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Integration of a driver monitor system (DMS) in a head-up display (HUD) gives the monitor camera a continuous view of the driver’s face, since the driver always faces the road ahead. However, with both infrared (IR) illuminator and IR camera packaged in the HUD, reflectivity of the windshield is important at IR wavelengths used by the camera. Not only is windshield IR reflectivity important for a clear camera image of the driver’s face, but increasing windshield reflectivity also decreases the effect of ambient sunlight on the camera image of the driver’s face. We describe a method to measure windshield reflectivity, both for the 940 nm band used by a DMS, and for visible light for the HUD. The measurement method uses a fiber-optic spectrometer, two collimating lenses, and a method to compensate for sample tilt. The lenses are mounted on a stage that adjusts the height above the sample.

A sensor that passively monitors the driver for intoxication has been demonstrated. The driver's blood alcohol concentration (BAC) is obtained by sensing alcohol and CO2 in air drawn from the vehicle cabin. With a legally drunk driver, the steady state alcohol concentration can be as low as 0.3 ppm, even with the doors and windows closed. The sensor uses infrared transmission to quantify alcohol vapor and CO2. A vapor concentrator increases alcohol sensitivity - an adsorber collects alcohol vapor and releases it as a concentrated burst at 1 minute intervals. A valid measure of driver BAC is ordinarily available 1.5 minutes after the driver gets in. Sensed CO2 must be above a threshold for a valid measurement.

An ultrasonic air temperature sensor, intended to help improve automatic climate control (ACC), has been demonstrated in a vehicle. Ideally, ACC should be based on inputs correlated with thermal comfort. Current ACC systems do not measure the air temperature best correlated to thermal comfort - at breath level in front of an occupant. This limits the thermal comfort that ACC can provide under transient conditions. An ultrasonic sensor measures the bulk air temperature, is transparent to the driver, and can use commercially available components. In a proof-of-concept test, we monitored the thermal transients in a vehicle during cool-down after a hot soak and also during warm-up after a cold soak. The ultrasonic path was along the roof console. The ultrasonic temperature always agreed to ±1 °C with the air temperature measured by a thermocouple at the midpoint of the ultrasonic path.

Variation of gasoline's driveability index (DI) limits control of the air-to-fuel ratio during cold starts. The DI of fuel purchased at the pump is correlated with ambient temperature. The DI variability that remains after accounting for this correlation is quantified for fuel samples collected in 1998. A new type of sensor to measure DI is introduced. The sensor is located in the fuel tank, above the highest liquid level. A small sample of fuel is heated at the end of each trip. Capacitance measurement is used to determine oxygenate concentration and to monitor the evaporation of the sample as a function of temperature. The sensor has been used to determine the DI of fuel on-board a vehicle.

Automatic climate control could be improved by measuring air temperature ultrasonically. Thermal comfort correlates better with bulk air temperature than with the temperature measured by the in-car sensor. The time of flight of an ultrasonic pulse through the air gives the bulk air temperature. In a proof-of-concept experiment, it is accurate to ± 0.5 °C from -40 to+60 °C. Two operational modes are demonstrated: pulse-echo in which a single transducer creates a pulse and detects its return from a reflector, and single-pass in which a source transducer creates a pulse that travels directly to a separate transducer.

Direct thermal detection of the passenger is considered for use in a system that would suppress deployment of the passenger-side airbag for a rear-facing infant seat. The temperature at the surface of the front passenger's seat is compared with the temperature at the surface of the driver's seat. If the two temperatures differ by more than a preset amount the airbag would be suppressed. It is shown that when the ambient temperature equals the passenger's skin temperature (at about 35 °C) seat surface temperature does not distinguish a normally seated adult from a rear facing infant seat. Attempts to circumvent this problem by adding a heater were either too slow or too insensitive for an airbag suppression system. However, direct thermal detection may add reliability to some other type of airbag suppression system, such as one based on passenger weight.