CN-116428970-B - Metrology system using light beams for position and orientation tracking

Abstract

The present invention provides a metrology system for use with a movement system that moves an end tool (e.g., a probe). The metrology system includes a sensor structure, a beam source structure, and a processing portion. The sensor structure includes a plurality of beam sensors. The beam source structure directs a beam of light to the beam sensor of the sensor structure. One of the beam source structure or the sensor structure is coupled to the end tool and/or an end tool mounting structure of the movement system that moves the end tool. The light beam directed to the light beam sensor causes the light beam sensor to generate a corresponding measurement signal. The processing portion processes the measurement signal from the beam sensor, the measurement signal being indicative of the position and orientation of the end tool.

Inventors

• J.D. Tobiason
• M. Nahong
• N. Raman
• T.S. Cook

Assignees

• 株式会社三丰

Dates

Publication Date

20260512

Application Date

20221221

Priority Date

20211227

Claims (20)

1. 1. A metering system for use with a movement system for moving an end tool, The mobile system includes: a movable structure including an end tool mounting structure, wherein an end tool is configured to be mounted to the end tool mounting structure, and A motion control system configured to control an end tool position and orientation based at least in part on controlling the movable structure to move at least a portion of an end tool mounted to the end tool mounting structure within a displacement volume, The metering system comprises: a sensor structure comprising a plurality of beam sensors; a beam source structure configured to direct a beam of light to the beam sensor of the sensor structure, wherein: one of the beam source structure or the sensor structure is configured to be coupled to at least one of the end tool or the end tool mounting structure, and The light beam directed to the light beam sensor is configured to cause the light beam sensor to generate a corresponding measurement signal, and A processing portion configured to process the measurement signal from the beam sensor of the sensor structure, wherein the measurement signal from the beam sensor is indicative of a position and an orientation of the end tool; Wherein: When the end tool is in a first position and a first orientation, the light beam from the light beam source structure directed to the light beam sensor of the sensor structure is configured to cause the light beam sensor to generate a corresponding first set of measurement signals indicative of the end tool being in the first position and the first orientation, and When the end tool is in a second position and a second orientation different from the first position and the first orientation, the light beam from the light beam source structure directed to the light beam sensor of the sensor structure is configured to cause the light beam sensor to generate a corresponding second set of measurement signals that are different from the first set of measurement signals and that indicate that the end tool is in the second position and the second orientation.
2. 2. The metrology system of claim 1, wherein each of the beam sensors comprises a two-dimensional position-sensitive sensor for which the measurement signal from the beam sensor is indicative of the two-dimensional position of a measurement point on the beam sensor produced by the beam.
3. 3. The metrology system of claim 1, wherein the beam source structure comprises one or more diffractive optical elements, and the beam from the beam source structure is a diffracted beam.
4. 4. The metering system of claim 1, wherein the movable structure is a movable arm structure.
5. 5. The metrology system of claim 1, wherein the motion control system is configured to sense and control the position and orientation of the end tool with a level of accuracy defined as a moving system accuracy based at least in part on sensing and controlling the position and orientation of the end tool using a plurality of position sensors included in the movable structure.
6. 6. The metrology system of claim 5, wherein the processing portion is operable to determine the position and orientation of the end tool with a level of accuracy that is better than the accuracy of the movement system based at least in part on processing the measurement signals from the beam sensor.
7. 7. The metrology system of claim 5, wherein the light beam directed by the light beam source structure to the sensor structure comprises a first light beam, and the determination of which light beam sensor the first light beam is directed to is based at least in part on a sensed position and orientation of the end tool as determined by using the plurality of position sensors included in the movable structure.
8. 8. The metrology system of claim 7, wherein the beam sensor to which the first beam is directed is a first beam sensor, and the processing portion is operable to determine the position and orientation of the end tool with a level of accuracy that is better than the accuracy of the movement system based at least in part on processing a first measurement signal from the first beam sensor, the first measurement signal being indicative of a position of a first measurement point as formed by the first beam on the first beam sensor for this purpose.
9. 9. The metrology system of claim 1, wherein the light beam directed by the light beam source structure to the sensor structure comprises a first light beam, and the determination of which light beam sensor the first light beam is directed to is based at least in part on an identification of a first characteristic of the first light beam.
10. 10. The metrology system of claim 9, wherein the light beam directed by the light beam source structure forms a pattern, and the first characteristic of the identified first light beam corresponds to an identifiable portion of the pattern in which the first light beam is included.
11. 11. The metrology system of claim 1, wherein the light beam from the light beam source structure directed to the light beam sensor of the sensor structure is configured to generate measurement points in locations on the light beam sensor that cause the light beam sensor to generate corresponding measurement signals, and the locations of the measurement points on the light beam sensor correspond to a first set of measurement point locations when the end tool is in the first position and the first orientation, and the locations of the measurement points on the light beam sensor correspond to a second set of measurement point locations that are different from the first set of measurement point locations when the end tool is in the second position and the second orientation.
12. 12. The metrology system of claim 1, wherein the light beams from the light beam source structure that are directed to the light beam sensor correspond to a first set of light beams when the end tool is in the first position and the first orientation, and the light beams from the light beam source structure that are directed to the light beam sensor correspond to a second set of light beams that are different than the first set of light beams when the end tool is in the second position and the second orientation.
13. 13. The metering system of claim 1, wherein: When the end tool is in the first position and the first orientation, the light beam from the light beam source structure directed to the light beam sensor of the sensor structure includes a first plurality of light beams directed to a first light beam sensor of the sensor structure, and When the end tool is in the second position and the second orientation, the light beams from the light beam source structure directed to the light beam sensor of the sensor structure include a second plurality of light beams directed to the first light beam sensor of the sensor structure, the second plurality of light beams being different than the first plurality of light beams for this purpose.
14. 14. The metrology system of claim 1, wherein the sensor structure comprises a first beam sensor configured to: Generating a first measurement signal when the end tool is in a first position and in a first orientation, for which purpose the first measurement signal is generated by the first beam sensor based at least in part on the beam source structure directing a first beam to form a measurement point at a corresponding first position on the first beam sensor, and A second measurement signal is generated that is different from the first measurement signal when the end tool is at least one of a second position that is different from the first position or a second orientation that is different from the first orientation, for which purpose the second measurement signal is generated by the first beam sensor based at least in part on the beam source structure that directs the first beam to form a measurement point at a corresponding second position that is different from the first position on the first beam sensor.
15. 15. The metering system of claim 14, wherein the processing portion is configured to: Determining that the end tool is in the first position and orientation based at least in part on processing the first measurement signal from the first beam sensor along with other measurement signals from the beam sensor of the sensor structure, and Determining that the end tool is in at least one of the second position or second orientation based at least in part on processing the second measurement signal from the first beam sensor along with other measurement signals from the beam sensor of the sensor structure.
16. 16. The metrology system of claim 1, wherein a metrology frame volume is defined at least in part by the sensor structure or the beam source structure, for which purpose the metrology frame volume is configured to surround at least a portion of the moving volume.
17. 17. The metering system of claim 1, wherein: the beam source structure is coupled to at least one of the end tool or the end tool mounting structure; the position and orientation of the beam source structure being indicative of the position and orientation of the end tool, and The measurement signal from the beam sensor is indicative of the position and orientation of the beam source structure.
18. 18. The metering system of claim 1, wherein: The sensor structure is coupled to at least one of the end tool or the end tool mounting structure; the position and orientation of the sensor structure being indicative of the position and orientation of the end tool, and The measurement signal from the beam sensor is indicative of the position and orientation of the sensor structure.
19. 19. A method for operating a metrology system including a sensor structure including a plurality of beam sensors, and a beam source structure configured to direct a beam of light to the beam sensors of the sensor structure, wherein one of the beam source structure or the sensor structure is configured to be coupled to at least one of an end tool or an end tool mounting structure of a movement system that moves the end tool, the method comprising: operating the beam source structure to direct a beam to a beam sensor of the sensor structure to indicate a position and an orientation of the end tool, wherein: the light beam directed to the light beam sensor causes the light beam sensor to generate a corresponding measurement signal; processing the measurement signals from the beam sensor of the sensor structure to determine the position and orientation of the end tool, and Position information is received from the movement system moving the end tool, wherein the position information indicates a position of the end tool with movement system accuracy, for which purpose the determination of the position and orientation of the end tool is based at least in part on the position information from the movement system and the processing of the measurement signals from the beam sensors of the sensor structure.
20. 20. The method of claim 19, wherein the light beam directed by the light beam source structure to the sensor structure forms a pattern and includes a first light beam in a first portion of the pattern, and the determination of to which light beam sensor the first light beam is directed is based at least in part on an identification of the first portion of the pattern in which the first light beam is included.

Description

Metrology system using light beams for position and orientation tracking Background Technical Field The present disclosure relates to metrology and movement systems, and more particularly to metrology systems that may be used with movement systems such as robots to track position and orientation. Description of related Art Manufacturing, workpiece inspection, and other processes often use mechanical movement systems to perform certain functions. For example, robotic systems or other movement systems may be used to move end tools to perform certain operations (e.g., related to workpiece inspection, manufacturing, etc.). For certain applications, various types of robots that may be used include articulated robots, selective compliance joint manipulator arm (SCARA) robots, rectangular robots, cylindrical robots, spherical robots, and the like. As one example of a component that may be included in a robot, a SCARA robot system (which may be, for example, an articulating robot system) may generally have a base, a first arm rotatably coupled to the base, and a second arm rotatably coupled to an end of the first arm. In various configurations, an end tool may be coupled to an end of the second arm (e.g., for performing certain work and/or inspection operations). Such a system may include a position sensor (e.g., rotary encoder) for determining/controlling the positioning of the arm and, correspondingly, the positioning of the end tool. In various embodiments, such systems may have a positioning accuracy of about 100 microns, subject to certain factors (e.g., rotary encoder performance in combination with mechanical stability of the robotic system, etc.). Some calibration techniques for improving the accuracy of SCARA systems are disclosed in U.S. patent No. 4,725,965 (referred to herein as the' 965 patent), which is incorporated by reference in its entirety. As described in the' 965 patent, a technique for calibrating a SCARA type robot is provided that includes a first rotatable arm and a second rotatable arm carrying an end tool. The calibration technique is related to the fact that the SCARA robot can be controlled using a kinematic model that, when accurate, allows the arm to be placed in a first and a second angular configuration in which the end tool carried by the second arm remains in the same position. To calibrate the kinematic model, the arm is placed in a first configuration to position the end tool above a fixed datum point. The arm is then placed in a second angular configuration to again nominally upper position the end tool in alignment with the datum point. An error in the kinematic model is calculated from the offset of the position of the end tool from the reference point when the arm is switched from the first angular configuration to the second angular configuration. The kinematic model is then compensated for based on the calculated errors. These steps are repeated until the error is zero, at which point the kinematic model of the SCARA robot is considered calibrated. As further described in the' 965 patent, the calibration technique may include the use of certain cameras. For example, in one embodiment, the datum point may be the center of the viewing area of the fixed television camera (i.e., on the ground below the end tool) and the output signal of the camera may be processed to determine the offset of the position of the end tool from the center of the viewing area of the camera when the linkage is switched from the first configuration to the second configuration. In another embodiment, the second arm may carry a camera, and the technique may begin by placing the arms in a first angular configuration in which a second predetermined interior angle between the arms is measured to center the camera carried by the second arm directly above the fixed datum. The arms are then placed in a second angular configuration in which an interior angle equal to a second predetermined interior angle is measured between the arms to again nominally center the camera above the datum point. Then, when the arm is switched from the first angular configuration to the second angular configuration, the output signal of the camera is processed to determine an offset of the reference point position as seen by the camera. The error in the known position of the camera is then determined from the offset of the reference point position seen by the camera. These steps are then repeated as part of the calibration process until the error approaches zero. While techniques such as those described in the' 965 patent may be used to calibrate the robotic system, it may be less desirable in certain applications to use such techniques (e.g., this may require a significant amount of time and/or may not provide the required level of precision for all possible orientations of the robot during certain operations, etc.). There is a need for a system that can provide improvements (e.g., for improving the reliability, repeatability, sp