Gripping Position Teaching by Workpiece Contour Intersection

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Solution Overview

Problem

Automated machine tool loading systems face challenges in efficiently learning and handling new, customer-specific workpieces, particularly due to the complexity and time required in defining gripping positions, which leads to increased setup times and downtime.

Innovation Solution

A method and device that utilize a plate-shaped device with a projection of a gripper's movement, allowing for the detection of workpiece geometry and intersection points without prior knowledge of the workpiece or gripper geometry, thereby determining a gripping position and establishing a workpiece coordinate system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If teaching is done by directly approaching various gripping positions with the robot, then the gripping positions can be accurately defined, but the setup time increases significantly due to multiple instructional steps

Engineering Contradiction:
Improvegripping position definition accuracyVSAvoidsetup time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies preliminary action by pre-defining gripping positions on a 2D plate before the actual workpiece is processed. The plate contains pre-marked positions that correspond to valid gripping locations, allowing the system to quickly reference these predetermined positions rather than performing time-consuming trial-and-error teaching with the robot. This preparatory setup enables rapid workpiece registration by simply matching the workpiece contour against the pre-defined plate positions.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent uses copying by creating a 2D representation (plate) that replicates the essential gripping information without requiring the full 3D robot teaching process. The plate serves as a simplified copy or model that contains all necessary gripping position data in an easily accessible format, eliminating the need to repeatedly perform complex robot instructional steps for each new workpiece.

Inventive Principle:
Principle #26Copying

2Reliability

If complex teaching steps are performed to define gripping positions, then accurate gripping can be achieved, but the machine tool downtime increases

Engineering Contradiction:
Improvegripping accuracyVSAvoidmachine tool efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent applies segmentation by separating the gripping position definition into two independent components: the 2D plate containing pre-defined positions and the workpiece contour. This segmentation allows the system to quickly match the workpiece against the plate without requiring complex integrated teaching steps, thereby maintaining gripping accuracy while reducing the time the machine tool is non-productive.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The 2D plate acts as an intermediary between the workpiece and the robot gripping system. Instead of directly teaching the robot for each workpiece, the plate serves as a mediator that contains pre-processing information, enabling rapid registration and reducing machine tool downtime while ensuring reliable gripping through the pre-defined position mappings.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Extent of automation

If CAD models and robot models are used to define gripping positions, then theoretical gripping points can be determined automatically, but the system requires prior knowledge of workpiece and gripper geometry

Engineering Contradiction:
Improveautomatic gripping position determinationVSAvoidprior geometry knowledge requirement
Core Design Contradiction:
Extent of automationVSDevice complexity

Solution Approach 1:

The patent uses a simple, inexpensive 2D plate as a disposable or single-use teaching aid for each workpiece type. Rather than requiring complex CAD and robot model integration, the system uses a straightforward plate with marked positions that can be quickly created and used, eliminating the need for sophisticated geometric modeling while maintaining automatic determination capability.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent extracts only the essential gripping position information from the complex CAD and robot model integration process, isolating it into a simple 2D plate representation. This extraction removes the complexity of requiring complete geometric models while retaining the core functionality of automatically determining gripping positions through contour matching against the simplified plate structure.

Inventive Principle:
Principle #2Taking out (Extraction)

Data Source

PatentEP3702108B1Method and apparatus for determining a gripping position for gripping a workpiece
Publication Date: 2025.06.11 DMG MORI BIELEFELD GMBH
  • EP3702108B1 patent drawingFigure 1
  • EP3702108B1 patent drawingFigure 2
  • EP3702108B1 patent drawingFigure 3

AI summary

The present invention relates to a method for determining a gripping position for grasping a workpiece 200, comprising: providing a signaling device 100 with a projection 110 of at least one gripping movement of a gripper 300, positioning the workpiece 200 in relation to the signaling device 100 such that an outer contour of the workpiece 200 intersects the projection 110 of at least one gripping movement, detecting points of intersection of the outer contour of the workpiece 200 with the projection 110 of at least one gripping movement, and determining the gripping position for grasping the workpiece 200 from the detected points of intersection.