Prosthetic Hand Wrist Locking for Lateral-Axis Palm Adjustment
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Solution Overview
Problem
Existing prosthetic hands lack ergonomic mechanisms for adjusting the position of the palm and fingers to resist rotation about a lateral axis and maintain adjusted positions effectively.
Innovation Solution
A prosthetic hand design featuring a wrist joint with a locking member that selectively engages an engagement part, allowing rotation in an unlocked position and locking in a locked position, using resilient biasing and discrete angular positions to stabilize the palm relative to the wrist attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a wrist connector is used to connect the prosthetic hand, then the prosthetic hand can be attached to the forearm, but the palm cannot be adjusted to rotate about a lateral axis
Solution Approach 1:
The wrist joint is segmented into multiple independent rotational capabilities: rotation about the longitudinal axis (supination/pronation) is provided by the wrist connector, while rotation about the lateral axis is provided by a separate locking mechanism with locking member and engagement part. This segmentation allows each component to specialize in one rotational degree of freedom, achieving comprehensive adjustability without requiring a single complex mechanism.
Solution Approach 2:
The locking member acts as an intermediary element between the palm part and the wrist attachment part. It selectively engages with the engagement part to enable or disable rotation about the lateral axis, providing a simple mechanical mediator that adds rotational adjustability without requiring complex actuation systems.
2Ease of operation
If the palm part is made rotatable relative to the wrist attachment part, then the hand position can be adjusted, but the adjusted position cannot be held securely
Solution Approach 1:
The locking mechanism transitions between two dynamic states: unlocked state where the palm part is free to rotate for adjustment, and locked state where the locking member engages the engagement part to hold the position securely. This dynamic switching allows the system to provide both ease of adjustment and position stability as needed.
Solution Approach 2:
The resiliently biased locking member automatically engages with the engagement part when the palm part is rotated to certain positions, providing self-locking functionality. The resilient biasing ensures the locking member springs into engagement to hold the adjusted position without requiring additional actuation or complex control mechanisms.
3Reliability
If a locking mechanism is added to secure the palm position, then the adjusted position can be held, but the device complexity increases
Solution Approach 1:
Instead of using a complex active locking system that requires power or complex actuation, the invention uses a passive locking mechanism where the locking member is resiliently biased to automatically engage with the engagement part at predetermined positions. The locking action is inverted from requiring active control to occurring automatically through resilient biasing, simplifying the mechanism while maintaining reliability.
Solution Approach 2:
The locking member's position is controlled by changing the parameter of resilient biasing force. The resilient element provides a continuous biasing force that drives the locking member into engagement with the engagement part at specific angular positions, eliminating the need for complex positional control systems while maintaining stable locking.
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 ergonomic adjustment and secure locking of the prosthetic hand's palm position, facilitating user convenience and stability through resilient biasing and discrete angular positions.
Implementation Method 1
A resilient element may extend across an opening in the locking member. The resilient element may abut a shoulder of the wrist attachment part to resiliently resist and limit movement of the locking member.
Data Source
AI summary
A prosthetic hand includes a wrist attachment part configured for connecting to a wrist connector; a palm part, the palm part and wrist attachment part being rotatably coupled together to form at least part of a wrist joint; and at least one locking member configured to selectively engage a corresponding engagement part coupled to the palm part, wherein the locking member is movable between an unlocked position, in which the locking member and engagement part are disengaged and the palm part is free to rotate relative to the wrist attachment part, and a locked position, in which the locking member and engagement part are lockingly engaged and the palm part is rotatably locked relative to the wrist attachment part, wherein an end face of the locking member is configured to be flush with an end face of the wrist attachment part when the locking member is in the locked position and the end face of the locking member is configured to be proud of the end face of the wrist attachment part when the locking member is in the unlocked position.