A revolution in driving pleasure - BMW reinvents steeringActive Steering from BMW gives the driver unprecedented support and assistance but keeps him in full control

Active steeringPhoto: BMW

Munich - BMW is once again revolutionizing the world of driving, or to be more precise, the world of steering. Introducing Active Steering, a unique and innovative new system controlling the position of the front wheels precisely according to the driver's commands. BMW is setting a new standard in agility, comfort and safety.In the future BMW drivers will benefit directly and noticeably from this breakthrough in technology - on fast stretches of the highway, on winding country roads, and when parking in town, and will enjoy even greater motoring pleasure in the process, with Active Steering further enhancing the typical virtues of BMW steering. Retaining its authentic feeling and feedback from steering in every respect, the car is even more dynamic than before. At the same time Active Steering raises motoring comfort to a new standard through its ergonomic benefits. Last but not least, Active Steering sets a new benchmark in traffic safety, ideally supplementing BMW's Dynamic Stability Control (DSC) suspension system, making the entire process of steering the car even more pleasant and relaxing than before, which helps to reduce driving fatigue to an absolute minimum.In contrast to the systems developed by other manufacturers working on steer-by-wire alone, without any mechanical link between the steering wheel and the front wheels, BMW's Active Steering still incorporates a mechanical steering column permanently connecting the steering wheel with the front wheels of the car. This not only guarantees full maintenance of all steering functions even if one of the assistance systems is not operating properly or breaks down altogether, but is also the prerequisite for the authentic steering "feel" the driver appreciates so much. By contrast, a steer-by-wire system alone is unable to simulate such realistic feedback to the driver. This is precisely why BMW is now becoming the first car maker in the world to consciously opt for Active Steering as the trend setting technology leading to all-out steer-by-wire.Development of Active Steering has now reached such a high standard that it will be introduced soon in one of BMW's next model generations. BMW will therefore be the first car maker in the world to offer the BMW customer the full pleasure of dynamic motoring with enhanced safety and motoring comfort all in one - and all this with the authentic steering experience so typical of a BMW.The core element of the revolutionary Active Steering system is the steering override function provided by a planetary gearbox integrated into a split steering column. Acting through a self-inhibiting gear wheel, an electric motor intervenes as required in this planetary gearbox, either increasing or taking back the steering angle of the front wheels. A further component is the individually controlled power steering (similar to BMW Servotronic already well known in the market) controlling steering forces as required. Interacting with one another, these two components

adjust the steering angle of the front wheels and the steering forces on the steering wheel to the respective situation on the road and the driver's requirements.Under normal driving conditions Active Steering varies the steering transmission particularly at low and medium speeds, thus making the car even more agile and nimble in its behavior. In critical situations Active Steering serves furthermore to change the steering angles of the wheels, thus stabilizing the car faster and more efficiently than the driver would be able to himself. And this offers dynamic driving advantages in many situations.Active Steering will give the driver significant dynamic driving benefits typically on country roads, where Active Steering chooses a more direct steering trans-mission ratio than a conventional steering system, making the car even more agile and nimble in its response. Quite appropriately, steering behavior of this kind is described as that typical "kart feeling", the driver enjoying an even more agile and dynamic motoring experience. When driving at very low speeds, on the other hand, for example when parking in town, the driver only has to turn the steering wheel twice thanks to this direct steering transmission ratio in order to maneuver his BMW smoothly and without the slightest effort into the most confined parking space.At higher speeds, for example on the Autobahn, the steering transmission ratio becomes increasingly indirect up to the level of a conventional steering (or even beyond). The level of steering forces increasing at the same time prevents any undesired and unwanted movement of the steering, giving the driver a significantly higher standard of driving stability. Active Steering serves to carry out driving maneuvers at high speeds even more spontaneously, keeping the driver safely in control through purely intuitive movements of the steering.Whenever driving stability is limited, for example on wet or slippery roads or in crosswinds, Active Steering quickly intervenes and improves driving stability so significantly that BMW's DSC Dynamic Stability Control only has to intervene where really necessary. This is also the case when applying the brakes on surfaces varying in grip (for example with the left-hand wheels running on dry asphalt offering good and secure grip, while the wheels on the right are running on a loose embankment or road shoulder) or when suddenly changing direction, for example to steer clear of an animal or an obstacle abruptly looming up in front of the car.BMW Active Steering therefore offers a unique solution in solving the conflict of interests typical of every conventional steering, providing harmony of agility, stability and comfort never seen in the past. Thanks to Active Steering, the BMW driver will benefit in future from significantly enhanced driving comfort, safety and maneuverability, enjoying typical BMW driving pleasure even more than before.(August 5, 2002)