# US 12,358,145 B2 · System and method for three-dimensional calibration of a vision system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,358,145 B2 - Document ID: US12358145B2 - Status: Granted - Kind: B2 - Application number: 17/198,333 - Filed: 2021-03-11 - Published: 2021-09-23 - Granted: 2025-07-15 - Earliest claimed: 2020-03-18 - Assignees: Cognex Corporation - Applicants: Cognex Corporation - Inventors: Xiaoguang Wang; Yukun Bian; Li Sun; David Y. Li - Web page: https://patentgrep.com/patent/US12358145B2 ## CPC - B25J 9/1692: {Calibration of manipulator} - B25J 9/1697: {Vision controlled systems} - G01B 11/245: using a plurality of fixed, simultaneously operating transducers ({G01B11/2408 - G01B11/2425, } G01B11/255 take precedence) - G01B 21/042: {Calibration or calibration artifacts (G01B3/30, G01B9/02072 take precedence)} - G06T 7/85: {Stereo camera calibration} - G05B 2219/39038: Determine position of two cameras by using a common reference grid - G05B 2219/39057: Hand eye calibration, eye, camera on hand, end effector - G06T 2207/30208: Marker matrix - B25J: MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES ({manipulators specially adapted for use in surgery A61B34/70; manipulators used in cleaning hollow articles B08B9/04}; manipulators associated with rolling mills B21B39/20; manipulators associated with forging machines B21J13/10; {manipulators associated with picking-up and placing mechanisms B23P19/007}; means for holding wheels or parts thereof B60B30/00; {vehicles with ground-engaging propulsion means, e.g. walking members B62D57/02, B62D57/032; devices for picking-up and depositing articles or materials between conveyors B65G47/90, B65G47/91; manipulators with gripping or holding means for transferring packages B65H67/065}; cranes B66C; {manipulators used in the protection or supervision of pipe-line installations F17D5/00; walking equipment adapted for nuclear steam-generators F22B37/006}; manipulators specially adapted for, or associated with, nuclear reactors G21C; {apparatus used for handling wafers during manufacture or treatment of semiconductor H10P72/50}) - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS - G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL - G05B: CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS (systems for controlling or regulating non-electric variables G05D; systems for regulating electric or magnetic variables G05F; control devices or systems insofar as characterised by mechanical features only G05G) ## Abstract This invention provides a system and method for calibration of a 3D vision system using a multi-layer 3D calibration target that removes the requirement of accurate pre-calibration of the target. The system and method acquires images of the multi-layer 3D calibration target at different spatial locations and at different times, and computes the orientation difference of the 3D calibration target between the two acquisitions. The technique can be used to perform vision-based single-plane orientation repeatability inspection and monitoring. By applying this technique to an assembly working plane, vision-based assembly working plane orientation repeatability, inspection and monitoring can occur. Combined with a moving robot end effector, this technique provides vision-based robot end-effector orientation repeatability inspection and monitoring. Vision-guided adjustment of two planes to achieve parallelism can be achieved. The system and method operates to perform precise vision-guided robot setup to achieve parallelism of the robot's end-effector and the assembly working plane. ## Claims ### Claim 1 A system for calibrating a vision system with respect to a 3D working space comprising: a vision system processor that receives image data captured by a single camera and applies vision system tools to the image data; a multi-layer 3D calibration target having a plurality of surfaces at a respective plurality of mutually differing displacements relative to the single camera and the plurality of surfaces having, respectively, discrete calibration patterns thereon, the image data comprising views of the plurality of surfaces of the multi-layer 3D calibration target disposed in a plurality of spatial locations of the 3D working space; and a determination process that analyzes the image data using the vision tools to compute, for each of a first spatial location and a second spatial location of the plurality of spatial locations of the 3D working space depicted in the image data, spatial relationships of at least two of the discrete calibration patterns disposed on different surfaces of the plurality of surfaces, wherein the first spatial location differs in three orthogonal dimensions from the second spatial location in the 3D working space, and determine a difference between the computed spatial relationship of the first spatial location and the computed spatial relationship of the second spatial location to provide results. ### Claim 2 (depends on 1) The system as set forth in claim 1 wherein the 3D calibration target is located on a robotic end effector. ### Claim 3 (depends on 2) The system as set forth in claim 2 wherein vision-guided robotics (VGR) control signals are transmitted between the vision system processor and a controller for the robotic end effector. ### Claim 4 (depends on 1) The system as set forth in claim 1 wherein the plurality surfaces of the calibration target comprise a main surface and a plurality of raised surfaces projecting therefrom. ### Claim 5 (depends on 4) The system as set forth in claim 4 wherein sides of the plurality of raised surfaces comprise a plurality of rectangular plates that are positioned at a non-orthogonal angle with respect to sides of the main surface. ### Claim 6 (depends on 1) The system as set forth in claim 1 wherein the plurality of surfaces respectively have a calibration pattern that defines a checkerboard pattern, the checkerboard pattern having one or more ID codes embedded thereinto that contain information related to location within the calibration pattern. ### Claim 7 (depends on 1) The system as set forth in claim 1 wherein the determination process analyzes the image data using the vision tools to compute a difference between the spatial relationship of the first spatial location and the spatial relationship calculated for another, second spatial location to provide the results. ### Claim 8 (depends on 7) The system as set forth in claim 7 wherein the results are used to determine parallelism between a first plane and a second plane. ### Claim 9 (depends on 7) The system as set forth in claim 7 wherein the results are used to determine repeatability of a spatial orientation of an object plane in the working space over a desired time interval. ### Claim 10 (depends on 1) The system as set forth in claim 1, further comprising, a camera assembly operatively connected to the vision system processor, having an optics assembly that is non-telecentric, wherein the 3D calibration target is moved and a closed loop 2D alignment process is applied before and after moving the 3D calibration target. ### Claim 11 A method for calibrating a vision system with respect to a 3D working space comprising the steps of: providing a multi-layer 3D calibration target having a plurality of surfaces at a respective plurality of mutually differing displacements and the plurality of surfaces having, respectively, discrete calibration patterns thereon; receiving image data containing views of the plurality of surfaces of the 3D calibration target in a plurality of spatial locations of the 3D working space and applying vision system tools to the image data; computing, for each of a first spatial location and a second spatial location of the plurality of spatial locations of the 3D working space depicted in the image data, spatial relationships of at least two of the discrete calibration patterns disposed on different surfaces of the plurality of surfaces, wherein the first spatial location differs in three orthogonal dimensions from the second spatial location in the 3D working space; and analyzing the image data using the vision tools to compute a difference between the computed spatial relationship of the first spatial location and the computed spatial relationship of the second spatial location to provide results. ### Claim 12 (depends on 11) The method as set forth in claim 11, further comprising, locating the 3D calibration target on a robotic end effector. ### Claim 13 (depends on 12) The method as set forth in claim 12, further comprising, transmitting vision-guided robotics (VGR) control signals between the vision system processor and a controller for the robotic end effector. ### Claim 14 (depends on 11) The method as set forth in claim 11 wherein the plurality surfaces of the calibration target comprise a main surface and a plurality of raised surfaces projecting therefrom. ### Claim 15 (depends on 14) The method as set forth in claim 14 wherein sides of the plurality of raised surfaces define a plurality of rectangular plates that are positioned at a non-orthogonal angle with respect to sides of the main surface. ### Claim 16 (depends on 11) The method as set forth in claim 11 wherein the plurality of surfaces respectively have a calibration pattern that defines a checkerboard pattern, the checkerboard pattern having one or more ID codes embedded thereinto that contain information related to location within the calibration pattern. ### Claim 17 (depends on 11) The method as set forth in claim 11, further comprising, analyzing the image data using the vision tools to compute a difference between the spatial relationship of the first spatial location and the spatial relationship calculated for another, second spatial location to provide the results. ### Claim 18 (depends on 17) The method as set forth in claim 17, further comprising, verifying parallelism between a first plane and a second plane based upon the results. ### Claim 19 (depends on 17) The method as set forth in claim 17, further comprising, verifying repeatability of a spatial orientation of the object plane in the working space over a desired time interval based upon the results. ### Claim 20 (depends on 11) The method as set forth in claim 11, further comprising, providing an optics assembly for a camera assembly that generates the image data, that is non-telecentric, and moving the 3D calibration target and applying a closed loop 2D alignment process before and after the moving of the 3D calibration target.