Bin Picking with an Intermediate Station for Precise Workpiece Removal

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing automated bin picking systems face challenges in process reliability, speed, and accuracy when removing workpieces from containers, particularly when workpieces are randomly arranged, as they require precise positioning and gripping, which is difficult with conventional grippers.

Innovation Solution

The introduction of an intermediate station where workpieces are deposited and then precisely positioned and separated using a second gripper, allowing for more flexible gripping options, such as magnetic or pneumatic grippers, which do not require exact alignment for initial removal from the container, and a controller for path planning and gripper control to optimize the process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a conventional gripper is used to directly remove workpieces from a container with randomly arranged workpieces, then the system structure is simple, but the positioning accuracy and gripping reliability are insufficient

Engineering Contradiction:
Improvepositioning accuracyVSAvoidsystem structure
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The system is divided into two functional segments: a first gripper for rough handling and removal of workpieces from the container, and a second gripper for precise positioning and gripping at the intermediate station. This segmentation allows each gripper to be optimized for its specific task, with the first gripper focusing on removal efficiency and the second gripper on positioning precision, thereby resolving the contradiction between positioning accuracy and system complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

An intermediate station is introduced as a mediator between the container and the final destination. The first gripper places workpieces at this intermediate station with relaxed positioning requirements, and the second gripper then picks them up for precise positioning. This intermediary structure decouples the positioning requirement from the removal operation, enabling high positioning accuracy without requiring the first gripper to achieve precise positioning during removal.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Manufacturing precision

If precise positioning is required during workpiece removal from the container, then the positioning accuracy is improved, but the process speed decreases due to the difficulty of gripping randomly arranged workpieces

Engineering Contradiction:
Improvepositioning accuracyVSAvoidprocess speed
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The gripping process is segmented into two stages: rapid removal by the first gripper without precise positioning requirements, and precise positioning by the second gripper at the intermediate station. This segmentation allows the system to achieve high process speed during the removal phase while maintaining high positioning accuracy during the positioning phase, eliminating the trade-off between speed and precision.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The first gripper performs preliminary action by removing workpieces from the container and placing them at the intermediate station without requiring precise positioning. This preliminary removal action prepares the workpieces for the subsequent precise positioning operation by the second gripper, allowing the system to prioritize speed in the first stage and precision in the second stage.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If the first gripper directly places workpieces at the final position, then the process steps are reduced, but the gripping reliability is insufficient due to the difficulty of achieving both removal and precise positioning in one step

Engineering Contradiction:
Improvegripping reliabilityVSAvoidnumber of process steps
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The gripping and positioning operation is segmented into two reliable steps: the first gripper reliably removes workpieces from the container with magnetic or pneumatic gripping, and the second gripper reliably positions them at the final location. Each gripper is optimized for its specific task, ensuring high gripping reliability for both removal and positioning operations, while the intermediate station provides a buffer that manages the increased process complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The intermediate station acts as a mediator that decouples the removal and positioning operations. The first gripper reliably places workpieces at the intermediate station without needing to achieve final positioning accuracy, and the second gripper then reliably transports them to the final position. This intermediary structure enhances gripping reliability by allowing each gripper to focus on its specific task without the complexity of combining both functions in one step.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Ease of operation

If magnetic or pneumatic grippers are used for initial removal, then the ease of operation is improved by allowing non-optimal gripping positions, but the positioning precision decreases

Engineering Contradiction:
Improvegripping flexibilityVSAvoidpositioning precision
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The system segments the gripping function: the first gripper (magnetic or pneumatic) provides ease of operation by allowing flexible gripping at non-optimal positions during removal, while the second gripper provides precise positioning at the intermediate station and final destination. This segmentation allows each gripper type to be used for its strengths, resolving the contradiction between gripping flexibility and positioning precision.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The intermediate station serves as a mediator that captures workpieces removed by the flexible but imprecise first gripper and transfers them to the precise second gripper. This intermediary structure allows the system to benefit from the ease of operation provided by magnetic or pneumatic grippers during removal while recovering positioning precision through the second gripper's accurate handling at the intermediate station and final destination.

Inventive Principle:
Principle #24Intermediary (Mediator)

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

This approach simplifies the emptying of containers, increases process efficiency, and ensures complete removal of workpieces, even when they are disordered, by allowing for non-optimal gripping positions and precise repositioning at the intermediate station, thereby enhancing reliability, speed, and accuracy.

Implementation Method 1

A magnetic and/or pneumatic gripper is particularly preferred as the first gripper for grasping the workpiece in the container

Methodology Applied
Scientific EffectMagnetic attraction: Magnetism

Implementation Method 2

A magnetic and/or pneumatic gripper is particularly preferred as the first gripper for grasping the workpiece in the container

Methodology Applied
Scientific EffectPneumatic pressure: Pressure Gradient

Data Source

PatentEP2679352B1Device for the automated removal of workpieces arranged in a container
Publication Date: 2021.12.22 LIEBHER VERZAHNTECHNIK GMBH
  • EP2679352B1 patent drawingFigure 1
  • EP2679352B1 patent drawingFigure 2
  • EP2679352B1 patent drawingFigure 3

AI summary

The device has detection unit (30) that is provided for detecting workpieces arranged in container. A gripper (34) is provided for gripping and removing the workpieces from container. A controller is provided for analyzing data of detection unit, and for path planning and controlling of gripper. An intermediate station (35) is provided for storing the pieces after removing from container. A positioning device (41) is provided for positioning and/or isolating the workpieces on/from intermediate station. An independent claim is included for a method for automated removal of work pieces arranged in container.