Powered Prosthetic Knee Coupling With Switchable Transmission Ratios
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Solution Overview
Problem
Existing prosthetic legs lack the ability to generate power for bending and stretching, particularly when ascending stairs under load.
Innovation Solution
A joint device with a power source and a power transmission unit featuring two power transmission paths with different transmission ratios, controlled by connection and disconnection mechanisms, allowing for variable angle adjustment between members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a hydraulic cylinder with a variable valve is used to adjust resistance, then resistance of bending and stretching can be generated, but power for bending and stretching cannot be generated
Solution Approach 1:
The patent applies dynamics by making the transmission ratio variable through switching between two different power transmission paths. The control unit dynamically selects which transmission path to use based on the operational requirements - using the first transmission ratio when high torque is needed (such as during stair ascent) and the second transmission ratio during normal walking, thereby enabling the system to generate both resistance and power as needed
Solution Approach 2:
The patent changes the transmission ratio parameter by providing two distinct power transmission paths with different transmission ratios. This allows the system to adjust the mechanical advantage and accordingly control both the resistance and power output characteristics of the artificial knee joint, resolving the contradiction between generating resistance and generating power
2Adaptability or versatility
If a single power transmission path is used, then device complexity is reduced, but the ability to adapt to different movement conditions (such as stair ascent vs. normal walking) is limited
Solution Approach 1:
The patent segments the power transmission system into two distinct power transmission paths, each with a different transmission ratio. This segmentation allows the system to handle different operational conditions (stair ascent, normal walking, etc.) through selective engagement, achieving high adaptability while keeping each individual transmission path relatively simple
Solution Approach 2:
The patent implements multi-functionality by designing a power transmission unit that can perform multiple functions through two different transmission paths. The same motor unit can provide different torque and speed characteristics by switching between transmission paths, making the system universally applicable to various movement conditions without requiring separate mechanisms for each function
Data Source
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AI summary
An electric prosthetic leg (1) includes a below-knee member (110), an above-knee member (120), a knee joint mechanism (130) configured to couple the below-knee member (110) and the above-knee member (120) such that a formed angle formed therebetween is variable, and an enlarging and reducing device (200) capable of enlarging and reducing the formed angle. The enlarging and reducing device (200) includes a motor (M) and a transmission (T). The transmission (T) includes a first transmission mechanism (T1) configured to transmit power of the motor (M) at a first transmission ratio, and a second transmission mechanism (T2) configured to transmit the power of the motor (M) at a second transmission ratio different from the first transmission ratio. The enlarging and reducing device (200) includes a first connection and disconnection mechanism (210) configured to switch between connection and disconnection of power in the first transmission mechanism (T1), and a second connection and disconnection mechanism (220) configured to switch between connection and disconnection of power in the second transmission mechanism (T2).