Robot Stack Transfer Using Force-Sensed Height Detection

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Solution Overview

Problem

In the graphic industry, especially in the handling of stacks of flat products, collisions and errors can occur when the exact positions of the conveying route and the palette are not known, leading to inefficient and potentially damaging stack transfer processes.

Innovation Solution

A procedure using a robotic arm with a gripping device and a power sensor to measure contact forces, allowing for precise determination of the height positions of the conveying route and the palette, thereby enabling collision-free and error-free transfer of stacks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the conveyor line height is adjusted to connect with folding machines of different heights, then adaptability is improved, but measurement precision of the conveyor line and pallet positions deteriorates

Engineering Contradiction:

ImproveadaptabilityVSAvoidmeasurement precision

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The robot performs preliminary measurement actions by moving the gripping device to predetermined positions and using the force sensor to detect contact forces before actual stack transfer. This preliminary measurement establishes the current height positions of the conveyor line and pallet, storing this data for collision-free transfer operations despite height adjustments

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The force sensor provides real-time feedback on contact forces when the gripping device touches the conveyor line or pallet. This feedback mechanism enables the robot to dynamically adjust its movements based on measured positions, maintaining measurement precision even when the conveyor line height is adjusted for different folding machines

Inventive Principle:

Principle #23Feedback

2Device complexity

If the exact positions of conveyor line and pallet are not known, then device complexity is reduced, but reliability of stack transfer deteriorates due to collisions and errors

Engineering Contradiction:

Improvedevice complexityVSAvoidreliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The robot system performs self-measurement of the conveyor line and pallet positions using its own force sensor, eliminating the need for external measurement devices. The robot autonomously determines height positions by detecting contact forces, ensuring reliable stack transfer without adding external complexity

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The force sensor replaces traditional mechanical measurement systems or external sensors. By using contact force detection instead of complex mechanical position measurement systems, the patent achieves reliable position determination with simpler device architecture

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If a force sensor is used to measure contact force and determine height positions, then measurement precision is improved, but device complexity increases due to additional sensing requirements

Engineering Contradiction:

Improvemeasurement precisionVSAvoiddevice complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The force sensor serves multiple functions: it detects contact forces, determines height positions of the conveyor line and pallet, and enables collision detection during stack transfer. This multi-functionality improves measurement precision without proportionally increasing device complexity, as one sensor accomplishes multiple measurement tasks

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 solution allows for the accurate and reliable transfer of stacks without collisions or errors, enhancing operational efficiency and reducing the risk of damage to equipment and products.

Implementation Method 1

the robot arm comprises at least one force sensor and that a set height position of the conveyor line and/or an assumed height position of the pallet is measured using the force sensor to determine a contact force with the conveyor line or with the pallet

Methodology Applied

Scientific EffectForce sensor detection: Force

Data Source

PatentEP4553020A1Method for transferring stacks of flat products from a conveying line with adjustable height to a pallet

Publication Date: 2025.05.14 HEIDELBERGER DRUCKMASCHINEN AG

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AI summary

A method according to the invention for transferring stacks of planar products from a height-adjustable conveyor to a pallet, using a robot arm (11), wherein the robot arm (11) comprises a gripping device (20) and the robot arm (11) lifts the stacks (6) with the gripping device (20) from the conveyor (2) at a picking position (30) and places them on the pallet (32) at a dropping position (31), is characterized in that the robot arm (11) comprises at least one force sensor (15) and that a set height position (43) of the conveyor (2) and/or an assumed height position (44) of the pallet (32) is measured using the force sensor (15) to determine a contact force to the conveyor (2) or to the pallet (32) and/or that a set or assumed height or horizontal position of a stop (49) is measured using the force sensor (15) to determine a contact force to the stop (49).The invention advantageously enables the collision-free and error-free placement of stacks of flat products. The invention is used, for example, in conjunction with folding machines or their delivery systems.