MEMS sensor measures acceleration, yaw rate in six axes

November 08, 2013 // By Christoph Hammerschmidt
Bosch has launch of a MEMS sensor which offers six degrees of freedom (6DoF) by measuring acceleration in all three spatial dimensions and yaw rates around all axes. The SMI130 is designed for non-safety-critical applications in the automotive industry, including in-dash navigation and telematics systems such as toll, eCall, and alarm systems.

For navigation systems, the combined inertial sensor offers two different benefits. First, it assists in situations where no GPS signal is available, such as tunnels, deep urban canyons, and off-road terrain. In combination with the vehicle's indicated speed, the sensor’s yaw rate signal provides the data required to determine the exact position of the vehicle according to the principles of dead reckoning. Second, navigation systems can use the acceleration signal to determine whether the vehicle is moving up or down and can use this information to derive its vertical position. This enables the system to identify the correct level in places where multiple roads are overlapping.

For manufacturers of navigation systems, the 2 x 3 sensing axes provided in the SMI130 offers a crucial advantage, enabling correction of the GPS signal regardless of the location of the navigation system within the vehicle.

The unique combination of sensing functionalities enables navigation system designers to utilize only one type of sensor for all applications, instead of multiple single-axis yaw rate sensors aligned differently according to the orientation and position of the navigation device.

Other applications that use information on vehicle movement can also benefit from the 6DoF sensor. The SMI130 also makes allows a more exact location definition of the vehicle for telematics and toll systems.

The measurement range of the yaw rate sensor can be adjusted in up to five steps between ±125°/s and ±2000°/s; the acceleration sensor offers four different measurement ranges between ±2g and ±16g. The yaw rate signal offers a resolution of 16 bit and the acceleration signal has a resolution of 12 bit. A temperature signal is also available. Further features include adjustable filter bandwidths and built-in self-testing capabilities. Combined, these features offer a significant degree of design flexibility. The SMI130 is supplied in a compact LGA package that measures just 3.0 x 4.5 x 0.95 mm, and is AEC-Q100 qualified for automotive applications.