Robotic Arm Pulley Tensioning With Sliding Block Belt Retention
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Solution Overview
Problem
Pulley arrangements in robotic arms tend to fail due to cable loosening and breakage, and they often require a compact design that can withstand high driving forces, while maintaining reliability and efficiency.
Innovation Solution
A pulley arrangement featuring a base pulley portion and an adjustable pulley portion with a driving member that wraps around both, along with sliding blocks for tensioning, providing bilaterally symmetrical tensioning and a compact design that can handle significant forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a compact pulley arrangement is used, then the space requirement is reduced, but the ability to withstand high driving forces deteriorates
Solution Approach 1:
The pulley arrangement is divided into a base pulley portion and an adjustable pulley portion that can be positioned independently. This segmentation allows the driving member to wrap around both portions, creating multiple force transmission paths that increase the arrangement's force withstanding capability while maintaining a compact overall structure.
Solution Approach 2:
The adjustable pulley portion is positioned within or adjacent to the base pulley portion, creating a nested configuration. The driving member wraps around both pulley portions in sequence, allowing the compact nested structure to handle significant forces through the cumulative effect of multiple wrap-around contact points.
2Device complexity
If a simple pulley arrangement is used, then the device complexity is reduced, but the reliability deteriorates due to cable loosening and breakage
Solution Approach 1:
The adjustable pulley portion can be positioned at different locations along the base pulley portion to dynamically adjust the wrapping configuration of the driving member. This dynamic adjustability allows optimization of tension distribution and wrap angles to prevent cable loosening and breakage while maintaining a relatively simple overall structure.
Solution Approach 2:
The adjustable pulley portion acts as an intermediary element between the base pulley portion and the driving member. By positioning this intermediate component, the system creates additional contact points and tension distribution mechanisms that enhance reliability against cable loosening and breakage without significantly increasing structural complexity.
3Device complexity
If the driving member is wrapped around a single pulley, then the device complexity is reduced, but the force transmission capability and reliability deteriorate
Solution Approach 1:
The force transmission path is segmented into two distinct wrap-around sections: one around the base pulley portion and another around the adjustable pulley portion. This segmentation of the force transmission path allows the system to handle higher forces through distributed contact while maintaining a relatively simple two-pulley configuration.
Solution Approach 2:
The base pulley portion and adjustable pulley portion are combined in series within the same force transmission path. The driving member wraps around both portions sequentially, merging their individual force transmission capabilities into a unified system that can handle significant forces while keeping the overall device complexity low.
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 solution enhances the reliability and compactness of pulley arrangements by maintaining tension and withstanding high forces, reducing the likelihood of failure and improving the operational performance of robotic arms.
Implementation Method 1
The first and second sliding blocks are configured to move circumferentially toward each other in response to compression of the adjustable pulley portion against the base pulley portion
Data Source
Figure 1A~1B
Figure 1C~1D
Figure 2A~2B
AI summary
In one variation, a pulley arrangement includes a base pulley portion rotatable within a driving plane, an adjustable pulley portion coupled to the base pulley portion wherein the adjustable pulley portion is rotatable relative to the base pulley portion within the driving plane, and a driving member including an end coupled to the adjustable pulley portion wherein at least a portion of the driving member is wrapped at least partially around the adjustable pulley portion. In another variation, a pulley arrangement includes a base pulley portion rotatable around an axis, an adjustable pulley portion coupled to the base pulley portion and movable in a first direction parallel to the axis, and a sliding block engaged with the adjustable pulley portion, wherein the sliding block moves in a second direction different from the first direction, in response to compression of the adjustable pulley portion against the base pulley portion.