Automatic Measuring System TCP Calibration via Camera
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Solution Overview
Problem
Existing automatic inside-diameter measuring systems face challenges in accurately setting the tool center point, especially when the measuring head is large and lacks a sharp point, leading to measurement errors due to difficulties in calibration and high costs associated with dedicated calibration tools for various types and sizes of measuring devices.
Innovation Solution
An automatic measuring system that includes a moving mechanism, such as an articulated robot, equipped with a measuring sensor tool and an observation camera, which uses camera calibration marks and sensor calibration parts to calibrate the position and posture offset between the camera and the measuring sensor tool, allowing for accurate control and measurement of dimensions or shapes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional TCP setting method using a sharp-pointed tool and calibration jig is used, then the tool center point can be set accurately for simple tools, but it cannot be applied to inside-diameter measuring devices with large measuring heads that do not have sharp points
Solution Approach 1:
The patent introduces a camera as an intermediary device to capture images of calibration marks on the calibration jig. The camera system (including observation camera, image processing unit, and robot control unit) serves as a mediator between the robot's positioning system and the calibration jig, enabling indirect but accurate determination of the tool center point for measuring devices without sharp points.
Solution Approach 2:
The patent replaces the traditional mechanical contact-based TCP setting method with an optical measurement system. Instead of physically contacting the calibration jig with a sharp-pointed tool, the system uses a camera to capture images of calibration marks and processes these images to calculate the tool center point, substituting mechanical contact with optical detection.
2Measurement precision
If dedicated calibration tools are prepared for each type and size of measuring device, then accurate calibration can be achieved, but the cost and complexity of preparing multiple specialized tools increases significantly
Solution Approach 1:
The patent creates a universal calibration jig with standardized calibration marks that can be used with any inside-diameter measuring device, regardless of type or size. The camera-based calibration system serves multiple functions: it calibrates different measuring devices, accommodates various measuring head sizes, and provides consistent calibration accuracy across all device types, eliminating the need for multiple specialized calibration tools.
3Measurement precision
If the measuring head is inserted close to the hole to be measured to minimize gap, then measurement accuracy improves, but the risk of collision between the measuring head and the object increases
Solution Approach 1:
The patent performs preliminary calibration actions before actual measurement. By first calibrating the robot's positioning system using the camera-based method to accurately determine the tool center point and its relationship to the calibration jig, the system establishes precise positioning parameters in advance. This preliminary calibration enables the measuring head to be inserted accurately into holes without collision during subsequent measurement operations.
Data Source
AI summary
An automatic measuring system includes a measuring sensor tool that detects a surface of an object to be measured to measure a dimension or a shape of the object to be measured, a moving mechanism that relatively moves the measuring sensor tool with respect to the object to be measured, and an observation camera that images the object to be measured. A position and an orientation (posture) of a point to be measured are acquired from image data obtained by imaging the object to be measured by the observation camera, the measuring sensor tool is caused by the moving mechanism to approach the point to be measured, taking into account a position and posture offset between the observation camera and the measuring sensor tool, and a measurement value of the point to be measured is acquired by the measuring sensor tool.