Camera Lens Motion Control Using Uncertainty-Based Input Shaping
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Solution Overview
Problem
Existing motion control systems for camera lenses in mobile devices face challenges in accurately adjusting lens positions due to uncertainties in manufacturing parameters, leading to inefficient and slow lens movements, especially for small adjustments, which affect image quality and productivity.
Innovation Solution
The system uses motion profiles that account for parameter uncertainties specific to the lens's position, selecting input shaping signals based on the estimated uncertainty to achieve precise and fast lens movements by determining the appropriate number of pulses in the input shaping signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conservative robustness estimates are used in open-loop control configurations, then precision is maintained across varying conditions, but seek time increases and performance deteriorates
Solution Approach 1:
The system dynamically adapts the motion profile based on real-time parameter uncertainty estimates. Instead of using a fixed conservative profile for all movements, the controller adjusts the motion characteristics (acceleration, velocity, positioning) according to the estimated uncertainty level, enabling faster movements when uncertainty is low while maintaining precision when uncertainty is high
Solution Approach 2:
The system changes control parameters (motion profile characteristics) based on the estimated parameter uncertainty. By monitoring uncertainty in actuator parameters and adjusting the motion profile accordingly, the system optimizes the trade-off between speed and precision for each specific movement scenario
2Manufacturing precision
If system identification methods are performed outside production line, then parameter characterization is thorough, but production productivity decreases
Solution Approach 1:
The system performs preliminary system identification and parameter characterization during the production process itself, rather than requiring separate post-production calibration steps. This allows thorough parameter measurement to be integrated into the manufacturing flow, maintaining accuracy without sacrificing productivity
Solution Approach 2:
The production line equipment itself is used to perform the system identification measurements on each actuator-lens module pair. The existing measurement capabilities of the production equipment are leveraged to characterize parameters directly at the point of manufacture, eliminating the need for separate external characterization facilities
3Productivity
If limited measurements are taken during production calibration, then production speed is maintained, but measurement precision and control accuracy deteriorate
Solution Approach 1:
The system uses periodic excitation signals during production calibration to extract multiple parameter estimates from limited measurements. By applying structured periodic inputs and analyzing the system response, accurate parameter characterization is achieved even with constrained measurement opportunities
Solution Approach 2:
The system applies excitation signals that are sufficient to extract the necessary parameter information within the limited production time window. Rather than attempting comprehensive measurements, the system uses targeted partial measurements that provide adequate accuracy for control purposes
4Adaptability or versatility
If high variability among actuators is accommodated, then adaptability increases, but device complexity and cost increase
Solution Approach 1:
The system implements feedback mechanisms that measure actual actuator-lens module pair behavior and use this information to adjust control parameters. By continuously monitoring performance and adapting control based on measured uncertainty, the system handles actuator variability without requiring complex pre-characterization or multiple hardware variants
Data Source
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AI summary
A motion control method comprising receiving a motion request to move the lens module from an initial position to a final position, determining a middle position between the initial position and the final position, determining an initial parameter value, a middle parameter value and a final parameter value based respectively on the initial position, the middle position and the final position, estimating a parameter uncertainty based on a maximum value and a minimum value wherein the maximum value is the greatest value among the initial parameter value, the middle parameter value and the final parameter and the minimum value is the smallest value among the initial parameter value, the middle parameter value and the final parameter and selecting a type of input shaping signal based on the estimated parameter uncertainty.