Rotating LiDAR Pulse Sequencing to Reduce Channel Cross-Talk
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Solution Overview
Problem
Current LIDAR systems face challenges in achieving real-time, multi-point scanning for accurate distance measurements, particularly in dynamic environments like autonomous vehicles, due to limitations in resolution and cross-talk between channels.
Innovation Solution
A rotatable LIDAR apparatus with multiple laser emitters and sensors arranged in staggered rows, using cross-correlation to determine time delays and varying pulse spacings to minimize cross-talk, along with a sequential channel order and dual ADC usage to enhance measurement accuracy and reduce interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple laser emitters and sensors are used to measure multiple surface points, then measurement precision and resolution are improved, but cross-talk between channels increases
Solution Approach 1:
The patent implements periodic action by using alternating measurement cycles where different sets of channels are activated in sequence. During each cycle, only specific channels transmit and receive signals while other channels remain inactive, creating periodic measurement patterns that prevent simultaneous signal interference between channels.
Solution Approach 2:
The patent applies dynamics by making the channel activation state changeable over time. The system dynamically switches between different channel configurations across multiple measurement cycles, allowing each channel to have dedicated time windows for transmission and reception, thereby eliminating cross-talk while maintaining multi-point measurement capability.
2Productivity
If multiple channels are activated simultaneously for real-time scanning, then productivity is improved, but cross-talk between channels increases
Solution Approach 1:
The system uses periodic action by organizing channel activation into repeating measurement cycles. Each cycle activates a specific subset of channels for a defined duration, then switches to another subset in subsequent cycles. This periodic pattern enables continuous real-time scanning across all channels while ensuring that no two channels are active simultaneously, thus preventing cross-talk.
Solution Approach 2:
The patent implements dynamics by making the channel activation configuration time-variable. The system dynamically reconfigures which channels are active during different time intervals within the measurement cycles, allowing all channels to participate in real-time scanning over the course of multiple cycles while maintaining temporal separation to eliminate cross-talk.
3Device complexity
If channels are used in a fixed sequence, then device complexity is reduced, but loss of time occurs due to overlapping flight times
Solution Approach 1:
The patent applies dynamics by making the channel measurement sequence adaptive rather than fixed. The system dynamically adjusts the measurement sequence based on the calculated flight times of previous channels, allowing channels to be measured in an order that prevents temporal overlap. This dynamic sequencing maintains relatively low complexity while eliminating time loss from overlapping measurements.
Solution Approach 2:
The system uses feedback by utilizing the measured flight time information from previously activated channels to determine the optimal timing and sequence for subsequent channel measurements. This feedback mechanism allows the system to adjust its measurement sequence in real-time, ensuring that channels are measured in an order that prevents overlap, thereby reducing measurement time without significantly increasing 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
This configuration enables high-resolution, real-time 3D mapping with reduced cross-talk, allowing for precise distance measurements and improved obstacle detection in dynamic environments.
Implementation Method 1
determining the propagation time of light between a measuring device and one or more target points
Implementation Method 2
measuring properties of the reflections of the light
Implementation Method 3
The light sensor may comprise a photodetector such as a photomultiplier or avalanche photodiode (APD) that converts light intensity to a corresponding electrical signal
Implementation Method 4
analysis logic communicatively coupled to the light sensor that analyzes a cross correlation of each emitted burst with a corresponding one of the reflected light bursts to determine a propagation time
Data Source
AI summary
A LIDAR system emits laser bursts, wherein each burst has at least a pair of pulses. The pulses of each pair are spaced by a time interval having a variable duration to reduce effects of cross-talk. For example, certain embodiments may have multiple emitter/sensor channels that are used sequentially, and each channel may use a different duration for inter-pulse spacing to reduce the effects of cross-talk between channels. The durations may also be varied over time. The emitters and sensors are physically arranged in a two-dimensional array to achieve a relatively fine vertical pitch. The array has staggered rows that are packed using a hexagonal packing arrangement. The channels are used in a sequential order that is selected to maximize spacing between consecutively used channels, further reducing possibilities for inter-channel cross-talk.