Artificial Tendon Actuation for Bi-Directional Limb Control
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Solution Overview
Problem
Existing devices for assisting mobility, such as those using artificial tendons, often struggle with maintaining bi-directional movement of limbs without slack or excessive strain, and fail to provide adequate control over grip force and feedback, particularly for individuals with mobility disabilities.
Innovation Solution
A device utilizing two artificial tendons on either side of an arm or finger, driven by an electric motor, with a self-inhibiting mechanism to maintain biasing force without power consumption, allowing for bi-directional movement with minimal slack and controlled tension, and incorporating features like free wheel functionality for safety and torque limiting to prevent injury.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If artificial tendons are used to assist limb movement, then mobility assistance is provided, but slack in the tendons occurs during bi-directional movement
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the tension and length of artificial tendons during bi-directional movement. The system modifies tendon parameters (tension force, extension length) based on movement direction and phase, ensuring optimal performance without slack or excessive strain throughout the complete range of motion.
Solution Approach 2:
The invention implements dynamics by creating a balanced tension system where two artificial tendons work in opposition. One tendon is pulled while the other is simultaneously slacked, and vice versa, allowing the system to adapt dynamically to movement direction changes while maintaining continuous control and preventing slack accumulation.
2Reliability
If artificial tendons are kept stretched without preload, then slack is avoided, but excessive strain may occur
Solution Approach 1:
The system dynamically adjusts tendon tension parameters within a controlled range. By modifying the degree of stretch and force application based on movement requirements, the system maintains tendons in a tensioned state to prevent slack while limiting maximum strain to safe levels through controlled parameter variation.
Solution Approach 2:
The patent applies partial action by using only the necessary portion of tendon tension required for each movement phase. Instead of maintaining constant maximum tension, the system applies optimal tension levels matched to specific movement requirements, avoiding excessive strain while preventing slack through controlled partial tensioning.
3Ease of operation
If electric motor is used to drive artificial tendons, then bi-directional movement is achieved, but power consumption increases
Solution Approach 1:
The system employs periodic action through alternating activation of the electric motor in different directions. The motor operates intermittently to pull one tendon while the other slackens, then reverses for the opposite movement direction. This periodic on-off operation reduces overall power consumption compared to continuous motor operation, while maintaining precise bi-directional control.
4Object-affected harmful factors
If torque limiting mechanism is added to prevent injury, then safety is improved, but device complexity increases
Solution Approach 1:
The patent implements beforehand cushioning by incorporating a torque limiting mechanism that prevents excessive force application before injury can occur. This protective mechanism is built into the system design to limit maximum torque output, cushioning against potential harmful effects while maintaining normal operational functionality.
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
Enables efficient, bi-directional movement of limbs with controlled tension and grip force, enhancing rehabilitation and safety for individuals with mobility disabilities by minimizing strain and preventing injuries from excessive forces.
Implementation Method 1
a biasing member (40) being arranged between the motor (32) and the driving mechanism (30), wherein the biasing member (40) is adapted to be stretched and/or compressed alternately when the artificial tendons (20, 21) are pulled and slacked alternately
Implementation Method 2
a self-inhibiting driving mechanism (30) for maintaining a built-up force or built-up strain or built-up biasing force without consumption of electric power
Data Source
AI summary
A device for pivoting an arm relative a joint. The device for pivoting the arm relative the joint includes at least one artificial tendon attached to a distal end of the arm and a driving mechanism, the driving mechanism being connected to and adapted to pull the tendon and the distal end of the arm.