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AKC 2.0: The Success Story Continues

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Electromobility and automated driving benefit considerably from the even more powerful second generation of the ZF Active Kinematics Control (AKC) rear axle steering. An overview.

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The AKC rear axle steering from ZF is advantageous in almost every driving situation. At low speeds it reduces the turning radius; at high speeds it increases driving stability. The improved second generation of AKC makes it easier to integrate automated driving functions. It is also ideal for battery-powered vehicles with long wheelbases.

Whether your are driving slowly through narrow alleys, backing into small parking spaces or taking sharp corners quickly, ZF's AKC (Active Kinematics Control) active rear axle steering system improves safety, dynamics and comfort in almost any driving situation. AKC is available in two versions: as central actuator or dual actuator. With dual actuators, one actuator each is positioned on the left and right rear wheel. Ideal for sports cars as this solution saves valuable installation space in the center of the rear axle. After all, this is often where engine, tank or other components are placed.

The central actuator variant with a single but larger and centrally positioned actuator is ideal for sedans, pick-ups or SUVs. Regardless of whether a central or dual actuator is used, both change the rear wheel toe angle and thus strongly influence the steering function despite a comparatively small travel distance. Thus, AKC not only increases maneuverability but also improves stability at high speeds. The latter leads to a plus in safety, especially during unexpected evasive maneuvers.

Active rear axle steering AKC is available in two variants: the central actuator (pictured above) or the dual actuator.

The second generation of AKC significantly improves this system. A larger steering angle now gives full-size high-end luxury cars and off-road vehicles the maneuverability of significantly smaller vehicles. Also electric cars with longer wheelbases benefit from this in particular. The increased actuating force of the actuators of more than eleven kilonewtons now allows the use of AKC in vehicles up to a total weight of 3.5 tons.

"The first AKC generation has already been a success story," says Frank Berger, adding: "In the current generation, we have increased the steering angle even further without abandoning the proven design principle." A larger adjustment stroke turns the rear wheels by up to ten degrees and makes the vehicle even more maneuverable and agile, explains Berger, head of the responsible development department at ZF.

The latest generation AKC offers rear steering angle of up to ten degrees.

Dr. Peter Holdmann, Head of Division Chassis Technology, explains the advantages, that Active Kinematics Control has in almost every driving situation.

With its increased performance and a new electronics architecture, AKC is equally fit for the requirements of automated and electrified mobility. For example, the "steer-by-wire" steering system simplifies the integration of automated driving functions. The developers are also keeping an eye on protecting the system against cyber attacks. "Due to the cybersecurity standards that mechatronic systems in the vehicle must fulfill, the requirements are constantly growing," says Philipp Niemeyer, head of the Safety and Security Team. "Our goal is to make data transfer and processing absolutely safe and reliable." State-of-the-art cybersecurity protects the control unit in the AKC from hacker attacks.

The second AKC generation celebrated its premiere in the fall of 2020 in an electric US luxury SUV. If all four wheels are turned into the same direction, the vehicle moves diagonally forwards or backwards. Thus, even the trickiest off-road passages can be mastered.