Selective Light Emitter Pulsing for Retroreflector-Aware LiDAR
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Solution Overview
Problem
LIDAR devices face interference from highly reflective surfaces like retroreflectors, which can flood light detectors and introduce ambiguity in 3D point cloud data interpretation, affecting edge detection and object detection operations.
Innovation Solution
A pulser circuit with parallel-connected light emitters and capacitors, controlled by switches and a shift register, allows selective emission of light pulses to avoid highly reflective surfaces by charging and discharging capacitors during specific periods, enabling precise control of light pulses and reducing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If light emitters continuously emit light to scan the environment, then the LIDAR device can generate 3D point cloud data, but retroreflectors in the environment cause interference by reflecting light back to light detectors
Solution Approach 1:
The patent divides the light emitter array into multiple independently controllable groups or individual emitters, allowing selective activation of specific light emitters based on the presence of retroreflectors in different angular sectors. This segmentation enables the system to maintain productivity by continuing to scan with unaffected emitters while eliminating interference by disabling those pointing at retroreflectors.
Solution Approach 2:
The patent applies different operational states to different light emitters based on local conditions - some light emitters are activated while others are deactivated depending on the specific angular sector and detected retroreflector locations. This local quality approach allows the system to optimize each sector independently, maintaining overall scanning productivity while eliminating local interference issues.
2Measurement precision
If all light emitters are activated to ensure complete environment coverage, then scanning accuracy is maintained, but interference from retroreflectors increases
Solution Approach 1:
The patent extracts or removes the harmful effect by selectively deactivating specific light emitters that would illuminate retroreflectors, while maintaining activation of other light emitters that do not cause interference. This extraction approach preserves measurement precision by keeping the majority of the scanning system operational while eliminating the specific interference sources.
Solution Approach 2:
The patent changes the operational parameter (activation state) of individual light emitters based on detected conditions. By dynamically adjusting which light emitters are on or off according to the presence of retroreflectors in different sectors, the system maintains measurement precision without the harmful interference that would result from uniform activation of all emitters.
3Object-affected harmful factors
If the LIDAR device selectively disables light emission towards retroreflectors, then interference is reduced, but the complexity of controlling individual light emitters increases
Solution Approach 1:
The patent merges the control functions by implementing a centralized controller that manages multiple light emitters through a unified control architecture. This merging approach reduces device complexity by consolidating control logic, using shared timing and synchronization mechanisms, and implementing coordinated deactivation patterns rather than requiring independent complex control for each light emitter.
Solution Approach 2:
The patent implements a universal control mechanism that can selectively deactivate any combination of light emitters based on a single set of control signals or lookup tables. This multi-functionality allows the same control circuitry to handle various retroreflector configurations and patterns, reducing the need for specialized control logic for each scenario and thereby reducing overall device complexity.
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
The solution effectively reduces interference from retroreflectors by selectively disabling light emission towards these surfaces, improving the accuracy of 3D point cloud data generation and reducing ambiguity in data processing.
Implementation Method 1
A pulser circuit with parallel-connected light emitters and capacitors, controlled by switches and a shift register, allows selective emission of light pulses by charging and discharging capacitors during specific periods
Implementation Method 2
During a third period, the pulse-control switch allows current flow that discharges one or more undischarged capacitors of the plurality of capacitors through one or more corresponding light emitters of the plurality of light emitters, thereby causing the one or more corresponding light emitters to emit respective pulses of light
Data Source
AI summary
An example circuit includes a plurality of light emitters connected in parallel between a first node and a second node. The circuit also includes a plurality of capacitors, with each capacitor corresponding to one of the light emitters, and a plurality of discharge-control switches, with each discharge-control switches corresponding to one of the capacitors. The circuit further includes a pulse-control switch connected to the plurality of light emitters. During a first period, the pulse-control switch restricts current flow, and each of the plurality of capacitors is charged via the first node. During a second period, one or more of the plurality of discharge-control switches allows current flow that discharges one or more corresponding capacitors. During a third period, the pulse-control switch allows current flow that discharges one or more undischarged capacitors of the plurality of capacitors through one or more corresponding light emitters.