Redundant Parallel Positioning Table for Synchrotron Diffractometers
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Solution Overview
Problem
Existing positioning devices for synchrotron diffractometers face challenges in handling heavy loads, requiring increased precision, speed, and compactness while maintaining stability, with limitations in workspace, load capacity, and complexity in motion control due to the design of actuation struts and singularities.
Innovation Solution
A redundant parallel positioning table with a modular design featuring four symmetrically arranged supporting legs, each comprising active and non-active positioning units, allowing for six-degrees-of-freedom motion and incorporating planar and spherical guiding surfaces to enhance stiffness, precision, and speed, while avoiding singularities through redundant actuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If hexapod structures are used for positioning, then precision and dynamics are improved, but the device volume and height become too big for the allocated diffractometer space
Solution Approach 1:
The positioning device is segmented into a base unit, a movable platform, and multiple supporting legs with actuators. This segmentation allows the system to achieve precise positioning through coordinated motion of individual segments while maintaining a compact overall structure suitable for diffractometer integration.
Solution Approach 2:
The supporting legs are designed with telescopic actuators that can be nested within each other, allowing the legs to extend only when needed for positioning operations. This nesting principle significantly reduces the device height and volume when not in use, solving the space constraint problem in diffractometers.
2Force
If the number of actuators and components in supporting legs is increased to improve load capacity, then the maximum manipulated load is improved, but the device complexity and singularity detection difficulty increase
Solution Approach 1:
Each supporting leg is designed as a universal module capable of handling both vertical loads and lateral forces. The legs incorporate multiple degrees of freedom with integrated actuators that can perform various positioning functions, allowing the system to achieve high load capacity with a standardized, less complex modular structure.
Solution Approach 2:
The device incorporates redundancy in its supporting leg structure, where each leg is designed to handle potential singularity conditions and load variations beforehand. This preemptive design approach allows the system to maintain stability and performance under varying loads without requiring overly complex real-time control systems.
3Measurement precision
If actuation struts are packed with motors, gearheads, guides, and sensors to improve positioning precision, then measurement precision is improved, but the workspace becomes restricted due to intersected actuators
Solution Approach 1:
The actuators are arranged in a three-dimensional configuration around the supporting legs, utilizing vertical and radial spaces that would otherwise be unused. This spatial arrangement allows motors, gearheads, and sensors to be positioned without intersecting the horizontal workspace, effectively adding dimensional utilization to resolve the conflict between precision components and workspace availability.
4Speed
If moving motorized legs are used to improve positioning speed, then positioning speed is improved, but undesired dynamic effects occur affecting maximum speed
Solution Approach 1:
Each motorized leg incorporates sensors that provide real-time feedback on position, velocity, and acceleration to the control system. This feedback mechanism allows for dynamic compensation of vibrations and resonant effects, enabling the system to achieve high positioning speeds while maintaining motion stability through active control.
Solution Approach 2:
The supporting legs are designed with movable motorized joints that can dynamically adjust their stiffness and damping characteristics during operation. This dynamic design allows the system to optimize for speed during rapid positioning while automatically compensating for stability issues during fine positioning, resolving the contradiction between speed and stability.
Data Source
AI summary
The present invention is related a redundant parallel positioning table device. More particularly, the present invention relates to a redundant parallel positioning table device for a precise positioning of heavy load samples, instrument and/or apparatus, e.g. in the context of diffractometer machines for synchrotron facilities.