LIDAR Retroreflector Detection and Avoidance
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Solution Overview
Problem
Conventional LIDAR devices face issues with range aliasing, cross-talk, detector saturation, and other errors due to the presence of retroreflectors or highly reflective objects, which can lead to inaccurate distance determination and spurious reflections.
Innovation Solution
The method involves detecting retroreflectors within the LIDAR's field of view and deactivating or reducing the intensity of the light emitter to prevent illumination, using a secondary light emitter with lower intensity pulses to identify retroreflectors, and reactivating the primary light emitter when the retroreflector is no longer detected, thereby minimizing cross-talk and improving measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the light emitter continuously emits high-intensity light pulses for distance measurement, then measurement speed and productivity are improved, but retroreflectors cause detector saturation, cross-talk, and range aliasing errors that deteriorate measurement precision
Solution Approach 1:
The light emitter dynamically adjusts its operational state between active and inactive based on real-time detection feedback. When a retroreflector is detected, the light emitter is deactivated to prevent saturation and cross-talk; when no retroreflector is present, it activates for normal distance measurement, creating a dynamic adaptation to environmental conditions
Solution Approach 2:
The system implements a feedback loop where the detector monitors reflected light pulses and identifies retroreflectors through characteristic pulse patterns. This detection information feeds back to control the light emitter's activation state, forming a closed-loop control system that automatically adjusts operation to avoid measurement errors
2Measurement precision
If the light emitter is deactivated to avoid retroreflector interference, then measurement precision is improved, but the ability to scan and detect objects is reduced
Solution Approach 1:
The patent extracts and isolates the retroreflector detection function from the general distance measurement function. A separate detection mechanism using the same light emitter and detector pair identifies retroreflectors through their unique reflective characteristics, allowing the system to selectively deactivate the light emitter only when and where retroreflectors are present, rather than globally disabling scanning
Solution Approach 2:
The light emitter deactivation is applied locally and selectively to specific measurement periods where retroreflectors are detected in specific angular positions, rather than globally deactivating the entire LIDAR system. This allows scanning to continue in other directions or at other times when retroreflectors are not present
3Measurement precision
If secondary light emitter with lower intensity is used to detect retroreflectors, then measurement precision is improved by avoiding saturation, but device complexity increases
Solution Approach 1:
The primary light emitter serves multiple functions: it acts as both the illumination source for distance measurement and the detection source for retroreflector identification. The same light emitter and detector pair is used for both normal LIDAR operation and retroreflector detection, eliminating the need for separate dedicated components and reducing overall device complexity
Solution Approach 2:
The system changes the operational parameters of the light emitter dynamically - using high-intensity pulses for normal distance measurement and low-intensity or deactivated state for retroreflector detection periods. This parameter modulation allows a single light emitter to effectively perform both functions without requiring physically separate components
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 effectively reduces errors caused by retroreflectors, enhances measurement precision, and prevents spurious reflections, allowing for more accurate distance determination and improved scanning capabilities.
Implementation Method 1
emitter subsystem of a LIDAR device may emit near-infrared light pulses
Implementation Method 2
at least a portion of the light pulses may be redirected back toward the LIDAR (e.g., due to reflection or scattering)
Implementation Method 3
detector subsystem may include a plurality of detectors and a corresponding controller configured to determine an arrival time of the respective light pulses with high temporal resolution
Implementation Method 4
detecting that the detector detects, during a first measurement period, at least one reflected light pulse indicative of reflection by a retroreflector
Data Source
AI summary
A light detection and ranging (LIDAR) device includes a light emitter configured to emit light pulses into a field of view and a detector configured to detect light in the field of view. The light emitter emits a first light pulse. The detector detects, during a first measurement period, at least one reflected light pulse that is indicative of reflection by a retroreflector based on a shape of a reflected light pulse, a magnitude of a reflected light pulse, and/or a time separation between two reflected light pulses. In response to detecting the at least one reflected light pulse indicative of reflection by a retroreflector, the light emitter is deactivated for one or more subsequent measurement periods. Additionally, the LIDAR device may inform one or more other LIDAR devices by transmitting to a computing device information indicative of the retroreflector being within the field of view of the light emitter.