Flexible Joint Movement Assistance Device with Load Sensor Feedback
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Solution Overview
Problem
Conventional joint-movement assisting devices with rigid external skeletons face challenges in accurately and stably exerting assist force during user movements, as they can apply excessive force and restrict joint movement, potentially hindering autonomous reactions to disturbances.
Innovation Solution
A joint-movement assisting device with a flexible assist force transmission part that uses a load sensor for feedback-controlled force exertion, allowing for accurate and stable support of muscular strength during movement, and includes an encoder for traction control to prevent excessive loads and improve response speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rigid external skeleton is used to provide assist force, then the assist force can be transmitted directly and stably, but the user's joint movement is excessively restricted and excessive force may be applied to the user's joint
Solution Approach 1:
The patent replaces the rigid external skeleton with a flexible assist force transmission part that can bend and deform. This flexible transmission part maintains stable force transmission while allowing the user's joint to move freely without excessive restriction, resolving the contradiction between force stability and movement freedom.
Solution Approach 2:
The patent changes the physical state of the transmission part from rigid to flexible, altering its mechanical properties. This parameter change enables the transmission part to adapt to joint movement while maintaining assist force, solving the contradiction between reliable force transmission and ease of operation.
2Ease of operation
If a flexible assist force transmission part is used, then the user's movement is not restricted, but the assist force cannot be exerted with high accuracy and stability due to slack, bend, and extension
Solution Approach 1:
The patent incorporates a load sensor that detects the actual assist force being transmitted through the flexible transmission part. This feedback information is used by the control unit to adjust and correct the assist force in real-time, compensating for errors caused by slack, bend, and extension, thereby achieving high accuracy despite using a flexible transmission mechanism.
3Measurement precision
If a rigid external skeleton is used, then the assist force can be applied with high accuracy, but the user's autonomous reaction to disturbances is hindered
Solution Approach 1:
The flexible transmission part allows the user's joint to move freely and respond autonomously to disturbances without the rigid constraints of an external skeleton. Combined with feedback control, this maintains accuracy while preserving the user's natural movement and reaction capabilities.
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 device effectively supports muscular strength without restricting user movement, enabling accurate and stable assist force delivery, even during disturbances, and enhances safety and training effectiveness.
Implementation Method 1
the assist force which is transmitted through the assist force transmission part is directly detected by a load sensor
Implementation Method 2
an encoder is provided to the driving means to detect an amount of traction of the assist force transmission part in the direction of tension
Implementation Method 3
the assist force transmission part includes an elastically deformable elastic part in at least a portion thereof in a lengthwise direction
Data Source
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AI summary
A joint-movement assisting device (10) including: (i) an assist force control means to adjust an output level of a driving means (17) in order to bring a load acting on an assist force transmission part (12) to a targeted assist force during action of an assist force; (ii) a slack prevention control means to operate the driving means (17) and exert a bias force on the assist force transmission part (12) in order to eliminate a slack thereof during non-action of the assist force; and a load sensor (34) to detect the load acting on the assist force transmission part (12) in a direction of tension. For at least one of the assist force control means and the slack prevention control means, the driving means (17) is feedback-controlled based on a detection value by the load sensor (34) in order to bring the acting load to the targeted assist force or bias force.