3 DOFs Decoupling Spherical Parallel Mechanism
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Solution Overview
Problem
Current 3 DOFs spherical parallel mechanisms lack decoupling capability, restricting the independent rotation of the moving platform in three directions.
Innovation Solution
A 3 DOFs decoupling spherical parallel mechanism is designed with a rotation assembly, first and second arc kinematic chains, and arc rods that allow the moving platform to rotate 360 degrees around a direction perpendicular to the fixed platform, enabling independent rotation in three directions through tangential movement of the arc rods along the kinematic chains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional spherical parallel mechanisms with intersecting prismatic pair axes are used, then 3 DOFs motion is achieved, but decoupling capability is lost and motion control becomes complex
Solution Approach 1:
The mechanism segments the motion control into three independent rotational DOFs by configuring three arc kinematic chains with their prismatic pair axes intersecting at a common point. Each arc rod independently controls one rotational DOF of the moving platform, achieving motion decoupling where each actuator controls only one degree of freedom without interfering with the others.
Solution Approach 2:
The invention uses arc-shaped kinematic chains instead of straight linear chains, introducing curvature in the kinematic path. The arc rods move along tangential directions of the arc chains, creating a geometric constraint that enables independent rotational control around the spherical center. This dimensional change from linear to arc geometry provides the decoupling capability.
2Adaptability or versatility
If arc prismatic pairs are used to restrict moving platform rotation, then working space is increased, but decoupling capability is not achieved
Solution Approach 1:
Each arc kinematic chain is configured with specific geometric parameters (arc radius, orientation) that are optimized for its particular rotational DOF. The first, second, and third arc chains have different spatial orientations and geometric characteristics, allowing each to independently control one rotational axis while contributing to the overall enlarged working space of the spherical parallel mechanism.
Data Source
AI summary
A 3 DOFs decoupling spherical parallel mechanism provided by the present disclosure comprises: a fixed platform, a rotation assembly, a moving platform, a first arc kinematic chain, a second arc kinematic chain, a first arc rod, and a second arc rod. In the 3 DOFs decoupling spherical parallel mechanism, the rotation assembly can drive the moving platform to rotate by 360 degrees around a direction being perpendicular to the fixed platform, and the first arc rod and the second arc rod reciprocate along tangential directions of the first arc kinematic chain and of the second arc kinematic chain respectively to enable the moving platform to rotate around an axis of a plane where the first arc kinematic chain or the second arc kinematic chain is located. In this way, the rotations of the moving platform in three directions are respectively driven by driving units in three directions and being independent from each other, such that the three rotation actions of the mechanism have decoupling capability.