What is BMW DSC (Dynamic Stability Control)

Old BMW Cars, we know about ASC as the old generation of DSC.

ASC in BMW is an advanced module from the ABS (Anti brake control), however the DSC is more advanced than ASC, and started to be seen on 2002-2003 BMW Models.

DSC sensor

Since 09/2005 only 1 DSC sensor is installed.

The DSC sensor is located on the seat cross member under the driver’s seat. A separate DSC sensor is used for the optional equipment “Active Steering” (redundant sensor system).

BMW DSC Location

The above picture shows the installation location on the BMW 3-Series.

Index Explanation
1 Cross member for the seat on the driver’s side
2 DSC sensor on vehicles without Active Steering (“simple” DSC sensor)
3 DSC sensor on vehicles with Active Steering (“redundant” DSC sensor)

Construction

The DSC sensor with optional equipment “Active Steering” consists of:

  • Housing with plug connector
  • Damper to prevent mechanical overloading
  • Sensor element with 2 yaw sensors
  • Printed circuit board for CAN interface with 2 acceleration sensors

The DSC sensor is linked to the DSC control unit by the F-CAN (chassis and suspension CAN).

DSC Items

Item Meaning Item Meaning
1 DSC sensor plug connection 2 Printed circuit board for CAN interface with 2 acceleration sensors
3 Housing gasket 4 ribbon cable
5 Sensor element 6 Housing
7 Upper housing section 8 2 yaw sensors
9 2 evaluation electronics 10 Plug connector
11 Lower housing section 12 Rubber damper
13 Upper tuning fork excited by vibrations 14 Lower tuning fork reacting with vibrations when turned around vertical axis

Operating principle

On vehicles with Active Steering, the DSC sensor redundantly delivers 2 yaw-rate signals and 2 lateral acceleration signals.

The yaw sensor comprises 2 tuning forks and measures the yaw rate (= rotation around the vertical axis).

The yaw rate is measured by a tuning-fork-shaped double fork. One side of the double fork is excited into vibration by a quartz crystal. This excitement generates high-frequency vibration of a defined amplitude (the arms move towards and away from one another). The double fork can be compared to a pirouetting ice skater. The skater spins faster when he pulls his arms in. The skater spins slower when he stretches his arms out. This means that the movement of the arms generates a force that influences the rotational speed. Therefore, the forced even rotational movement (stationary in relation to the high-frequency vibration of the arms) generates a force. Due to this force, the bottom freely movable arms on the double fork vibrate back and forth. These vibrations are electrically evaluated in the evaluation electronics in the DSC sensor. The vibrations are a measure of the yaw rate (= rotational movement around the vertical axis).

Leave a Reply

Your email address will not be published. Required fields are marked *