Integrated Pulley Lug Structure for Compact Robotic Arm Joints
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Solution Overview
Problem
Current surgical robots employ strap drive trains for robotic arm movement, which require a compact design to avoid interference in limited spaces, but this results in a large joint size due to the thickness of the pulley and lugs, compromising operational accuracy and reliability.
Innovation Solution
A pulley design with a wheel portion featuring a main arc face and a branch arc face, forming a continuous circular arc surface for strap wrapping, and a lug portion that protrudes radially to connect the pulley to a driven unit, reducing the thickness of the connection and eliminating the need for additional tabs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a traditional pulley design with separate lugs and tabs is used to connect the robotic arm to the driven unit, then the connection is stable and reliable, but the joint size becomes large due to the thickness of the pulley and lugs, causing interference in limited spaces
Solution Approach 1:
The patent merges the pulley wheel and the lug into a single integrated component. The lug is formed as an extension of the pulley wheel itself, eliminating the need for separate lugs and tabs. This integration reduces the overall joint size while maintaining the connection stability through the unified structure that combines the strap-driven arc surface and the connection protrusion into one reliable assembly.
Solution Approach 2:
The integrated pulley-lug component serves multiple functions simultaneously: it acts as the strap-driven pulley with the arc surface for strap wrapping, and also serves as the connection element (lug) that protrudes to connect with the driven unit. This multi-functionality eliminates the need for separate connection components, reducing joint size while maintaining reliability.
2Volume of moving object
If the pulley thickness is reduced to minimize joint size, then interference between multiple robotic arms is avoided, but the connection reliability and stability may be compromised
Solution Approach 1:
The patent optimizes the pulley design by utilizing the radial dimension effectively. The lug protrudes radially from the pulley wheel, allowing the connection to be made at the periphery rather than requiring increased axial thickness. This dimensional approach reduces pulley thickness while maintaining connection reliability through the radial extension of the lug.
Solution Approach 2:
The integrated design allows different parts of the component to have optimized local properties: the pulley wheel portion has the appropriate thickness and arc surface for strap engagement, while the lug portion extends radially to provide the connection function. This local optimization ensures that each functional area has the necessary characteristics without requiring the entire component to be thicker.
Data Source
AI summary
A pulley and a structure having the pulley connected with a driven unit are provided. The pulley includes a wheel portion and a lug portion. The wheel portion includes two circular end surfaces opposing each other and a side surface connecting the two end surfaces. The side surface includes a main arc face and a branch arc face. The branch arc face has a head end connected to the main arc face and a tail end configured to connect a strap. The branch arc face has a width in an axial direction of the wheel portion smaller than a width of the main arc face. The lug portion is fixed to the wheel portion, disposed at a position adjacent to the branch arc face along the width of the main arc face and extends to protrude beyond the branch arc face in a radial direction of the wheel portion.