Elliptical Trajectory Mechanism for Natural Walking Motion
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Solution Overview
Problem
Existing rotary rehabilitation devices for ankle mobilization and muscle strengthening do not effectively replicate the natural movement sequences of walking, as they typically use circular movements that are not medically suitable for rehabilitation.
Innovation Solution
A device with a rotary drive that adapts to simulate natural walking movements by allowing the articulation point to follow an elliptical or asymmetrical 'figure of eight' trajectory, utilizing a loose bearing and adjustable angles between components to mimic the natural gait pattern, promoting blood circulation and muscle regeneration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a simple circular motion is used in rotary rehabilitation devices, then the device structure is simple and easy to manufacture, but the movement pattern does not replicate natural walking motion and is not medically suitable for rehabilitation
Solution Approach 1:
The device transitions from a fixed circular motion to a dynamic elliptical motion by introducing a mechanism with adjustable parameters. The pedal follower mechanism allows the motion trajectory to be dynamically adjusted between circular and elliptical paths, enabling the device to adapt to different rehabilitation stages and patient needs while maintaining structural simplicity.
Solution Approach 2:
The invention changes the motion parameters from a fixed circular path to a variable elliptical path by adjusting the mechanism geometry. The elliptical motion is achieved by modifying the position of the pedal follower relative to the crank center, allowing control over the ellipticity parameter. This parameter change enables replication of natural walking motion while keeping the overall device structure simple.
2Reliability
If an elliptical or figure eight trajectory is implemented to replicate natural walking motion, then medical suitability for rehabilitation is improved, but the device structure becomes more complex
Solution Approach 1:
The pedal follower mechanism serves multiple functions: it generates the elliptical motion trajectory, it allows adjustment between different motion patterns (circular to elliptical), and it simplifies the overall structure by combining what would otherwise require separate complex mechanisms. This multi-functionality reduces device complexity while achieving the desired elliptical trajectory for natural walking motion replication.
Solution Approach 2:
The pedal follower acts as an intermediary element that converts the simple rotary motion of the crank into the complex elliptical trajectory required for natural walking motion. This intermediary mechanism is relatively simple in structure but effectively mediates between the simple rotary drive and the complex motion pattern needed for rehabilitation, avoiding the need for complex multi-linkage mechanisms.
3Ease of operation
If the device automatically carries the patient's leg through the movement sequence, then patient effort is reduced and blood circulation is promoted, but the device requires more complex control and power systems
Solution Approach 1:
The device is designed to automatically carry the patient's leg through the complete movement sequence without requiring patient activation or control input. The motor-driven crank mechanism automatically generates the elliptical trajectory, and the pedal follower mechanism automatically guides the footplate through the natural walking motion path. This self-service operation reduces patient effort to minimal levels while maintaining a relatively simple control system that requires no complex sensors or feedback loops.
Data Source
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AI summary
A device for adapting an approximately natural leg movement to a rotational movement is described, comprising: a fixed bearing (3), a pedal rod (13) with a first pivot point articulated to the fixed bearing (3) and a second pivot point (2) that can perform a rotational movement (9) about the fixed bearing (5), a foot cup (4) for receiving the foot of a patient, and a bar (17) connected to the foot cup (4) at a first endpoint, wherein the device has an extension arm (14, 16) comprising a first and a second pivot point (1, 2), wherein the first pivot point (1) is articulated to the bar (17) and the second pivot point (2) is articulated to the pedal rod (13).