Mirror Angular Positioning Control for Vibration Suppression
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Solution Overview
Problem
Conventional galvano apparatuses face challenges in accurately positioning laser irradiation due to mirror vibrations in the falling direction, which leads to processing errors, especially when rapidly positioning the laser at multiple locations, as existing detectors cannot effectively detect these vibrations and suppress them in time.
Innovation Solution
A mirror positioning control system that includes a rotary encoder, a calculator, and an estimator to calculate and adjust the electric current supplied to the motor, using a transfer function model to estimate the facet angle error angle and adjust the current to ensure the mirror reaches the target angle within a tolerance, thereby suppressing vibrations and improving positioning accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dynamic balance adjustment is performed on the motor rotating shaft, then mirror vibration in the falling direction is suppressed, but vibration cannot be sufficiently removed when rapidly positioning the laser irradiation position
Solution Approach 1:
The control unit calculates and adjusts the electric current supplied to the motor in advance before the mirror reaches the target position, based on a model representing the relationship between electric current and facet angle error angle. This preliminary action allows vibration suppression without sacrificing positioning speed, as the adjustment is computed proactively rather than reactively.
Solution Approach 2:
The system uses a model-based feedback mechanism where the control unit continuously monitors positioning operations and adjusts the electric current based on the calculated facet angle error angle. This feedback loop ensures vibration suppression while maintaining high positioning speed through intelligent current control.
2Measurement precision
If the detector is used to detect the mirror rotational angle, then the rotational angle can be monitored, but the vibration of the mirror in the falling direction cannot be detected
Solution Approach 1:
The control unit acts as an intermediary that uses a model to infer the facet angle error angle (vibration) from the detected rotational angle. Instead of directly detecting vibration, the system calculates it based on the relationship between electric current and mirror angle, thereby recovering information that the detector alone cannot provide.
Solution Approach 2:
The system creates a virtual model of the mirror's vibrational state based on the detected rotational angle and electric current relationship. This model copy allows the system to estimate and compensate for vibrations even though the physical detector cannot directly measure them.
3Productivity
If positioning operations are performed continuously at multiple irradiation positions, then productivity is improved, but vibration waves superpose to generate large vibrations
Solution Approach 1:
Before each positioning operation, the control unit calculates the appropriate electric current adjustment based on the model, ensuring that vibration is suppressed in advance. This preliminary calculation prevents vibration accumulation during continuous positioning operations, allowing high productivity without vibration superposition.
Solution Approach 2:
The model-based feedback mechanism continuously adjusts the electric current for each positioning operation based on calculated facet angle error angles. This ensures that vibrations from previous operations do not accumulate, maintaining reliable vibration control during continuous high-speed positioning.
Data Source
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AI summary
The present invention provides an apparatus for angular positioning of a mirror, the apparatus including a motor configured to rotate a mirror, a detector configured to detect a rotational angle of the mirror, a controller configured to supply an electric current to the motor so that the rotational angle of the mirror reaches a target angle, to estimate, based on a model representing a relation between a value of the electric current to be supplied to the motor and a face tangle error angle of the mirror, a face tangle error angle of the mirror to which the electric current is supplied, and to, if the estimated angle exceeds a tolerance, perform a process of adjusting of a supply of the electric current to the motor so that the face tangle error angle of the mirror falls within the tolerance.