Optical Image Stabilizer Actuator Control via Frequency-Adaptive PID Switching
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Solution Overview
Problem
Existing optical image stabilizers face challenges in accurately controlling actuators to prevent image blur caused by low and high frequency hand-shakes, as proportional-integral-derivative (PID) controllers struggle to optimize coefficients for both frequencies, leading to excessive oscillation and inadequate compensation.
Innovation Solution
An apparatus and method that determine the hand-shake frequency using a distance calculator and a PID coefficient selection and switching controller, applying specific PID coefficients for low or high frequencies to the PID controller, optimizing actuator control for both frequencies by storing and switching between pre-determined coefficient sets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single set of PID coefficients is used to control the actuator, then the controller is simple to implement, but it cannot accurately control both low and high hand-shake frequencies
Solution Approach 1:
The patent implements dynamic switching of PID coefficients based on detected hand-shake frequency. The controller transitions from using fixed coefficients to dynamically selecting between different coefficient sets (first set for low frequency, second set for high frequency) based on real-time frequency detection, thereby adapting the control parameters to match the actual operating conditions.
Solution Approach 2:
The patent changes the control parameters (PID coefficients) based on the detected hand-shake frequency. When low frequency is detected, the first PID coefficient set is applied; when high frequency is detected, the second PID coefficient set is applied. This parameter switching enables accurate control across different frequency domains without increasing the fundamental controller structure complexity.
2Reliability
If PID coefficients are optimized for high frequency hand-shake, then high frequency stabilization is improved, but low frequency hand-shake causes excessive oscillation
Solution Approach 1:
The patent segments the hand-shake frequency control into two distinct domains: low frequency control and high frequency control. By creating separate PID coefficient sets optimized for each frequency range and switching between them based on detected frequency, the system avoids the trade-off that occurs when a single coefficient set must serve both domains.
Solution Approach 2:
The patent applies different PID coefficient parameters depending on the detected hand-shake frequency. The first PID coefficient set is optimized for low frequency to prevent excessive oscillation, while the second PID coefficient set is optimized for high frequency to improve stabilization. This dynamic parameter adjustment eliminates the harmful oscillation caused by mismatched coefficients.
3Reliability
If PID coefficients are optimized for low frequency hand-shake, then low frequency stabilization is improved, but high frequency hand-shake compensation becomes inadequate
Solution Approach 1:
The patent divides the control strategy into frequency-specific segments. The first PID coefficient set handles low frequency optimization, while the second PID coefficient set handles high frequency optimization. By segmenting the control parameters according to frequency domains, the system achieves reliable low frequency stabilization without sacrificing high frequency compensation accuracy.
Solution Approach 2:
The patent implements dynamic coefficient selection that adapts to the detected hand-shake frequency. When low frequency is detected, the system uses coefficients optimized for low frequency stabilization. When high frequency is detected, it switches to coefficients optimized for high frequency compensation, thereby maintaining accuracy across both frequency ranges.
4Object-generated harmful factors
If the actuator is controlled to prevent high frequency hand-shake, then high frequency oscillation is reduced, but the lens module moves excessively for low frequency hand-shake
Solution Approach 1:
The patent changes the PID control parameters based on detected hand-shake frequency to optimize actuator response. When high frequency is detected, coefficients are adjusted to reduce oscillation. When low frequency is detected, different coefficients are applied to appropriate the lens module movement distance, preventing excessive movement while maintaining stabilization effectiveness.
Solution Approach 2:
The patent implements dynamic adjustment of control parameters that adapts the actuator's response characteristics to the detected frequency. This dynamic parameter switching ensures that the lens module movement is appropriately scaled for each frequency domain, reducing high frequency oscillation without causing excessive low frequency movement.
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 approach minimizes position errors and oscillations, ensuring effective image stabilization by accurately adjusting the actuator's movement based on the detected hand-shake frequency, preventing image blur across both low and high frequency domains.
Implementation Method 1
The VCM has a coil mounted outside a camera lens module to control a direction and an amount of current flowing in the coil and to move the lens module to a desired position
Data Source
AI summary
Embodiments of the invention provide an apparatus for controlling an actuator in an optical image stabilizer. The apparatus includes a hand-shake frequency determination unit configured to determine a hand-shake frequency based on distance data output from a distance calculator which is configured to calculate a distance based on an output from a motion sensor. The apparatus further includes a proportional-integral-derivative coefficient selection and switching controller configured to apply proportional-integral-derivative coefficients suitable for the determined hand-shake frequency to a PID controller.