LiDAR Malfunction Detection via Remote Photodetector Arrays
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Solution Overview
Problem
Traditional LIDAR systems face challenges in providing unobstructed views of surroundings while minimizing cost and weight, as external placement exposes expensive components to weather and damage, and existing solutions do not effectively address the need for detailed 3D depth imaging with minimal LIDAR units.
Innovation Solution
A distributed LIDAR system using coherent fiber optic image bundles (CFOBs) to transfer light reflections from multiple fields of view to a remotely located ranging subassembly, allowing for centralized range sensing and reducing the number of LIDAR units required by multiplexing light reflections onto a shared photodetector array.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If LIDAR is placed externally on the vehicle, then unobstructed field of view is achieved, but the expensive photodetector array is exposed to weather and damage
Solution Approach 1:
The LIDAR system is divided into separate functional modules: light emitters are placed externally in multiple FOVs while the expensive photodetector array and ranging electronics are located remotely inside the vehicle. This segmentation allows the FOV-critical components to be external while protecting the sensitive detection components.
Solution Approach 2:
Coherent fiber optic image bundles serve as intermediaries to transfer optical images from external FOVs to the internal photodetector array. The CFOBs enable the photodetector to be located remotely while still receiving optical information from external fields of view, thus protecting the expensive component while maintaining FOV coverage.
2Area of stationary object
If multiple discrete LIDARs are used to provide adequate coverage, then field of view coverage is improved, but cost and weight increase
Solution Approach 1:
Multiple FOVs from different locations around the vehicle are combined and transferred through separate CFOBs to a single shared photodetector array. This merging approach provides comprehensive FOV coverage equivalent to multiple LIDARs while using only one photodetector array, significantly reducing weight and cost.
Solution Approach 2:
A single photodetector array performs the detection function for multiple FOVs simultaneously by receiving optical images from multiple CFOBs. This multi-functional approach replaces what would traditionally require multiple separate LIDAR units, reducing overall system weight while maintaining comprehensive coverage.
3Weight of stationary object
If a single photodetector array serves multiple FOVs remotely, then cost and weight are reduced, but malfunction detection becomes more difficult
Solution Approach 1:
The system uses two photodetector arrays that simultaneously receive optical images from the same FOV through separate CFOBs. The malfunction indicator continuously compares the optical images and electronic signals from both detectors, providing real-time feedback to detect malfunctions such as degraded photonic efficiency or temperature drift in either detector or associated circuitry.
Solution Approach 2:
The malfunction detection mechanism monitors changes in key parameters including optical image quality, signal strength, temperature, and timing characteristics from the two photodetector arrays. By tracking parameter variations and comparing them against expected ranges, the system can detect malfunctions in the remote photodetector system.
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 solution enables remote placement of LIDAR electronics, protecting expensive components from environmental damage, improving accuracy and reliability, while reducing system cost, complexity, and weight, and enhancing design flexibility for adaptive field of view configurations.
Implementation Method 1
a first coherent fiber optic image bundle operable to transfer the light reflections from the field of view to the remotely located ranging subassembly
Implementation Method 2
a second coherent fiber optic image bundle operable to transfer the light reflections from the field of view to the remotely located ranging subassembly, wherein the remotely located ranging subassembly is operable to detect the light reflections from the plurality of fields of view using a single photodetector
Data Source
AI summary
In one embodiment a LIDAR can comprise two similar photodetector arrays and a malfunction indicator circuit operable to generate a malfunction signal when a measure of difference between range data from similar directions reported by each of the photodetectors exceeds a threshold value. A challenge associated with LIDARs is malfunction detection and failsafe operation in the event of a malfunction. Embodiments provide for two photodetectors in a shared remote ranging subassembly to address the challenges of malfunction detection. The two photodetector arrays can each receive light reflections from overlapping angular ranges in one or more FOVs (e.g. transferred using CFOBs) and thereby function to provide redundancy and confirmation of reflection distances. Within embodiments a reflection splitter can serve to uniformly distribute laser reflections from a common field of view among two photodetectors, thereby providing each with a half-resolution image for range comparison.