Phase-Modulated Lissajous Scanning for ROI Resolution Control
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Solution Overview
Problem
LIDAR systems using Lissajous scanning face limitations in achieving flexible and configurable scanning patterns with varying resolutions across different regions of interest, resulting in low resolution at the center and high resolution at the edges, which is not suitable for applications like object tracking.
Innovation Solution
An oscillator system with variable frequency ratios between two oscillation frequencies, modulated by phase adjustments, allows for dynamic control of Lissajous scanning patterns and regions of interest, enabling adjustable pixel density and resolution within a single frame period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If constant scanning frequencies with a defined frequency ratio are used to achieve a specific Lissajous pattern and frame rate, then the frame rate is maintained, but the resolution is low at the center and high at the edges
Solution Approach 1:
The patent applies dynamics by making the scanning frequencies time-varying instead of constant. The first scanning frequency is modulated according to a first time-varying function and the second scanning frequency is modulated according to a second time-varying function, allowing the frequency ratio to vary over time. This dynamic adjustment enables flexible control of the Lissajous pattern to achieve desired resolution distribution while maintaining frame rate.
Solution Approach 2:
The patent changes the scanning parameters by introducing time-varying frequency modulation. The scanning frequencies are no longer fixed but are modulated according to specific time-varying functions, which allows dynamic adjustment of the frequency ratio and phase difference to optimize resolution distribution across different regions of interest.
2Measurement precision
If the frequency difference is reduced to obtain higher resolution, then the resolution improves, but the frame rate decreases
Solution Approach 1:
The patent resolves this contradiction by making the frequency ratio dynamic rather than fixed. By modulating the scanning frequencies according to time-varying functions, the system can adjust the frequency difference dynamically - reducing it in regions requiring high resolution while maintaining overall frame rate through compensating frequency adjustments at different times.
Solution Approach 2:
The patent applies local quality by enabling different resolution characteristics in different regions of the scanning pattern. Through phase modulation and frequency ratio variation, the system can concentrate scanning points in specific regions of interest to achieve higher local resolution without sacrificing overall frame rate.
3Measurement precision
If sub-framing is used to combine new data and old data, then the resolution can be improved, but the assumption that neighboring pixels are not fast changing may not hold
Solution Approach 1:
The patent ensures continuous scanning without data combination from different frames. By using time-varying frequency modulation within a single frame period, the system achieves high resolution through continuous, uninterrupted scanning, eliminating the need for sub-framing and the associated assumptions about pixel stability.
4Ease of operation
If the Lissajous pattern has high symmetry with identical properties in each quadrant, then the scanning is simple, but the resolution cannot be optimized for specific regions of interest
Solution Approach 1:
The patent introduces asymmetry by modulating the phase difference between the two scanning frequencies according to time-varying functions. This breaks the symmetry of the traditional Lissajous pattern, allowing different resolution characteristics in different quadrants and regions, while maintaining configurable adaptability for specific regions of interest.
Solution Approach 2:
The patent enables different scanning resolutions in different regions by using phase and frequency modulation. The system can configure specific regions of interest to have higher resolution by adjusting the time-varying functions to concentrate scanning points in those regions, while other regions maintain lower resolution.
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 enhances scanning resolution and flexibility, allowing for higher resolution at specific areas while maintaining a constant frame rate, improving the accuracy and adaptability of LIDAR systems for diverse applications.
Implementation Method 1
The driver circuit is configured to modulate at least one of the first oscillation phase or the second oscillation phase to modulate the variable frequency ratio
Data Source
AI summary
An oscillator system includes a first oscillator structure configured to oscillate about a first rotation axis at a first oscillation frequency; a second oscillator structure configured to oscillate about a second rotation axis at a second oscillation frequency; a driver circuit configured to generate a first driving signal to drive an oscillation of the first oscillator structure with a first oscillation phase and the first oscillation frequency and generate a second driving signal to drive an oscillation of the second oscillator structure with a second oscillation phase and the second oscillation frequency. The first oscillation frequency and the second oscillation frequency have a variable frequency ratio with respect to each other that varies over time. The driver circuit is configured to modulate at least one of the first oscillation phase or the second oscillation phase to modulate the variable frequency ratio.