Parallel Link Actuation for Variable-Radius Spherical Motion Control
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Solution Overview
Problem
Existing parallel link mechanisms struggle to maintain a consistent center of rotation for the distal end member, limiting its movement to a sphere with a fixed radius and making independent control of the radius of rotation during rotational movement impossible, which complicates the operation and control of the distal end member.
Innovation Solution
A parallel link mechanism with a proximal end member connected to a distal end member through three or more link mechanisms, where the first to fourth link members form revolute pairs, intersecting at a spherical link center point, allowing the distal end member to move on a sphere with a variable radius, and incorporating posture control drive sources to adjust the posture of the distal end member relative to the proximal end member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the link length is increased to achieve a large operating range of the traveling plate, then the operating range is improved, but the size of the entire mechanism increases
Solution Approach 1:
The invention employs a parallel link mechanism where the distal end member can move on a sphere with variable radius. The mechanism dynamically adjusts the effective operating radius through the spherical movement capability, allowing a compact structure to achieve a large operating range without increasing overall mechanism size. The five-bar chain configuration enables dynamic reconfiguration of the movement path.
Solution Approach 2:
The invention transitions from planar movement to spherical movement by allowing the distal end member to move on a sphere. This dimensional change from 2D to 3D spherical coordinates enables the mechanism to achieve a larger operating range within a compact volume by utilizing spatial freedom in multiple dimensions.
2Productivity
If the distal end member is allowed to move in a wide operating range at high speed, then the productivity is improved, but the control precision of the radius of rotation deteriorates
Solution Approach 1:
The invention incorporates posture control drive sources that can independently control the radius of rotation while maintaining high-speed operation. The control system provides feedback to adjust the spherical movement parameters, ensuring precise control of the distal end member's position and posture despite high-speed movements across a wide operating range.
3Adaptability or versatility
If the distal end member operates with two degrees of freedom of rotation, then the adaptability is improved, but the ease of operation deteriorates due to inability to control radius independently
Solution Approach 1:
The invention segments the control functions by providing independent control mechanisms for the radius of rotation and the rotational movement. The posture control drive sources are distributed across the link mechanisms, allowing independent adjustment of spherical coordinates (radius, polar angle, azimuthal angle) without coupling effects, thereby simplifying operation despite maintaining two degrees of freedom.
Data Source
AI summary
A parallel link mechanism includes a proximal end member and three or more link mechanisms. Three or more link mechanisms connect the proximal end member to a distal end member. In three or more link mechanisms, a first center axis of a first revolute pair unit and a second center axis of a second revolute pair unit intersect at a spherical link center point. Fifth center axes of respective fifth revolute pair units of three or more link mechanisms overlap each other and intersect with the spherical link center point.