Page 56

EETE NOV 2014

A47E_EETimes_2_37x10_875_A45.qxd 9/29/14 12:20 PM Page 1 HIGH VOLTAGE ADJUSTABLE OUTPUT MODULES DC-DC Converters 100-1500 VDC Output NEW SAR SERIES! High Voltage Isolated 100 to 1500 VDC Output Adjustable, Down To 0 VDC Output Output Power 3 Watts Minature Design: 1.1” x 0.8” x 0.4” ht. 12 grams Typical Weight Surface Mount & Thru Hole Models Available Output Center Tap for Dual Output Use Input/Output and Over/Under Voltage Protection Over Temperature Protection Fully Encapsulated for Use In Rugged Environments Military Screening Options per Selected MIL-STD-883 Methods with Expanded Operating Temperatures Available, -40˚ to +85˚C For full characteristics of these and the entire PICO product line, see PICO’s Full line catalog at www.picoelectronics.com PICO ELECTRONICS, Inc. 143 Sparks Ave., Pelham, New York 10803 E Mail: info@picoelectronics.com Pico Representatives Germany ELBV/Electronische Bauelemente Vertrieb E-mail: info@elbv.de Phone: 0049 89 4602852 Fax: 0049 89 46205442 England Ginsbury Electronics Ltd. E-mail: rbennett@ginsbury.co.uk Phone: 0044 1634 298900 Fax: 0044 1634 290904 MEMS inertial sensors provide the equilibrium sense to your car By Peter Spoden and Michael Baus With the new SMI7 inertial sensor family, Bosch introduces a new sensor generation which detects the state of motion in a car with a new level of performance. This enables modern advanced driver assistance functions in addition to the established functions for safety features. MEMS sensors for acceleration and rotation entered the automotive market about 15 years ago. Acceleration sensors Fig. 1: SMI7 inertial sensors for vehicle were providing high-g signals of crashes in airbag systems, whereas gyroscopes dynamics functions. and low-g sensors were providing signals for roll-over detection and ESP® systems. Typically, systems for active and passive safety demand for a high degree of functional safety (addressed by a redundant system architecture) and for a moderate performance of sensors with respect to offset stability (±100 mg or ±3.5 °/s) and to noise (<15 mg¬RMS or 0.4 (°/s)RMS). The ongoing introduction of advanced driver assistance systems and comfort features to modern cars relies on improved sensing capabilities of inertial sensors: The low-g offset stability needs to be narrowed down to ±50 mg (and an impressive 20 mg for short-term drifts) and the noise being as quiet as 6 mgRMS or 0.2 (°/s)RMS, respectively. Reflecting the different sets of requirements Fig. 2: Measurement of the low-g output of SMI7 in the range from -40 °C to +85 °C. (summarized in Table 1), Bosch developed two product categories for its SMI7 sensor family - see figure 1: SMI700 and SMI710 support advanced comfort and driver assistance functions (ADAS) such as adaptive cruise control, hill-hold control, roll-stability control, active damping systems or vehicle motion observers. Active and passive safety functions are targeted by the second product category, constituted by SMI740 for ESP® and SMI720 for roll-over sensing. If a car is equipped with SMI7 sensors, the integrated gyroscopes will notice whether the chassis is rolling or pitching, or whether the car is skidding in a curve (the ESP® system will react). The low-g accelerometers will assist when starting at a steep hill. They will notice whether the chassis is jumping (the damper control will react) or whether the driver is accelerating or braking. Considering all this information, the SMI7 components truly provide the equilibrium sense to the car. They could even be used to improve the performance of a GNSS based navigation system on the road to automated driving capabilities. Unlike the signals of inertial sensors in a smart phone, the signals of automotive sensors are connected in the safe vehicle communication infrastructure. In combination with several other car internal sensors and the aid of appropriate algorithms, SMI7 signals are the basis for high reliable life saving functions. Therefore these sensors are designed in such a way that one can trust the signals they provide under the demanding conditions a car might be exposed to. Bosch addressed these topics with special focus on functional safety, thermal drifts and on vibration robustness to provide highest levels of safety and availability. SMI7 sensors can be used in applications with a rating up to ASIL D according to ISO26262, which is the international Peter Spoden is Product Manager for Inertial Sensors at Robert Bosch GmbH - www.bosch.com Michael Baus is Project Manager at Robert Bosch GmbH 44 Electronic Engineering Times Europe November 2014 www.electronics-eetimes.com


EETE NOV 2014
To see the actual publication please follow the link above