Abstract: A dual-electrode occupant detection system configured to determine an occupant presence on a seat assembly. The system includes two electrodes that each generates an electric field in response to an applied excitation signal. The two electrode signals arising therefrom can be measured individually and/or combined to detect more reliably an occupant. Such a configuration advantageously avoids the added expense and complication of an electrode arrangement that relies on an underlying shield layer to reduce electrode signal degradation caused by a seat heater element.

Abstract: A vehicle seat occupant detection device configured to indicate if a seat of a vehicle is occupied based on a weight of an occupant occupying the seat is provided. The device includes a spring and a sensor. The spring is configured to urge the device toward an unoccupied state. The sensor is configured to cooperate with the spring in order to determine an amount of deflection of the spring. In this way, the spring operates both as a return spring and an object that the sensor can detect and thereby determine the relative proximity of the spring.

Abstract: An occupant sensor mat configured to be located proximate to a seating surface of a vehicle seat assembly. The mat includes a sensor electrode formed of conductive material and configured to radiate an electric field in response to an excitation signal for determining an occupant presence proximate to the seating surface. A heater element is configured to underlie the sensor electrode. The heater element is formed of conductive material and configured to radiate heat in response to electrical current for warming an occupant residing on the seating surface. An incompressible spacer is interposed between the sensor electrode and the heater element. The incompressible spacer formed of a material sufficiently flexible for locating proximate to a seating surface, and sufficiently incompressible to prevent a substantial change in capacitive coupling between the sensor electrode and the heater element from before to while an occupant resides on the seating surface.

Abstract: A seat occupant sensor and heater device configured for use in a vehicle seat including an occupant detection electrode and a seat heating element. The occupant detection electrode may be configured to capacitively detect and classify a seat occupant in accordance with Federal Motor Vehicle Safety Standard FMVSS-208. The device includes a compressible spacer disposed intermediate to the occupant detection electrode and the seat heating element. The compressible spacer is configured to reduce capacitive coupling between the occupant detection electrode and the seat heating element when uncompressed and increase capacitive coupling between the occupant detection electrode and the seat heating element when compressed. The seat occupant sensor and heater device may exclude a fabric covering on the occupant detection electrode in order to improve sensitivity of the occupant detection electrode in high humidity conditions, i.e. relative humidity near or above 85 percent.

Abstract: A dual-electrode occupant detection system configured to determine an occupant presence on a seat assembly. The system includes two electrodes that each generates an electric field in response to an applied excitation signal. The two electrode signals arising therefrom can be measured individually and/or combined to detect more reliably an occupant. Such a configuration advantageously avoids the added expense and complication of an electrode arrangement that relies on an underlying shield layer to reduce electrode signal degradation caused by a seat heater element.

Abstract: A seat belt reminder system includes an occupant sensor to detect an occupant in a seat of a vehicle and a buckle sensor to detect when a seat belt is latched to a seat belt buckle. A controller detects whether the seat belt buckle is latched and a wireless transmitter sends the buckle status to a remote receiver in the vehicle. The controller and transmitter are powered by a battery that is separate from the vehicle electrical system. The controller, transmitter, and battery may be incorporated into the occupant sensor. A separate power supply for the controller and transmitter and a wireless connection to the receiver in the vehicle eliminates the need for a wiring harness from the seat to the vehicle. The seat belt reminder system may provide long battery life by connecting the controller and transmitter to the battery only when the seat is occupied.

Abstract: An occupant detection system with noise reduction, a controller having noise reduction for an occupant detection system and a method for reducing noise in an occupant detection system. A high order digital filter is used to filter harmonics of a noise signal from an electrode signal used to determine an occupant presence or absence of the occupant. A way of sampling the electrode signal and the implementation of the high order digital filter cooperate such that the signal processing can be performed by a lower cost general purpose microprocessor as opposed to using a higher cost digital signal processor.

Abstract: A seat assembly including a seat cushion, a heating element, a heating circuit, a occupant sensing circuit, and an isolation circuit. The seat cushion has a seating surface, the heating element is adjacent the seating surface and is formed of electrically conductive material. The heating circuit is coupled to the heating element for supplying electrical current to the heating element for generating heat. The occupant sensing circuit is also coupled to the heating element for sensing the presence of an occupant near the heating element. The isolation circuit is interposed between the heating circuit and the heating element for isolating the heating circuit from the occupant sensing circuit.

Abstract: An occupant detection system with noise reduction, a controller having noise reduction for an occupant detection system and a method for reducing noise in an occupant detection system. A high order digital filter is used to filter harmonics of a noise signal from an electrode signal used to determine an occupant presence or absence of the occupant. A way of sampling the electrode signal and the implementation of the high order digital filter cooperate such that the signal processing can be performed by a lower cost general purpose microprocessor as opposed to using a higher cost digital signal processor.

Abstract: An occupant detection system, a controller for an occupant detection system and a method of detecting an occupant. The presence or absence of the occupant varies the dielectric properties of an area proximate to influence the electrical impedance of the electrode. The electrode impedance is determined based on based on the excitation signal frequency, the excitation signal magnitude, and the electrode signal magnitude, and thereby determine an occupant presence based on the electrode impedance. The excitation signal magnitude is adjusted to optimize the electrode signal magnitude. The electrode signal magnitude is optimized to be large enough to be accurately measured, but not so large as to cause excessive radiated emissions. The excitation signal magnitude may be adjusted for each excitation signal frequency so the electrode signal magnitude is optimized regardless of frequency.

Abstract: An occupant detection system and method are provided. The system includes a capacitive sensor having an electrode arranged in a seat proximate to an expected location of an occupant for sensing an occupant presence approximate thereto. The capacitive sensor is configured to provide an output indicative of the sensed occupant presence. Occupant detection circuitry is included for processing the capacitive sensor output and determining a wet seat condition and generating a wet seat fault based on a determined wet seat condition. The occupant detection circuitry further detects a state of occupancy of the seat based on the capacitive sensor output and the wet seat fault.

Abstract: An electrode formed of electrically conductive material and configured for use in an occupant sensing system. The electrode includes an antenna portion and a diagnostic portion. The antenna portion is configured to provide an electrical impedance indicative of an occupant presence. The diagnostic loop portion is configured to provide an electrical conductivity indicative of a condition of the electrode.

Abstract: A vehicle crash sensing system and method are provided for sensing a vehicle crash event. The system includes a linear acceleration sensor located on a vehicle for sensing linear acceleration along a first sensing axis and generating a linear acceleration signal. The system has linear crash sensing logic for determining a crash event along the first sensing axis as a function of the sensed linear acceleration. The system also has signal processing circuitry for processing the linear acceleration signal and generating a processed linear acceleration signal. The system has an angular rate sensor located on the vehicle for sensing an angular roll rate of the vehicle about a second sensing axis and generating a roll rate signal. The system further includes rollover crash sensing logic for determining a rollover event of the vehicle about the second sensing axis as a function of the processed linear acceleration signal and the roll rate signal.

Abstract: Image processing parameters of an imaging chip in a vision-based occupant sensing system are adjusted for each frame based on ambient illumination responsive information obtained in the idle period preceding that frame. The same sensing data is also used to determine if active illumination is needed to supplement existent ambient illumination during the ensuing image acquisition interval. The inter-frame ambient illumination is detected with an external light sensor or with selected pixels of the imaging chip, and the information is used to calculate and set the gain and integration time of the imaging chip. In applications where the resolution of the imaging chip significantly exceeds the resolution required for occupant sensing, intensity data from one or more otherwise inactive pixels is averaged with the intensity data from the normally active pixels to adapt the sensitivity of the imaging chip to changing ambient illumination.

Abstract: A seat assembly including a seat cushion, a heating element, a heating circuit, a occupant sensing circuit, and an isolation circuit. The seat cushion has a seating surface, the heating element is adjacent the seating surface and is formed of electrically conductive material. The heating circuit is coupled to the heating element for supplying electrical current to the heating element for generating heat. The occupant sensing circuit is also coupled to the heating element for sensing the presence of an occupant near the heating element. The isolation circuit is interposed between the heating circuit and the heating element for isolating the heating circuit from the occupant sensing circuit.

Abstract: A vehicle crash sensing system and method are provided for sensing a vehicle crash event. The system includes a linear acceleration sensor located on a vehicle for sensing linear acceleration along a first sensing axis and generating a linear acceleration signal. The system has linear crash sensing logic for determining a crash event along the first sensing axis as a function of the sensed linear acceleration. The system also has signal processing circuitry for processing the linear acceleration signal and generating a processed linear acceleration signal. The system has an angular rate sensor located on the vehicle for sensing an angular roll rate of the vehicle about a second sensing axis and generating a roll rate signal. The system further includes rollover crash sensing logic for determining a rollover event of the vehicle about the second sensing axis as a function of the processed linear acceleration signal and the roll rate signal.

Abstract: The capacitance of a shielded capacitive load cell is determined so as to minimize the effect of stray or parasitic capacitance between the load cell and other objects including the shield. The load cell conductors are coupled across input and output terminals of an operational amplifier that is tied to a reference voltage. A constant current is applied to the load cell, and the resulting rate of change in voltage at the amplifier output is measured as a representation of the load cell capacitance. In a vehicle seat sensor application including an electromagnetic interference shield between the load cell and the seating surface, the amplifier output is coupled to the load cell electrode furthest from the shield, the amplifier maintains the other load cell electrode at a virtual reference voltage, and the shield is tied to the reference voltage.

Abstract: A vehicle seat occupant classification system uses a pressure responsive, fluid filled bladder and pressure sensor adapted for engagement with an underside of a foam seat cushion so as to generate a pressure signal corresponding to the weight of an occupant on an upper side of the foam seat cushion. A humidity sensor responds to relative humidity of air adjacent the pressure sensor and/or foam seat cushion to generate a humidity signal that is used to compensate at least one of the pressure signal, a stored reference pressure value and a stored threshold value, from which at least in part; an occupant classification is determined.

Abstract: A vehicle seat occupant classification system uses a pressure responsive, fluid filled bladder and pressure sensor adapted for engagement with an underside of a foam seat cushion so as to generate a pressure signal corresponding to the weight of an occupant on an upper side of the foam seat cushion. A humidity sensor responds to relative humidity of air adjacent the pressure sensor and/or foam seat cushion to generate a humidity signal that is used to compensate at least one of the pressure signal, a stored reference pressure value and a stored threshold value, from which at least in part; an occupant classification is determined.

Abstract: An improved vehicle restraint system includes a seat belt tension sensor and an occupant detection control module for characterizing the occupant of a vehicle seat to determine whether to allow or suppress deployment of supplemental inflatable restraints for the occupant. The belt tension sensor includes on-board signal processing circuitry and is coupled to occupant detection control module via a two wire interface that both powers the sensor and its signal processing circuitry and supports communication of belt tension data to the occupant detection control module. The sensor produces an electrical signal responsive to seat belt tension, and the processing circuitry generates one of a specified number of messages pertaining to the range of the measured tension, and then modulates the current through the two wire interface to communicate the generated message to the occupant detection control module.