Three-Finger Robot Gripper for Secure Low-Pressure Handling
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Solution Overview
Problem
Current robot grippers lack versatility and dexterity, often damaging or failing to securely hold objects due to uneven pressure distribution and are ill-suited for handling various shapes.
Innovation Solution
A modified two-finger gripper with a third finger that supports the object's weight, allowing slight pressure from the first and second fingers, and a 2D scanner for precise object detection and positioning, enabling secure handling of diverse objects without damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a two-finger gripper squeezes an object to hold it, then the object can be held securely, but the object may be crushed or escape if it yields to pressure
Solution Approach 1:
The gripper is segmented into three independent fingers (first, second, and third fingers) that can be controlled separately. The third finger is dedicated to supporting the object's weight from below, while the first and second fingers apply only light squeezing force from above to maintain grip. This segmentation allows the gripping function to be divided into weight support and securing functions, eliminating the need for high squeezing pressure and thus preventing crushing damage.
Solution Approach 2:
The third finger acts as an intermediary element between the gripper and the object, specifically positioned to support the object's weight from below. This intermediary structure bears the gravitational load, allowing the first and second fingers to exert minimal force solely for maintaining grip stability, thereby preventing both escape and crushing of the object.
2Reliability
If a two-finger gripper applies squeezing pressure to hold an object, then the object can be secured, but the pressure is concentrated on a limited surface region causing damage
Solution Approach 1:
The gripping function is segmented across three fingers with different functions: the third finger provides upward support force distributed over its contact area, while the first and second fingers provide downward securing force. This segmentation distributes the mechanical interaction across multiple contact points and surfaces, reducing concentrated pressure and preventing surface damage.
3Object-affected harmful factors
If a three-finger gripper uses curved fingers to seize objects without pressing, then objects are not damaged, but the gripper is ill-suited for handling cuboid-shaped objects
Solution Approach 1:
The gripper employs dynamic, independently controllable fingers that can adjust their positions and orientations. The first and second fingers can be positioned to contact vertical surfaces of cuboid objects, while the third finger supports from below. This dynamic positioning capability allows the same three-finger structure to adapt to both curved and angular geometries, maintaining versatility while preventing damage through minimal pressing force.
4Force
If the third finger is positioned under the object to support weight, then less squeezing force is needed, but the finger may interfere with object placement on support
Solution Approach 1:
The third finger is dynamically controllable and can be repositioned along the second axis independently of the first and second fingers. During object placement operations, the third finger can be moved to clear the placement path or repositioned to a side location, allowing the object to be placed on the support without interference. After placement, the third finger can return to its weight-supporting position underneath the object.
Solution Approach 2:
The third finger can be preliminarily positioned to support the object's weight before the object is fully placed on the support surface. This preliminary support action allows for controlled placement and reduces the risk of the object slipping or being damaged during the placement process, while still enabling easy positioning through subsequent finger retraction or relocation.
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A robot gripper (0, 0' ) comprises a palm (5) and first and second fingers (1, 2) connected to said palm (5) that have gripping surfaces (12) facing each other for gripping an object (19) between them and that are displaceable with respect to each other along a first axis (8) normal to said gripping surfaces (12). The palm (5) further carries at least a third finger (3) having a support surface (12), wherein, when the gripper (0, 0' ) is in a use pose in which the support surface (12) is oriented horizontally and facing upward, the first axis (8) is also horizontal and the gripping surfaces (14) are located above the support surfaces (13).