Torso-Mounted Shoulder Exoskeleton With Orthogonal Joint Triad

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Solution Overview

Problem

Existing robotic arm exoskeletons for shoulder rehabilitation lack portability, anthropomorphic range of motion, and powered kinematic sequences necessary for anatomically correct shoulder movement, particularly in torso-mounted designs that provide torso-to-shoulder articulation and singularity-free shoulder workspace.

Innovation Solution

A torso-mounted exoskeleton with a scapula elevation assembly, shoulder rotation assembly providing three-axis rotation about the glenohumeral joint, elbow pitch assembly, and wrist roll assembly, combined with adjustable linear links to match anatomical limb lengths, and co-located high-power actuator modules for force transmission at multiple points.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a torso-mounted design is used to provide portability and torso-to-shoulder articulation, then mobility and energy transfer capability are improved, but device complexity increases

Engineering Contradiction:

ImproveportabilityVSAvoiddevice complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The exoskeleton is divided into modular functional assemblies (scapula elevation assembly with first rotary joint, shoulder rotation assembly with second and third rotary joints, elbow pitch assembly with fourth rotary joint, wrist roll assembly with fifth rotary joint) that can be independently designed, adjusted, and maintained. Each assembly handles specific degrees of freedom, reducing overall system complexity while maintaining portability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The exoskeleton employs adjustable linear links (thoracic linkage, scapula linkage, upper arm linkage, forearm linkage) that can be dynamically reconfigured to match different anatomical limb lengths. This dynamic adaptability allows the device to maintain portability across different users while managing the complexity through standardized adjustment mechanisms.

Inventive Principle:

Principle #15Dynamics

2Device complexity

If single-axis revolute joints are used to simplify the structure, then device complexity is reduced, but anthropomorphic range of motion is limited due to linkage interference

Engineering Contradiction:

Improvedevice complexityVSAvoidanthropomorphic range of motion

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The exoskeleton transitions from single-axis revolute joints to a multi-axis rotational system with orthogonal-axis triad at the shoulder (second, third, and fourth rotary joints with mutually orthogonal axes). This dimensional expansion enables full three-dimensional shoulder rotation matching human anatomy without linkage interference, as the orthogonal arrangement eliminates mechanical conflicts present in single-axis designs.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The exoskeleton introduces torso-to-shoulder articulation as an intermediary mechanism between the torso and the arm. This intermediate articulation system (scapula elevation assembly) properly transmits forces and motions from the torso to the shoulder joint, enabling anatomically correct movement sequences without requiring overly complex direct torso-arm connections.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If the shoulder workspace is expanded to match human range of motion, then anthropomorphic capability is improved, but singularities may occur when joint axes align

Engineering Contradiction:

Improveshoulder workspaceVSAvoidsingularity-free operation

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The exoskeleton employs an asymmetric orthogonal-axis triad configuration at the shoulder where the second rotary joint axis is skewed medially (downward toward the torso) in the frontal plane rather than being symmetrically aligned. This asymmetric arrangement shifts the singularity location inward toward the body, making it unreachable by the human arm during normal rehabilitation exercises, thereby eliminating singularity issues within the operational workspace.

Inventive Principle:

Principle #4Asymmetry

4Manufacturing precision

If adjustable link lengths are implemented to match anatomical limb lengths, then anthropomorphic accuracy is improved, but device complexity increases

Engineering Contradiction:

Improveanatomical matching precisionVSAvoiddevice complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS7862524B2Portable arm exoskeleton for shoulder rehabilitation

Publication Date: 2011.01.04 CARIGNAN CRAIG R

AI summary

The present invention relates to an exoskeleton interface apparatus that parallels human arm motion and is comprised of a serial assemblage of five powered linkages and joints based at a rigid support structure worn on the torso of the human subject. Such apparatus generates shoulder rotation using three orthogonal revolute joints mounted on serial linkages encompassing and intersecting at the anatomical glenohumeral joint. Elevation of the shoulder joint is articulated using a link member driven by a single revolute joint mounted in the torso structure. Passive adjustable linkages are used to match variation in anatomical forearm length, upper arm length, and scapula-to-glenohumeral radius. A plurality of integrated dc motor/harmonic drive transmission modules is co-located on adjoining linkages to power the joints. Force is exchanged with the human at the handgrip and elbow brace, and reacted to the torso structure via the base attachment. The present invention is applicable in particular to rehabilitation of the shoulder.