Parallel Link Hub Layout for Wide-Range Precise End Effector Motion

Solution Overview

Problem

Existing parallel link mechanisms face challenges in achieving fast and precise operation with a wide range while supporting a heavy end effector, particularly when working on spherical or cylindrical surfaces, due to increased inertia and weight, which limits their ability to perform accurate and efficient tasks.

Innovation Solution

A link actuation device with a proximal and distal end side link hub and three or more link mechanisms, where the end effector is disposed to face inside the arrangement of the link hubs, reducing the moment of inertia and allowing for a two-degrees-of-freedom mechanism with a wide range of movement, enabling fast and accurate operation even with heavy end effectors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the end effector is mounted on the distal end side link hub in conventional parallel link mechanisms, then the operating range can be extended, but the moment of inertia increases due to the distance from the rotation axis, resulting in slower operation and reduced positioning accuracy

Engineering Contradiction:

Improveoperating rangeVSAvoidoperation speed

Core Design Contradiction:

Adaptability or versatilityVSSpeed

Solution Approach 1:

The patent inverts the conventional mounting arrangement by placing the end effector on the proximal end side link hub instead of the distal end side, and positions the workpiece on the distal end side link hub. This inversion reduces the moment of inertia of the end effector about the rotation axis, enabling faster operation and more accurate positioning while maintaining a wide operating range through the parallel link mechanism's geometry

Inventive Principle:

Principle #13The other way round (Inversion)

2Adaptability or versatility

If the end effector is mounted on the distal end side link hub, then the operating range can be extended, but the positioning accuracy decreases due to increased moment of inertia

Engineering Contradiction:

Improveoperating rangeVSAvoidpositioning accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent inverts the conventional mounting arrangement by placing the end effector on the proximal end side link hub instead of the distal end side, and positions the workpiece on the distal end side link hub. This inversion reduces the moment of inertia of the end effector about the rotation axis, enabling faster operation and more accurate positioning while maintaining a wide operating range through the parallel link mechanism's geometry

Inventive Principle:

Principle #13The other way round (Inversion)

3Adaptability or versatility

If the end effector is mounted on the distal end side link hub, then the operating range can be extended, but the energy consumption increases due to increased moment of inertia

Engineering Contradiction:

Improveoperating rangeVSAvoidenergy consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent inverts the conventional mounting arrangement by placing the end effector on the proximal end side link hub instead of the distal end side, and positions the workpiece on the distal end side link hub. This inversion reduces the moment of inertia of the end effector about the rotation axis, enabling faster operation and more accurate positioning while maintaining a wide operating range through the parallel link mechanism's geometry

Inventive Principle:

Principle #13The other way round (Inversion)

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 configuration allows for compact and efficient operation with reduced moment of inertia, enabling fast and precise positioning and movement of the end effector over a wide range, effectively addressing the limitations of existing mechanisms by minimizing interference and maintaining low energy consumption.

Implementation Method 1

three or more link mechanisms, each coupling the distal end side link hub to the proximal end side link hub such that a posture of the distal end side link hub is variable relative to the proximal end side link hub

Methodology Applied

Scientific EffectRotational movement: Hinge

Implementation Method 2

Two or more link mechanisms among the three or more link mechanisms are each provided with an actuator which arbitrarily changes the posture of the distal end side link hub relative to the proximal end side link hub

Methodology Applied

Scientific EffectMechanical force: Mechanical Force

Data Source

PatentEP3072644B1Link actuation device

Publication Date: 2022.11.02 NTN CORP

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AI summary

This link actuation device (51A) includes: a proximal end side link hub (2); a distal end side link hub (3); and three or more link mechanisms (4) which each couple the distal end side link hub (3) to the proximal end side link hub (2). Each link mechanism (4) includes: proximal side and distal side end link members (5, 6), and an intermediate link member (7). The link mechanism (4) is provided with an actuator (53) which arbitrarily changes the posture of the distal end side link hub (3) relative to the proximal end side link hub (2). A workpiece (62) is disposed on the proximal end side link hub (2), and an end effector (61) is disposed in the distal end side link hub (3) so as to face inside of arrangement of the link hubs (2, 3) and perform work onto the workpiece (62).