Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle subsystem or accessory control
Reexamination Certificate
1999-12-22
2001-10-02
Camby, Richard M. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle subsystem or accessory control
C180S068200, C055S283000, C454S075000
Reexamination Certificate
active
06298291
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to air quality sensors and, more specifically, to a method of establishing a filtered baseline signal for an air quality sensor.
2. Description of the Related Art
Air quality sensors (AQS) are sensors that sense noxious gases. Such sensors can be used by a climate control system of a motor vehicle to shut off intake air into an occupant compartment of the motor vehicle, thus preventing pollution and undesired smells from reaching occupants in the occupant compartment. Typically, the air quality sensors use a heated thin film, which reacts with certain gases and changes resistance. These air quality sensors generally fall into one of two categories: reducing or oxidizing, according to the kind of gases they can detect. Reducing air quality sensors detect such gases as unburned hydrocarbons in diesel exhaust, carbon monoxide, methane from cattle in feedlots, etc. Oxidizing air quality sensors detect such gases as nitrogen oxides, ozone and chlorine.
The signal from the air quality sensors can be related to absolute concentrations of particular gases, but because the sensors detect such a wide variety of gases and are exposed in use to an unpredictable mix, comparing the signal to any absolute level is not very useful. Rather, it is desirable to take advantage of the transient characteristics of typical signals obtained from these air quality sensors on a moving motor vehicle. Most of the time, the air quality sensor will produce a background signal level characteristic of the regional air mass the motor vehicle is moving through. When the motor vehicle passes through a plume from a point source of detectable gases, a spike in the signal will occur and then fade away as the motor vehicle moves out of the plume. The background signal level will slowly change as the motor vehicle moves from one region to another such as from rural to urban areas.
It is desirable to provide a baseline filter for air quality sensor signal processing. It is also desirable to provide a baseline filter for establishing a moving baseline for the background signal level and take action when the signal level exceeds a certain threshold above this baseline for an air quality sensor. It is further desirable to provide a method that tracks the baseline of a signal from an air quality sensor without unduly following spikes. Therefore, there is a need in the art to provide a method of establishing a baseline filter for an air quality sensor.
SUMMARY OF THE INVENTION
Accordingly, the present invention is a method of establishing a baseline filter for an air quality sensor in a motor vehicle including the step of providing an air quality sensor for intake air into an occupant compartment of the motor vehicle. The method also includes the step of establishing a moving baseline for a background signal level from the air quality sensor. The method further includes the step of shutting off intake air into an occupant compartment of the motor vehicle when the background signal level exceeds a certain threshold above the moving baseline, thereby preventing undesired gases in the intake air from reaching occupants in the occupant compartment.
One advantage of the present invention is that a method is provided of establishing a baseline filter for an air quality sensor. Another advantage of the present invention is that the method tracks the baseline of a signal from an air quality sensor without following spikes, but following baseline changes while spikes occur. Yet another advantage of the present invention is that the method may be used with an unprocessed signal from an air quality sensor. Still another advantage of the present invention is that the baseline filter establishes a moving baseline for the background signal level so that action may be taken when the signal level exceeds a certain threshold above this baseline for an air quality sensor.
Other features and advantages of the present invention will be readily appreciated, as the same becomes better understood, after reading the subsequent description when considered in connection with the accompanying drawings.
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Dage Gerhard Allen
Davis, Jr. Leighton Ira
Hoeschele John David
Camby Richard M.
Shelton Larry I.
Visteon Global Technologies Inc.
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