Under-actuation Gripper for Asymmetrical Objects
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Solution Overview
Problem
Conventional robot grippers are optimized for bilaterally symmetrical objects and struggle to stably grip asymmetrical objects or thin objects placed on inclined surfaces, limiting their adaptability and efficiency in various manufacturing environments.
Innovation Solution
An under-actuation type gripper is designed with a frame, multiple finger portions, and a driving portion. Each finger portion includes a first link with joints, a second link forming a trapezoidal link mechanism, and a third link forming a double parallelogram link mechanism, allowing for adaptive gripping and active control of the finger tip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional robot grippers are designed with symmetric finger structures, then they can effectively grip bilaterally symmetrical objects, but they fail to stably grip asymmetrical objects or thin objects on inclined surfaces
Solution Approach 1:
The finger structure is divided into multiple independent links (first link, second link, third link) that can move relative to each other. This segmentation allows each link to adapt its position and orientation to match asymmetrical object surfaces, enabling stable gripping of diverse objects without requiring a completely complex redesign of the entire gripper structure.
Solution Approach 2:
The gripper employs dynamic link mechanisms (trapezoidal link mechanism and double parallelogram link mechanism) that allow the finger links to change their configuration during the gripping process. This dynamic adaptability enables the finger to conform to asymmetrical object shapes and maintain stable contact, resolving the contradiction between adaptability and structural simplicity.
2Ease of operation
If the finger structure uses fixed rigid links, then the structure remains simple, but the finger tip cannot be actively controlled or adapt to asymmetrical surfaces
Solution Approach 1:
The finger structure transitions from fixed rigid links to dynamic link mechanisms with multiple degrees of freedom. The first link connects to the driving portion, the second link forms a trapezoidal mechanism, and the third link forms a double parallelogram mechanism. This dynamic structure enables active control of the finger tip position and orientation while maintaining a relatively simple overall design through the use of standard mechanical linkages.
Solution Approach 2:
The link mechanisms act as intermediaries between the driving portion and the finger tip. These intermediate links (first link, second link, third link) transmit and transform the driving force while enabling complex finger tip movements. This intermediary structure allows active control of the finger tip without requiring direct complex actuation at the tip itself, balancing ease of operation with manageable device complexity.
3Productivity
If conventional grippers use uniform finger closure motion, then they are efficient for standardized symmetrical products, but they cannot stably grip asymmetrical objects
Solution Approach 1:
The finger is segmented into multiple links that can move independently, allowing each segment to adapt to the local surface geometry of asymmetrical objects. This segmentation maintains efficient closure motion for standardized objects while enabling reliable adaptation to asymmetrical shapes, resolving the contradiction between productivity and reliability across different object types.
Solution Approach 2:
The link mechanism design provides universal adaptability - the same finger structure can efficiently grip both symmetrical standardized objects and asymmetrical objects. The first link, second link, and third link work together to provide both the rapid closure needed for productivity and the adaptive conforming needed for reliability, making the gripper universally effective across different object types.
Data Source
AI summary
An under-actuation type gripper capable of gripping asymmetrical objects is provided. The under-actuation type gripper may include: a frame providing a base surface; at least two or more finger portions provided on the frame in a form of facing each other and having a finger tip at an end; and a driving portion mounted onto the frame and configured to provide a driving force to the finger portion so as to grip an object to be gripped, wherein the finger portion includes: a first link installed between the driving portion and the finger tip, providing a contact surface for the object to be gripped, and having at least one joint portion; a second link connected to longitudinal upper and lower ends of the first link and forming a trapezoidal link mechanism with the first link; and a third link connected to longitudinal upper and lower ends of the first link, forming a double parallelogram link mechanism with the first link in a longitudinal direction of the first link, and being unlocked from the second link.