Prosthetic Knee Joint Transmission for Stair-Climbing Torque Control
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Solution Overview
Problem
Prosthetic legs with joint devices cannot generate power for bending and extension, making it difficult to smoothly go up stairs, as they rely on resistance adjustment rather than active power transmission.
Innovation Solution
A joint device with a power source and a dual power transmission system, featuring first and second transmission gear ratios, allowing for the extension and bending of the connecting unit via a motor-driven mechanism, enabling efficient power transmission for varying angles and operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single power transmission path with fixed gear ratio is used, then the structure is simple, but the prosthetic leg cannot adapt to different operation conditions (e.g., stair climbing requiring high torque vs. normal walking requiring high speed)
Solution Approach 1:
The patent applies dynamics by making the transmission gear ratio changeable during operation. The prosthetic leg switches between a first transmission gear ratio (for high torque during stair climbing) and a second transmission gear ratio (for high speed during normal walking), allowing the system to adapt its characteristics dynamically based on operational requirements rather than being fixed.
Solution Approach 2:
The patent changes the transmission parameter (gear ratio) to adapt to different operation conditions. By switching between different transmission gear ratios, the system modifies its mechanical characteristics to match the demands of either stair climbing or normal walking, thereby improving versatility without requiring completely separate systems for each function.
2Power
If resistance adjustment mechanism is used, then the structure is simple, but the prosthetic leg cannot generate sufficient power for bending and extension operations
Solution Approach 1:
The patent replaces the passive resistance adjustment mechanism with an active motor-driven power transmission system. Instead of merely adjusting hydraulic resistance, the system uses a motor to generate power and transmits it through gear mechanisms, enabling the prosthetic leg to actively produce the bending and extension forces needed for stair climbing and other demanding operations.
Solution Approach 2:
The patent introduces dynamic power generation through a motor that can actively adjust its output based on operational needs. The motor-driven system with switchable gear ratios provides variable power output, allowing the prosthetic leg to generate sufficient force during stair climbing while maintaining efficiency during normal walking, thereby improving power capability beyond what passive resistance mechanisms can achieve.
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
Enables smooth extension and bending of the knee joint mechanism, particularly during stair climbing, by switching between different power transmission paths based on the required operation speeds and power generation, enhancing the functionality of prosthetic legs.
Implementation Method 1
a motor (M) that outputs rotary power
Implementation Method 2
a first transmission mechanism (T1) through which the power is transmitted at a first transmission gear ratio; and a second transmission mechanism (T2) through which the power is transmitted at a second transmission gear ratio different from the first transmission gear ratio
Data Source
AI summary
An electric prosthetic limb is provided with: a below-knee side member; an above-knee side member; a knee joint mechanism that connects the below-knee side member and the above-knee side member in a manner such that an angle formed therebetween is variable; and an extendable device that is capable of extending and contracting to change the angle formed between the below-knee side member and the above-knee side member. The extendable device is provided with a motor and a transmission transmitting power from the motor. The transmission is provided with: a first transmission mechanism that transmits the power from the motor at a first transmission gear ratio; and a second transmission mechanism that transmits the power from the motor at a second transmission gear ratio different from the first transmission gear ratio.