Exoskeleton Ankle Link with Oblique Pivot Axis
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Solution Overview
Problem
Existing exoskeletons face challenges in achieving stability and accurately replicating human walking motion while being compact and moderate in weight, with complex, bulky, and energy-intensive ankle structures.
Innovation Solution
The exoskeleton features a mechanical ankle link with a first pivot axis parallel to the knee link pivot axis and a second pivot axis forming an angle of 30° to 60° with the support plane, along with two parallel actuators and a compression spring assembly to enhance stability and biomechanical movement replication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a complex ankle structure with multiple actuators is used to enable terrain adaptation, then the foot structure can adapt to terrain, but the device becomes bulky, heavy and energy intensive
Solution Approach 1:
The patent extracts the terrain adaptation function from a complex multi-actuator system and implements it through a passive mechanical linkage system. The ankle pivot link with oblique axis and the foot pivot link work together to provide terrain adaptation without requiring additional active actuators, thus reducing device complexity while maintaining adaptability.
Solution Approach 2:
The ankle pivot link serves multiple functions: it provides the primary pivot connection between foot structure and lower leg structure, enables terrain adaptation through its oblique orientation, and works in conjunction with the foot pivot link to achieve both planar contact and oscillation phases. This multi-functionality reduces the need for separate dedicated components.
2Device complexity
If the ankle pivot link has an oblique pivot axis to reproduce natural human movements, then the structure is simplified and weight is reduced, but stability during walking motion may be compromised
Solution Approach 1:
The patent introduces a second degree of freedom through the foot pivot link, which rotates about a pivot axis substantially parallel to the knee pivot axis. This adds a dimensional aspect to the motion that complements the oblique ankle pivot, enabling both stability during standing phase and natural oscillation during walking phase.
Solution Approach 2:
The mechanical linkage system dynamically adapts its configuration during the walking cycle. During the standing phase, the linkage positions ensure planar contact and stability, while during the oscillation phase, it allows natural foot movement patterns. The system transitions between these states automatically based on the walking phase.
3Weight of moving object
If a compact ankle structure is used to reduce weight and bulk, then the lateral use of space is reduced, but it may be difficult to achieve both stability and accurate reproduction of human walking motion
Solution Approach 1:
The patent optimizes specific geometric parameters of the mechanical linkage, including the oblique angle of the ankle pivot axis (between 0° and 30° with the support plane) and the orientation of the foot pivot axis. These parameter choices enable the compact structure to accurately reproduce human walking kinematics while maintaining stability.
Data Source
AI summary
The invention relates to an exoskeleton including: a foot structure; a lower leg structure; a mechanical knee link having a pivot axis; and a mechanical ankle link connecting the foot structure to the lower leg structure and including a first pivot connection having a first pivot axis that is substantially parallel to the pivot axis of the mechanical knee link, and a second pivot connection having a second pivot axis that is perpendicular to the first pivot axis and forms an angle of between 30° and 60° with the support plane when the exoskeleton is upright and at rest.