Parallel Kinematic Structure Reducing Inertia

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Solution Overview

Problem

Existing parallel kinematic structures face challenges in achieving a balance between motion range and stiffness, often resulting in high inertia and low mechanical eigen-frequencies due to the arrangement of actuators within the structure, while also being costly and difficult to fabricate.

Innovation Solution

A parallel kinematic structure comprising at least two kinematic chains with a planar joint arrangement and a passive anti-planar joint arrangement, where the anti-planar joint has translational and rotational degrees of freedom, and the planar joint has translational and rotational degrees of freedom, allowing for enhanced fabrication, cost-effectiveness, and operability by distributing the load and reducing inertia.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If actuators are arranged within and carried by the structure in non-parallel kinematic structures, then large motion ranges are achieved, but high inertia and low stiffness result

Engineering Contradiction:

Improvemotion rangeVSAvoidinertia

Core Design Contradiction:

Adaptability or versatilityVSWeight of moving object

Solution Approach 1:

The patent extracts the actuators from the moving structure and relocates them to the fixed base. This extraction eliminates the inertia of actuators from the moving mass while maintaining their actuation function through the parallel kinematic chain, directly resolving the contradiction between motion range and inertia.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent inverts the conventional arrangement by placing actuators on the fixed side rather than the moving side. This inversion allows the actuators to drive the system through the parallel chains without being carried by the moving mass, thereby reducing inertia while preserving adaptability.

Inventive Principle:

Principle #13The other way round (Inversion)

2Adaptability or versatility

If actuators are arranged within the structure, then large motion ranges are achieved, but low stiffness results due to single kinematic chain transmission

Engineering Contradiction:

Improvemotion rangeVSAvoidstiffness

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The patent merges multiple kinematic chains in parallel to transmit forces and torques from the actuators to the end effector. This parallel arrangement combines the load-bearing capacity of multiple chains, significantly increasing stiffness while maintaining the motion range capability through coordinated actuation.

Inventive Principle:

Principle #5Merging (Combining)

3Weight of moving object

If parallel kinematic structures are used to reduce inertia and increase stiffness, then motion ranges are reduced compared to non-parallel structures

Engineering Contradiction:

ImproveinertiaVSAvoidmotion range

Core Design Contradiction:

Weight of moving objectVSAdaptability or versatility

Solution Approach 1:

The patent employs passive anti-planar joint arrangements that dynamically adapt their constraints based on the configuration of the parallel chains. This dynamic constraint mechanism allows the structure to maintain large motion ranges while the parallel architecture reduces inertia, resolving the contradiction between these two parameters.

Inventive Principle:

Principle #15Dynamics

4Reliability

If complex parallel kinematic structures are designed to achieve desired performance, then fabrication difficulty and cost increase

Engineering Contradiction:

ImproveperformanceVSAvoidfabrication difficulty

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent segments the kinematic structure into modular units including planar joint arrangements, passive anti-planar joint arrangements, and end effector sections. Each module can be independently manufactured and assembled, significantly reducing fabrication difficulty and cost while maintaining the desired performance through the coordinated operation of segmented components.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS8984982B2Parallel kinematic structure

Publication Date: 2015.03.24 FORCE DIMENSION SARL

AI summary

A parallel kinematic structure comprises at least two kinematic chains being functionally arranged in parallel. Each of the two kinematic chains has, at a moveable end thereof, at least one degree of freedom, and comprising a passive anti-planar joint arrangement having a translational degree of freedom and two rotational degrees of freedom. Each anti-planar joint arrangement has an input section and an output section. At least one of the kinematic chains comprises a planar joint arrangement having at least one of at least one translational degree of freedom and a rotational degree of freedom, the planar joint arrangement having an output section. Further, the planar joint arrangement is adapted for active movements in at least one of its degrees of freedom. The input section of the anti-planar joint arrangement and the output section of the respective planar joint arrangement are coupled. The parallel kinematic structure further comprises a moveable end-effector section coupled with the output sections of the anti-planar joint arrangements.