Dynamic Stability Control (DSC)
Dynamic Stability Control (DSC) adds to safety by facilitating vehicle control even in adverse driving conditions or on tough surfaces.
Dynamic Stability Control (DSC) is the nucleus of the chassis control systems in BMW vehicles. It ensures the highest possible levels of stability when driving, and it maximizes traction of all wheels when setting off or accelerating. It is able to detect the first signs of oversteering or understeering and helps keep the vehicle safely on course, even if the tyres have varying levels of grip.
Dynamic Stability Control (DSC) is the nucleus of the chassis control systems in BMW vehicles. It ensures the highest possible levels of stability when driving, and it maximizes traction of all wheels when setting off or accelerating. It is able to detect the first signs of oversteering or understeering and helps keep the vehicle safely on course, even if the tyres have varying levels of grip.
Sophisticated sensors permanently check how the vehicle is driving. Information comes a range of sensors monitoring wheel rotation, steering angle, lateral forces, pressure and yaw (degree of rotation around the vertical axis).
A simulation model stored in the DSC control unit to ensure stability ("one-/two-track model") and can be compared information coming from the steering wheel and accelerator: if there is too great a difference between the model and how the vehicle is currently travelling, DSC acts to increase stability or traction.
The engine and brake management systems are targeted specifically; xDrive is also included in all-wheel drive vehicles. Reducing or increasing the engine torque or braking individual wheels can improve stability and traction. Active Steering’s integrated yaw regulation system can even help significantly reduce steering effort and the extent of DSC’s contribution to stability.
A simulation model stored in the DSC control unit to ensure stability ("one-/two-track model") and can be compared information coming from the steering wheel and accelerator: if there is too great a difference between the model and how the vehicle is currently travelling, DSC acts to increase stability or traction.
The engine and brake management systems are targeted specifically; xDrive is also included in all-wheel drive vehicles. Reducing or increasing the engine torque or braking individual wheels can improve stability and traction. Active Steering’s integrated yaw regulation system can even help significantly reduce steering effort and the extent of DSC’s contribution to stability.
Dynamic Stability Control 8+
Installed on vehicles:
- 5 Series & 6 Series - E60, 61, 63, 64 with Rear-wheel and All-wheel drive
- 3 Series - E90, 91, 92 with All-wheel drive
- X3 - E83
The new features for 8+ are:
Brake Standby
Brake standby pretensions the brakes to decrease the brakes response time during rapid release of the accelerator pedal. A low brake pressure is created without a noticeable deceleration taking place. The distance between the brake pad and rotors is eliminated. If no brake application takes place within half a second, the pretension is reduced. The brake standby feature is only active at speeds above 70km/h.
Brake Disc Drying
Brake disc drying removes the moisture that gathers on the brake rotors during driving on wet roads. This feature is similar to brake standby, as it creates a low brake pressure without a noticeable deceleration. The brakes are regularly wiped down depending on the intensity of the rain, figured by the speed of the windshield wipers and if the vehicle is traveling faster than 70km/h.
Detection/Compensation during brake-fade
Brake -fade compensation is required when the brake discs/rotors are at a high temperature. The DSC can detect brake fade by comparing the vehicles current deceleration to stored values base on brake pressures. When brake fade compensation is active, a general yellow brake warning lamp or yellow check control message will appear in the instrument cluster. The brake pressures will be increased until deceleration values are within specification and/or the brake pedal is no longer depressed or the vehicle is below a certain speed.
Start-off Assistance
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Start-off assistance prevents the vehicle from rolling downhill when moving your foot from the brake pedal to the accelerator pedal. The DSC maintains brake pressure to hold the vehicle until sufficient torque is generated by the engine to move the vehicle. If the parking brake is applied or no movement is made within 2 seconds after the brake pedal is released, the start-off assist will be deactivated.
Soft stop
When braking to a complete stop, soft stop prevents the vehicle from jolting to a stop. The brake pressures are reduced to the rear axle just before the vehicle is stopped. From road speed signals and deceleration values the DSC can calculate the moment that the stop will be completed, then reduces rear brake pressures accordingly. Soft stop is only active on light braking applications.
The inputs needed for the DSC to perform a regulation or interventions are:
- Brake pressure
- Steering angle
- Wheel speeds
- Lateral acceleration speeds
- Yaw rates
The components that make up the DSC 8+ system are:
- DSC hydraulic/control unit
- Brake lamp switch
- Wheel speed sensors
- DSC sensor
- Steering angle sensor
- Internal brake pressure sensors
- Brake pad wear sensors
- DTC button
- Brake fluid level switch
DSC communicates with the following control units:
DME: The DME controls the engine output to prevent wheel slip during a DSC intervention. The DME also uses the right rear wheel speed signal to check plausibility of misfires.
RLS: The rain light sensor is used for the brake disc drying feature to determine when to wipe the brake discs.
CAS – M-ASK/CCC: The left rear wheel speed signal from the DSC is used to determine if the vehicle is moving or at a standstill.
SGM: Data interface/Gateway
KGM: Data interface/Gateway
JBE: Data interface/Gateway
ACC: The DSC uses the request from the Active Cruise Control to apply the brakes to the wheels. On an E90 the request comes from the LDM for brake application.
LM: The DSC sends a signal to the Light Module to activate the brake lamps when ACC is active and applying the brakes. The light module is used to activate the rear lamps on E60, 61, 63, 64 vehicles.
FRM: The DSC sends a signal to the Footwell module to activate the brake lamps when the ACC is active and applying the brakes. The FRM is used to activate the rear lamps on E90, 91, 92 vehicles.
KOMBI: The instrument cluster is used to display the indicator and warning lamps for DSC functions and is also a gateway.
EGS: The EGS uses wheel speed signals to control shifting characteristics as during cornering or in winter conditions.
CID: The CID is used to display check control messages from the DSC. The Flat Tire monitoring is initialized through the CID, also HDC is activated through the CID.
TCU: The TCU is used to pinpoint the vehicles position if a navigation system isn’t installed on the vehicle. The front wheel speed signals are used to determine vehicle positions.
DME: The DME controls the engine output to prevent wheel slip during a DSC intervention. The DME also uses the right rear wheel speed signal to check plausibility of misfires.
RLS: The rain light sensor is used for the brake disc drying feature to determine when to wipe the brake discs.
CAS – M-ASK/CCC: The left rear wheel speed signal from the DSC is used to determine if the vehicle is moving or at a standstill.
SGM: Data interface/Gateway
KGM: Data interface/Gateway
JBE: Data interface/Gateway
ACC: The DSC uses the request from the Active Cruise Control to apply the brakes to the wheels. On an E90 the request comes from the LDM for brake application.
LM: The DSC sends a signal to the Light Module to activate the brake lamps when ACC is active and applying the brakes. The light module is used to activate the rear lamps on E60, 61, 63, 64 vehicles.
FRM: The DSC sends a signal to the Footwell module to activate the brake lamps when the ACC is active and applying the brakes. The FRM is used to activate the rear lamps on E90, 91, 92 vehicles.
KOMBI: The instrument cluster is used to display the indicator and warning lamps for DSC functions and is also a gateway.
EGS: The EGS uses wheel speed signals to control shifting characteristics as during cornering or in winter conditions.
CID: The CID is used to display check control messages from the DSC. The Flat Tire monitoring is initialized through the CID, also HDC is activated through the CID.
TCU: The TCU is used to pinpoint the vehicles position if a navigation system isn’t installed on the vehicle. The front wheel speed signals are used to determine vehicle positions.
