Variable-Axis Parallel Mechanism for Singularity Avoidance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Three-degree-of-freedom parallel mechanisms face challenges in force and torque transmission due to standard kinematic pairs with fixed axes, leading to unfavorable kinematic chain behavior and difficulty in avoiding singularities.
Innovation Solution
Incorporating flexible kinematic chains with axis-variable revolute pairs, where one end of the fixed member is fastened on the fixed platform and the other end fits against an inclined surface of the movable member, allowing the spherical hinge connecting rod to rotate and change axis direction, enhancing force and torque transmission while avoiding singularities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If standard kinematic pairs with fixed axes are used, then the structure is simple and easy to manufacture, but force and torque transmission is unfavorable and singularities cannot be avoided
Solution Approach 1:
The patent applies the dynamics principle by replacing fixed-axis revolute pairs with variable-axis revolute pairs. The axis of the revolute pair changes its orientation dynamically during motion, allowing the mechanism to adapt to different configurations and avoid singularities. This is achieved through the spherical hinge connection that enables the axis to pivot while maintaining the kinematic chain's functionality.
Solution Approach 2:
The patent implements parameter changes by allowing the axis orientation of the revolute pair to vary during operation. Instead of maintaining a fixed axis orientation, the mechanism changes the axial parameter dynamically, which improves force transmission characteristics and eliminates singular positions where the mechanism would fail.
2Device complexity
If standard kinematic pairs with fixed axes are used, then the structure is simple, but force and torque transmission efficiency is poor
Solution Approach 1:
The dynamics principle is applied to optimize power transmission by making the revolute pair axis variable rather than fixed. This allows the mechanism to maintain favorable force and torque transmission characteristics throughout its range of motion, preventing situations where power transmission becomes inefficient or impossible due to singular configurations.
3Device complexity
If standard kinematic pairs with fixed axes are used, then the mechanism structure is simple, but singularities cannot be avoided
Solution Approach 1:
The patent resolves the singularity problem by applying the dynamics principle to create variable-axis revolute pairs. The axis orientation changes during motion, which allows the mechanism to pass through configurations that would be singular for fixed-axis pairs, thereby eliminating singularities from the mechanism's operation.
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 flexible kinematic chains improve the stability and reliability of the parallel mechanism, enabling effective force and torque transmission and preventing singularities, resulting in a more stable and dexterous three-degree-of-freedom parallel mechanism suitable for applications like machine tools, aeronautical simulation, and medical equipment.
Implementation Method 1
The spherical pair is accommodated in the fixed member, and a spherical hinge connecting rod of the spherical pair penetrates the movable member
Data Source
AI summary
A three-degree-of-freedom parallel mechanism, includes a fixed platform, a movable platform, and three kinematic chains, where at least one of the three kinematic chains is a flexible chain; and the flexible chain includes a first connecting rod, a second connecting rod, and an axis-variable revolute pair, the axis-variable revolute pair includes a fixed member, a movable member, and a spherical pair, one end of the fixed member is fastened on the fixed platform, the other end of the fixed member fits and abuts against an inclined surface of the movable member, the spherical pair is accommodated in the fixed member, a spherical hinge connecting rod of the spherical pair penetrates the movable member, the first connecting rod is rotatably connected to the spherical hinge connecting rod and the second connecting rod, and the second connecting rod is spherically hinged to the movable platform.