MUNICH, Germany Automotive tier one Continental AG has combined yaw rate and acceleration sensors in one component. The device aims at ESC and other safety-related systems, offering compact design at lower cost. Unlike comparable sensors, it is not based on MEMS technology but implemented as capacitive sensors.
The combination of the two sensors in one SMD component also results in better vibration resistance and lower temperature susceptibility, the company claims. At the same time, the integration of the sensors in silicon offers designers the option to improve sophisticated assistance systems such as Adaptive Cruise Control (ACC) or Active Front Steering, the company said. In addition, Continental plans to use the component to further develop its ContiGuard safety system.
According to Ralf Schnupp, head of Inertial Sensors in Continental's Chassis and Safety Division, acceleration and yaw rate sensors are key to providing Electronic Stability Control (ESC) systems with the necessary information about the vehicle's condition. The system measures the turning speed of the wheels, the car's lateral and longitudinal acceleration, steering movements, yaw ratio and rotational speed. It uses these data to calculate in which direction the vehicle is traveling and the driver is steering.
To date, micromechanical sensors (MEMS) have been used specifically for the acceleration sensor. Now, according to the vendor for the first time ever, purely capacitive sensors made exclusively from silicon will be used for yaw rate and acceleration sensing. These are more cost-effective and offer higher resolution, i.e. increased sensitivity to measurement. They also ensure only very slight deviations in measurement accuracy in series production and, above all, only slight deviations in measurement readings over a long service life, the company says.
One of the biggest challenges facing development engineers when attempting to integrate the sensors into one component was preventing unwanted frequencies and signal cross-talk between sensors. Through the use of silicon sensors, Continental claims it has achieved a higher level of resistance to resonance and vibration, as well as to ambient temperatures of up to 125°C.
The compact design of the sensor cluster means it takes up less space in the vehicle, making it easier to fit and more cost-effective, and also enabling the use of ESC in models of all vehicle categories. Through the integration of the combined yaw rate and acceleration sensor in ESC or airbag control units, reliability in safety-critical applications can be increased as fewer external components have to be used and linked together.
In addition to the standard application for ESC, use of the integrated sensor cluster also meets with so-called high-precision specifications. This improves the performance of advanced systems such as Adaptive Cruise Control (ACC), Active Front Steering and Intelligent Headlamp Control. It also increases the accuracy of fault monitoring on redundant systems. On intelligent cruise control, for example, more powerful sensors offer improved radar accuracy.
The integrated signal processor monitors and analyzes the internal signals. This covers all levels of the signal chain. If the system detects a fault, it is saved in a non-volatile memory and can be read using diagnostic equipment. This expands the range of diagnostic options, both for the sensors themselves and for the sensor cluster as a whole.
The sensor cluster will go into serial production with several vehicle OEMs at the beginning of next year, the company said.