Parallel Link Mechanism With Singular-Point Avoidance
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Solution Overview
Problem
Existing parallel link mechanisms face challenges in achieving a wide operating range without increasing size and reducing rigidity, and the presence of singular points limits their operational flexibility and control.
Innovation Solution
A parallel link mechanism with a two-degrees-of-freedom design, incorporating specific axis angles and maximum bending angles to avoid singular points, allowing for a wide operating range and smooth motion, coupled with a link actuating device for posture control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the link length is increased to set the operating range of the travelling plate to be large, then the operating range is improved, but the dimensions of the entire mechanism are increased and the size of the device is increased
Solution Approach 1:
The invention changes the operating parameters by increasing the operating angle of each link to 90° or more. This parameter change allows the mechanism to achieve a larger operating range without proportionally increasing the link lengths and overall device dimensions, thereby resolving the contradiction between operating range and device size
Solution Approach 2:
The invention employs a spherical parallel link mechanism where the links are arranged radially from a central axis, creating a spherical working space. This spherical configuration allows the traveling plate to move through a wide range of positions and orientations within the spherical volume, achieving large operating range without requiring long linear link extensions that would increase device size
2Adaptability or versatility
If the link length is increased to set the operating range of the travelling plate to be large, then the operating range is improved, but the rigidity of the entire mechanism is reduced
Solution Approach 1:
By changing the operating angle parameter to 90° or more, the mechanism achieves large operating range while maintaining shorter link lengths. This parameter optimization prevents the rigidity loss that would occur with excessively long links, as the links remain sufficiently stiff while still providing the required range of motion through the spherical configuration
Solution Approach 2:
The mechanism divides the motion function across multiple links arranged in parallel, with each link contributing to the overall operating range. This segmentation allows each individual link to maintain adequate rigidity while the collective arrangement provides the large operating range, as no single link needs to be excessively long
3Adaptability or versatility
If the operating angle of each link is increased to 90° or more, then the operating range is improved, but the device complexity increases due to precise angle control requirements
Solution Approach 1:
The spherical parallel link mechanism structure itself provides geometric constraints that naturally guide the motion along the spherical path. The mechanism's geometry inherently maintains the 90° or more operating angles through its radial link arrangement and spherical joint configuration, eliminating the need for complex active control systems to enforce these angle requirements
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 mechanism achieves a compact size with a wide operating range, smooth motion, and high precision, avoiding singular points, enabling efficient operation and durability.
Implementation Method 1
each of the link mechanisms includes: a proximal side end link member rotatably coupled at one end thereof to the proximal end side link hub; a distal side end link member rotatably coupled at one end thereof to the distal end side link hub; and a center link member rotatably coupled at both ends thereof to other ends of the proximal and distal side end link members
Data Source
AI summary
In a parallel link mechanism, a distal end side link hub is coupled to a proximal end side link hub via three link mechanisms such that a posture of the distal end side link hub can be changed. Each link mechanism includes a proximal side end link member, a distal side end link member, and a center link member, and forms a quadric chain link mechanism composed of four revolute pairs. A singular point occurs when a central axis of the proximal or distal end side link hub and a central axis which is a rotation axis of a revolute pair section of the proximal or distal side end link member and the center link member coincide with each other. An axis angle of the center link member is specified such that a posture in which the singular point occurs is avoided.