Compliant Robotic End-of-Arm Tool for Bin Picking

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Solution Overview

Problem

Industrial robot manipulators face challenges in automating the bin picking process due to the variability in part locations and orientations, leading to errors such as part damage, obstruction, entanglement, and collision, which existing technologies have not adequately addressed.

Innovation Solution

A robot system equipped with a compliant end-of-arm tool that includes a moveable arm, a computing device, and force-sensing capabilities to monitor and adjust the force exerted during part removal, allowing for intelligent responses to errors and improved grasping and extraction of parts from a bin.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a rigid end-of-arm tool is used for bin picking, then the robot can maintain precise positioning and control, but parts are damaged and grasp failures occur due to lack of compliance with variable part orientations

Engineering Contradiction:
Improvepositioning precisionVSAvoidgrasp success rate
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The end-of-arm tool incorporates compliance mechanisms that dynamically adjust stiffness parameters along different axes. The tool can be stiffer in directions requiring precision and more compliant in directions needing adaptation to part orientations, resolving the contradiction between positioning precision and grasp reliability

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The rigid end-of-arm tool is replaced with a dynamically adaptable compliant tool that can change its mechanical properties during operation. This allows the tool to transition between rigid and compliant states as needed, maintaining positioning precision while improving grasp success rate through adaptive compliance

Inventive Principle:
Principle #15Dynamics

2Device complexity

If the robot attempts to pick parts with fixed force, then the control system is simple, but parts become damaged or the grasp fails when parts are obstructed or entangled

Engineering Contradiction:
Improvecontrol system complexityVSAvoidpart extraction success
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

Force sensors are integrated into the end-of-arm tool to provide real-time feedback on contact forces during grasping and extraction. The control system uses this feedback to dynamically adjust applied force, preventing part damage while successfully extracting obstructed or entangled parts, resolving the contradiction between control simplicity and extraction reliability

Inventive Principle:
Principle #23Feedback

3Extent of automation

If vision systems are used to identify part locations and orientations, then automated bin picking can be implemented, but errors occur when parts are obstructed, entangled, or interlocked in ways not detected by vision software

Engineering Contradiction:
Improvebin picking automationVSAvoiderror detection accuracy
Core Design Contradiction:
Extent of automationVSReliability

Solution Approach 1:

The vision system is combined with force sensing capabilities in the end-of-arm tool. While vision provides initial part location and orientation information, force sensors detect actual contact conditions during grasping and extraction, including obstructed or entangled parts that vision cannot detect, resolving the contradiction between automation extent and error detection accuracy

Inventive Principle:
Principle #5Merging (Combining)

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 system enhances the reliability and flexibility of bin picking by reducing part damage and improving the success rate of part extraction through intelligent force monitoring and adjustment, enabling the robot to adapt to various error conditions and orientations.

Implementation Method 1

A robot system equipped with a compliant end-of-arm tool that includes a moveable arm, a computing device, and force-sensing capabilities to monitor and adjust the force exerted during part removal

Methodology Applied
Scientific EffectForce feedback: Feedback

Data Source

PatentEP2331301B1Robotic picking of parts from a bin using force feedback
Publication Date: 2018.10.17 ABB RES LTD
  • EP2331301B1 patent drawingFigure 1
  • EP2331301B1 patent drawingFigure 2
  • EP2331301B1 patent drawingFigure 3

AI summary

A robot is used to pick parts from a bin. The robot has a compliant apparatus and one or more tools are connected to the apparatus to perform the picking. The compliant apparatus has mechanisms for monitoring and/or controlling its compliance. The compliant apparatus can have various embodiments. Force sensing can be used during removal of grasped parts from the bin to determine the force exerted on the picking tool(s). The signal indicative of the exerted force can be used by the robot controller to determine the weight of the parts that may be held by the picking tool(s). The robot has one or more devices which can be the picking tool to stir the parts in the bin.