Pose measuring and aligning of a micro glass tube and a hole on the micro sphere

To ensure high uniformity of the inner space of the hollow sphere after assembly, the glass tube must be inserted into the hole on the sphere towards the center of the sphere. This paper deals with the pose measuring of the hole on the sphere and the glass tube and pose aligning of the two objects. The sphere is 500 mm in diameter with a 20 mm hole on it, and the glass tube is 17 mm in diameter. Novel pose measuring method for the hole on the sphere and the glass tube is developed, using two microscopic cameras, each one acquires a projection vector of the object to be measured. A plane containing the optical axis of the microscopic camera and the pose vector of the object is determined, with the microscopic camera calibrated in advance. Pose vector of the object to be measured can be calculated by the intersection of the two planes acquired by the two microscopic cameras. Error analysis of the pose measuring method is conducted and experimental results were consistent with analytical results. Less than 0.7° pose aligning error is achieved using the proposed pose measuring method and pose aligning method.