Robot Gripper Spindle Drive With Dual Nut Anti-Jamming Structure

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Solution Overview

Problem

Existing robot grippers face issues with jamming and mechanical failure due to unreliable gear mechanisms, which disrupt the movement of gripper fingers and prevent proper opening and closing.

Innovation Solution

A robot gripper design featuring a spindle drive with a dual nut system and parallel link arrangement, where the first nut body is connected to the second nut body via a parallel link arrangement, allowing for parallel offset and independent movement perpendicular to the drive spindle, ensuring that forces and moments are absorbed by the spindle without causing jamming.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional single nut system is used in the spindle drive, then the structure is simple, but jamming and mechanical failure occur due to unreliable gear mechanisms

Engineering Contradiction:
Improvereliability of gearboxVSAvoidcomplexity of nut system
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The single nut system is divided into two separate nut bodies (first nut body and second nut body), each independently mounted on the drive spindle. This segmentation allows each nut to handle specific loads independently, preventing jamming while maintaining structural simplicity through modular design

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Each nut body is given specific local functionality: the first nut body handles forces in one direction while the second nut body handles forces in another direction. This local differentiation of function allows the system to reliably handle multi-directional loads without requiring a complex unified mechanism

Inventive Principle:
Principle #3Local quality

2Ease of operation

If the nut bodies are rigidly connected, then the structure is stable, but movement freedom is restricted causing jamming

Engineering Contradiction:
Improvemovement freedom of nut bodiesVSAvoidstability of nut body arrangement
Core Design Contradiction:
Ease of operationVSStability of the object's composition

Solution Approach 1:

The connection between the two nut bodies is made dynamic through the parallel link arrangement, which allows the distance between nut bodies to change during operation. This dynamic connection enables each nut to move independently to absorb forces while maintaining their relative positional relationship, preventing jamming while preserving stability

Inventive Principle:
Principle #15Dynamics

3Force

If the nut bodies are mounted close to each other, then the structure is compact, but force transmission is insufficient

Engineering Contradiction:
Improveforce transmission capabilityVSAvoidvolume of nut system
Core Design Contradiction:
ForceVSVolume of moving object

Solution Approach 1:

The two nut bodies are arranged in a spatial configuration along the drive spindle axis rather than side-by-side. This dimensional arrangement allows force transmission in multiple directions while maintaining a compact overall volume, as the nuts utilize the axial space efficiently without requiring lateral expansion

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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

The design prevents jamming and mechanical failure, ensuring reliable movement of gripper fingers and maintaining functionality even in the event of power failure, with forces and moments being effectively transmitted to the spindle, maintaining grip security.

Implementation Method 1

a parallel link arrangement configured to hold the first nut body at a predetermined distance from the second nut body and allowing a parallel offset of the first nut body from the second nut body

Methodology Applied
Scientific EffectParallel mechanism:

Implementation Method 2

the first nut body and the second nut body are mounted in a frame by means of a sliding bearing, wherein the sliding bearing is configured to mount the first nut body and the second nut body in such a way that they can be moved independently of each other perpendicular to the drive spindle in one plane and drive forces are transmitted axially to the drive spindle

Methodology Applied
Scientific EffectSliding bearing:

Implementation Method 3

a spindle drive comprising a drive spindle rotated in the gripper body by the motor and an output spindle nut running on the drive spindle, which is coupled to a finger carrier connected to the first gripper finger in order to move the first gripper finger by means of a rotation of the drive spindle driven by the motor, the output spindle nut is adjusted linearly

Methodology Applied
Scientific EffectScrew mechanism: Screw

Data Source

PatentEP3585572B1Robot gripper having a drive device
Publication Date: 2021.05.05 KUKA DEUT GMBH
  • EP3585572B1 patent drawingFigure 1
  • EP3585572B1 patent drawingFigure 2~4
  • EP3585572B1 patent drawingFigure 5a~5c

AI summary

The invention relates to a robot gripper (1) having a drive device (20), which comprises a motor (M) and a gearbox, wherein the gearbox has a spindle drive, which has a drive spindle (21), driven in rotation in the main gripper body (12) by the motor (M), and an output spindle nut (22) running on the drive spindle (21), said output spindle nut (22) being coupled to a finger carrier (17) which is connected to a first gripper finger (16.1) in order to move the first gripper finger (16.1), wherein the output spindle nut (22) has a first nut body (22.1), which has a first thread (22a) corresponding to the drive spindle (21), has a second nut body (22.2), which has a second thread (22b) corresponding to the drive spindle (21), and the first nut body (22.1) is connected to the second nut body (22.2) by means of a parallel-link arrangement (50), which is configured to keep the first nut body (22.1) at a predetermined distance from the second nut body (22.2) and at the same time to allow a parallel offset of the first nut body (22.1) from the second nut body (22.2).