Laser Ranging Device Angle-Based Distance Correction

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Solution Overview

Problem

Traditional laser ranging devices face significant errors in distance measurement when the ranging target is close to the light projection unit, as the interval between the light projection and receiving units is not sufficiently small compared to the measured distance, leading to inaccurate calculations.

Innovation Solution

A ranging device and method that includes a light projection circuit, a light receiving circuit, and a processor to measure the time of flight of laser light and calculate the distance using the light projection angle, allowing for accurate distance determination even when the ranging target is close by considering the light projection angle and the distance between the light projection and receiving units.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If approximate calculation ignoring the interval between light projection unit and light receiving unit is used, then device complexity is reduced, but measurement precision deteriorates when the ranging target is close

Engineering Contradiction:

Improvecalculation complexityVSAvoiddistance measurement precision

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent dynamically switches between two calculation modes based on the measured distance. When the ranging target is far away, the simplified approximate calculation is used. When the target is close and the ratio of interval to distance exceeds a threshold, the system automatically switches to the precise calculation mode that incorporates the interval between light projection unit and light receiving unit, thus adapting the calculation complexity to the measurement requirements.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the calculation parameters based on the measurement conditions. The key parameter is whether to include the interval between light projection unit and light receiving unit in the distance calculation. This parameter is adjusted dynamically: excluded for far targets (simplified mode) and included for close targets (precise mode), allowing the system to optimize between computational simplicity and measurement accuracy.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If the interval between light projection unit and light receiving unit is made sufficiently small, then measurement precision is improved, but device complexity and size increase

Engineering Contradiction:

Improvedistance measurement precisionVSAvoiddevice structure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

Instead of mechanically reducing the interval between light projection unit and light receiving unit to improve precision, the patent substitutes a computational approach. The system uses software-based correction algorithms that calculate the true distance by compensating for the fixed interval, replacing the need for physical miniaturization with mathematical processing.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent treats the interval between light projection unit and light receiving unit as a known parameter and changes the calculation methodology to account for it. Rather than trying to make this parameter approach zero physically, the system incorporates it into the distance calculation formula, transforming a structural constraint into a computational variable.

Inventive Principle:

Principle #35Parameter changes

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

Enables accurate measurement of the distance between the light projection unit and the ranging target, even when the target is close, by using the light projection angle and the distance between the light projection and receiving units, thereby reducing measurement errors.

Implementation Method 1

measure a time from a time when the light projection circuit projects the laser light to a time when the light receiving circuit receives the reflected light

Methodology Applied

Scientific EffectTime of flight: Time of Flight

Implementation Method 2

receive reflected light of the laser light projected by the light projection circuit

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentUS20230358535A1Ranging device, computer-readable recording medium storing ranging program, and ranging method

Publication Date: 2023.11.09 FUJITSU LTD

AI summary

A ranging device includes: a light projection circuit configured to project laser light; a light receiving circuit configured to receive reflected light of the laser light projected by the light projection circuit; and a processor configured to: measure a time from a time when the light projection circuit projects the laser light to a time when the light receiving circuit receives the reflected light; calculate a first distance from the light projection circuit to the light receiving circuit via a ranging target, by using the time; and specify a third distance between the light projection circuit and the ranging target, by using a light projection angle of the laser light, the first distance, and a second distance between the light projection circuit and the light receiving circuit when a ratio of the first distance with respect to the second distance is equal to or less than a predetermined threshold.