Robot Paint Trajectory Adaptation for Deformed Workpieces

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Solution Overview

Problem

Automated painting processes using robots face challenges due to dimensional deviations in manufactured parts from CAD models, leading to potential collisions and inefficiencies in paint application, which can result in suboptimal quality and increased energy consumption.

Innovation Solution

A method involving the creation of a realistic 3D model of the part by detecting real characteristic points, applying deformations to match nominal model coordinates, and generating adapted paint trajectories to ensure precise positioning and avoid collisions, utilizing image analysis and artificial intelligence for accurate detection and trajectory generation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the robot uses a nominal 3D model for painting, then the painting process is simple and efficient, but the robot may collide with the part due to dimensional deviations

Engineering Contradiction:
Improvecollision preventionVSAvoidmodeling complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system performs a preliminary measurement step before painting to capture the real geometry of the part. A realistic 3D model is constructed from measured points, and the robot trajectory is adapted to this realistic model, preventing collisions before they occur during the actual painting operation.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

Instead of using the nominal CAD model directly, the system creates a copy of the part's actual geometry through measurement points and constructs a realistic 3D model that replicates the true dimensions and position of the part, allowing the robot to navigate safely around actual features.

Inventive Principle:
Principle #26Copying

2Manufacturing precision

If the robot measures the part before painting, then the trajectory adapts to real geometry, but the measurement process consumes time and energy

Engineering Contradiction:
Improvetrajectory accuracyVSAvoidenergy consumption
Core Design Contradiction:
Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The system measures only the essential characteristic points of the part rather than scanning the entire surface. This partial measurement approach provides sufficient information to construct a realistic 3D model and adapt the trajectory, reducing the time and energy required while maintaining the necessary precision for collision-free painting.

Inventive Principle:
Principle #16Partial or excessive action

3Manufacturing precision

If the robot moves close to the part for precise painting, then paint application quality improves, but the risk of collision increases

Engineering Contradiction:
Improvepaint application precisionVSAvoidcollision risk
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The system uses feedback from the measurement step to update the realistic 3D model, which then guides the robot trajectory. This closed-loop approach ensures the robot maintains the optimal close distance for precise painting while continuously adapting to the actual part geometry, preventing collisions through real-time trajectory adjustment.

Inventive Principle:
Principle #23Feedback

4Adaptability or versatility

If the system uses a realistic 3D model with stress simulations, then the model adapts to real part deformations, but the processing complexity increases

Engineering Contradiction:
Improvemodel adaptabilityVSAvoidprocessing complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The system applies stress simulations to the nominal 3D model to generate a realistic model that accounts for actual part deformations. By changing the geometric parameters of the model based on measured characteristic points and simulated stresses, the system adapts to real part variations while maintaining a manageable processing complexity through automated calculations.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4159386A1Method for painting a workpiece including generating a trajectory adapted to the real workpiece
Publication Date: 2023.04.05 EXEL INDUSTRIES
  • EP4159386A1 patent drawingFigure 1~4
  • EP4159386A1 patent drawingFigure 5~6
  • EP4159386A1 patent drawingFigure 7

AI summary

The invention relates to a method (1) of painting a part (2) by means of a painting robot (3) comprising a robotic arm (4) equipped with a paint projection device (5), the method (1) comprising, a step S1 of modeling a realistic 3D model (3Dr) corresponding to the part (2) as deformed and positioned in a paint cell, the realistic 3D model (3Dr) comprising paint trajectory information adapted to the part as deformed and positioned in the paint cell, and a paint projection step S2 during which the paint projection device (5) is moved along the paint trajectory in relation to the part (2).