Modular 2-DOF Prosthetic Wrist With Adjustable Tendon Stiffness
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Solution Overview
Problem
Existing prosthetic wrist devices are bulky, heavy, and inflexible, offering limited functionality, and fail to accommodate the growing needs of pediatric patients due to their developmental changes, necessitating a lightweight, adaptable, and cost-effective solution.
Innovation Solution
A prosthetic wrist unit with a 2 degrees of freedom mechanism, comprising a wrist base unit, joint, locking mechanism, and tendon system, allowing for flexion-extension and abduction-adduction movements, with adjustable stiffness through tendons and an actuator for manual or automatic tension control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If traditional prosthetic wrist structures are used, then the device provides basic wrist support, but the device becomes bulky and heavy
Solution Approach 1:
The prosthetic wrist is divided into separate modular components including a wrist base unit, hand mechanism, connecting piece, and locking mechanism. This segmentation allows each component to be optimized independently for weight and function, reducing overall system weight while maintaining structural integrity through standardized connection interfaces.
Solution Approach 2:
The locking mechanism is extracted as a separate detachable component from the wrist base unit. This allows the main wrist structure to be minimized in weight while the locking function is provided by a separate piece that attaches only when needed, reducing the weight of the continuously worn portion.
2Adaptability or versatility
If fixed prosthetic devices are used, then the structure is simple, but the device cannot accommodate changing body sizes of pediatric patients
Solution Approach 1:
The prosthetic wrist incorporates dynamic adjustability through the locking mechanism that can transition between locked and unlocked states. The connecting piece can be detached and reattached at different positions on the wrist base unit, allowing the device to adapt to changing patient size without requiring complex continuous adjustment mechanisms.
Solution Approach 2:
The wrist base unit is designed with multiple connection slots that can accommodate different hand mechanism sizes. The same basic wrist structure serves multiple patients of different ages and sizes by simply changing the connecting piece or hand mechanism attachment position, providing universal adaptability.
3Ease of operation
If traditional wrist prostheses are used, then the basic structure is provided, but the device offers limited ability to grasp, position and move the prosthetic hand
Solution Approach 1:
The wrist base unit incorporates two degrees of freedom through rotational movement capability around two perpendicular axes. This dynamic movement is enabled by the connecting piece rotating within the wrist base unit's connection slots, allowing the prosthetic hand to be positioned in multiple orientations for improved grasping and manipulation without requiring complex actuation systems.
4Duration of action of stationary object
If heavy prosthetic devices are used, then structural strength is maintained, but the device requires frequent replacement due to patient growth
Solution Approach 1:
The prosthetic system is segmented into a permanent wrist base unit and replaceable hand mechanisms. The wrist base unit maintains its structural strength and can be reused indefinitely, while only the lighter hand mechanisms need replacement as the patient grows, extending the overall device lifespan without requiring the entire system to be replaced.
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 functional and lightweight wrist movements, adaptable to user growth, and reduces the need for frequent replacements, enhancing daily life activities with improved grasping and positioning capabilities.
Implementation Method 1
at least one tendon (50) ensuring the joint stiffness of the prosthetic wrist unit (1)
Data Source
AI summary
A prosthetic wrist unit providing a connection between the arm and a hand mechanism, comprising a wrist base unit with at least one connection slot into which the hand mechanism is to be inserted and at least one connecting piece enabling the rotational movement of the prosthetic wrist unit; a joint including a joint seat and a joint body; a locking mechanism comprising a locking mechanism opening into which the joint body is inserted and enabling the prosthetic wrist unit to operate in two positions, i.e., fixed or movable; an arm coupling unit into which the joint and the locking mechanism are inserted and which restricts the movement of the joint and the locking mechanism; and at least one tendon ensuring the joint stiffness of the prosthetic wrist unit.