Seat sensor

This month, Sensata Technologies demonstrated several occupant sensing approaches that, it said, could help engineers design seat belt alert systems that are more accurate and provide a better level of consumer convenience and safety.

At the SAE 2007 World Congress, the company showed a new piezo electric sensor, as well as a current Monocrystalline Silicon Strain Gauge (MSG) force sensor, both of which give engineers a range of design options.

The new piezo electric sensor solves the problem of traditional weight-only detection systems, which often cannot differentiate between a person or a heavy object such as a box or bag of groceries, creating annoying false seat belt alerts.

A piezo electric wire, incorporated into a pad easily mounted under the seat cushion and providing input to an electronic module, senses the frequency response of a human and can determine the relative position of the passenger.

The Sensata piezo sensor can be built into a variety of seat structures, including A- or B-surface mounting, and accommodates all seat covering options including ventilated seats. A three-position sensor is available for rear seats.

Due to the sensor's ability to accurately measure weight and passenger position, the technology is also being considered for use with new Federal Motor Vehicle Safety Standard 208 classification air bag deployment systems, providing a single, integrated solution for two important consumer safety issues.

Sensata also demonstrated its MSG Occupant Weight Sensor (OWS) that employs a silicon MEMS strain gauge element glass bonded to a stainless steel diaphragm. Four MSG sensors are easily mounted within the seat structure to create accurate weight measures for safe airbag deployment and compliance to FMVSS208.

The sensors are available in several designs: an axial or flange rigid sensor, a rigid sensor with a Stress Reduction Component (SRC) or an SRC at flange centre style to give designers a range of design and mounting options.