Catapult Ankle Prosthesis Energy Storage
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Solution Overview
Problem
Current prosthetic ankle systems for amputees lack small, lightweight designs that can provide power comparable to the human neuromuscular system, leading to mobility deficits and decreased community involvement due to inadequate energy production during walking.
Innovation Solution
A prosthetic ankle system utilizing a catapult mechanism to store energy in springs throughout the gait cycle and release it during push-off, allowing for a smaller, low-power motor and reduced weight, with a microcontroller implementing a finite state machine for efficient energy management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a high-power motor is used to provide sufficient energy during push-off, then the power output is adequate, but the weight of the prosthetic ankle increases
Solution Approach 1:
The motor performs preliminary action by winding the spring during the swing phase and early stance phase, storing energy before it is needed. This allows the motor to operate at low power for most of the gait cycle, then release the stored energy through the spring during push-off, achieving high power output without requiring a heavy high-power motor.
Solution Approach 2:
The system uses periodic action by cycling between motor-driven spring winding during non-push-off phases and spring-driven foot propulsion during push-off. This periodic switching between energy storage and energy release phases allows the lightweight motor to provide sufficient average power while the spring provides peak power during push-off.
2Weight of moving object
If a lightweight design with small motor is used, then the weight is reduced, but the energy production capability is insufficient
Solution Approach 1:
The spring acts as an intermediary energy storage device between the lightweight motor and the foot. The motor winds the spring during the swing phase and early stance phase, storing energy that is then released during push-off. This intermediary mechanism allows a small, lightweight motor to effectively produce high energy output during critical moments without requiring the motor itself to be large or heavy.
Data Source
AI summary
Catapult ankles and related methods are disclosed. An example ankle prosthesis for operation in a swing phase and in a stance phase includes a motor, wherein the motor is configured to store energy with a first spring during the swing phase and plantarflex the ankle prosthesis during a push off portion of the stance phase.