Single Actuator Powered Ankle Toe Prosthesis
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Solution Overview
Problem
Current robotic prostheses for individuals with below-knee amputations lack the ability to actively generate movements and inject net-positive energy into the gait cycle, leading to inefficient and unstable ambulation.
Innovation Solution
A robotic ankle-foot prosthesis that utilizes a single actuator to power both the ankle and toe joints, mimicking the biomechanical functions of the biological ankle and toe joints, while maintaining the weight, size, and battery life of passive prostheses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a single actuator powers both ankle and toe joints, then the prosthesis weight and size are reduced, but the device complexity increases
Solution Approach 1:
The patent combines the actuation of the ankle joint and toe joint into a single integrated actuator system. The linear actuator is mechanically coupled to both joints through a shared transmission mechanism, allowing one actuator to simultaneously control both joints. This merging reduces the overall weight and component count compared to using separate actuators for each joint.
Solution Approach 2:
The single linear actuator serves multiple functions by powering both the ankle joint and toe joint through its mechanical connection to both. The actuator system is designed to provide coordinated motion to both joints, making it a multi-functional component that replaces what would traditionally require two separate actuators.
2Volume of moving object
If a linear actuator is used to power both joints, then the prosthesis size is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The patent employs a dynamic transmission mechanism that allows the single linear actuator to adaptively control the ankle and toe joints. The mechanism includes movable linkages and joints that can dynamically adjust their configuration during operation, enabling the system to accommodate variations in manufacturing tolerances while maintaining proper kinematic relationships between the actuator and both joints.
Solution Approach 2:
The design allows for adjustment of key geometric parameters in the transmission mechanism, such as linkage lengths and joint positions. This adjustability compensates for manufacturing variations and enables fine-tuning of the kinematic properties to achieve the desired coordinated motion between the ankle and toe joints.
3Use of energy by moving object
If the actuator powers both joints simultaneously, then energy efficiency is improved, but the control difficulty increases
Solution Approach 1:
The patent incorporates feedback mechanisms including encoders or sensors on the actuator and potentially on the joints themselves. This feedback allows the control system to monitor the actual positions and motions of both joints and adjust the actuator output accordingly, enabling coordinated control despite the coupled nature of the system. The feedback loop helps manage the control complexity by providing real-time information about system state.
Solution Approach 2:
The mechanical transmission mechanism is designed to naturally coordinate the motion of the ankle and toe joints through its kinematic structure. The geometry of the linkages and joints creates inherent coupling relationships that guide the system toward proper coordinated motion, reducing the computational burden on the control system and simplifying the control task while maintaining energy efficiency.
Data Source
AI summary
Disclosed herein is a robotic ankle foot prosthesis that replicates the key biomechanical functions of the biological ankle and toe joints while matching the weight, size, and battery life of passive microprocessor-controlled prostheses. A single actuator powers the ankle and toe joints. The mechanism maximizes the mechanical energy regeneration during walking while imitating the physiological features of energy injection by way of the ankle joint and energy dissipation by way of the toe joint.