Freescale Xtrinsic smart sensor applications enable advanced automotive active safety

It is reported that Freescale Semiconductor is currently expanding its Xtrinsic smart sensor solution series by adding MMA6900Q and MMA6901Q accelerometers to achieve advanced automotive active safety applications.

Cars have been equipped with passive safety systems, such as airbags and seat belt systems, to minimize injuries caused by crashes for many years. Recently, the industry has begun to adopt mature and intelligent active safety systems to help prevent unexpected events. Electronic stability control (ESC) is an active safety system that ensures the safety of passengers by monitoring the driving environment using multiple intelligent sensors.

It is learned that ESC can prevent nearly one-third of fatal car accidents. Therefore, the National Highway Traffic Safety Administration (NHTSA) stipulates that most models in 2012 must be equipped with this technology. ESC measures the vehicle's lateral and longitudinal acceleration through high-performance, low-gravity two-axis sensors to help the driver achieve control of the vehicle. When the sensors record potentially unstable driving conditions, the system will send data to the car's engine and braking system to automatically assist the driver in maintaining control of the vehicle.

“Freescale has been a leader in providing sensor technology to automakers as they incorporate more intelligence and connectivity into vehicle designs,” said Demetre Kondylis, vice president and general manager of Freescale’s Sensor and Actuation Solutions Division. “By providing advanced safety through the new Xtrinsic smart accelerometers, Freescale allows designers to reduce space and cost and meet key safety standards ahead of schedule.”

The Xtrinsic MMA6900Q and MMA6901Q accelerometers offer a wide dynamic sensing range with very high resolution, enabling designers of advanced automotive safety systems to filter out extraneous signals, such as parasitic vibrations, that could interfere with the vehicle's lateral acceleration measurements.

XtrinsicMMA6900Q and MMA6901Q accelerometers are based on Freescale's next-generation high-aspect ratio microelectromechanical system (HARMEMS) technology, which is a mature technology suitable for airbag sensing applications. Now not only does this technology improve the stability of the sensor, but HARMEMS technology also provides over-damped mechanical response and excellent signal-to-noise ratio to meet customer requirements. Over-damped HARMEMS technology is highly immune to high-frequency, high-amplitude parasitic vibrations---an important performance because active safety applications (such as ESC) are now widely installed in the cabin or hood of the car.

For ESC applications, using Freescale DSP signal chain to achieve higher signal-to-noise ratio can cover a large range, improve sensitivity, and make the noise less than one least significant bit (LSB).

Freescale low-g accelerometers can also be used in countless embedded applications that require the measurement of subtle forces, including shock, vibration, tilt, movement or acceleration. From industrial equipment to robotics to heavy agricultural equipment, industrial manufacturers rely on low-g accelerometers to achieve unique safety and convenience features in their products.