Active Steering: Introduction: Notes
Active Steering is the most recent BMW development in the innovative steering systems sector.
Active Steering varies the steering gear ratio from direct to indirect and vice versa as a function of the vehicle's speed.
The benefits of Active Front Steering are:
- direct steering with no more than minimal movements of the steering wheel at the low end of the speed range
- More indirect steering at higher speeds in conjunction with yaw-rate control
Active Steering, including Servotronic, is available as an option (option 217).
Active Steering gives the vehicle an even sportier character.
New for the E70 is the 3rd generation Active Steering:
- Yawing moment compensation has been fully integrated as a function in the Active Steering control unit
- Cumulative steering angle sensor discontinued
- Digital motor-position sensor
- Commissioning exclusively via service function in BMW diagnosis system
On the X5, Active Steering is available for the first time on an all-wheel drive vehicle.
In 03/2007 the actions described for the E70 will also be implemented on the BMW 5-Series. Other model series will follow later.
Option 216 "Servotronic" is not available without Active Steering.
Active Steering is not available in conjunction with option 3AC "Trailer coupling with folding ball head".
New for the BMW 3-Series was:
- Yaw moment compensation as additional function
- Output stages for the Servotronic valve and the ECO valve are integrated into the Active Steering control unit
- Only 1 DSC sensor (redundant)
New for the BMW 5 and 6-Series from 09/2005 was:
- Active Steering control unit taken from BMW 3-Series
- This allows the Servotronic valve and the ECO valve to be directly actuated by the Active Steering control unit
- Only 1 DSC sensor as on BMW 3-Series
With option 216 "Servotronic", the body gateway module (KGM) actuates the Servotronic valve.
A conventional steering system inevitably constitutes a compromise:
on the one hand, the steering cannot be too direct as otherwise it would be overly sensitive when the vehicle is travelling at high speed. On the other hand it is practical to have much more direct steering for maneuvering at low speeds and for parking. The new Active Front Steering system is the ideal trade-off. The directness of the steering of a vehicle fitted with AFS varies with speed.
This results in three major benefits:
- enhanced agility
- enhanced comfort
- enhanced safety