Flexible Wire Power Transmission Mechanism for Medical Manipulators
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Solution Overview
Problem
Conventional medical manipulators face limitations in power transmission due to issues such as elastic deformation, inadequate rotational rigidity, and fatigue fractures, particularly when using wires or links, which affect their operability and durability, especially when dealing with complex movements and high load torques.
Innovation Solution
A power transmission mechanism utilizing a flexible power transmission member, such as a wire, with a driving link and driven pulley system, where the wire is doubled to reduce stress and secured by clamping members, and a mechanical fuse mechanism is incorporated to prevent damage from excessive torque, ensuring high reliability and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a wire with small diameter is used in the power transmission mechanism, then the size of the mechanism is reduced, but elastic deformation increases and sufficient power transmission cannot be achieved
Solution Approach 1:
The wire is divided into multiple segments (first wire segment and second wire segment) that are doubled back and secured by clamping members. This segmentation allows the wire to maintain smaller diameter while distributing stress across multiple sections, reducing elastic deformation and improving power transmission capability.
Solution Approach 2:
The wire is configured to extend in multiple directions (first direction and second direction opposite to each other) rather than a single linear path. This dimensional change allows the power transmission mechanism to achieve sufficient rigidity and power transmission with a smaller wire diameter by utilizing the spatial arrangement of doubled wire segments.
2Reliability
If the diameter of the pulley is sufficiently larger than the diameter of the wire, then a sufficient life is obtained and fatigue fracture is prevented, but the power transmission mechanism becomes larger and rigidity decreases
Solution Approach 1:
The wire is segmented into multiple sections secured by clamping members at intervals along its length. This segmentation reduces the span between support points, allowing the use of smaller diameter pulleys while maintaining sufficient service life and preventing fatigue fracture, as each segment is better supported and experiences reduced bending stress.
3Strength
If a link is made sufficiently thick to prevent buckling, then structural integrity is maintained, but the weight increases
Solution Approach 1:
The rigid link structure is replaced with a flexible wire-based power transmission system using pulleys. Instead of relying on thick links to resist buckling, the invention uses tension-based wire segments guided by pulleys, achieving equivalent structural integrity with significantly reduced weight, as wires have much higher strength-to-weight ratios than solid links.
4Strength
If two links are disposed in parallel to prevent buckling, then buckling resistance is improved, but the assembly precision requirement increases
Solution Approach 1:
The parallel link configuration is replaced with a single wire segmented into multiple sections secured by clamping members. This substitution eliminates the need for precise parallel alignment of multiple links, as the wire segments are individually secured and naturally maintain their positions through tension and clamping, significantly reducing assembly precision requirements.
5Device complexity
If the wire is not doubled and secured by clamping members, then the structure is simpler, but stress concentration occurs and reliability decreases
Solution Approach 1:
The wire is divided into multiple secured segments rather than a single continuous span. Clamping members are positioned at intervals along the wire to create multiple short supported sections, which distributes stress and prevents concentration at any single point, thereby reducing fatigue fracture risk while maintaining reasonable structural complexity.
Solution Approach 2:
The wire is pre-secured by clamping members at predetermined positions before operation. This preliminary securing action ensures proper stress distribution and alignment from the start of operation, preventing stress concentration and improving reliability by establishing correct mechanical conditions before loads are applied.
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 enables a robot or manipulator with high rigidity, wide movement range, and enhanced reliability, preventing fatigue and damage from overloads, while maintaining a compact and lightweight design suitable for precise operations.
Implementation Method 1
a flexible power transmission member (51), an input rotation shaft (52), a driving link (53) and a driven pulley (54)
Implementation Method 2
the flexible power transmission member is hung around the driving pulley (54)
Implementation Method 3
transmits a rotation torque of the input rotation shaft (52) to the flexible power transmission member (51)
Data Source
Figure 1A~1B
Figure 2~3
Figure 4
AI summary
A robot has a flexible power transmission member, an input rotation axis rotated by a power generation source, a driving link connected at both ends of the flexible power transmission member, which transmits a rotation torque of the input rotation axis to the flexible power transmission member, and a driven pulley around which the flexible power transmission member is hung.