Occupant Classification via Electric Field and Vibration Sensing
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Solution Overview
Problem
Current occupant classification systems, particularly in vehicles, face challenges in accurately differentiating between various types of occupants and objects due to environmental factors and the inability to reliably distinguish between live and non-live loads, leading to misclassification issues.
Innovation Solution
A system combining electric field sensing with mechanical vibration sensing, utilizing a movable element and a capacitive sensing circuit to measure current and vibration changes, which enhances classification accuracy by integrating signals from both sensors to control safety restraints effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electric field sensing is used alone, then the system can detect the presence of objects on the seat, but it cannot reliably differentiate between child seats, small children, and adults
Solution Approach 1:
The patent combines electric field sensing with mechanical vibration sensing into a single integrated system. The electric field sensor detects the presence of objects on the seat, while the mechanical vibration sensor (movable element) detects vibrations caused by occupant movement. By merging these two sensing modalities, the system achieves reliable differentiation between child seats, small children, and adults, resolving the limitation of electric field sensing alone.
2Reliability
If only electric field sensors are used, then the system structure remains simple, but the system is highly sensitive to environmental conditions and cannot reliably classify occupants
Solution Approach 1:
The patent merges electric field sensing with mechanical vibration sensing into a single integrated system. The electric field sensor detects the presence of objects on the seat, while the mechanical vibration sensor (movable element) detects vibrations caused by occupant movement. By merging these two sensing modalities, the system achieves reliable differentiation between child seats, small children, and adults, resolving the limitation of electric field sensing alone.
Solution Approach 2:
The movable element acts as an intermediary between the occupant and the sensing system. It mechanically couples the occupant's movement to the sensing circuit, converting mechanical vibrations into electrical signals that can be processed. This intermediary mechanism enhances reliability by providing a physical connection that is less susceptible to environmental interference compared to pure electric field sensing.
3Measurement precision
If electric field sensing is used, then the system can detect objects on the seat, but it cannot distinguish between live and non-live loads
Solution Approach 1:
The patent employs mechanical vibration sensing through a movable element that detects vibrations caused by occupant movement. Live loads (humans) generate characteristic vibration patterns through breathing, heartbeat, and muscle movements, while non-live loads (child seats, bags) do not. By measuring these mechanical vibrations, the system can reliably distinguish between live and non-live loads, overcoming the limitation of electric field sensing.
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 integrated system improves occupant classification accuracy by reducing sensitivity to environmental conditions and effectively differentiating between various occupant types and loads, enhancing the reliability of safety restraint systems.
Implementation Method 1
an electric field sensor located in the vehicle seat. The electric field sensor includes a first conductor positioned below the seating surface of the seat. A sensing circuit is configured to supply a first signal to the first conductor. The sensing circuit includes measurement electronics configured to measure the current being supplied to the first conductor. The measurement is affected by the presence of an object on the seating surface
Implementation Method 2
a movable element located in the vehicle seat. The movable element is configured to move when there is downward force on the element. The measurement electronics are also configured to measure the vibration of the moveable element
Data Source
AI summary
A system for classifying an occupant located on a seating surface of a vehicle seat. The system includes a movable element and an electrode located in the vehicle seat. A sensing circuit is provided to supply a signal to the conductor. The sensing circuit also includes measurement electronics configured to measure the signal to the conductor and the vibration of the moveable element. A controller is configured to discriminate between different types of objects located on the seating surface based on changes in the signal being supplied to the conductor and the vibration of the moveable element.