Over-Constrained Two-Rotation Parallel Mechanism With Large Rotation Space
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Solution Overview
Problem
Current over-constrained two-rotation parallel mechanisms lack designs with high rigidity, large working space, and easy calibration, while kinematically equivalent mechanisms with same kinematics but different structures are not well-represented in existing technologies.
Innovation Solution
A class of over-constrained two-rotation parallel mechanisms with equilateral triangle bases and moving platforms, featuring four branches with specific rotating and universal joint configurations, including RRS, RPUR, RRU, UPRR, and SR series branches, providing high rigidity, large working space, and easy control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If non-over-constrained two-rotation parallel mechanism is used, then the structure is simple and rotation is flexible, but the rigidity is reduced
Solution Approach 1:
The patent employs over-constrained dynamic structures with multiple rotating pairs and universal joints that maintain flexibility while enhancing rigidity through redundant constraints. The mechanism dynamically adapts its constraint distribution to maintain both simplicity and strength.
Solution Approach 2:
The patent changes the constraint parameters by introducing over-constrained conditions with specific rotating pair configurations (first rotating pair, second rotating pair, universal joints) that transform the mechanism from under-constrained to over-constrained, thereby improving rigidity while maintaining operational flexibility through parameter optimization.
2Device complexity
If traditional parallel mechanism configurations are used, then the structure is conventional, but the working space is limited
Solution Approach 1:
The patent extends the mechanism into additional dimensional spaces by configuring branches in three-dimensional space with specific spatial arrangements of rotating pairs and universal joints, thereby expanding the working space beyond conventional two-dimensional parallel mechanism configurations.
Solution Approach 2:
The patent employs nested branch configurations where multiple links and joints are arranged in hierarchical structures (RRS, RPUR, RRU series branches), allowing compact packaging while maintaining large working space through nested spatial arrangements.
3Measurement precision
If complex calibration is required, then the control precision can be high, but the calibration process becomes difficult
Solution Approach 1:
The patent employs symmetric copying of branch structures (four branches with equivalent RRS, RPUR, RRU configurations) that replicate the same kinematic characteristics, allowing calibration to be performed once and automatically copied to all branches, thereby maintaining high precision while simplifying the calibration process.
Solution Approach 2:
The patent designs universal joint configurations and standardized rotating pairs that serve multiple functions across different branches, enabling a single calibration procedure to validate the entire mechanism, thus achieving high control precision with simplified calibration operations.
Data Source
AI summary
The present invention relates to a class of over-constrained two-rotation parallel mechanism with same kinematics, which comprises a base, a moving platform and four branches connecting the base and the moving platform, wherein the base and the moving platform are equilateral triangles, both ends of each of the first branch, the second branch and the third branch are respectively connected to end points of the base and the moving platform, both ends of the fourth branch are respectively connected to center points of the base and the moving platform, the first branch and the third branch both consist of a first rotating pair. The parallel mechanism of the present invention has a large rotation space and high rigidity, and can be used for positioning equipment such as missile launchers.