Multi-Axis Positioning Stage With 5-DOF Joints for Submicron Precision
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Solution Overview
Problem
Hexapods, despite being the preferred multi-axis positioning stage, are cost-prohibitive due to the need for complex computing and high-performance actuators to manage synergistic motion, and they suffer from tolerance stack-up issues, making them expensive and difficult to achieve submicron precision.
Innovation Solution
A multi-axis positioning stage using prismatic actuators with five degrees of freedom, supported by magnetic joints and a baseplate, allows independent actuator movement without binding, eliminating the need for complex algorithms and reducing costs by avoiding rotary or linear bearings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If hexapod structure is used to achieve multi-axis positioning, then positioning capability is improved, but device complexity and cost increase exponentially
Solution Approach 1:
The hexapod system is segmented into six independent actuators, each capable of independent motion control. This segmentation allows each actuator to be controlled separately without requiring complex coordinated motion algorithms, simplifying the overall system complexity while maintaining multi-axis positioning capability.
Solution Approach 2:
Instead of using a parallel hexapod structure where multiple actuators work together synergistically (requiring complex coordination), the invention inverts the approach by using independent actuators with spherical joints that allow each actuator to move independently. This inversion eliminates the need for complex motion profile calculations and coordination algorithms.
2Measurement precision
If spherical joints with tight tolerances are used to improve resolution, then positioning precision is improved, but manufacturing cost and complexity increase exponentially
Solution Approach 1:
The invention extracts and eliminates the spherical bearings from the actuator joints, replacing them with a direct spherical joint design where a spherical surface contacts a flat surface. This removal of intermediate bearing components simplifies manufacturing while maintaining the ability to achieve tight tolerances and high resolution.
Solution Approach 2:
The invention replaces expensive, high-precision spherical bearings with simpler, more cost-effective spherical joint surfaces that can be manufactured at tighter tolerances. These simpler joint surfaces are easier and cheaper to manufacture while providing sufficient precision for the application.
3Manufacturing precision
If hexapod with high-performance actuators is used to achieve submicron precision, then positioning precision is improved, but actuator capability requirements and cost increase exponentially
Solution Approach 1:
The positioning task is segmented into six independent single-axis movements, each handled by a separate actuator. This segmentation allows each actuator to perform simple, straightforward motion without requiring complex coordinated control, reducing the performance capability requirements of individual actuators while achieving submicron precision through the cumulative effect of all six actuators.
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 proposed stage achieves submicron precision at a fraction of the cost of hexapods, with scalable axes and simplified actuator control, overcoming tolerance stack-up issues and enabling precise, cost-effective positioning.
Implementation Method 1
Magnetic force, gravity, and/or a pliable polymer, such as silicone, may be employed to keep the up to five DOF pivot points in contact with their respective (that is, top or bottom) plate
Implementation Method 2
Magnetic force, gravity, and/or a pliable polymer, such as silicone, may be employed to keep the up to five DOF pivot points in contact with their respective (that is, top or bottom) plate
Data Source
Figure 1(a)~1(l)
Figure 2~3
Figure 4
AI summary
A parallel position manipulator includes a top plate, a baseplate and a plurality of prismatic joint actuators. Each actuator includes an actuator joint having five Degrees of Freedom (DOF) at either the base plate or the top plate. When one or more of the actuators extends or contracts, the pivot points, or five DOF actuator joint, of the remaining actuators are allowed to shift in any axis other than that actuator's primary axis of motion.