The practical design of in-vehicle telematics device with GPS and MEMS accelerometers

Latest generation of vehicle tracking devices relies not only on Global Positioning System (GPS) but also uses a low-cost Micro-Electro-Mechanical Systems (MEMS) accelerometers. This combination supports new services as driving style characterization and Automatic Crash Notification (ACN). Focus will be on practical considerations of such telematics unit. Work will consider boundaries of allowed errors and minimal requirements for sensors and mounting requirements. Sensor range for crash detection and impact angle estimation was tested on field trials with two units containing accelerometers range of 18g and 2g. Kinematic orientation of vehicle is evaluated in series of field trials with resulting standard deviation of estimation of 1.67°. The second run of experiments considers dynamic range and sampling rate of sensors during collision. Sensor range of 8g (typical for current telematics devices) can be used to detect crash without accurate knowing of impact angle.