Concentric Joint Mechanism for Multi-DOF Robot Arm Control

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Solution Overview

Problem

Traditional robot arms with multiple degrees of freedom face issues such as extra torques, space occupancy, and mutual interference due to multiple motors, and electromagnetic induction methods struggle with magnetism control and mechanical calculations, making smooth control difficult.

Innovation Solution

A concentric joint mechanism comprising a flexible spherical body, first and second friction wheels, and a fixing device, where the friction wheels drive the spherical body to rotate in multiple directions, increasing driving force and reducing friction, allowing precise control of the robot arm's motion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple motors are used in a tandem manner to achieve multiple degrees of freedom, then the robot arm can simulate motion of human limbs, but extra torques appear and mutual interference occurs between motors

Engineering Contradiction:

Improvemultiple degrees of freedomVSAvoidmutual interference between motors

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent combines multiple motor functions into a single motor by using a flexible spherical body that can rotate around multiple concentric axes. The single motor drives the flexible spherical body through friction wheels, and the flexibility of the spherical body allows it to achieve multiple degrees of freedom without requiring multiple separate motors, thereby eliminating mutual interference between motors.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent uses a flexible spherical body made of elastic material that can dynamically adapt its shape and orientation. This flexibility allows the spherical body to rotate around multiple concentric axes and achieve complex motion patterns that would otherwise require multiple rigid motors, reducing device complexity while maintaining adaptability.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If multiple motors are disposed in a tandem manner, then multiple degrees of freedom are achieved, but more space is occupied

Engineering Contradiction:

Improvemultiple degrees of freedomVSAvoidspace occupied by motors

Core Design Contradiction:

Adaptability or versatilityVSVolume of moving object

Solution Approach 1:

The patent merges multiple motor units into a single motor system. By using one motor to drive a flexible spherical body that can rotate around multiple concentric axes, the patent achieves multiple degrees of freedom without the space requirements of multiple separate motors, significantly reducing the volume occupied by the actuation system.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent implements a nested structure where the flexible spherical body contains multiple friction wheels that rotate around different concentric axes. This nested arrangement allows multiple rotational degrees of freedom to be achieved within a compact volume, as each friction wheel is positioned inside the spherical body rather than requiring separate external motor mounts.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Ease of operation

If electromagnetic induction controlling method is used to achieve multiple degrees of freedom, then magnetism control allows motion control, but difficulty in magnetism control and excessive space occupied make it incapable of practical operation

Engineering Contradiction:

Improvemotion controlVSAvoiddifficulty in magnetism control

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent replaces the electromagnetic induction system with a purely mechanical friction-based drive system. Instead of using electromagnetic fields to control motion, the patent uses a single motor connected to friction wheels that contact the flexible spherical body. This substitution eliminates the complexity of magnetism control while maintaining the ability to achieve multiple degrees of freedom through mechanical means.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 mechanism enables smooth and precise control of the robot arm's motion with multiple degrees of freedom, reducing interference and complexity compared to traditional motor-based systems and electromagnetic induction methods.

Implementation Method 1

a first friction wheel disposed inside the frame and abutting against the flexible spherical body for driving the flexible spherical body to rotate

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS7857727B2Concentric joint mechanism capable of rotating with multiple degrees of freedom

Publication Date: 2010.12.28 MICRO STAR INTERNATIONAL CO LTD

AI summary

A concentric joint mechanism includes a frame, a flexible spherical body, a first friction wheel, a first power device, and a fixing device. The flexible spherical body is disposed inside the frame. The first friction wheel is disposed inside the frame and abuts against the flexible spherical body for driving the flexible spherical body to rotate in a first direction. The first power device is connected to the first friction wheel for providing power to the first friction wheel. The fixing device is connected to the frame and abuts against the flexible spherical body for fixing the flexible spherical body inside the frame together with the first friction wheel.