Passive Exoskeleton Elastic Torque Compensation
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Solution Overview
Problem
Existing passive assistive exoskeletons for reducing physical effort, particularly in tasks involving raised arms, lack ergonomic efficiency and convenience due to limited freedom of movement and inadequate compensation for resistive moments.
Innovation Solution
A passive assistive exoskeleton with an elastic mechanism that generates torque proportional to the elevational angle of a joint, featuring a compensation device with a first and second rotatable member connected by an elastic mechanism, allowing for adjustable pre-tension settings to optimize assistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If elastic means are coupled to arm supports to compensate gravity, then vertical support is provided, but freedom of movement is limited
Solution Approach 1:
The exoskeleton is divided into separate functional modules: a garment carrying the joint engagement, a mobile frame providing rotational freedom, and a compensation device with elastic mechanism. This segmentation allows each component to perform its specific function without constraining the others, resolving the contradiction between force compensation and movement freedom.
Solution Approach 2:
The mobile frame is designed to dynamically assume positions corresponding to the operator's joint movements. The frame can rotate about the first axis and the second rotatable member can rotate about the second axis, allowing the system to adapt to various arm positions while maintaining gravitational compensation through the elastic mechanism.
2Reliability
If a fixed compensation mechanism is used, then gravitational support is provided, but adaptability to different task positions is reduced
Solution Approach 1:
The compensation device incorporates multiple rotational degrees of freedom through the mobile frame and second rotatable member. This dynamic structure maintains reliable gravitational compensation while adapting to different arm elevations and task positions, resolving the contradiction between reliability and adaptability.
Solution Approach 2:
The elastic mechanism parameters (pre-tension, stiffness) can be adjusted to optimize compensation for different task requirements. The system changes its operational parameters based on the joint position and task demands, maintaining reliable compensation across varying conditions.
3Ease of operation
If complex articulated joints are used to allow freedom of movement, then mobility is improved, but device complexity increases
Solution Approach 1:
The mobility function is segmented into the mobile frame and second rotatable member, which are separate from the main compensation mechanism. This segmentation simplifies the overall structure by dedicating specific components to specific functions, reducing overall device complexity while maintaining freedom of movement.
Solution Approach 2:
The system provides partial compensation through the elastic mechanism rather than attempting to fully control all movement aspects. This partial action approach simplifies the device by not requiring complex control systems for all degrees of freedom, while still providing beneficial assistance.
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 system provides improved ergonomics and convenience by effectively compensating resistive moments, allowing for a range of movements while maintaining comfort and reducing operator effort.
Implementation Method 1
an elastic mechanism having at least one elastic element, arranged for acting on the second rotatable member to impart on the first axis of rotation a moment opposite to the resistive moments
Implementation Method 2
The elastic mechanism may be spring-based including at least one elastic spring element
Data Source
AI summary
A system for assisting an operator in exerting efforts comprises a garment that can be worn by the operator, which is to engage, when worn, the mutually mobile parts of a joint of the operator. The system defines at least one axis of rotation that is to assume a position corresponding to the joint of the operator. A device is carried by the garment and designed to operate so as to compensate the resistive moments that act on the joint during the effort exerted by the operator. A compensation device is provided equipped with a rotational assembly, which has a neutral position and is able to determine a pre-set plot of the assisting torque that is a function of the angle of rotation of the joint. The compensation device may include a tension regulation device to regulate a moment obtained about the joint of the operator.