidar system, the ranging precision and the maximum operation distance are assessed. As to the dual-galvanometer-based scanning lidar system, after the investigation of the characteristics of control voltage versus the scanning angle and the verification of simulation trajectory, the calibration experiment of the two-dimension scanning trajectory is completed. Through the result of the experiment where the target was located at 5 m away, an improved scheme for space information extraction has been proposed, i.e. in the system the light trigger is used instead of electricity trigger, which can allow the single point ranging precision of the system increased from 10.5~12 cm to 6~7.5 cm, thus the spatial information extraction experiments were completed.(4) To correct pincushion distortion of dual-galvanometer scanning trajectory, this paper proposes a calibration algorithm for the galvanometer control voltage, as well as provides the simulation process and completes the calibration experiment. We have used triangular wave function instead of harmonic function to improve the uniformity of the y axis scanning spot and completed the simulation analysis of correction result. According to the characteristic of galvanometer scanning in x axis, we have adopted seven order approximation of triangle wave function as control function for X scanning mirror with considering the drop point problem of galvanometer vibration and the uniformity of x direction scanning point, thereafter giving the final simulation result.