LIDAR Histogram Peak Calibration for Accurate Time-of-Flight Ranging

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing LIDAR systems face challenges in providing robust distance accuracy down to a few centimeters, particularly under varying ambient conditions, due to limitations in detector technologies like single photon avalanche diodes (SPADs) with limited dynamic range and susceptibility to background noise light.

Innovation Solution

An optical measurement system that includes a light source transmitting pulse trains, a photosensor detecting reflected photons, and a circuit to identify and calibrate distance based on photon counts accumulated in registers, using histogram analysis to distinguish initial peaks from object reflections and ambient noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If single photon avalanche diodes (SPADs) are used to measure time-of-flight, then sensitivity to photons is improved, but dynamic range is limited and susceptibility to background noise light increases

Engineering Contradiction:

Improvedistance accuracyVSAvoiddynamic range

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The system performs preliminary calibration by identifying the initial peak corresponding to housing reflections before measuring object distances. This preliminary action establishes a reference point that enables accurate distance measurements while compensating for the limited dynamic range of SPAD detectors.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system converts the harmful effect of housing reflections and background noise into a beneficial calibration reference. By identifying and utilizing the initial peak from housing reflections, the system transforms what would be interference into a useful reference for accurate distance measurement, effectively converting harm into benefit.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Measurement precision

If single photon avalanche diodes (SPADs) are used to detect reflected photons, then sensitivity is improved, but susceptibility to ambient background noise light increases

Engineering Contradiction:

Improvephoton detection sensitivityVSAvoidsusceptibility to background noise light

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The system converts the harmful background noise and housing reflections into a beneficial calibration reference by identifying the initial peak. This reference peak enables the system to distinguish between noise and actual object reflections, transforming the harmful ambient light into a useful tool for improving measurement precision.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The system uses feedback from the identified initial peak to calibrate subsequent distance measurements. By continuously referencing the housing reflection peak, the system can compensate for background noise variations and maintain high detection sensitivity across different ambient conditions.

Inventive Principle:

Principle #23Feedback

3Measurement precision

If histogram analysis is used to identify initial peaks, then distance calibration accuracy is improved, but processing complexity increases

Engineering Contradiction:

Improvedistance calibration accuracyVSAvoidprocessing complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The system extracts only the essential information needed for calibration by identifying the initial peak in the histogram. Rather than processing the entire histogram data set, the system focuses on extracting the specific peak position and characteristics, thereby improving calibration accuracy while minimizing processing complexity.

Inventive Principle:

Principle #2Taking out (Extraction)

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

Enhances distance accuracy by distinguishing initial peaks from object reflections, improving LIDAR performance under diverse ambient conditions.

Implementation Method 1

A LIDAR system measures the distance to an object by irradiating a landscape with pulses from a laser

Methodology Applied

Scientific EffectLaser: Laser

Implementation Method 2

detect photons from the one or more pulse trains that are reflected off of a housing of the optical measurement system

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 3

A distance to an object can be determined based on a time-of-flight from transmission of a pulse to reception of a corresponding reflected pulse

Methodology Applied

Scientific EffectTime of flight: Time of Flight

Data Source

PatentUS12529770B2Processing time-series measurements for LIDAR accuracy

Publication Date: 2026.01.20 OUSTER INC

AI summary

An optical measurement system may include a light source and corresponding photosensor configured to emit and detect photons reflected from objects in a surrounding environment for optical measurements. An initial peak can be identified as resulting from reflections off a housing of the optical measurement system. This peak can be removed or used to calibrate measurement calculations of the system. Peaks resulting from reflections off surrounding objects can be processed using on-chip filters to identify potential peaks, and the unfiltered data can be passed to an off-chip processor for distance calculations and other measurements. A spatial filtering technique may be used to combine values from histograms for spatially adjacent pixels in a pixel array. This combination can be used to increase the confidence for distance measurements.