Semi-Passive Knee Exoskeleton With Clutched Spring Assistance
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Solution Overview
Problem
Existing exoskeletons are either bulky and costly due to reliance on actuators or limited in functionality as passive systems tailored for specific tasks, lacking energy efficiency and adaptability for various movements.
Innovation Solution
A semi-passive knee exoskeleton assembly with a clutch mechanism activated by a motor, integrating a spring and sensors to store and release energy efficiently, providing assistance during running, walking, and transitioning between sitting and standing positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If active exoskeletons employ actuators with controls to assist wearer movements, then adjustable support and weight-bearing capacity are improved, but cost, bulkiness (weight and size), and limited battery life worsen
Solution Approach 1:
The patent extracts the actuator components from the exoskeleton system, replacing them with a purely passive mechanical design. The spring-based mechanism eliminates the need for motors, batteries, and electronic controls, thereby reducing weight while maintaining the ability to provide weight-bearing support through mechanical energy storage and release.
Solution Approach 2:
The patent replaces the active electromechanical system with a passive mechanical system. Instead of using actuators and electronic controls, the invention employs a spring mechanism that provides support through purely mechanical means, substituting complex electromechanical components with simple mechanical elements.
2Weight of moving object
If passive exoskeletons use mechanical components to provide assistance, then lightweight and energy-efficient design is improved, but functionality is limited to specific tasks
Solution Approach 1:
The patent introduces dynamic adjustability to the passive mechanical system through a movable linkage mechanism. This allows the spring-based exoskeleton to adapt its mechanical properties in real-time based on the user's movement requirements, enabling it to function effectively across multiple tasks rather than being fixed for a single purpose.
Solution Approach 2:
The patent designs the passive mechanical system to serve multiple functions through its adjustable linkage mechanism. The same spring-based structure can provide assistance for walking, running, and other movements by dynamically adjusting its mechanical characteristics, thereby achieving universality without requiring multiple specialized devices.
3Device complexity
If passive exoskeletons are tailored for a specific task, then mechanical simplicity is maintained, but energy efficiency for prolonged use is reduced
Solution Approach 1:
The patent utilizes parameter changes in the spring mechanism's mechanical properties to optimize energy efficiency. By adjusting the spring constant, pre-load, and linkage geometry, the system can be tuned to efficiently store and release mechanical energy across a range of movements, maintaining simplicity while improving energy efficiency for prolonged use.
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
The semi-passive exoskeleton reduces muscle effort and enhances mobility by storing and releasing mechanical energy, offering lightweight, ergonomic, and cost-effective support with minimal actuation, adapting to different movements and speeds.
Implementation Method 1
a spring connected to the thigh link at one end thereof, and to the arm link at an opposing end thereof
Data Source
AI summary
An exoskeleton for assisting a user to run/walk is provided. The exoskeleton assembly comprises a thigh link and a shank link for attaching to the user, an arm link pivotally articulated thereto, a spring connected to the thigh link and arm link, a transmission configured to control movement between the arm and the shank links, one or more sensors, and a controller. The transmission has a clutch, operable by the controller, configured to selectively engage/disengage the shank link with the spring. The controller is configured, in response to indications received from the one or more sensors, to engage the clutch to store the user's knee energy in the spring or to provide stored energy from the spring to the user's knee, and to disengage the clutch to prevent the exoskeleton from interfering with the user's knee motion.