Multi-Link Spherical Joint Structure for Stable Independent Truss Motion

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Solution Overview

Problem

Conventional spherical joints used in trusses are unstable and uncontrollable, unable to handle loads from actuators and exhibit dependent linkage positions, necessitating an improved design for enhanced stability and control.

Innovation Solution

A hollow, partially spherical joint design featuring shell rail sections and rotatable members with outer and inner cups that move along arcuate paths, allowing for independent rotation and load distribution without ball bearings, coupled with actuators for enhanced control and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If conventional spherical joints with ball bearings are used, then the joint allows free rotation with low friction, but the truss becomes unstable and uncontrollable

Engineering Contradiction:

Improvefree rotation capabilityVSAvoidtruss stability

Core Design Contradiction:

Ease of operationVSStability of the object's composition

Solution Approach 1:

The spherical joint is divided into multiple independent rotatable members (first rotatable member, second rotatable member, etc.), each capable of independent rotation about axes passing through the shell center. This segmentation allows each member to rotate freely while maintaining overall truss stability through controlled independent motion

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The joint employs multiple rotatable members with axes intersecting at the shell center, allowing dynamic adjustment of linkage positions. Each rotatable member can independently change its orientation, enabling the truss to adapt its configuration while maintaining stability through controlled dynamic positioning rather than fixed constraints

Inventive Principle:

Principle #15Dynamics

2Device complexity

If conventional spherical joints are used, then the joint structure is simple, but the truss cannot handle actuator loads

Engineering Contradiction:

Improvejoint structure complexityVSAvoidactuator load capacity

Core Design Contradiction:

Device complexityVSStrength

Solution Approach 1:

The joint incorporates multiple rotatable members with rotation axes oriented in different dimensions, all intersecting at the shell center. This multi-dimensional arrangement distributes actuator loads across multiple members and axes, increasing load capacity while maintaining relatively simple individual member structures

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

Multiple rotatable members are combined within a single spherical shell, with their rotation axes converging at the shell center. This merging of multiple rotational elements into one integrated joint structure allows the system to handle actuator loads through combined structural support while presenting a unified joint interface

Inventive Principle:

Principle #5Merging (Combining)

3Device complexity

If conventional spherical joints are used, then the joint design is straightforward, but linkage positions become dependent on other linkages

Engineering Contradiction:

Improvejoint design simplicityVSAvoidlinkage position independence

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The joint is segmented into multiple independently rotatable members, each with its own rotation axis passing through the shell center. This segmentation enables each linkage to control its position independently through its dedicated rotatable member, eliminating positional dependence on other linkages while keeping the overall design straightforward

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Each rotatable member can dynamically adjust its orientation independently, allowing linkage positions to be controlled autonomously. The dynamic capability of each member to rotate about its own axis through the shell center provides positional independence while maintaining design simplicity through standardized rotational joints

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS11635107B1Multi-link spherical joint with collocated centers of rotation

Publication Date: 2023.04.25 UNITED STATES OF AMERICA AS REPRESENTED BY THE ADMINISTRATOR NAT AERONAUTICS & SPACE ADMINISTRATION

AI summary

A joint includes a shell that is hollow and at least partially spherical. The shell includes a plurality of shell rail sections including a first shell rail section. The first shell rail section includes a portion of an outer surface of the shell, a portion of an inner surface of the shell, and an opening edge section that defines a shell opening. The joint also includes a plurality of rotatable members including a first rotatable member. The first rotatable member includes an outer cup positioned at least partially outside of the shell and having an outer track surface, and an inner cup positioned at least partially inside of the shell and having an inner track surface. The first shell rail section is positioned at least partially between the outer and inner track surfaces.