New inertial sensor cluster for vehicle dynamic systems

Abstract

The concept of Bosch's new sensor cluster SC-MM3.x has been first presented at the AMAA conference in 2003[1]. This sensor cluster will replace the current DRS-MM1.x, which was the first silicon micromachined angular velocity and lateral acceleration sensor for the Bosch ESP system. Start of series production will be in the spring of 2005. The sensor cluster features a new generation of silicon microma-chined angular velocity and acceleration sensor elements, outstanding fully digital electronic readout circuits, a modular concept for hardware and software and many new safety features, which lead to a flexible and reliable solution for many vehicle dynamic systems. Compared to previous generations, robustness against vibration and EMI have been increased significantly. The single sensor elements are featured with a digital SPI interface and, due to the plastic IC package the sensor elements can be integrated into electronic control units of automotive equipment manufacturers. The sensor cluster has been designed to fulfill the requirements not only of the Bosch ESP system, but also of other systems which make use of angular velocity and acceleration signals, e.g. HHC (Hill hold control), APB (Automated Parking Brake), ACC (Adaptive Cruise Control), 4w (Four wheel drive), ROM (Roll Over Mitigation), RoSe (Roll over Sensing) or EAS (Electronic Active Steering). Signal monitoring is no longer performed by the ECU of the higher level vehicle dynamic system only, but in addition self monitoring has been implemented within the sensor cluster. This new safety concept is explained in detail. The result of our development is an open CAN interface for all relevant angular velocity and acceleration signals which vehicle systems of all kinds can make use of. In this paper, the accuracies and characteristics of the sensor elements are presented as well as other results of our tests. For advanced vehicle dynamic systems an even higher level of safety is required compared to the ESP system. This can be achieved by redundance of the sensor elements in combination with a two microcontroller concept and intelligent software algorithms. Because of its modular design the SC-MM3.x is best suited for those systems.