Repairing 3D Objects Using Photogrammetry and Tool Path Generation

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Solution Overview

Problem

Three-dimensional objects, such as compressor blades and bladed disks, are difficult to repair precisely without introducing distortions and stresses, especially when manufacturer specifications are insufficient or outdated due to shape changes during service use.

Innovation Solution

A system that uses a photogrammetry device and a controller to scan the object, calculate a nominal surface location and contour, and generate tool paths for material removal or addition to restore the object to its desired shape, allowing for precise repair without altering the object's bulk structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of repair

If traditional machine tools are used to repair three-dimensional objects, then material can be removed or added, but the repair process introduces distortions and stresses into the object

Engineering Contradiction:
Improverepair capabilityVSAvoidobject stability
Core Design Contradiction:
Ease of repairVSStability of the object's composition

Solution Approach 1:

The patent replaces traditional mechanical machine tools with a robotic system that uses computer-controlled tools and automated positioning. The robotic arm with precision actuators substitutes manual or conventional mechanical machining, enabling more precise material removal and addition while minimizing disturbances to the object's stress state and geometric integrity.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Ease of manufacture

If manufacturer specifications are used for repair, then a standardized approach is available, but the specifications are insufficiently detailed or unavailable when parts have changed shape during service use

Engineering Contradiction:
Improverepair standardizationVSAvoidspecification accuracy
Core Design Contradiction:
Ease of manufactureVSLoss of information

Solution Approach 1:

The patent creates a digital copy of the object's actual geometry through 3D scanning and photogrammetry. This digital model replaces the need for physical manufacturer specifications or drawings, capturing the object's current as-built geometry including any shape changes that occurred during service. The digital twin enables precise repair planning based on the actual object state rather than outdated or insufficient documentation.

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The system incorporates feedback by scanning the object before and during the repair process to verify measurements and adjust the repair plan. The photogrammetry device continuously monitors the object's geometry, providing real-time feedback to the control system, which then adjusts material removal and addition operations to achieve the desired repair outcome while accounting for any unexpected variations in the object's current state.

Inventive Principle:
Principle #23Feedback

3Manufacturing precision

If a computer-controlled tool path is based on an original manufacturer three-dimensional specification, then precision is maintained, but the path is not appropriate for efficient repair of a worn, non-conforming or damaged part

Engineering Contradiction:
Improvedimensional accuracyVSAvoidrepair efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent employs a dynamic repair approach where the tool path is not fixed in advance based on original specifications, but is adaptively generated and adjusted during the repair process. The system dynamically creates the tool path by comparing the scanned actual geometry with the target geometry, allowing the repair process to efficiently address only the specific worn, non-conforming, or damaged regions rather than following a rigid pre-programmed path based on original manufacturer dimensions.

Inventive Principle:
Principle #15Dynamics

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

Enables efficient and precise repair of non-conforming three-dimensional objects by accurately determining the necessary material removal or addition, ensuring the object meets performance specifications while minimizing stress and repair costs.

Implementation Method 1

a photogrammetry device adapted to scan the three-dimensional object

Methodology Applied
Scientific EffectPhotogrammetry: Photogrammetry

Data Source

PatentEP2254728B1System and method for repairing objects
Publication Date: 2019.09.11 ROLLS ROYCE CORP
  • EP2254728B1 patent drawingFigure 1
  • EP2254728B1 patent drawingFigure 2
  • EP2254728B1 patent drawingFigure 3

AI summary

A system is disclosed including a three-dimensional object having a non- conforming region, and a photogrammetry device adapted to scan the three- dimensional object. The system further includes optical reference targets and a controller structured to perform functions of repairing the three-dimensional object. The controller commands the photogrammetry device to scan the three-dimensional object, and calculates a nominal surface location and contour for the three-dimensional object. The controller further commands the photogrammetry device to scan the non- conforming region of the three-dimensional object, and calculates a material removal tool path comprising a path adapted to remove material from the object located beyond the nominal surface location and contour. The controller generates a solid model of the damaged region of the object based on the nominal surface location and contour, and computes a material addition tool path according to the solid model.