XY Table Drive Unit Positioning for Zero Moment Balance
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Solution Overview
Problem
The XYθ table apparatus with three drive units has low positioning accuracy due to uneven movement of the movable table's end parts when one drive unit applies force in the X-direction, and increasing the number of drive units to four improves accuracy but increases costs.
Innovation Solution
An XYθ table apparatus with three drive units, where one drive unit applies force in the X-direction to the center of the movable table, and two symmetric drive units apply forces in the Y-direction, with plane guide bearings positioned to balance moment forces, ensuring zero total moment on the center axis line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If one drive unit exerts drive force in the X-direction to one end part of the movable table, then the structure is simple with three drive units, but the positioning accuracy is low due to uneven movement of end parts
Solution Approach 1:
The patent applies asymmetry by positioning the single X-direction drive unit at the center of the movable table in the Y-direction, rather than at an end part. This central positioning creates a symmetric force distribution that eliminates the uneven movement and positioning errors that would occur with asymmetric end-part positioning, while still maintaining the simple three-drive-unit configuration.
Solution Approach 2:
The patent introduces a moment force balancing mechanism as an intermediary concept. By calculating and balancing the moment forces generated by friction at the plane guide bearings against the moment force from the drive unit, the system mediates the force distribution to prevent rotational deviations, thereby maintaining positioning accuracy without adding extra drive units.
2Manufacturing precision
If four drive units are used to apply drive forces in both X and Y directions, then positioning accuracy improves, but the cost increases due to additional drive unit
Solution Approach 1:
The patent extracts the unnecessary fourth drive unit from the system. By demonstrating that three properly positioned drive units (one at the center for X-direction, two symmetrically for Y-direction) are sufficient to achieve high positioning accuracy through moment force balancing, the invention removes the redundant component while maintaining performance.
Solution Approach 2:
The patent changes the positional parameters of the drive units and plane guide bearings to optimize performance. Specifically, it positions the X-direction drive unit at the center and the Y-direction drive units symmetrically, while also positioning the plane guide bearings to achieve moment force balance, thereby achieving high accuracy with fewer units.
3Manufacturing precision
If the plane guide bearings are positioned to balance moment forces, then positioning accuracy is maintained with three drive units, but the arrangement becomes more complex
Solution Approach 1:
The patent applies local quality by optimizing the positioning of plane guide bearings at specific locations where they generate balanced moment forces. Rather than uniformly distributing bearings, it places them at strategic positions that create the necessary moment balance, achieving high precision with a simple bearing arrangement that matches the drive unit configuration.
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
This configuration achieves excellent positioning accuracy with three drive units, maintaining cost-effectiveness while preventing deviations and rotations during movement, enhancing the rigidity and accuracy of the movable table's linear and rotational movements.
Implementation Method 1
a frictional force generated at each of the plurality of plane guide bearings
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
One first drive unit (5) that advances or recedes in the X-direction and that exerts a drive force in the X-direction to a movable table (2) is arranged to exert a drive force to a center position in the Y-direction of one end part in the X-direction of the movable table (2). Two second drive units (6, 7) that advance or recede in the Y-direction that is perpendicular to the X-direction, and that exert the drive forces in the Y-direction to the movable table (2) are arranged to be point-symmetric with respect to the center (O) of the movable table (2) as the center of symmetry. Plural plane guide bearings (3) are arranged at positions such that the total sum of the moment forces of the respective plane guide bearings (3) is zero on the center axis line in the X-direction of the movable table (2). This moment force is calculated by multiplying a frictional force generated at the plane guide bearing (3) by the movement of the movable table (2) by a distance in the Y-direction between the plane guide bearing (3) and the first drive unit (5).