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IR technology enhances driver safety

-January 27, 2014

Driver's safety and driver's awareness features are becoming a major area of growing standard features making the change from OEM options for new vehicles. A few short years ago, display systems, steering wheel-mounted controls and heads-up displays were rare items relegated to only top-of-the-line luxury vehicles.

However, with the insurance industry recognizing the value of these technologies in reducing accidents and hence lowering their payout liability, car manufacturers have been quick to adopt the technologies, thus providing a reduced cost of ownership on their cars.

One of the major cost reduction technologies comes from using high-intensity IR-based subsystems. These IR systems, such as those available from OSRAM, typically consist of an IR LED or solid-state laser source along with either a standard IR detector or a full multi-pixel solid-state image sensor and an image processing IC.

These systems have been around for decades, are in full production and have been cost reduced from other industries, making their use in both Drivers Assistance (traditional automotive specification) and in-cabin applications. The advances in the processing and power efficiency now allows the components to work over the full -40°C to +105°C temperature range, and have almost no heat issues that would impact their placement in-cabin near the occupants.

One of the areas in which these devices are being used is for in-cabin touchless gesture control. Using an array of IR sources and detectors, the system can now detect specific gesture controls such as up, down, scan and select.

Since there is a distributed array of detectors, the system can tell if the motion of the gesture is from left to right or right to left. This allows the system to determine if the command is coming from the driver or the front seat passenger. As a result, the head unit system can limit the functions and options based on the rules for distracted driver regulations. As one example, selecting pre-sets on the entertainment system may be allowed for the driver, but from the passenger side, full access to adjustments of the infotainment system are possible.

A new application that is possible from these IR systems is Drowsy Driver detection. This is a setup that uses high-intensity 900 to 960-nm IR sources with a multi-pixel image sensor detector subsystem. Like a standard visual spectrum imaging setup, the system works by doing image processing on the face of the driver to tell if their eyes are open or closed (see figure, courtesy of Osram). The advantage of the IR system is it is not impaired if the driver has glasses or sunglasses.

The high-intensity low-power IR LED sources help create a full closed loop for the signal processing flow that is in the millisecond range, so it creates timely alarms. As these components are similar to the function in the gesture detection application, in addition to open or closed eyes, it can detect head motion to see if the driver is nodding off, without a change in the driver's eyelid position.

The use of IR as the subsystem allows the pricing of these applications to not only be put in to high-end luxury cars, but are cost effective enough to be designed in as standard features on entry-level and economy cars.

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