Hybrid Pulse-CW LiDAR with Unified Range and Velocity Detection

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Solution Overview

Problem

Existing LiDAR technologies face limitations in accurately determining the instantaneous velocity of objects due to averaging over time intervals, and combining range and velocity measurements using separate devices leads to inaccuracies and inconsistencies.

Innovation Solution

The integration of pulsed and continuous optical signals within a common optical circuit for LiDAR systems, allowing for simultaneous direct range and velocity measurements, reduces ambiguity and enhances accuracy by using bidirectional amplifiers and balanced photodetectors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If separate devices are used for range and velocity measurements, then device functionality is provided, but measurement accuracy and consistency deteriorate

Engineering Contradiction:

Improvedevice functionalityVSAvoidmeasurement accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent combines range and velocity measurement functionalities into a single LiDAR device that transmits both pulsed and continuous optical signals simultaneously. The pulsed signals enable direct range detection through time-of-flight measurement, while the continuous signals enable Doppler velocity detection. This merging eliminates the need for separate devices and ensures both measurements are taken from the same optical path and timing reference, thereby improving measurement accuracy and consistency.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The LiDAR device is designed with multi-functionality to perform both range and velocity measurements using a single system. The optical transmission circuit can generate and transmit both pulsed and continuous optical signals, and the detection circuit can process both types of reflected signals to extract range and velocity information. This universal design provides complete measurement functionality while maintaining high accuracy through unified signal processing.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Loss of information

If multiple measurements are taken to determine velocity, then velocity information is obtained, but time consumption increases

Engineering Contradiction:

Improvevelocity informationVSAvoidmeasurement time

Core Design Contradiction:

Loss of informationVSLoss of time

Solution Approach 1:

The patent employs continuous optical signals for Doppler velocity detection, allowing velocity measurement to occur continuously rather than requiring multiple discrete measurements over time. The continuous signal enables real-time velocity determination through Doppler frequency shift analysis, eliminating the time delay associated with taking multiple sequential measurements. This continuous measurement approach provides immediate velocity information while maintaining measurement accuracy.

Inventive Principle:

Principle #20Continuity of useful action

3Length of stationary object

If measurement time is extended for long-distance detection, then detection capability is improved, but noise and edge effects increase

Engineering Contradiction:

Improvedetection distanceVSAvoidnoise and edge effects

Core Design Contradiction:

Length of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The patent uses pulsed optical signals with specific pulse widths and repetition rates to optimize long-distance detection. By transmitting periodic pulses rather than continuous signals for range measurement, the system can integrate returns over extended periods to improve signal-to-noise ratio at long distances. The pulsed nature allows for time-gated detection that minimizes edge effects and background noise, enabling accurate range measurement at significant distances while suppressing harmful interference.

Inventive Principle:

Principle #19Periodic action

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 improves the accuracy and consistency of range and velocity measurements, reduces the need for multiple measurements, and allows for longer measurement times, especially at significant distances, while minimizing noise and edge effects.

Implementation Method 1

By determining a time delay between a signal emission and an arrival of the reflected signal, direct detection LiDAR can determine a distance to the object

Methodology Applied

Scientific EffectTime of flight: Time of Flight

Implementation Method 2

Coherent LiDAR devices, which utilize the Doppler effect, can determine a longitudinal (radial) component of the object's velocity by detecting a change in the frequency of the arrived wave from the frequency of the emitted signal

Methodology Applied

Scientific EffectDoppler effect: Doppler Effect

Data Source

PatentUS12055630B2Light detection and ranging device using combined pulse and continuous optical signals

Publication Date: 2024.08.06 WAYMO LLC

AI summary

The subject matter of this specification relates to a light detection and ranging (LiDAR) device that comprises, in some implementations, a pulsed-laser source configured to generate a pulsed optical signal, a continuous wave (CW) laser source configured to generate a CW optical signal, one or more optical amplifier circuits configured to amplify at least the pulsed optical signal, a combiner configured to combine the pulsed optical signal and the CW optical signal into a hybrid transmission signal, and at least one photodetector configured to receive a reflection signal produced by reflection of the hybrid transmission signal by a target.