Research On Calibration Method Of Vehicle-borne Mobile Measurement System Based On Spherical Model

Vehicle-borne mobile measurement system(VMMS)is a highly integrated measurement instrument with multiple sensors.The convenient,efficient and accurate features provide a solution for the refined urban management and multi-survey integration.As a kind of highly integrated precision measurement instrument with multiple sensors,the calibration accuracy of the spatial relationship between sensors,especially laser scanner and integrated navigation system,has become the main factor restricting the final measurement accuracy of mobile measurement system.Main work content:(1)On the basis of the research on the domestic and foreign calibration method of the boresight parameters between the laser scanner and inertial measurement unit of the VMMS.Based on the geometric positioning model and combined with the characteristics of VMMS,various error sources of VMMS and their influence on system accuracy are analyzed.The influence of boresight error and different order of magnitude of boresight error on the accuracy are analyzed emphatically.(2)According to the laser footprint location equation containing system boresight parameters,the minimum distance deviation between the laser footprint on the sphere and the spherical equation is used as the constraint condition.According to the effect of boresight angles error on the overall error of the system is much greater than that of the offset error,the boresight angles and the offset are solved separately by a step-by-step calculation method.The stop threshold of iterative calculation is determined according to the error of different orders of magnitude.(3)System accuracy and model reliability verification experiment.The data are collected from other calibration field and the outfields simulating the actual operating environment,and the internal and external coincidence accuracy of system are evaluated.The experimental results show that this method can effectively eliminate the influence of boresight error and has good reliability.After calibration,the internal coincidence accuracy is 0.007m,and the external coincidence accuracy is 0.028m.