BMW ASF active steering system1

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BMW ASF active steering system1 [Copy link]

Consumers who are addicted to the charm of the BMW brand but have always complained about its overly conservative body shape can finally make a move this time! Under the revolutionary design aesthetics guidance of Mr. Chris Bangle, the design director of the BMW Group, the BMW Innovation 5 Series uses bold and clear lines to outline its extremely dynamic and fashionable shape. Every detail is absolutely exquisite, avant-garde but not ostentatious, passionate but not losing its inner qualities. The BMW Innovation 5 Series, which claims to be a "mobile work of art", combines power, aesthetics and control in one, which can instantly inspire all your imaginations about a car. It implements its tangible unique personality into every subtle detail. This is the feeling I expressed when I participated in the last test drive of the BMW New 5 Series.

　　Indeed, starting with the E20 5 Series that debuted in 1972, the past 30 years have seen the E28, E34 and E39, and the current E60 model is undoubtedly the most visually impactful model in the history of the 5 Series. More importantly, it inherits the 5 Series' iconic handling and excellent ride comfort.

Since its launch in July 2003, the BMW 5 Series has won numerous international awards:

　　2003
　　
　　 German Business Invention Award
　　 for Best Invention - L'Aotpmobile Magazine, France

　　2004

　　 Best Technology Award - Automobile Magazine, USA
　　 Best New Technology Award - Canadian Automotive Journalists Association
　　　International Automotive Styling Award
　　 Best Luxury Car - Money Magazine
　　　Best Sedans in the Class - Forbes Magazine Annual Car Buying Guide
　　　Car Guide Medal - American Automobile Association won for three consecutive years
　　 Technology Star of the Year - Automobile Magazine, USA
　　 Annual German iF Outstanding Design Award
　　Chicago Athenaeum Museum "Architecture and Design Award"

　　However, even though BMW generously gave me a hearty driving pleasure throughout the driving process, I still felt regretful. This is because the AFS active steering system, which was first used in the BMW E60 innovative 5 series and E63 6 series, did not appear in the configuration list of BMW Brilliance. Not only me, but also the BMW technical instructor who was present at the time could not hide his disappointment.

　　In early March, BMW Brilliance finally announced the official introduction of BMW's unique AFS active steering system, and held a media test drive event at Shanghai Hualong Airport on the 15th to allow people to experience the AFS active steering system in depth. Taking this opportunity, Sina Auto will take you to learn about BMW's original active steering system.

　　How does the AFS steering system work?

　　So what kind of technology is the AFS active steering system? We know that the steering transmission ratio between the steering wheel and the front wheels is strictly fixed, and the driver's instructions are always transmitted in the same way (even if the transmission ratio gradually increases as the steering wheel steering angle approaches the lock point). Direct steering is ideal at low speeds, but not suitable for high speeds, because at high speeds, the steering sensitivity will increase due to physical reasons, and the steering response needs to be more indirect. The same principle also applies to the opposite situation, that is, indirect steering is suitable for high speeds, but at low speeds, steering becomes very laborious and the driver has to spend more effort to turn the steering wheel. Therefore, traditional steering systems are usually the result of a compromise between two extreme situations.

Working principle analysis diagram

　　The AFS active steering system, which is the first of its kind in BMW, is controlled by electronic by-line-wire technology. When driving at low and medium speeds, it can actively assist the steering wheel's steering gear ratio according to the vehicle speed, so that a small turn of the steering wheel at low speeds can complete a large turn of the wheels, making it easier to make U-turns on ordinary roads or park on the roadside; on the contrary, when cruising at high speeds, the steering wheel's steering range will monitor the vehicle's status through the active deviation control function. In conjunction with the DSC dynamic stability control system, it can reduce excessive deviation or instability of the vehicle, and can also reduce the driver's chance of wrong operation in an emergency, which not only increases driving safety, but also improves high-speed stability, making the passengers in the car more at ease. (As the vehicle speed changes, the steering ratio between the steering wheel and the wheels changes continuously from 10:1 to 18:1. However, for safety reasons, when the speed exceeds 120 kilometers, the ratio is fixed at the maximum value and no longer changes.)

A one-size-fits-all race for the BMW 530i?

　　Main features of AFS active steering system:

　　1. When parking, the steering wheel gear ratio will be increased, which means that the driver can complete the parking action easily and effortlessly without turning the steering wheel to the bottom;

　　2. When driving in urban areas or on ordinary country roads, AFS has a sharper and more direct feel than ordinary steering systems, making the vehicle more responsive;

　　3. When the vehicle speed increases, the inertia of the steering wheel will hinder the driver's inadvertent steering wheel turning action, and the signal transmission is not as sensitive as at low speed, which improves driving safety;

　　4. When the vehicle is in a sharp turn under intense driving, AFS will reduce the steering wheel sensitivity to maintain a more intuitive steering feel. Even in more urgent situations, the regulator inside AFS will intervene one step earlier than DSC to maintain vehicle stability.

　　5. When the braking force on both sides is uneven (for example, when the friction force on both sides is unequal), the AFS system will automatically enhance the stabilizing force in advance.