Occupant detection and classification system
View Patent ↗An occupant detection system includes a controller, a sensing electrode, and a shield electrode, the electrodes disposed in a vehicle seat. The controller is electrically coupled to the sensing electrode and shield electrode by a sensing circuit. The controller is configured to send an input signal to the sensing electrode, the shield electrode, or both and measures current, impedance, or capacitance values to determine the presence of an object on the seat, to classify the object, or both.
1. A system for detecting an occupant in a vehicle comprising:
a sensing electrode mountable in a seat bottom of a vehicle seat;
a shield electrode located in the vehicle seat below the sensing electrode;
a sensing circuit operatively coupled to the sensing electrode and the shield electrode;
a controller operatively coupled to the sensing circuit, wherein the controller operates to configure the sensing circuit to apply a plurality of signals to the shield electrode; and
a belt tension sensor operatively coupled to the controller and configured for measuring tension in a seatbelt;
wherein the controller is configured to detect the presence of an object in the seat by detecting a relative force applied to the seat by the object and by calculating a force value related to the impedance between the sensing electrode and the shield electrode by using the results of separate measurements performed when each of the plurality of signals are applied to the shield electrode;
wherein the controller is configured to classify the object based on a signal from the belt tension sensor;
wherein one of the plurality of signals is applied to the sensing electrode and wherein the controller is configured to detect the presence of a wet seat by calculating a detection value related to the impedance from the sensing electrode to ground;
wherein the plurality of signals include first, second and third signals and wherein the controller operates to configure the sensing circuit to apply the first signal to the sensing electrode and to alternately apply the second signal and the third signal to the shield electrode;
wherein the controller operates to configure the sensing circuit to alternately couple a plurality of impedances between the sensing electrode and the shield electrode; and wherein the separate measurements used in the calculation of the detection value and force value are taken when the coupling impedances are in different configurations;
wherein the separate measurements are first, second, third, and fourth current measurements, and wherein the first and second current measurements occur when the second signal is applied to the shield electrode and the third and fourth current measurements occur when the third signal is applied to the shield electrode; and
wherein the first and third current measurements occur when none of the plurality of impedances are coupled between the sensing electrode and shield electrode and the second and fourth current measurements occur when the plurality of impedances are coupled between the sensing electrode and shield electrode.
2. A system for detecting an occupant in a vehicle comprising:
a sensing electrode mountable in a seat bottom of a vehicle seat;
a shield electrode located in the vehicle seat below the sensing electrode;
a sensing circuit operatively coupled to the sensing electrode and the shield electrode;
a controller operatively coupled to the sensing circuit, wherein the controller operates to configure the sensing circuit to apply a plurality of signals to the shield electrode;
wherein the controller is configured to detect the presence of an object in the seat by detecting a relative force applied to the seat by the object and by calculating a force value related to the impedance between the sensing electrode and the shield electrode by using the results of separate measurements performed when each of the plurality of signals are applied to the shield electrode;
wherein one of the plurality of signals is applied to the sensing electrode and wherein the controller is configured to detect the presence of a wet seat by calculating a detection value related to the impedance from the sensing electrode to ground;
wherein the plurality of signals include first, second and third signals and wherein the controller operates to configure the sensing circuit to apply the first signal to the sensing electrode and to alternately apply the second signal and the third signal to the shield electrode;
wherein the controller operates to configure the sensing circuit to alternately couple a plurality of impedances between the sensing electrode and the shield electrode; and wherein the separate measurements used in the calculation of the detection value and force value are taken when the coupling impedances are in different configurations;
wherein the separate measurements are first, second, third, and fourth current measurements, and wherein the first and second current measurements occur when the second signal is applied to the shield electrode and the third and fourth current measurements occur when the third signal is applied to the shield electrode; and
wherein the first and third current measurements occur when none of the plurality of impedances are coupled between the sensing electrode and shield electrode and the second and fourth current measurements occur when the plurality of impedances are coupled between the sensing electrode and shield electrode.