Articulated Mechanical Arm Wire Path Length Holding Structure
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Solution Overview
Problem
Existing cable-driven articulated robotic arms face challenges in maintaining constant wire path lengths between the drive unit and the end effector, leading to instability and inefficiency due to varying wire lengths during link rotations.
Innovation Solution
A length holding structure is implemented, where wires are fixed at specific points on the links and connected to the drive unit, ensuring that the path length between the drive unit and the third link remains constant, using pulleys and interlocking gears to maintain wire tension and prevent unwanted rotation of the end effector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If wires are connected to the driver through moving links, then the link weight and size can be minimized, but the wire path length varies during link rotation causing coupled motion and instability
Solution Approach 1:
A reel is introduced as an intermediary component between the wire and the moving link. The reel rotates with the link while the wire is wound on it, allowing the wire path length to remain constant even during link rotation. This mediator resolves the contradiction by enabling both lightweight links and stable motion control.
2Device complexity
If the wire path length is allowed to vary during link rotation, then the mechanism can be simpler, but the end effector experiences coupled motion and position instability
Solution Approach 1:
The reel acts as a mediator that maintains constant wire path length while the link rotates. By winding the wire on the reel, the system achieves precise end effector positioning without complex wire path management, resolving the contradiction between simplicity and precision.
Solution Approach 2:
The reel is designed to rotate dynamically with the link, adapting its orientation to maintain constant wire path length throughout the motion range. This dynamic adjustment enables precise control while keeping the mechanism relatively simple.
3Length of moving object
If the driver is located at a part with no motion or little motion, then the link can be minimized in weight and size, but wire path length variations cause coupled motion
Solution Approach 1:
The reel serves as a mediator that decouples the wire path length from link rotation. By placing the reel on the link and winding the wire on it, the system achieves both compact link dimensions and motion independence, as the wire path length remains constant regardless of link position.
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
This solution stabilizes the end effector's position by keeping wire path lengths constant, reducing torque disturbances and enhancing the control of link movements, thereby improving the driving efficiency and stability of the robotic arm.
Implementation Method 1
The path forming structure includes a first pulley provided on the second link; a second pulley rotatably coupled to the second rotation shaft; a third pulley provided on the second pulley; and a pair of fourth pulleys provided on the second pulley.
Implementation Method 2
the length holding structure may include a first interlocking gear provided on the second link; and a second interlocking gear provided on the second pulley to engage with the first interlocking gear
Data Source
Figure 1
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Figure 2B
AI summary
The invention relates to an articulated mechanical arm. The mechanical arm comprises a link unit; and a drive unit configured to drive the link unit; wherein the link unit comprises: a first link; a second link rotatably coupled to the first link; a third link rotatably coupled to the second link; a plurality of wires, each of which is fixed at one end thereof to the third link, and is connected at the other end thereof to the drive unit, and through which a driving force is transmitted from the drive unit to the third link; a path forming structure configured to define for each of the wires a path between the drive unit and the third link; and a length holding structure configured to hold substantially constant a length that each of the wires extends between the drive unit and the third link.