Robot Thumb Structure Reducing Servo Resistance
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Solution Overview
Problem
Conventional robot thumbs are bulky due to large servos, which hinder compactness and result in a small output force due to the resistance moment between phalanges, limiting their grip and power efficiency.
Innovation Solution
A thumb structure with a proximal phalanx, distal phalanx, fixing member, linking member, and two actuating assemblies that allow the proximal phalanx to move in two degrees of freedom, reducing the need for a servo between phalanges and enabling a more compact and efficient grip mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a servo is arranged between the proximal and distal phalanges to actuate the distal phalanx, then the thumb can achieve movement of both phalanges, but the resistance moment of the proximal and distal phalanges relative to the lower end of the proximal phalanx becomes relatively large, resulting in small output of the servo
Solution Approach 1:
The patent introduces a fixed member that rotates relative to the proximal phalanx, adding a rotational degree of freedom at a different location. This dimensional change in the actuation mechanism allows the distal phalanx to be actuated without placing a servo between the phalanges, thereby reducing the resistance moment while maintaining movement capability
Solution Approach 2:
The fixed member acts as an intermediary element between the proximal and distal phalanges. By introducing this intermediate rotating component, the system achieves distal phalanx movement through a different mechanical path that avoids the high resistance moment problem of direct servo placement between phalanges
2Ease of operation
If two servos are used to actuate the proximal and distal phalanges, then the thumb achieves full movement capability, but the structure becomes bulky and compactness of the hand is compromised
Solution Approach 1:
The patent extracts the servo from the space between the proximal and distal phalanges and relocates it to the lower end of the proximal phalanx. This extraction eliminates the need for a second servo while maintaining full movement capability, thereby reducing the overall volume of the thumb structure
Solution Approach 2:
The fixed member serves multiple functions: it acts as a mounting base for the servo, provides a rotational joint for the proximal phalanx, and enables actuation of the distal phalanx through its rotation. This multi-functionality eliminates the need for separate components, reducing overall structure volume
Data Source
AI summary
A thumb structure includes a proximal phalanx, a distal phalanx rotatably connected to one end of the proximal phalanx, a fixing member connected to the proximal phalanx through a first ball joint, a linking member having opposite ends that are connected to the distal phalanx and the fixing member through a second ball joint and a third ball joint, a first actuating assembly to drive the proximal phalanx to swing in a direction of a first degree of freedom, and a second actuating assembly to drive the proximal phalanx to swing in a direction of a second degree of freedom.