Monocular Vision Pose Measurement Based on Docking Ring Component

The gear structure is an important part of the transmission device. The majority of manual methods are currently used to complete the assembly of the large internal gear. Manual assembly is difficult and inefficient. Therefore, an online measurement method for the assembly pose of the gear structure based on monocular vision is proposed. After the critical features of the gear structure have been detected, a duality elimination method based on traversal mapping dots is proposed to obtain the correct solution for the spatial circle pose. Concurrently, the circle pose optimization model is established to enhance pose precision. Then, a new calibration board was designed to finish the hand-eye calibration of the parallel mechanism and camera. Finally, the correction amount required to complete the internal and external teeth assembly is calculated based on the iterative update of the pose measurement method. Experimental results show that the comprehensive accuracy of the pose measurement method exceeds 0.2 mm, the average assembly time is approximately 14 minutes, and the assembly success rate is approximately 97%. It has been realized that simulation gear structure parts can be assembled automatically.

Section: Introductionmentioning

confidence: 99%

Online measurement method for assembly pose of gear structure based on monocular vision

Kong

Zhou

Huang

2023

“…While a space vehicle is performing a mission, it is necessary to measure the position and posture of the spacecraft, but there is an ambiguity problem in the positioning of a single circle in space. Therefore, Miao [19] introduced the distance invariance constraint into the solution of the position and posture of a single circle, which can obtain a reliable position and posture solution. Considering the influence of thermal deformation on the posture calculation, Cheng [20] proposed a posture evaluation method based on temperature compensation and 3D tolerance.…”

Section: Introductionmentioning

confidence: 99%

An improved posture evaluation method for cylindrical intersecting holes on large aerospace components based on monocular vision

Deng¹,

Lili²,

Hao³

et al. 2022

Cylindrical intersecting holes(CIHs) are common connection and location reference features in assembly of large aerospace structures such as missile and rocket cabins. The posture accuracy of assembly holes significantly impacts the relative position accuracy of joined parts and fatigue strength of finished product. At present, monocular vision measurement is widely used in automatic drilling of assembly holes for its integration simplicity and lower cost, but in most research, only the front face edge of the hole is used in the measurement model, and the hole end surface is usually assumed to be plane, which inevitably leads to precision loss. In this research, a novel posture measurement method for CIHs is proposed. Firstly, by introducing an ambiguity removal strategy, a coarse posture estimation method based on plane hypothesis of the two end surfaces of CIHs is suggested. Secondly, considering that there is no simply explicit expression for CIHs edge, thus it is difficult to adopt the conventional model projection based pose optimization method. In view of this, the three-dimensional points corresponding to the edge pixels of CIHs image are derived, and the pose optimization model is established by minimizing the deviations between the distance from the points to the CIHs axis and the hole radius. Moreover, to better control the direction parameters of CIHs during the global optimization process, the approximately perpendicular and intersection constraints between CIHs axis and cylindrical component axis are involved in solution. The effectiveness of the posture measurement method is verified by comparative experiments with current methods and CMM, which demonstrates improvements on both measurement accuracy and robustness.

“…Wei et al [21] used the angle constraint between the two lines which are coplanar with the space circle to eliminate ambiguities. Miao et al [22] used the Euclidean invariance of the distance from the reference point to the circle's center as a constraint to solve the pose ambiguity. Zhang et al [23] used the geometric method to prove that there was a dual solution when the reference point was located at the maximum vertex plane of the cone formed by the optical center and the contour of the ellipse in image.…”

Section: Introductionmentioning

confidence: 99%

Precise pose and radius estimation of circular target based on binocular vision

Liu¹,

Liu²,

Duan³

et al. 2019

A novel method of estimating circle pose and radius is proposed, based on binocular vision. This method uses the special vectors that are irrelevant to the unknown radius to calculate the normal vector of the circular plane, which is the foundation for calculating the vanishing line of the circular plane in the imaging plane. The projections of the circle center on the left and right image are calculated afterwards through the vanishing line. Then, the circle center is reconstructed by the triangulation technology of binocular stereo vision. Finally, the radius of the circular target is calculated through the relative positions of points in the same coordinate system. The estimates of normal vector, center position, and radius size are unique and definite, so there is no need for a subsequent screening process. When the radius is unknown, most of the conventional circle pose estimation methods are unusable. However, the proposed method has no prerequisites about the circular target in order to estimate the pose and radius of the circular target, which improves flexibility and extends the application field. Besides estimating the pose of a circular target of unknown radius, the proposed method can also be applied to the vision measurement of the radius of a circular object. Both actual measurement experiments and noise simulation experiments are performed. The results show that the proposed method is more precise and robust than conventional methods.