System Research Of Active Optical Alignment For High Precision Dual Camera Module

Binocular stereo vision based on dual camera module has been widely used in smartphone.It is also widely used in facial recognition,autopilot,industrial robot's vision system,target tracking,3D measurement,and location of assembly.Active alignment of dual camera module optical axis is one of the important assembly process requirements of stereo vision.The active alignment result affects the immersive experience and functional accuracy of stereo vision.At present,positioning and assembling through the external structure of the module,or calculating and positioning in the center of the image,lead to complex algorithm processing in the later stage,which is difficult to meet the industry requirements.Fisrt,a binocular stereo vision system is proposed by self-imaging of the module in this paper.The stereo vision system uses the stereo vision calibration technology to obtain the actual optical axis and module posture to adjust the optical axis by active alignment.Second,an on-line measurement method of baseline is developed.Third,the velocity profile and vibration suppression are considered during the assembly process.In this paper,the traditional calibration method of binocular stereo vision is analyzed.It is noted that the advantages of this calibration method include high accuracy,clear mathematical model,and comprehensive theoretical background.To further improve the practicability of the calibration method,a two-step calibration approach is proposed to optimize the initial parameters.Moreover,a circular calibration target method is presented to improve the calibration accuracy.Experiments are conducted to obtain repeatable results which demonstrate the feasibility and accuracy of the new calibration scheme.For baseline measurement of the dual camera module,a Moire fringe principle based method is proposed.The optical path,optical parameter calculation and hardware system implementation of using Moire fringe are analyzed and designed.Image edge superposition,Fourier transform,and waveform smoothing are used during image processing.The vibration of the system is studied by finite element analysis and simulation to achieve high speed,high accuracy and stability.A feasible method to isolate the vibration is presented and verified.Through the planning of velocity profile,the vibration of the system is reduced significantly.And the compensation method of vibration suppression by adjusting the parameters in the motion controller is also proposed and studied.The results obtained from practical application are repeatable.The research works presented in this paper have practical reference for the design and implementation of the future active alignment system with optical imaging.