Planar Positioning Workbench With Parallel Kinematics for Nanometer Precision
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Solution Overview
Problem
Existing planar positioning devices face challenges in achieving high precision and speed due to cumulative positioning errors in stacked systems, difficulty in achieving low height, and varying dynamic requirements, especially in nanometer-scale applications like semiconductor technology.
Innovation Solution
A planar positioning device utilizing a 3-PRR parallel kinematic unit with four drives arranged symmetrically, including two drives on a common axis and two on separate axes, allowing for redundant motion and motion attenuation, combined with Halbach arrays and 1D/2D sensor grids for precise position detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If stacked single-axis systems are used for positioning, then positioning functionality is achieved, but positioning errors accumulate and precision deteriorates
Solution Approach 1:
The positioning system is segmented into multiple independent linear drives (first, second, third, and fourth linear drives) that operate in parallel rather than stacked. Each drive independently contributes to positioning without accumulating errors from sequential operations, thereby maintaining precision while achieving the required positioning functionality.
Solution Approach 2:
The patent transitions from a vertical stacked configuration to a planar arrangement where linear drives are distributed across different spatial dimensions (X and Y axes). This dimensional redistribution eliminates cumulative positioning errors by ensuring all drives operate simultaneously in a coordinated manner rather than sequentially.
2Length of moving object
If stacked systems are used to achieve positioning, then positioning capability is provided, but the height of the device increases
Solution Approach 1:
The patent redistributes the positioning drives from a vertical stack to a horizontal planar arrangement. The first and second linear drives operate along one axis while the third and fourth drives operate along a perpendicular axis, transforming the vertical height problem into a horizontal layout solution that maintains compactness while improving precision.
Solution Approach 2:
Multiple linear drives are merged into a coordinated parallel system where the first, second, third, and fourth drives work simultaneously rather than sequentially. This merging allows the system to achieve positioning in a single operational layer, reducing overall device height while maintaining positioning accuracy through coordinated operation.
3Measurement precision
If redundant drives are added for precision, then positioning accuracy improves, but device complexity and cost increase
Solution Approach 1:
The patent employs an asymmetric distribution of drive functions where the first and second linear drives share a common axis, creating a balanced yet asymmetric configuration. This asymmetric design allows for optimized error compensation without requiring complete symmetry, reducing the number of drives needed while maintaining high positioning accuracy through strategic placement and coordination.
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 solution enables high precision, adaptability, and cost-effectiveness by reducing installation space and costs, while providing increased precision and the ability to detect and compensate for errors and deformations, ensuring accurate and efficient positioning.
Implementation Method 1
The collinear linear guides/drives respectively comprise a common linear guide and two linear motors with guide carriages as sliders, which are arranged spaced apart on the guide and moveable collinearly and independently of one another in both directions. Alternatively, 'conventional' magnetic tracks are also possible. Both Halbach arrays and conventional magnetic tracks can be designed on one side and in a U-shape.
Data Source
AI summary
The invention relates to a planar positioning apparatus for positioning loads on a predetermined plane, said positioning apparatus comprising:—a base plate having a flat surface that extends parallel to and at a specific distance from the predefined positioning plane, thus defining same;—four identical linear guides/drives which are collinearly fastened to or on the base plate in pairs parallel to the two other linear guides/drives; and—a parallel kinematic unit which comprises a load platform, is disposed between the parallel linear guides/drives, and is rotationally connected to the rotors of all linear drives via one passive joint each.