Electro-adhesion Gripper Fractal Electrodes Isotropic Holding Force

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Solution Overview

Problem

Traditional electro-adhesion grippers exhibit anisotropy in holding force, making it unreliable for workpieces with varying orientations and sizes, as the force is stronger perpendicular to the comb-like electrode structure than parallel, leading to insecure grip under unfavorable conditions.

Innovation Solution

The electro-adhesion gripper employs a fractal pattern for its electrodes, which are designed based on two-dimensional fractal space-filling curves, allowing for direction-independent holding forces and efficient use of electric field strengths, enabling secure grip of workpieces regardless of size or orientation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If traditional comb-like electrodes are used, then the structure is simple and easy to manufacture, but the holding force exhibits anisotropy and is direction-dependent

Engineering Contradiction:
Improveease of manufactureVSAvoidholding force reliability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent transitions from traditional one-dimensional comb-like electrode structures to two-dimensional fractal space-filling curve patterns. This dimensional change allows the electrodes to fill the adhesion surface more uniformly in all directions, eliminating the preferred directionality of holding force while maintaining manufacturing simplicity through pattern replication.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The fractal space-filling curve pattern introduces asymmetric, space-filling geometries that uniformly distribute electric fields in all directions. Unlike symmetric comb structures that create directional bias, the fractal pattern's self-similar asymmetric structure ensures isotropic holding force characteristics across the adhesion surface.

Inventive Principle:
Principle #4Asymmetry

2Reliability

If fractal pattern electrodes are used, then direction-independent holding force is achieved, but the electrode structure becomes more complex

Engineering Contradiction:
Improveholding force consistencyVSAvoidelectrode structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The fractal electrode pattern is constructed by segmenting the adhesion surface into self-similar geometric units that repeat at different scales. This segmentation approach allows complex space-filling coverage to be achieved through simple repetitive patterns, reducing actual manufacturing complexity despite the sophisticated geometric outcome.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The fractal space-filling curve pattern employs nested, self-similar structures where the same geometric motif repeats at multiple scales within the electrode design. This nesting principle allows the complex overall pattern to be generated from simple repeating units, making the structure manageable and manufacturable despite its space-filling complexity.

Inventive Principle:
Principle #7Nested doll (Nesting)

3Force

If narrow insulation widths are used between electrodes, then higher electric field strengths and greater holding forces are achieved, but insulation breakdown risk increases

Engineering Contradiction:
Improveholding forceVSAvoidinsulation breakdown risk
Core Design Contradiction:
ForceVSObject-affected harmful factors

Solution Approach 1:

The fractal electrode geometry dynamically adapts the electric field distribution across the adhesion surface, creating regions of varying field strength that follow the space-filling pattern. This dynamic field distribution allows narrow insulation widths to be utilized effectively in low-stress regions while maintaining overall system reliability through the self-similar structure's inherent load distribution.

Inventive Principle:
Principle #15Dynamics

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 design provides a consistent and high holding force in all directions, suitable for various workpiece geometries and orientations, with minimal insulation requirements, enhancing the gripper's versatility and effectiveness.

Implementation Method 1

When the electric field is switched on, a workpiece in contact with the adhesion surface adheres to it due to electrostatic attraction to opposing charges induced in the workpiece

Methodology Applied
Scientific EffectElectrostatic attraction: Electrostatics

Data Source

PatentEP3443659B1Electro-adhesion gripper comprising fractal electrodes
Publication Date: 2020.05.13 TRUMPF GMBH & CO
  • EP3443659B1 patent drawingFigure 1
  • EP3443659B1 patent drawingFigure 2
  • EP3443659B1 patent drawingFigure 3

AI summary

An electro-adhesion gripper (60a; 60b) for holding workpieces (53; 54; 64), comprising a first electrode (41; 51) and a second electrode (42; 52), which are embodied in an intermeshing fashion in a plan view of the electrodes (41, 42; 51, 52), wherein at least in a partial region in the plan view of the electrodes (41, 42; 51, 52) the first electrode (41; 51) and the second electrode (42; 52) are embodied in accordance with the edge lines of a two-dimensional fractal space-filling curve of second or higher order. The invention provides an electro-adhesion gripper which can be used to make available reliably a direction-independent, high holding force on a workpiece parallel to the adhesion surface.