Yaw rate and lateral acceleration sensor, component description - GF42.45-P-5120TX

MODEL 211.0/2 as of 1.6.06 except CODE (494) USA version except CODE (498) Japan version 

MODEL 211.0/2 as of 1.7.06 with CODE (494) USA version with CODE (498) Japan version 

MODEL 219.3 

Fig 1: Locating Yaw Rate And Lateral Acceleration Sensor

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Location 

The yaw rate and lateral acceleration sensor is under the front passenger seat on the vehicle floor.

Task 

Recording the yaw rate (yaw angle rate) of the vehicle about the vertical axis and the lateral acceleration.

The ESP control unit (N47-5) uses the yaw angle velocity, the lateral acceleration and the steer angle of the front wheels (calculated from the steering wheel angle) to determine the lateral forces on the wheels.

Design 

Combined sensor for yaw rate and lateral acceleration in a micro-mechanical design.

Function 

The sensors for yaw rate and lateral acceleration are combined in the yaw rate and lateral acceleration sensor. The micromechanical system of sensors converts the different accelerations of the vehicle about its transverse and perpendicular axis into electrical signals which can be evaluated due to the deflection of vibrating masses.

The different types of masses are deflected differently according to the movement of the vehicle (cornering or decelerating).

The electronic analysis system records these signal changes and passes them on to the ESP control unit.

Fig 2: Partial Function Of Yaw Rate Sensor

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Yaw rate sensor, partial function 

The movement of the vehicle causes both vibrating members (d) to vibrate horizontally. If, as a result of rotary motion of the vehicle (skidding), a rotary motion is superimposed on this linear motion, a force (Coriolis force) acts on the vibrating members (d). The electronic analysis system calculates the rotational speed from the changes in the vibration states.

Fig 3: Partial Function Of Lateral Acceleration Sensor

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Lateral acceleration sensor, partial function 

The electronic analysis system controls the inert seismic mass so that it is held at its initial position. The lateral acceleration is then determined by the voltage required to maintain the initial position during operation.