Vehicle Occupant Posture Control Using Likelihood Ratio Detection
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Solution Overview
Problem
Existing vehicle control systems face challenges in accurately determining a safe seating posture of passengers due to variations in seating likelihood caused by factors like sitting posture, seat position, vehicle internal structure, and imaging conditions, leading to increased decision time and passenger stress.
Innovation Solution
A vehicle control apparatus that uses a controller to derive reference and immediate posture likelihoods, calculates a likelihood ratio, and sets a flag based on these ratios to accurately determine seating posture, reducing the need for multiple sensors and lowering decision time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high threshold is set for seating likelihood to accurately determine seating posture, then measurement precision is improved, but decision time increases causing passenger stress
Solution Approach 1:
The system changes the parameter used for decision-making from absolute seating likelihood to a ratio between reference posture likelihood and immediate posture likelihood. This transformation allows the system to maintain high measurement precision while reducing decision time, as the ratio provides a more stable and discriminative metric that is less sensitive to variations in imaging conditions and individual sitting styles.
2Loss of time
If a low threshold is set for seating likelihood to reduce decision time, then decision time decreases, but measurement precision deteriorates making it difficult to accurately determine seating posture
Solution Approach 1:
The system transforms the decision parameter from absolute likelihood to a ratio of likelihoods (reference posture likelihood divided by immediate posture likelihood). This parameter transformation enables the system to make rapid decisions with a lower threshold while maintaining high accuracy, because the ratio metric is inherently more discriminative and less affected by environmental variations.
3Measurement precision
If the system waits for all persons in the vehicle to exceed the threshold before making a seating decision, then measurement precision for all passengers is improved, but loss of time increases due to additional waiting
Solution Approach 1:
The system applies the likelihood ratio transformation to enable more efficient multi-passenger assessment. The ratio metric provides stronger statistical separation between seated and non-seated states, allowing the system to confidently determine posture for multiple passengers with less accumulated observation time, thereby reducing total waiting time while maintaining group-level accuracy.
Data Source
AI summary
A vehicle control apparatus includes a controller configured to derive reference posture likelihood and immediate posture likelihood at a first time, and calculate a likelihood ratio of the reference posture likelihood to the immediate posture likelihood at the first time, the reference posture likelihood indicating likelihood that posture of an object is a reference posture and the immediate posture likelihood indicating likelihood that the posture of the object is an immediate posture, turn on a flag indicating that the posture of the object is the reference posture in a case in which the reference posture likelihood is equal to or greater than a threshold, and the likelihood ratio is equal to or greater than a first predetermined value, and turn off the flag in a case in which the reference posture likelihood is less than the threshold, or the likelihood ratio is less than the first predetermined value.