Gripper Compensation Unit for Precise Collision-Tolerant Handling

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Solution Overview

Problem

Existing automated workpiece handling devices face challenges in accurately positioning grippers due to the deformation of flexible compensation units under load, leading to unreliable operation and increased complexity in determining the gripper's position, especially when handling unordered workpieces.

Innovation Solution

A device with a rigid compensation unit that only allows evasive movement when a predetermined high load is exceeded, ensuring the gripper maintains a defined position during normal operation and uses sensors to detect collisions without monitoring deformation, allowing for precise control and reduced failure rates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a flexible compensation unit is used to allow evasive movement of the gripper upon collision, then the gripper can still grasp the workpiece after collision, but the exact position of the gripper becomes difficult to determine due to deformation

Engineering Contradiction:
Improvegripper operation reliabilityVSAvoidgripper position determination precision
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent changes the physical state of the compensation unit from flexible to rigid by applying a predetermined initial load (pre-tensioning). This parameter change allows the unit to remain rigid during normal operation for precise position determination, while still enabling evasive movement when collision forces exceed the initial load threshold.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent applies a preliminary counteracting force (initial load) to the compensation unit to prevent unwanted deformation during normal operation. This pre-tensioning counteracts the natural flexibility, ensuring the gripper maintains its defined position until a collision occurs that exceeds the predetermined load threshold.

Inventive Principle:
Principle #9Preliminary anti-action

2Adaptability or versatility

If a flexible element is used to compensate for position deviations, then the gripper can adapt to position errors, but the system becomes more complex and prone to malfunctions due to the need for precise deformation monitoring

Engineering Contradiction:
Improvegripper adaptability to position errorsVSAvoidsystem complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent transforms the compensation unit from a continuously flexible element requiring deformation monitoring into a rigid structure with a defined yield point. This parameter change eliminates the need for complex monitoring systems while maintaining adaptability - the unit remains rigid during normal operation and only yields when collision forces exceed the predetermined initial load.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces a complex, fragile flexible element with a simpler rigid structure that has a predetermined failure point. This simplified design is less prone to malfunction and easier to manufacture, while still providing the necessary collision compensation function.

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

3Measurement precision

If the compensation unit remains rigid below a high initial load, then the gripper maintains a defined position during normal operation, but the initial load must be set higher than the load from gripper and workpiece weight

Engineering Contradiction:
Improvegripper position definition precisionVSAvoidinitial load magnitude
Core Design Contradiction:
Measurement precisionVSForce

Solution Approach 1:

The patent applies a preliminary counteracting force (initial load) to the compensation unit to prevent unwanted deformation during normal operation. This pre-tensioning counteracts the natural flexibility, ensuring the gripper maintains its defined position until a collision occurs that exceeds the predetermined load threshold.

Inventive Principle:
Principle #9Preliminary anti-action

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 enables safe and precise movement of the gripper, reducing the likelihood of unnecessary aborts and improving the reliability of the gripping process, even when handling unordered workpieces, by maintaining a defined position and using sensors to manage collisions effectively.

Implementation Method 1

a compensation unit which enables an evasive movement of the gripper when a predetermined initial load on the gripping arm is exceeded

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP2679354B1Device and method for the automated handling of workpieces
Publication Date: 2022.06.22 LIEBHER VERZAHNTECHNIK GMBH
  • EP2679354B1 patent drawingFigure 1
  • EP2679354B1 patent drawingFigure 2
  • EP2679354B1 patent drawingFigure 3

AI summary

The apparatus has an object detecting unit that is provided for detecting the workpieces, and is arranged on a gripper arm grippers for gripping the workpieces. A controller is used for analyzing the data of the object detection unit for path planning and control of the gripper arm and gripper. An input unit (46) is rigid, when a predetermined first load of the gripper arm crossing allows an alternate movement of the gripper.The first loading is greater than the load applied to the gripper by the gripped workpiece. Independent claims are included for the following: (1) a method for automated handling of workpieces; and (2) a computer program for automated handling of workpieces.