Artificial Finger Worm Gear Decoupling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing artificial finger elements for prostheses lack autonomy, with control members external to the finger element, restricting their use as single-finger prostheses or modular components, and often suffer from motor damage under load due to fixed worm gear arrangements or unrealistic, stiff movements.
Innovation Solution
A finger element with a carrier component, articulated phalanges, a servo drive with a self-locking worm gear, and a decoupling mechanism between the drive shaft and threaded screw, combined with elastic couplings and guidances to mimic natural finger resilience and movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the worm gear is fixed permanently to the motor shaft, then the drive structure is simplified, but the motor is vulnerable to damage under high load and the worm drive may block
Solution Approach 1:
The drive system is segmented into separate functional components: the motor shaft, the threaded screw, and the worm gear are decoupled from each other. The motor shaft drives the threaded screw directly, while the worm gear engages with the screw to provide motion transmission to the phalanx. This segmentation allows each component to handle specific loads independently, preventing overload damage to the motor.
Solution Approach 2:
The threaded screw acts as an intermediary element between the motor shaft and the worm gear. It receives rotational motion from the motor shaft and transmits it through the worm gear mechanism to the phalanx, while also serving as a load-bearing element that can deform elastically under high loads to protect the motor from damage.
2Device complexity
If stiff push- and pull-rods are used to achieve distal phalanx movements, then the mechanical structure is simplified, but the movements become unrealistic and robot-like, unsuited for sensitive picking tasks
Solution Approach 1:
The threaded screw is designed with elastic properties, allowing it to deform flexibly under load. This elasticity enables the finger element to produce natural, compliant movements during sensitive picking tasks, rather than rigid robot-like motions. The elastic deformation of the screw absorbs shocks and adapts to varying contact forces, mimicking natural finger behavior.
3Reliability
If a bevel gear transmission is added to decouple the drive shaft and threaded screw, then the worm wheel load is reduced, but the construction volume increases significantly
Solution Approach 1:
The functions of the drive shaft and threaded screw are merged into a single integrated component. The threaded screw is directly coupled to the motor shaft, eliminating the need for separate bevel gear transmissions. This merging achieves both load reduction and compact size, as the threaded screw itself serves as the decoupling mechanism while maintaining a small form factor suitable for single-finger prostheses.
4Adaptability or versatility
If the finger element is designed as an autarkic unit with all control members enclosed, then it can be used as a single-finger prosthesis, but the construction becomes more complex
Solution Approach 1:
The finger element is designed as a universal, self-contained unit that can function independently as a single-finger prosthesis or as an integrated component in a multi-finger prosthesis system. All necessary control members (motor, threaded screw, worm gear) are enclosed within the finger element itself, eliminating the need for external control mechanisms and enabling versatile application across different prosthetic configurations.
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 the finger element to function autonomously as a single-finger prosthesis with enhanced durability and natural-like movement, suitable for sensitive tasks and varied finger sizes, while maintaining a compact construction.
Implementation Method 1
a self-locking worm gear that engages in a cog segment and moves it synchronously to the rotation movement of the drive shaft
Implementation Method 2
an elastic connection, in form of a threaded screw that is form-fittingly coupled in rotation direction to the drive shaft, for instance via a cogging or a matched joint
Data Source
AI summary
The invention relates to a finger element, comprising a carrier component (1), a first finger member (5) having a first articulated connection (2) to the carrier component, a second finger member (6) having a second articulated connection (7) to the first finger member, an actuator for the first articulated connection (2) with a motor having a drive shaft, and a worm gear having a threaded worm, and a toothed segment engaging on the threaded worm, and further comprising a coupling mechanism (8) between the first and second articulated connections. The object of the invention is to modify a finger element such that the finger element in the active and passive functions thereof and in the dimensions thereof comes very close to a natural finger. The object is achieved in that the threaded worm is positively mounted axially movably on the drive shaft and axially guided through separate guides.