US-12626083-B2 - Fiducial tag structure

US12626083B2US 12626083 B2US12626083 B2US 12626083B2US-12626083-B2

Abstract

A fiducial tag structure includes a polyhedral structure and a plurality of fiducial tags. The polyhedral structure includes a plurality of surfaces that are non-coplanar. Each of the plurality of fiducial tags is formed on one of the plurality of surfaces, and each of the plurality of fiducial tags includes a two-dimensional pattern carrying code information.

Inventors

PO-CHIEH CHANG

Assignees

HON HAI PRECISION INDUSTRY CO., LTD.

Dates

Publication Date: 20260512
Application Date: 20241107
Priority Date: 20240417

Claims (8)

1 . A fiducial tag structure comprising: a polyhedral structure comprising a plurality of surfaces, wherein the plurality of surface is-non-coplanar; and a plurality of fiducial tags, each of the plurality of fiducial tags formed on a corresponding surface of the plurality of surfaces, and each of the plurality of fiducial tags comprising a two-dimensional pattern carrying code information; wherein the two-dimensional pattern is formed by paint printing, spraying or drawing, each of the plurality of fiducial tags is readable and recognizable by a Light Detection and Ranging (LiDAR) system thereby generating a position and an attitude of the LiDAR system; the polyhedral structure further comprises a plurality of pixel blocks, each of the plurality of pixel blocks is three-dimensional and rotatable, and the two-dimensional pattern changes as at least one of the plurality of pixel blocks rotates.
2 . The fiducial tag structure according to claim 1 , wherein each of the plurality of pixel blocks comprises at least two surfaces comprising pixels carrying different code information; the pixels are selectively visible, by rotating at least one of the plurality of pixel blocks, the pixels carrying different code information are selected to be visible, thereby changing the two-dimensional pattern.
3 . The fiducial tag structure according to claim 2 , wherein each of the surfaces of the polyhedral structure is composed of surfaces of a portion of the plurality of pixel blocks on a same plane; and the pixels selected to be visible on the same surface of the polyhedral structure collectively form one two-dimensional pattern of one of the plurality of fiducial tags.
4 . The fiducial tag structure according to claim 1 , wherein each of the plurality of pixel blocks comprises two end surfaces parallel to each other and a plurality of side faces between the two end faces, at least one of the plurality of side faces is provided with the pixel; and each of the plurality of pixel blocks comprises a rotation axle perpendicular to the two end faces, allowing each of the plurality of pixel blocks to rotate around the rotation axle.
5 . The fiducial tag structure according to claim 4 , wherein the rotation axle extends from a center of one of the two end faces to a center of another one of the two end faces.
6 . The fiducial tag structure according to claim 1 , wherein the two end faces are in a squared shape.
7 . The fiducial tag structure according to claim 1 , wherein each of the plurality of pixel blocks is a cuboid.
8 . The fiducial tag structure according to claim 1 , wherein each of the plurality of pixel blocks is a hexagonal prism.

Description

FIELD The subject matter herein generally relates to a fiducial tag structure. BACKGROUND A fiducial tag is a special symbol used in computer vision. The fiducial tag has been used for attitude and position estimation of a camera mounted on a robot in three-dimensional space, thus enabling the robot to navigate and locate in unknown environments. In addition, in three-dimensional space, a LiDAR system is employed to emit laser light towards the fiducial tag. The laser light reflected by the fiducial tag propagates back and is subsequently received by the LiDAR system. Based on the reflected laser light, the LiDAR system can detect and decode the information within the fiducial tag. This information is then utilized by the robot, equipped with a LiDAR sensor, for attitude and position estimation, thereby aiding in localization. However, the LiDAR system cannot decode the laser light reflected by the fiducial tag when the fiducial tag is placed at a specific angle, thereby rendering it unable to obtain information (such as global coordinates) from the fiducial tag for improving localization in three-dimensional space. Therefore, there is room for improvement within the art. BRIEF DESCRIPTION OF THE DRAWINGS Implementations of the present disclosure will now be described, by way of embodiment, with reference to the attached figures, wherein: FIG. 1 shows a fiducial tag structure according to a first embodiment of the present disclosure. FIG. 2 shows a polyhedral structure in FIG. 1. FIG. 3 shows a fiducial tag in FIG. 1. FIG. 4 shows the fiducial tag structure according to a second embodiment of the present disclosure. FIG. 5 shows the fiducial tag structure according to a third embodiment of the present disclosure. FIG. 6 shows a pixel block in FIG. 5. FIG. 7 shows a pixel block according to at least one embodiment of the present disclosure. FIG. 8 shows a fiducial tag structure fixed on a carrying device. FIG. 9 shows a fiducial tag structure including a covering device. DETAILED DESCRIPTION It will be appreciated that for simplicity and clarity of illustration, where appropriate, reference numerals have been repeated among the different figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein can be practiced without these specific details. In other instances, methods, procedures and components have not been described in detail to avoid obscuring the relevant feature being described. Also, the description should not be considered as limiting the scope of the embodiments described herein. The drawings are not necessarily to scale, and the proportions of certain parts have been exaggerated to better illustrate details and features of the present disclosure. Several definitions that apply throughout this disclosure will now be presented. The term “comprising,” when utilized, means “including, but not necessarily limited to”; it specifically indicates open-ended inclusion or membership in the so-described combination, group, series, and the like. “Above” means one layer is on top of another layer. In one example, it means one layer is situated directly on top of another layer. In another example, it means one layer is situated over the second layer directly or indirectly with more layers or spacers in between. When a feature or element is herein referred to as being “on” another feature or element, it can be directly on the other feature or element or intervening features and/or elements may also be present. It will also be understood that, when a feature or element is referred to as being “connected”, “attached” or “coupled” to another feature or element, it can be directly connected, attached, or coupled to the other feature or element or an intervening features or elements may be present. As shown in FIG. 1, a fiducial tag structure 100 provided in the present embodiment is applied to a LiDAR system. The fiducial tag structure 100 includes a plurality of fiducial tags 20 carrying code information. Each fiducial tag 20 can be read and recognized by the LiDAR system to estimate its position and attitude of the LiDAR in three-dimensional space. The following will explain the fiducial tag structure 100 of the present disclosure through embodiments. First Embodiment As shown in FIG. 1, FIG. 2 and FIG. 3, the fiducial tag structure 100 of the present embodiment includes a polyhedral structure 10 and the fiducial tags 20. The polyhedral structure 10 includes a plurality of non-coplanar surfaces 11. Each fiducial tag 20 is formed on one of the surfaces 11, and each fiducial tag 20 includes a two-dimensional pattern 22 carrying code information. The polyhedral structure 10 is a polyhedron and includes the surfaces 11. Specifically, in this embodiment, the polyhedral structure 10