Lidar Imaging Apparatus Using Compressive Sensing and DMD
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Solution Overview
Problem
Current lidar imaging systems for motor vehicles face challenges with signal-to-noise ratio, especially in the near infrared range, and longer wavelengths offer better eye safety but are limited by detector technology, leading to high costs and reduced range due to small detector sizes and noise issues.
Innovation Solution
The implementation of compressive sensing processing in conjunction with a digital micromirror device (DMD) and a single pixel detector, along with an optical concentrator, to enhance signal resolution and reduce costs by using smaller, less expensive detectors, and autocorrelation processing to filter out false alarms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If longer wavelengths are used for lidar imaging, then eye safety is improved and laser power can be increased, but detector technology becomes limited and noisy
Solution Approach 1:
The detector is divided into multiple pixels arranged in a matrix, with each pixel independently detecting light from different angular directions. This segmentation allows the system to use multiple small pixels instead of one large noisy pixel, improving signal-to-noise ratio while maintaining long wavelength operation
Solution Approach 2:
The same detector array is used for both imaging and depth measurement functions. The detector serves dual purposes: capturing spatial information through the lens and measuring time-of-flight for depth mapping, eliminating the need for separate detector systems
2Measurement precision
If larger detector areas are used to improve range, then detection capability is enhanced, but noise increases due to material defects
Solution Approach 1:
The detector area is segmented into multiple small pixels rather than using one large pixel. Each small pixel has fewer material defects and lower noise, while the array of pixels collectively provides large effective detection area for improved range and capability
3Measurement precision
If high-resolution detectors are used to improve image quality, then measurement precision is enhanced, but system cost increases significantly
Solution Approach 1:
The system uses a moderate-resolution detector array combined with compressive sensing techniques to achieve high-quality images. By capturing partial information at multiple time points and using computational reconstruction, the system achieves high measurement precision without requiring expensive high-resolution detectors
Solution Approach 2:
The system changes the temporal parameter by capturing multiple measurements at different time points rather than relying on spatial resolution alone. This temporal sampling approach, combined with compressive sensing algorithms, enables high-quality reconstruction from lower-resolution detector data, reducing system cost
4Ease of manufacture
If small detector sizes are used to reduce cost, then system cost is reduced, but range is limited due to reduced light collection area
Solution Approach 1:
Multiple small detector pixels work together to provide large effective collection area. The segmentation into angularly-resolved pixels allows each small pixel to detect light from specific directions, and the collective array provides sufficient light collection for extended range
Solution Approach 2:
The system uses pulsed laser illumination with periodic timing, synchronizing detector measurements with each pulse. This allows integration of signals over multiple pulses, improving signal-to-noise ratio and extending detection range despite using small detector pixels
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 allows for cost-effective lidar imaging with improved signal-to-noise ratio and longer range within eye safety limits, enabling effective depth mapping and image reconstruction even in adverse weather conditions, while reducing the need for expensive high-resolution detectors.
Implementation Method 1
an emitting section (23) adapted to emit a pulsed light beam (3) and to change the direction of the light beam (3) in two dimensions perpendicularly to the light beam (3)
Implementation Method 2
a receiving section (24) having a lens objective (11)
Implementation Method 3
a digital micromirror device DMD (6) comprising a matrix of mirrors, where each mirror of the DMD (6) is controllable to change at least between a first position where light entering the imaging apparatus (30) through said lens objective (11) is directed on said lidar detector (8), and a second position where light entering the imaging apparatus (30) through said lens objective (11) is directed on said further photo detector (9)
Implementation Method 4
a lidar detector (8) and a further photo detector (9)
Implementation Method 5
said electronic processing unit (19) is adapted to determine the time-of-flight of a laser pulse (3) from said emitting section (23) to said lidar detector (8)
Data Source
Figure 1~2
Figure 3~4
Figure 5A~5H
AI summary
A lidar imaging apparatus (30) for a motor vehicle comprises an emitting section (23) adapted to emit a pulsed light beam (3) and to change the direction of the light beam (3) in two dimensions perpendicularly to the light beam (3), a receiving section (24) having a lens objective (11), a digital micromirror device (6) comprising a matrix of mirrors (7), a lidar detector (8) and a further photo detector (9), and an electronic processing unit (19). Each mirror (7) of the digital micromirror device (6) is controllable by said electronic processing unit (19) to change at least between a first position where light entering the lidar imaging apparatus (30) through said lens objective (11) is directed on said lidar detector (8), and a second position where light entering the lidar imaging apparatus (30) through said lens objective (11) is directed on said further photo detector (9). Said electronic processing unit (19) is adapted to determine the time-of-flight of a laser pulse from said emitting section (23) to said lidar detector (8), and to perform compressive sensing processing on the signal provided by said further photo detector (9) .