Mobility Solutions

Enhanced driving safety Bosch acceleration sensors for chassis control World’s first low-g sensors with PSI5 interface

  • Precise acceleration measurement in the ±1.6 g and ±16 g range
  • PSI5 interface digitally outputs measured values
  • Programmable for application engineering
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  • February 21, 2011
  • Mobility Solutions
  • Press releases
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press release

Chassis control systems can make an important contribution to driving comfort and safety in cars, and they are based on sensors that precisely record the dynamics of the chassis and body. The two new Bosch SMB431 and SMB433 low-g acceleration sensors are tailor-made for this task. The SMB431 records vertical movements of the body in a range of ±1.6 g (where 1 g = 9.81 m/s2). The SMB433 measures the wheels’ vertical accelerations in the ±16 g range. The two new sensors are already available in sample quantities for engineering purposes.

Sensors for wheel systems and car bodies
The SMB431 und SMB433 sensors are specially configured for use in active suspension systems, which reduce the fluctuations in wheel load and thus help vehicles stay on the road.

Three (or more) SMB431 sensors can be used to reliably record both the acceleration of the body along the z-axis, and its pitch and roll movements. Simultaneously, the SMB433 can be used to precisely record wheel acceleration. The control unit receives all the sensor signals and continuously adjusts the shock absorber action to the current road conditions.

The control unit regulates suspension damping and reduces body movement to make driving safer and more comfortable. The braking distance is shortened, and the danger of a rollover is reduced. The vehicle's occupants experience higher driving comfort and less chassis movement.

The SMB431 and SMB433 sensors have a range of applications beyond chassis control, including tilt measurement for trunk-lid control. Both sensors have fully digital signal processing and use a digital two-wire PSI5 interface, which is the same interface used in airbag systems. Compared with analog interfaces, the PSI5 interface provides fail-safe signal transfer and can also be used for programming, and thus for applying the sensor to the control system. The PSI5 interface also lowers complexity by reducing the amount of external wiring and sensor cabling needed.

Bosch: a MEMS sensors leader
The two MEMS sensors are part of an extensive product portfolio that also includes sensors for acceleration, yaw rate, pressure, torque, and air mass. Bosch has been active in MEMS for more than 20 years, making it a pioneer in the field. With more than 900 patents for MEMS and well over 1.2 billion MEMS sensors delivered, Bosch is a leading supplier in this product segment.

 SMB431 and SMB433 low-g sensors:
 key specifications
 Measuring range ±1.6 g (SMB431) and
 ±16 g (SMB433)
 filter frequencies
 30 Hz, 60 Hz, 120 Hz, 240 Hz
 Digital two-
 wire interface
 Housing SOIC14n
 (base area 6 mm x 8.6 mm)

The Bosch Group is a leading global supplier of technology and services. In 2013, its roughly 281,000 associates generated sales of 46.1 billion euros. (NB: Due to a change in accounting policies, the 2013 figures can only be compared to a limited extent with the 2012 figures). Its operations are divided into four business sectors: Mobility Solutions, Industrial Technology, Consumer Goods, and Energy and Building Technology. The Bosch Group comprises Robert Bosch GmbH and its roughly 360 subsidiaries and regional companies in some 50 countries. If its sales and service partners are included, then Bosch is represented in roughly 150 countries. This worldwide development, manufacturing, and sales network is the foundation for further growth. In 2013, the Bosch Group invested some 4.5 billion euros in research and development and applied for some 5,000 patents. This is an average of 20 patents per day. The Bosch Group's products and services are designed to fascinate, and to improve the quality of life by providing solutions which are both innovative and beneficial. In this way, the company offers technology worldwide that is “Invented for life.”

The company was set up in Stuttgart in 1886 by Robert Bosch (1861-1942) as “Workshop for Precision Mechanics and Electrical Engineering.” The special ownership structure of Robert Bosch GmbH guarantees the entrepreneurial freedom of the Bosch Group, making it possible for the company to plan over the long term and to undertake significant up-front investments in the safeguarding of its future. 92 percent of the share capital of Robert Bosch GmbH is held by Robert Bosch Stiftung GmbH, a charitable foundation. The majority of voting rights are held by Robert Bosch Industrietreuhand KG, an industrial trust. The entrepreneurial ownership functions are carried out by the trust. The remaining shares are held by the Bosch family and by Robert Bosch GmbH.

Additional information is available online at and,

PI7177 - February 21, 2011

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