Worm Gear Joint Mechanism for Robotic Gripper Posture Control
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Solution Overview
Problem
Conventional gripping mechanisms for robots and prosthetic hands face challenges in gripping various shapes due to limited degrees of freedom and increased production costs associated with multiple motors, making it difficult to set intended postures and apply proper frictional force.
Innovation Solution
A joint mechanism with a first link, second link, and third link, connected by worms and worm wheels, where the worms are rotatable and movable, allowing for adjustment of angles to accommodate different article shapes without the need for multiple motors, using a connecting member and centering means to stabilize and adjust the posture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple motors are used to increase degrees of freedom for gripping various shapes, then the ability to set intended postures is improved, but production cost increases
Solution Approach 1:
The patent combines multiple drive functions into a single motor by using a worm gear mechanism. The worm (driven by one motor) simultaneously engages with multiple worm wheels attached to different links, enabling one motor to control the rotational movement of multiple links. This merging approach reduces the number of motors from multiple to one, lowering production cost while maintaining the ability to achieve various gripping postures
Solution Approach 2:
The worm gear mechanism serves multiple functions: it provides rotational movement to multiple links, maintains gripping force through self-locking capability, and enables posture adjustment. The single worm gear system universally controls multiple degrees of freedom, making the mechanism multi-functional and reducing the need for separate motors for each function
2Device complexity
If a single motor with worm gear is used to reduce complexity, then production cost is reduced, but the ability to grip various shapes is limited
Solution Approach 1:
The patent segments the worm gear mechanism into multiple independent worm wheels, each attached to a different link. This segmentation allows the single worm to independently control each link's rotation, providing multiple degrees of freedom. The segmented approach enables the mechanism to adapt to various article shapes by adjusting each link's position independently, compensating for the single motor limitation
Solution Approach 2:
The mechanism employs dynamic adjustment capability where the worm can rotate to different positions and engage with different worm wheels at different angles. This dynamic positioning allows the single motor to achieve multiple gripping postures and adapt to various article shapes by continuously adjusting the relative positions and angles of the links
3Adaptability or versatility
If worms are made movable in axis direction to adjust posture, then adaptability to different shapes is improved, but mechanism complexity increases
Solution Approach 1:
The patent adds translational movement capability to the worm along its axis, introducing a new dimension of motion. This axial movement allows the worm to adjust its position relative to the worm wheels, enabling posture adjustment and adaptation to different article shapes. By utilizing motion in another dimension (axial direction in addition to rotation), the mechanism achieves enhanced adaptability without requiring complex additional components
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 gripping of various article shapes with a simplified arrangement, reducing production costs and improving the ability to set intended postures, while maintaining balance and stability through rotational and translational movements of the shaft.
Implementation Method 1
a first worm and a second worm coupled to each other by the connecting member, the first worm and the second worm each being rotatable about its axis and movable in an axis direction thereof; a first worm wheel in mesh with the first worm to pivotally move the first link with respect to the second link; and a second worm wheel in mesh with the second worm to pivotally move the third link with respect to the second link
Data Source
AI summary
The joint mechanism includes a first link, a second link, a third link, a shaft supported on the second link to be rotatable about an axis thereof, and movable in an axis direction thereof, a first worm and a second worm mounted on the shaft, a first worm wheel in mesh with the first worm to pivotally move the first link with respect to the second link, and a second worm wheel in mesh with the second worm to pivotally move the third link with respect to the second link. The first link and the third link are pivotally moved in opposite directions to each other by rotating the shaft, and pivotally moved in identical directions to each other by moving the shaft in the axis direction.