6-DOF Stage Positioning With Maglev Measuring Head Compensation
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Solution Overview
Problem
Existing positioning systems face challenges in achieving high-accuracy measurements of a movable object in six degrees of freedom relative to a stationary object due to large fluctuations in scanning distance and tilts, particularly when using magnetic levitation units, which require substantial calibration and computational efforts.
Innovation Solution
A positioning device with two intersecting linear axes, where a measuring head is supported by a second magnetic levitation unit, allowing it to compensate for unwanted movements, thereby minimizing fluctuations and improving measurement accuracy by using two 6-DOF encoders to determine the position relative to a carrier device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a measuring head is mounted on a linear axis to determine stage position, then position measurement is enabled, but large fluctuations and tilts in scanning distance occur due to guiding errors and axis movements
Solution Approach 1:
A second magnetic levitation unit is introduced as an intermediary between the linear axis and the measuring head. This intermediary actively compensates for unwanted movements and tilts of the linear axis, stabilizing the scanning distance between the measuring head and the stage while enabling accurate position measurement through the 6-DOF encoders.
2Manufacturing precision
If magnetic levitation is used for fine positioning of the stage, then positioning accuracy is improved, but device complexity increases due to additional control systems
Solution Approach 1:
The magnetic levitation units serve multiple functions: they provide fine positioning of the stage, support the measuring head, and actively compensate for linear axis movements. This multi-functionality reduces the need for separate compensation mechanisms, thereby managing device complexity while achieving high positioning accuracy.
3Adaptability or versatility
If two intersecting linear axes are used for pre-positioning, then positioning capability in multiple directions is improved, but fluctuations in scanning distance increase due to guiding errors
Solution Approach 1:
The second magnetic levitation unit operates with active feedback control to sense and compensate for unwanted movements and tilts of the linear axes. This feedback mechanism stabilizes the scanning distance despite the presence of multiple linear axes with guiding errors, maintaining measurement precision while preserving multi-directional positioning capability.
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 significantly reduces calibration and computational efforts, enhancing measurement accuracy by compensating for scanning distance and tilt fluctuations, enabling precise positioning of a stage relative to a tool on a carrier device.
Implementation Method 1
a first magnetic levitation unit is configured to support the stage on a first one of the two linear axes
Implementation Method 2
A second magnetic levitation unit is disposed on the second one of the two linear axes and is configured to actively move the measuring head in the six degrees of freedom
Data Source
AI summary
A positioning device for positioning a stage relative to a tool mounted on a carrier device includes two intersecting linear axes disposed one above the other for pre-positioning the stage. A first magnetic levitation unit is configured to support the stage on one of the linear axes, the stage being actively movable for fine positioning in six degrees of freedom. A measuring head and first and second 6-DOF encoders are configured to determine a position of the stage relative to the carrier device. The measuring head is mounted on the other linear axis. The first 6-DOF encoder is disposed between the carrier device and the measuring head and the second 6-DOF encoder is disposed between the measuring head and the stage. A second magnetic levitation unit disposed on the other linear axis is configured to actively move the measuring head in the six degrees of freedom.