Passive Binocular Optical Motion Capture Technology Under Complex Illumination

Passive optical motion capture technology is an effective mean to conduct high-precision pose estimation of small scenes of mobile robots; nevertheless, in the case of complex background and stray light interference in the scene, due to the influence of target adhesion and environmental reflection, this technology cannot estimate the pose accurately. A passive binocular optical motion capture technology under complex illumination based on binocular camera and fixed retroreflective marker balls has been proposed. By fixing multiple hemispherical retroreflective marker balls on a rigid base, it uses binocular camera for depth estimation to obtain the fixed position relationship between the feature points. After performing unsupervised state estimation without manual operation, it overcomes the influence of reflection spots in the background. Meanwhile, contour extraction and ellipse least square fitting are used to extract the marker balls with incomplete shape as the feature points, so as to solve the problem of target adhesion in the scene. A FANUC m10i-a robot moving with 6-DOF is used for verification using the above methods in a complex lighting environment of a welding laboratory. The result shows that the average of absolute position errors is 5.793 mm, the average of absolute rotation errors is 1.997°, the average of relative position errors is 0.972 mm, and the average of relative rotation errors is 0.002°. Therefore, this technology meets the requirements of high-precision measurement in a complex lighting environment when estimating the 6-DOF-motion mobile robot and has very significant application prospects in complex scenes.