Redundant Parallel Positioning Table for Heavy-Load Precision Motion
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Solution Overview
Problem
Current positioning systems for heavy loads in synchrotron diffractometer applications face challenges with insufficient load capacity, limited workspace, and complexity in design, leading to issues with precision, speed, and stability, particularly in compact environments.
Innovation Solution
A redundant parallel positioning table device with a 6-4-213 kinematic mechanism, featuring four symmetrically arranged supporting legs with redundant actuation, allowing for modular design and compact structure, enabling precise and fast movements in six degrees of freedom, and accommodating heavy loads with enhanced stiffness and dexterity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a standard hexapod parallel kinematic mechanism is used for positioning heavy loads, then the payload capacity and positioning precision are improved, but the device volume and height become too large for the available diffractometer working space
Solution Approach 1:
The positioning device is segmented into a stationary base, a moveable table, and four supporting legs arranged in pairs. Each supporting leg is independently actuated, allowing the system to achieve positioning functionality with fewer components than a traditional hexapod, thereby reducing device volume while maintaining positioning precision for heavy loads
Solution Approach 2:
Each supporting leg is designed with redundant actuation capability that can provide both vertical support and positioning functions. This multi-functionality allows the four-leg configuration to replace the traditional six-leg hexapod structure, reducing the overall device volume and height while maintaining the ability to handle heavy loads with required precision
2Force
If the rotation center point distance is increased to accommodate heavy loads, then the load capacity is improved, but the rotation center point distance moves outside the available diffractometer working space
Solution Approach 1:
The supporting legs are arranged in pairs with specific spatial orientations that allow the rotation center to be positioned within the working space envelope. The paired arrangement creates balanced force distribution that maintains load capacity while keeping the rotation center distance within the available diffractometer working space dimensions
3Measurement precision
If redundant actuation is implemented in the supporting legs, then the positioning precision and stability are improved, but the device complexity increases
Solution Approach 1:
The redundant actuation functions are merged into the existing supporting leg structures. Each supporting leg integrates multiple actuation capabilities within a unified mechanical framework, allowing the system to achieve enhanced positioning precision and stability without proportionally increasing overall device complexity
Solution Approach 2:
The actuation system parameters are optimized by implementing redundant actuation only in the supporting legs where it provides maximum benefit for positioning precision. This selective parameter change approach maintains stability and precision while controlling the increase in device complexity
Data Source
AI summary
A redundant positioning table device with six or fewer degrees of freedom having four modular legs extended from a base to a table, each legs being with three levels and the same types of joints. In one embodiment, the bottom joint is planar and active, the middle joint is prismatic and passive, and the top joint is spherical and passive. In another embodiment, the bottom joint is prismatic and passive, the middle joint is planar and active, and the top joint is spherical and passive. Fewer than six degrees of freedom is achieved by reducing the number of degrees of freedom of designated joints.