Electromagnetic Motor Commutation Model for Faster Precision Positioning
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Solution Overview
Problem
Existing calibration processes for electromagnetic motors in lithographic apparatuses are time-consuming and cumbersome due to numerous variables and mechanical tolerances, leading to inaccuracies in motor positioning.
Innovation Solution
A method to determine a motor-dependent commutation model for electromagnetic motors, involving a coil array and magnet array, using a compensation matrix to correct for discrepancies between desired and actual motor forces, thereby improving positioning accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If known calibration processes are used for electromagnetic motors, then positional accuracy can be achieved, but the process becomes time-consuming and cumbersome due to many variables
Solution Approach 1:
The patent changes the parameters of the commutation model by introducing a motor-specific compensation matrix that accounts for mechanical tolerances and physical property variations. This transforms the general commutation model into a tailored model for each specific motor, reducing the number of calibration variables and steps required while maintaining high positional accuracy.
Solution Approach 2:
The patent performs preliminary characterization of motor-specific parameters (mechanical tolerances, physical properties) during manufacturing or initial setup. This preliminary action creates a compensation matrix that can be directly applied in the commutation model, eliminating the need for time-consuming calibration processes later while ensuring accurate positioning.
2Ease of operation
If a general commutation model is used for electromagnetic motors, then the model is simple to apply, but positioning accuracy deteriorates due to mechanical tolerances and physical property variations
Solution Approach 1:
The patent applies local quality by introducing motor-specific compensation parameters into the commutation model. Instead of using a uniform general model for all motors, each motor receives a tailored compensation matrix that accounts for its specific mechanical tolerances and physical properties. This localized adaptation maintains ease of model application while significantly improving positioning accuracy for each individual motor.
3Measurement precision
If calibration processes account for many variables to improve accuracy, then positioning precision improves, but the complexity of the calibration process increases
Solution Approach 1:
The patent extracts the complex motor-specific parameters (mechanical tolerances, physical property variations) from the calibration process and incorporates them into a pre-determined compensation matrix. This extraction removes the complexity of handling multiple variables during calibration while maintaining the precision benefits, as the compensation matrix encapsulates all necessary corrections in a straightforward form.
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 method provides a more efficient and accurate positioning of electromagnetic motors, reducing inaccuracies caused by mechanical and physical variations in motor components.
Implementation Method 1
a second member comprising a magnet array configured to generate a spatially alternating magnetic field, whereby the first member and the second member are configured to displace relative to each other in N degrees of freedom
Data Source
AI summary
The invention provides a method of determining a motor-dependent commutation model for an electromagnetic motor, whereby the electromagnetic motor comprises a first member comprising a coil array comprising at least M coils, and a second member comprising a magnet array configured to generate a spatially alternating magnetic field, whereby the first member and the second member are configured to displace relative to each other in N degrees of freedom, N<M, by supplying the at least M coils with respective at least M currents Im, thereby generating forces in the N degrees of freedom, the method comprising the steps of: obtaining a commutation model G for the electromagnetic motor, the general commutation model G providing a relationship between desired forces Fc in the N degrees of freedom and the at least M currents Im applied to the coil array by Im=G*Fc.