Multiple Pulse LIDAR Array for High-Density 3D Imaging
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Solution Overview
Problem
Existing LIDAR systems face challenges in achieving high-density 3-D point cloud measurements over a broad field of view due to limitations in pulse repetition rate, leading to decreased point cloud density and increased noise from external sources like sunlight and other LIDAR systems, which affects measurement accuracy and range.
Innovation Solution
The implementation of a multiple pulse LIDAR system that emits a sequence of pulses with spatial and temporal separation, encoded using diversity schemes to minimize cross-talk and noise rejection, allowing for accurate distance measurement and improved noise immunity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single laser emitter/detector combination is used with a rotating mirror to scan across a plane, then the system structure is simple, but the field of view is limited and point cloud density decreases
Solution Approach 1:
The patent divides the single laser emitter/detector into multiple independent emitter-detector pairs arranged in an array. Each pair independently emits and detects light pulses, effectively segmenting the measurement function across multiple channels. This segmentation enables simultaneous measurement across multiple spatial locations, dramatically expanding the field of view while maintaining simple individual component structures.
Solution Approach 2:
The patent transitions from a single-point measurement approach to a multi-point spatial array approach. By arranging multiple emitter-detector pairs in a two-dimensional array, the system adds spatial dimensionality to the measurement capability, enabling simultaneous coverage of a broad three-dimensional field of view rather than scanning point-by-point.
2Measurement precision
If the pulse repetition rate is increased to improve point cloud density, then measurement accuracy improves, but noise from external sources like sunlight increases
Solution Approach 1:
The patent introduces temporal coding as an intermediary mechanism between the light pulses and the detection process. Each emitter-detector pair is assigned a unique temporal code pattern, and the system uses correlation analysis to identify which coded pulses correspond to which detectors. This coding intermediary allows the system to distinguish between signals from different spatial locations and reject noise from external sources, enabling high pulse repetition rates without increased noise interference.
Solution Approach 2:
The patent replaces traditional mechanical filtering methods with a digital signal processing approach using temporal coding and correlation analysis. Instead of using physical filters to block sunlight or other environmental noise, the system uses coded pulse sequences and digital signal processing to distinguish between valid return signals and noise, achieving superior noise rejection at high pulse repetition rates.
3Area of stationary object
If multiple pulses are emitted in rapid succession to expand field of view, then coverage area increases, but cross-talk between pulses increases
Solution Approach 1:
The patent uses temporal coding as an intermediary mechanism to manage the complexity of rapid pulse emission. Each emitter-detector pair is assigned a unique temporal code, and the system uses correlation analysis to distinguish between pulses from different sources. This coding intermediary enables the system to emit multiple pulses in rapid succession across a broad field of view while maintaining clear separation between pulse signals and preventing cross-talk interference.
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 accuracy and range of 3-D point cloud measurements by reducing cross-talk and noise interference, enabling a broader field of view with higher point cloud density and faster image updates, suitable for applications like autonomous vehicles.
Implementation Method 1
A LIDAR system employs pulses of light to measure distance to an object based on the time of flight (TOF) of each pulse of light
Implementation Method 2
A portion of the light reflects from the object and returns to a detector of the LIDAR system
Implementation Method 3
pulses of light are generated by a laser emitter
Implementation Method 4
The light pulses are focused through a lens or lens assembly
Implementation Method 5
The time it takes for a pulse of laser light to return to a detector mounted near the emitter is measured and a distance is derived from the time measurement with high accuracy
Data Source
AI summary
Methods and systems for performing multiple pulse LIDAR measurements are presented herein. In one aspect, each LIDAR measurement beam illuminates a location in a three dimensional environment with a sequence of multiple pulses of illumination light. Light reflected from the location is detected by a photosensitive detector of the LIDAR system during a measurement window having a duration that is greater than or equal to the time of flight of light from the LIDAR system out to the programmed range of the LIDAR system, and back. The pulses in a measurement pulse sequence can vary in magnitude and duration. Furthermore, the delay between pulses and the number of pulses in each measurement pulse sequence can also be varied. In some embodiments, the multi-pulse illumination beam is encoded and the return measurement pulse sequence is decoded to distinguish the measurement pulse sequence from exogenous signals.