Multi-Shaft Telescopic Shaft for Parallel Robot Workspace Expansion

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Solution Overview

Problem

Telescopic shafts in parallel kinematics robots limit the working area due to their fixed maximum and minimum lengths, restricting the distance the end effector can move from the base, with conventional designs typically having an extension factor of two or less.

Innovation Solution

The design incorporates multiple shafts with axial movement and constraining mechanisms such as pulley-line, chain-sprocket, or spring arrangements to predetermine relative movements, optimizing the extension factor and minimizing inertial loading and maximum relative velocity, while also incorporating balancing mechanisms to counteract gravity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If conventional telescopic shafts with no more than two shafts are used, then the structure is simple, but the extension factor is limited to about two

Engineering Contradiction:
Improveextension factorVSAvoidnumber of shafts
Core Design Contradiction:
Length of moving objectVSDevice complexity

Solution Approach 1:

The telescopic shaft is divided into multiple shafts (first shaft, second shaft, third shaft) that can move relative to each other in axial direction. This segmentation allows the overall extension factor to exceed two by having each shaft segment contribute to the total extension, resolving the contradiction between simple structure and high extension factor.

Inventive Principle:
Principle #1Segmentation

2Length of moving object

If multiple shafts with independent relative movements are used to increase extension factor, then the extension factor increases, but the maximum relative velocity between shafts increases

Engineering Contradiction:
Improveextension factorVSAvoidmaximum relative velocity
Core Design Contradiction:
Length of moving objectVSSpeed

Solution Approach 1:

The constraining means merges the movement control of multiple shafts by predetermining the relationship between their relative movements. This coordination ensures that shafts move in a synchronized manner, minimizing the maximum relative velocity between any pair of shafts while maintaining the high extension factor achieved through multiple shafts.

Inventive Principle:
Principle #5Merging (Combining)

3Length of moving object

If multiple shafts with independent relative movements are used to increase extension factor, then the extension factor increases, but the inertial loading increases

Engineering Contradiction:
Improveextension factorVSAvoidinertial loading
Core Design Contradiction:
Length of moving objectVSForce

Solution Approach 1:

The constraining means combines the inertial effects of multiple shafts by coordinating their movements. By predetermining the sequence and relationship of relative movements, the system minimizes the peak inertial loading that would otherwise result from independent, uncoordinated shaft movements, while still achieving the desired high extension factor.

Inventive Principle:
Principle #5Merging (Combining)

4Length of moving object

If shafts move simultaneously with different velocities, then the extension factor is maximized, but the maximum relative velocity between shafts increases

Engineering Contradiction:
Improveextension factorVSAvoidmaximum relative velocity
Core Design Contradiction:
Length of moving objectVSSpeed

Solution Approach 1:

The system employs dynamic movement coordination where the velocities of different shafts are adjusted in real-time based on their positions and the desired extension factor. The constraining means ensures that shafts move at optimized velocities that maximize extension while keeping relative velocities between shafts minimized, rather than moving all shafts at constant or independently maximized speeds.

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 approach increases the working area of parallel kinematics robots by enhancing the extension factor beyond two, reducing inertial loading, and balancing the effect of gravity, thereby expanding the operational range of the end effector.

Implementation Method 1

constraining means configured to predetermine the first relative movement in relation to the second relative movement

Methodology Applied
Scientific EffectMechanical constraint:

Implementation Method 2

balancing means configured to balance the effect of gravity

Methodology Applied
Scientific EffectGravity: Gravitation

Implementation Method 3

a line and a pulley pair

Methodology Applied
Scientific EffectPulley mechanism: Pulley

Implementation Method 4

a chain and a sprocket pair

Methodology Applied
Scientific EffectChain drive: Chain

Implementation Method 5

a rack and a pinion pair

Methodology Applied
Scientific EffectRack and pinion mechanism: Rack and Pinion

Implementation Method 6

an extension spring

Methodology Applied
Scientific EffectElastic potential energy: Elasticity

Implementation Method 7

a compression spring

Methodology Applied
Scientific EffectElastic potential energy: Spring

Implementation Method 8

gas spring

Methodology Applied
Scientific EffectGas pressure:

Data Source

PatentEP3580019B1A telescopic shaft for a parallel kinematics robot
Publication Date: 2023.05.10 ABB (SCHWEIZ) AG
  • EP3580019B1 patent drawingFigure 1a~1d
  • EP3580019B1 patent drawingFigure 2~4

AI summary

A telescopic shaft (10) comprises a first shaft (20), a second shaft (30) configured to enable a first relative movement in an axial direction (50) between the first and second shafts (20, 30), and a third shaft (40) configured to enable a second relative movement in the axial direction (50) between the second and third shafts(30, 40), and a third relative movement in the axial direction (50) between the first and third shafts (20, 40). The second shaft (30) is located between the first and third shafts (20, 40). The telescopic shaft (10) is configured to connect a base (210) of a parallel kinematics robot (200) to an end effector (220) of the same for the purpose of transferring torque. By providing the telescopic shaft (10) with more than two shafts (20, 30, 40) with mutual relative movements between the same, an extension factor (the relation between the maximum and minimum lengths of the telescopic shaft) and by that the working area of the parallel kinematics robot (200) can be increased.