Laser Centering of Robotic Arm for Tubesheet Alignment
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Solution Overview
Problem
In nuclear steam generator and balance of plant eddy current inspections, robots face alignment issues due to parallax when positioning tools in tubesheets, leading to potential tool damage and unsuccessful insertions.
Innovation Solution
A method and system utilizing a robot with a guide-tube, camera, and lasers to refine alignment by projecting laser beams onto the tubesheet, forming patterns that allow for precise positioning of the tool relative to the tubesheet holes, ensuring coaxial alignment and preventing misinsertions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a camera mounted on the end-effector is utilized to monitor the alignment of the tool to a particular hole in the tubesheet, then the alignment can be monitored, but parallax causes misalignment between the tool and the hole
Solution Approach 1:
A laser alignment system serves as an intermediary reference framework between the camera and the physical hole. The laser projects a pattern (crosshair or circle) that creates a virtual reference plane, allowing the camera to accurately locate the hole center without parallax error affecting the measurement. The laser pattern acts as a mediator that translates the 3D spatial relationship into a 2D image plane reference.
Solution Approach 2:
The patent replaces direct mechanical/optical alignment methods (camera-only approach) with a laser-based optical reference system. Instead of relying solely on camera geometry and parallax correction, the laser provides a stable, predefined reference framework that substitutes for complex mechanical alignment procedures and simplifies the measurement process.
2Reliability
If the tool is misaligned with a hole in the tubesheet, then the motorized drive may push the tool into the face of the tubesheet, but preventing this requires more precise alignment mechanisms
Solution Approach 1:
The laser alignment system performs preliminary alignment verification before the tool insertion action. By projecting the laser pattern and confirming the tool is properly aligned with the hole center in advance, the system prevents misalignment issues before they can cause damage during the motorized drive insertion process.
Solution Approach 2:
The laser pattern serves as an intermediary reference that mediates between the tool positioning system and the hole location. This intermediary provides a clear, visible reference that simplifies the alignment verification process and increases reliability without requiring complex mechanical stoppers or physical guides.
3Manufacturing precision
If lasers are positioned around the guide-tube to project laser beams onto the tubesheet, then alignment precision is improved, but device complexity increases
Solution Approach 1:
The laser alignment system is integrated into the existing robotic end-effector structure, allowing the same apparatus to serve both the tool positioning function and the alignment reference function. The laser components are mounted on the guide-tube or end-effector, making the alignment system portable and adaptable to different tooling configurations without requiring separate fixed infrastructure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively addresses alignment challenges, enabling accurate and safe insertion of tools into tubesheet holes, reducing the risk of tool damage and improving the efficiency of eddy current inspections and other operations on tubes.
Implementation Method 1
a plurality of lasers positioned around an exterior of the guide-tube and operable to output a plurality of laser beams toward the tubesheet
Implementation Method 2
via the camera, detecting a pattern of laser spots formed by the laser beams on a surface of the tubesheet adjacent the first hole in the tubesheet
Data Source
AI summary
In a system and method of working tubes coupled to a tubesheet having a number of holes, wherein each hole in fluid communication with one of the tubes, an end-effector is positioned by a robot in coarse or rough alignment with a first hole in the tubesheet. Via lasers positioned on the end-effector, laser spots are formed on a surface of the tubesheet adjacent the first hole. The laser spots are detected by a camera and the alignment of the end-effector relative to the first hole in the tubesheet is refined via the robot based on the detected pattern of laser spots. The tool is then moved into the tube that is in fluid communication with the first hole in the tubesheet to work on (inspect, plug, sleeve or weld) the tube.