Dual-Threshold Seat Occupancy Sensor for False Detection Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing seat occupancy detection systems in vehicles face challenges in providing stable and reproducible output signals across a wide temperature range and are prone to temporary false detections due to dynamic load changes and temperature influences, leading to unclear occupancy status determination.
Innovation Solution
A seat occupancy detection system utilizing at least two pressure sensors with different triggering sensitivities, where the 'occupied' state is maintained until the first switching threshold is reached or fallen below, and the second switching threshold is used to generate a trigger signal for the 'occupied' status, ensuring stable detection without false positives from light objects or dynamic weight changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single pressure sensor with one switching threshold is used, then the device complexity is low, but false detections occur due to dynamic acceleration forces and temperature changes exceeding the threshold
Solution Approach 1:
The pressure sensor is segmented into multiple sensor elements (first sensor element with first switching threshold, second sensor element with second switching threshold). Each element has different triggering sensitivities, allowing the system to distinguish between temporary dynamic forces and genuine occupancy. The first sensor element detects lower threshold events while the second detects higher threshold events, and their combined evaluation eliminates false detections.
2Measurement precision
If the switching threshold is set low to detect light objects, then detection sensitivity increases, but false detections occur due to temperature changes and dynamic forces
Solution Approach 1:
The evaluation unit acts as an intermediary that processes signals from both sensor elements. It applies logical evaluation (AND operation) to combine the outputs, meaning both sensor elements must indicate occupancy for a false positive to be eliminated. This intermediary processing layer filters out temperature-induced and dynamic force-induced false signals while maintaining sensitivity to genuine occupancy.
3Reliability
If the switching threshold is set high to avoid false detections, then reliability improves, but light objects cannot be detected
Solution Approach 1:
Different sensor elements have different local qualities in terms of switching thresholds. The first sensor element has a lower threshold suitable for detecting light objects, while the second has a higher threshold for confirming genuine occupancy. This local differentiation allows the system to maintain high sensitivity without sacrificing reliability, as the combined evaluation ensures both thresholds are satisfied.
4Reliability
If multiple sensor elements with different thresholds are used, then false detections are suppressed, but the device complexity increases
Solution Approach 1:
Multiple sensor elements with different thresholds are merged into a single pressure sensor assembly. The first and second sensor elements are integrated within the same sensor structure, sharing common components such as the flexible circuit board and evaluation unit. This merging approach reduces overall system complexity compared to using separate sensors, while still achieving reliable false-detection suppression through combined signal evaluation.
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 system provides clear and reproducible output signals across a large temperature range, suppressing erroneous detections and maintaining accurate occupancy status even during dynamic weight fluctuations, ensuring reliable operation.
Implementation Method 1
at least two sensor elements are provided, which have two different triggering sensitivities. The first sensor element has a first trigger sensitivity dictated by a first pressure switching threshold and the second sensor element has a second trigger sensitivity dictated by a second pressure switching threshold.
Data Source
AI summary
The invention relates to an occupancy detection device for detecting the occupancy status of a seat, in particular a motor vehicle seat, with at least one pressure sensor 1 comprising at least one first sensor element 2 and at least one second sensor element 3, wherein the pressure sensor 1 is positioned between a seat cover and a cushion core 5 and the pressure sensor provides at least one output signal depending on the occupancy status of the seat, characterized in that the first sensor element 2 has a first trigger sensitivity by means of a first switching threshold S1 exerted by pressure and the second sensor element 3 has a second trigger sensitivity by means of a second switching threshold S2 exerted by pressure, wherein the first trigger sensitivity is higher than the second trigger sensitivity and, accordingly, the first switching threshold S1 is lower than the second switching threshold S2.where reaching the second switching threshold S2 is used as a trigger signal for a seat occupancy state and this state is only reset when the first switching threshold S1 of the at least one first sensor element 2 is again undercut.