Driver Critical-State Duration Detection for Microsleep Warnings

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Solution Overview

Problem

Current driver drowsiness and microsleep detection systems in vehicles are inefficient in distinguishing between critical and non-critical states, particularly in cases of short-term eye closures and sensor errors, leading to inadequate warning timing and reliability.

Innovation Solution

A method using a sensor device, such as a camera or infrared sensor, to monitor the driver's eye area and generate status signals, with a counter mechanism that increments for critical states and holds constant or reduces for non-critical states, allowing for early detection of microsleep and robustness against short-term sensor errors, and issuing a warning when a predetermined threshold is exceeded.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the counter is reset immediately when the driver's eyes are detected open, then the system responds quickly to non-critical states, but short oscillations and sensor errors cause false resets and reduce detection reliability

Engineering Contradiction:
Improveresponse speedVSAvoiddetection reliability
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

The system performs a preliminary check by comparing the current eye state with the previous eye state before resetting the counter. This preliminary action prevents immediate reset on transient signals, bridging short oscillations and sensor errors while maintaining reliable microsleep detection

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system cushions against false resets by implementing a state comparison mechanism that protects the counter from premature reset due to short-term sensor errors or brief eye openings, ensuring reliable critical state detection

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

2Measurement precision

If the counter accumulates all eye closed durations, then the system detects microsleep accurately, but short-term sensor errors and brief eye openings cause false positive warnings

Engineering Contradiction:
Improvemicrosleep detection precisionVSAvoidfalse positive warnings
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The system uses feedback by continuously comparing the current eye state with the previous eye state before updating the counter. This feedback mechanism filters out transient errors and brief non-critical eye closures, preventing false positive warnings while maintaining accurate microsleep detection

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system dynamically adjusts the counter update logic based on the comparison between current and previous states. By making the counter increment conditional on state transitions rather than simple accumulation, the system distinguishes between critical microsleep and non-critical brief eye openings

Inventive Principle:
Principle #15Dynamics

3Loss of time

If the system warns immediately when critical duration threshold is reached, then early warning is provided, but short oscillations in the signal cause premature or repeated warnings

Engineering Contradiction:
Improvewarning timingVSAvoidwarning reliability
Core Design Contradiction:
Loss of timeVSReliability

Solution Approach 1:

The system performs a preliminary verification by comparing current and previous eye states before triggering a warning. This preliminary check ensures that warnings are only issued for sustained critical states rather than transient oscillations, maintaining both timely and reliable warning performance

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3275370B1Method and device for determining a duration of a critical state of a driver of a vehicle
Publication Date: 2024.02.28 ROBERT BOSCH GMBH
  • EP3275370B1 patent drawingFigure 1~2
  • EP3275370B1 patent drawingFigure 3~4

AI summary

The invention relates to a method for determining the duration of a critical condition of a driver (104) of a vehicle (100). In this method, a state signal (108) is read in, representing a condition of the driver (104) detected by a sensor device (106) of the vehicle (100). It is then checked whether the state signal (108) represents the critical condition or a non-critical condition of the driver (104). If the state signal (108) represents the critical condition, a counter value representing the duration of the critical condition is incremented. If the state signal (108) represents the non-critical condition, the counter value is held constant. If, after a reference holding time (th), the state signal (108) represents the non-critical condition, the counter value is decremented.