Driver Monitoring via Schlieren Respiration Sensing for Drowsiness

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Solution Overview

Problem

Existing driver monitoring systems face challenges in accurately detecting driver drowsiness, especially in low illuminance environments, and are prone to false detections due to variations in facial shapes and eye blinking habits. Additionally, these systems struggle with measuring heart rate when the driver is not wearing a seatbelt or holding the steering wheel, and UWB radar systems can be affected by external electromagnetic fields and environmental conditions.

Innovation Solution

A driver monitoring apparatus using a Schlieren camera to detect the driver's respiratory rate and volume by imaging the change in air density due to respiration, allowing for accurate identification of drowsy driving states and providing a control request for warning messages through vehicle displays or speakers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a conventional camera is used to monitor driver drowsiness, then the system can identify driver state through facial images, but the image quality is insufficient in low illuminance environments and false detection rate is high

Engineering Contradiction:

Improvedriver state detection accuracyVSAvoidfalse detection rate

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent introduces a Schlieren camera as an intermediary device that detects air density changes caused by respiration rather than directly observing facial features. This mediator (air density field) provides more reliable physiological information for drowsiness detection, eliminating the false detection problems associated with facial image analysis in conventional cameras.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the optical-mechanical facial recognition system with a Schlieren-based air density detection system. Instead of relying on mechanical/optical facial feature extraction that fails in low light, the system uses light refraction through air density variations to detect respiratory patterns, providing more accurate and reliable drowsiness detection.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If a heart rate sensor is used to monitor driver drowsiness, then the system can measure heart rate, but it cannot measure heart rate when the driver is not wearing a seat belt or not holding the steering wheel

Engineering Contradiction:

Improveheart rate measurement capabilityVSAvoidmeasurement coverage under different driving postures

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The Schlieren camera system provides universal monitoring capability that works regardless of the driver's posture or contact with vehicle components. By detecting respiratory-induced air density changes in the space around the driver's face, the system maintains measurement coverage whether the driver is wearing a seat belt, holding the steering wheel, or in any other driving position.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Measurement precision

If UWB radar is used to monitor driver drowsiness, then the system can detect driver state, but the detection is affected by external electromagnetic fields and environmental conditions such as temperature and humidity

Engineering Contradiction:

Improvedriver state detection capabilityVSAvoidsensitivity to electromagnetic fields and environmental conditions

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent converts the potentially harmful effect of environmental factors into a useful detection mechanism. Instead of trying to shield against air density variations caused by temperature and humidity, the system uses the Schlieren effect to detect light refraction through these very air density changes, which are directly caused by respiration. This transforms environmental sensitivity into a detection advantage.

Inventive Principle:

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

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

The Schlieren camera-based system effectively reduces false detection rates and provides reliable monitoring of driver drowsiness, even in challenging environments, by focusing on respiratory patterns rather than facial images alone.

Implementation Method 1

a Schlieren camera configured to photograph an image of a driver... imaging the change in air density due to respiration

Methodology Applied

Scientific EffectLight refraction: Refraction

Implementation Method 2

a Schlieren mirror in a shape of a concave mirror that reflects light

Methodology Applied

Scientific EffectLight reflection: Reflection

Data Source

PatentUS12211294B2Driver monitoring apparatus, vehicle and control method

Publication Date: 2025.01.28 HYUNDAI MOTOR CO LTD

AI summary

In accordance with one aspect of the disclosure, a driver monitoring apparatus includes: a camera having a field of view facing a driver's seat of a vehicle and configured to provide image data; and a controller configured to process the image data, and the controller is configured to identify at least one of a respiratory rate per minute or a respiratory volume of a driver based on the image data, identify whether the driver is in a state of a drowsy driving based on at least one of the respiratory rate per minute or the respiratory volume of the driver, and provide a control request to output a warning message through a display and speaker of the vehicle based on the drowsy driving of the driver.