The Practical Design of In-vehicle Telematics Device with GPS and MEMS Accelerometers

The latest generation of vehicle tracking devices relies not only on Global Positioning System (GPS) but also uses low-cost Micro-Electro-Mechanical Systems (MEMS) accelerometers. This combination supports new services such as driving style characterization and Automatic Crash Notification (ACN). Our focus will be on practical considerations of such a telematics unit. The paper will consider the 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. The kinematic orientation of vehicle is evaluated in a series of field trials with a resulting standard deviation of estimation of 1.67°. The second run of experiments considers the dynamic range and sampling rate of sensors during collision. A sensor range of 8g (typical for present-day telematics devices) can be used to detect crash without accurate knowledge of impact angle.