Simulation Study Of Monocular-vision-based Multiple Target Board Pose Tracking In The Large Field-of-view

Assembly is an important step in aircraft manufacturing. More and more digital measurementmethods have been applied to aircraft assembly in recent years. A simulation platform VSM has beenestablished in this paper with multiple targets based on the Archer-M system which is a monocularvision-based airborne equipment pose measurement system. The VSM platform offers a way to studyhow the factors such as target board structure parameters, random error of target position, keyalgorithm error of system and measurement field setting affect the Archer-M system measurementresults. The main contents and achievements of this paper are as follows.1. The VSM simulation software platform has been established after studying the model and thekey algorithm of the Archer-M system. The internal relation between the related factors and theperformance of the system has been revealed through a lot of simulation experiments. Themonocular-vision virtual measurement environment of the aircraft airborne equipment’s attitudes canbe conveniently set up in the platform. The lights’ distribution and light spots’ centroid position ofspace LED is simulated on the image plane. The image noise level is flexibly set and the sub pixel ofthe light spots’ centroid position on the image plane can be changed according to the need and thegeometrical structure of the target plate by adjusting the input parameters. On the basis of the relatedinfluence factors which can be flexibly set and changed, the simulation attitude measurement resultsof the space relative multiple targets are obtained and the results would be statistical analyzed tooutput in the VSM.2. By changing the sub pixel location of simulation target spots’ centroid on the image plane, thepositioning error of three typical center algorithms has been researched. The mechanism of the systemerrors of the three algorithms have been revealed through experimental methods. With these results,the target spot centroid location algorithm and the compensation method can be selected.3. By analyzing the target spots’ centroid localization accuracy influenced by the image noise onthe VSM platform, the reconstruction results in the X, Y, and Z axis are different in each noise levels.Based on the results, the intrinsic reasons why the measurement error in Z axis direction (depthdirection) is larger in monocular vision system has been given.4. The sensitivity of image point is presented to describe how the follow factors effect themeasuring results such as LED points’ distribution, pose between the target board and camera.Besides, the calculation formula of the sensitivity has been given. A series of simulation experimentshave been designed on VSM simulation software platform and the curves of the sensitivity of various factors can be obtained, which provides important foundation for the design of target board and howthe measuring field set in Archer-M system.