Adaptive Arm Support with Variable Lift Force
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Solution Overview
Problem
Existing arm support systems, such as static armrests, are ineffective for tasks requiring moderate to large ranges of motion as they fail to alleviate fatigue caused by resisting gravity, especially in activities like construction, surgery, and painting, where users need to maintain arms extended for extended periods.
Innovation Solution
An adaptive arm support system with a spring-loaded mechanism that modifies the lift force based on arm orientation, using mechanisms like varying tension element angles, pulley radii, and cam systems to provide a variable offset force that increases when the arm is raised and decreases when lowered, thereby reducing fatigue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a spring-loaded arm support system is used, then the system provides lift force to support the arm, but the spring force increases with displacement making the force greatest at the lowest position where lift is needed least
Solution Approach 1:
The patent applies dynamics by making the mechanical advantage variable rather than fixed. The arm support system uses a movable pulley that changes position along the tension element as the arm moves, dynamically adjusting the mechanical advantage to match the varying lift requirements at different arm positions.
Solution Approach 2:
The patent changes the parameter of mechanical advantage from a constant value to a variable value that depends on arm position. By varying the mechanical advantage parameter, the system optimizes the force distribution so that greater mechanical advantage is applied when the arm is lowered and less when raised.
2Device complexity
If static arm rests are used, then the structure is simple, but the system is only effective for tasks within a restricted area and does not aid tasks involving greater range of motion
Solution Approach 1:
The patent transforms the static arm rest into a dynamic system where the pulley can move along the tension element. This dynamic capability allows the system to adapt to various arm positions and ranges of motion while maintaining structural simplicity through the use of basic mechanical components.
Solution Approach 2:
The patent segments the support function into two independent parts: the harness that attaches to the user and the arm support mechanism that provides lift. This segmentation allows the arm support portion to move independently and adapt to different positions without complicating the overall structure.
3Force
If the spring is deflected to apply more net lift force, then the force in the spring increases, but the mechanical advantage on the system increases making the force greatest when the arm is lowered
Solution Approach 1:
The patent makes the mechanical advantage dynamic by allowing the pulley to change its position relative to the tension element based on arm position. When the arm is lowered and the spring deflects more, the pulley position adjusts to reduce mechanical advantage, preventing excessive force application at positions where lift is needed least.
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 adaptive arm support system effectively reduces user fatigue by providing a variable lift force that matches the user's arm position, allowing for extended periods of task performance without excessive strain, thus improving comfort and productivity in tasks requiring extensive arm movement.
Implementation Method 1
A spring-loaded arm support system is simple and does not require external power
Implementation Method 2
Varying radii in pulleys about which a tension element is wrapped
Implementation Method 3
cam systems to provide a variable offset force
Implementation Method 4
one or more compensation elements coupled to the arm support to apply an offset force to at least partially offset a gravitational force acting on the arm
Data Source
AI summary
Systems and methods are provided for supporting an arm of a user using a harness configured to be worn on a body of a user; and an arm support coupled to the harness configured to support an arm of the user, the arm support configured to accommodate movement of the arm while following the movement without substantially interfering with the movement of the user's arm. One or more compensation elements may be coupled to the arm support to apply an offset force to at least partially offset a gravitational force acting on the arm as the user moves and the arm support follows the movement of the user's arm, the one or more compensation elements providing a force profile that varies the offset force based on an orientation of the arm support.