Siemens Corporate Technology researchers in cooperation with the Fraunhofer Society for Microelectronic Circuits and Systems in Duisburg, Germany have developed the first three-dimensional object recognition sensor based entirely on semiconductor components.

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The new method, called multiple double short time integration (MDSI), directs near-infrared, low-power laser pulses through the passenger compartment of the vehicle. A Complementary Metal Oxide Semiconductor (CMOS) image converter with extremely short integration time detects the reflected light, which is then processed by an image converter chip. In only one thousandth of a second, the distances of 1,000 different object points are simultaneously measured to an accuracy of one centimeter, creating a three-dimensional image of objects within the passenger compartment.

"The new semiconductor-based design is extremely robust and can be mass produced, taking advantage of economies of scale," said Bruce Wrenbeck, Siemens Automotive Director of Safety Electronics Restraint Systems. "Its efficiency and cost effectiveness allows the three-dimensional occupant recognition sensor to lend itself to many different applications."

Previously, occupant sensing has been accomplished by utilizing a laser pulse deflected by a mirror, a highly technical method that is not as robust or timely as required by the automotive industry.

In order for three-dimensional occupant sensing to be applicable to the automotive industry, the issues of unit size, processing speed and computer memory needed to be addressed.

"First, the technology must be transparent to the end customer. The CMOS enables us to miniaturize the sensing electronics, plus it allows us to use a laser that has a low power requirement," said Wrenbeck. "Processing speed and memory are extremely critical. The time it takes for the system to continuously reacquire occupant data must be as close to real time as possible. Always knowing the position of the occupant will enable the system to more intelligently deploy airbags during collisions."

Wrenbeck states that Siemens Automotive is looking to use the occupant sensor to augment the control and safety of air bag triggering on passenger vehicles.

"Mat or weight sensors in the seat gives us the occupant classification, but 3-D sensing enhances this data with a position measurement," said Wrenbeck. "And as position measurements gain increased mapping capability and resolution, occupant safety systems will become more and more intelligent."

Three-dimensional occupant sensing technology currently is in the development phase and is projected to be in production by 2005.

Siemens Automotive is a tier-one supplier of automotive and electrical-electronic systems and components with applications covering gasoline and diesel powertrain systems, safety and chassis systems, body electronics, electric motor drives and driver information systems. Worldwide sales in fiscal year 1998/1999 totaled $3.6 billion.