Method and system for detecting an occupant in a vehicle seat

Abstract

An occupant detection system comprises an electrode arrangement for placement into a seat of an automotive vehicle and an evaluation circuit operatively connected to the electrode arrangement. The latter includes a first electrode for emitting an electric field into a detection region above the vehicle seat, a second electrode and an electric insulator layer sandwiched between the first and second electrodes. When the electrode arrangement is in place in the seat, the first electrode forms with vehicle ground a first capacitor having a first capacitance, which is influenceable by an occupying item in the detection region through interaction of the occupying item with the electric field, the first electrode forms with the second electrode a second capacitor having a second capacitance and the second electrode forms with at least one of vehicle ground and a third electrode a third capacitor having a third capacitance. As a first indicator of the seat occupancy state, a measure of the first capacitance is determined while the first electrode is caused to emit an electric field into said detection region and the second electrode is operated as a driven shield for the first electrode. The fluctuations of at least one of the first, second and third capacitances are measured and the frequency spectrum of the measured fluctuations is analysed, which yields a second indicator of the occupancy state. The derivation of the occupancy state of the seat is then based on both the first indicator and the second indicator.

Description

technical field [0001] The present invention relates generally to the detection of occupants in vehicle seats and, in particular, to detection using capacitive detection systems. Background technique [0002] As used herein, an occupant detection system refers to a system suitable for detecting the occupancy state of a vehicle seat. Some electric field sensors or proximity sensors are referred to as capacitive sensors specifically to generate a signal in response to the influence of the thing being sensed (person, human body part, pet, object, etc.) under the action of the electric field emitted by the capacitive sensor sensor. Capacitive sensors generally comprise at least one electrode to which an oscillating electrical signal is applied when the sensor is in operation, and which subsequently emits an electric field into a region of space in the vicinity of the electrode. When an occupant or an object is placed in this region of space, it interacts with the electric fiel...

AI Technical Summary

Problems solved by technology

[0005] A challenge with capacitive occupant detection systems is reliable detection of wet seat covers which can lead to false occupant detections

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