LiDAR Window Blockage Detection via Scanning Mirror Positioning
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Solution Overview
Problem
Solid-state LiDAR systems face interference and degradation in performance due to blockages on the window, such as water drops, snow, and dirt, which affect the maximum detectable distance and quality of the environmental map, and can generate false returns.
Innovation Solution
The LiDAR system employs a scanning mirror and photodetectors that operate in both active and passive modes, where the scanning mirror moves to different positions to direct light from the window to specific photodetectors, allowing for the identification of blockages by comparing light detection at various positions, and the controller can activate cleaning or maintenance actions if blockages are detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the LiDAR system operates continuously in active mode, then productivity is improved, but reliability deteriorates due to window blockages from water drops, snow, and dirt
Solution Approach 1:
The system alternates between active scanning mode and passive blockage detection mode. The scanning mirror periodically stops at predefined positions to enable photodetectors to detect window blockages without emitting light pulses, then resumes active scanning. This periodic switching allows continuous environmental mapping while intermittently checking for blockages that would compromise reliability.
Solution Approach 2:
The LiDAR system performs self-diagnosis by using its own photodetectors and scanning mirror to detect window blockages. The system monitors its own operational status by analyzing light patterns detected at specific mirror positions, enabling autonomous detection of contamination without external intervention or separate sensing systems.
2Reliability
If the scanning mirror stops at multiple positions for blockage detection, then reliability is improved, but productivity deteriorates due to increased detection time
Solution Approach 1:
The system performs blockage detection at selected scanning positions rather than continuously throughout the entire scanning cycle. The scanning mirror stops at specific predefined positions where photodetectors check for blockages, performing partial detection actions sufficient to identify contamination without requiring complete scanning cycle interruptions. This balances detection reliability with minimal time loss.
3Measurement precision
If the system uses multiple photodetectors for blockage detection, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The existing photodetector array serves dual functions: detecting reflected light pulses from environmental objects during active scanning and detecting window blockages during passive monitoring. The same photodetectors and scanning mirror used for primary LiDAR operation are repurposed for blockage detection, eliminating the need for separate dedicated sensors and reducing overall system complexity while maintaining detection precision.
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 the reliability and accuracy of the LiDAR system by effectively identifying and mitigating the impact of window blockages, ensuring consistent and accurate environmental mapping for autonomous vehicle operations.
Implementation Method 1
Light is emitted into the field of view of the photodetectors and the photodetectors detect light that is reflected by an object in the field of view
Implementation Method 2
the scanning mirror moves to different positions to direct light from the window to specific photodetectors
Implementation Method 3
The time of flight of reflected photons detected by the photodetectors is used to determine the distance of the object that reflected the light
Data Source
AI summary
A LiDAR system includes a casing having a window, a light emitter in the casing, a light sensor including an array of photodetectors, and a scanning mirror between the window and the light sensor. The LiDAR system includes a controller programmed to move the scanning mirror to a plurality of different positions when the light emitter is inactive. The scanning mirror is aimed at a different subset of the photodetectors in the different positions. The controller is programmed to operate at least some of the photodetectors when the scanning mirror is in different positions and the light emitter is inactive. The controller is programmed to identify a blockage on the window based on comparison of detected light at different positions of the scanning mirror.