Products for Cars
VMC VMC

Maneuverable Into the Smallest Parking Space

Min Reading Time
Narrow inner-city streets or awkwardly positioned parking garage barriers make even experienced drivers break out in a sweat. ZF combines smart software with innovative actuators to improve the maneuverability of passenger cars.
Kathrin Wildemann,
author_image
Kathrin Wildemann has been a part of the permanent Copy Team at ZF since 2016. In her online and offline articles, she likes to cover electromobility and other topics that involve sustainability.
When it comes to mobility over the next few years, the dream of a private robot taxi in your own garage will remain just a dream. At best, drivers will be able to take their hands off the steering wheel for short periods as things stand now. Instead, the automotive industry is focusing on advanced driver assistance systems (ADAS) that offer customers more comfort and safety.

The focus in this area is often on adaptive cruise control and emergency braking assist systems which are intended to prevent monotony and dangerous crashes during long intercity trips. However, significant potential for improvement also exists at the other end of the speed scale: Overcrowded parking garages, tiny parking spaces or tight inner-city streets constitute one of the major stress factors on the road for many drivers. Impatient drivers behind getting too close also compound the problem of a tight parking space. Parking and maneuvering accidents are among the most common causes of dents, scratches and even major damage. In Germany, they account for almost 40 percent of all car accidents, making ADAS systems such as parking and maneuvering assistants hugely popular.

Smart software needs innovative hardware

Smart software needs innovative hardware

With its unrivaled product portfolio throughout the industry, ZF offers solutions for all these use cases – from sensors and smart control systems to innovative actuators. These actuators will always be required because the hardware is the prerequisite for ensuring that all control commands are implemented precisely in the car and that drivers can control the vehicle in the easiest, most convenient way possible. This applies specifically to maneuverability: As a specialist in Vehicle Motion Control, ZF draws on its long-standing chassis experience to make future models even more agile.

EasyTurn front axle concept: U-turn instead of three-point turn

EasyTurn front axle concept: U-turn instead of three-point turn

The EasyTurn suspension strut axle concept is a prime example of such hardware innovation. With this innovative concept, ZF doubles the possible steering angle of current front axles from approximately 40 degrees to up to 80 degrees. This wheel position also turns larger vehicle models into agile runabouts that can slip into any parking space or turn in a space the size of a soccer goal where necessary – with a U-turn rather than a cumbersome three-point turn. EasyTurn, for example, reduces the turning radius of a typical midsize passenger car from ten to seven meters. And incidentally, the new system fits in perfectly with the current trend toward zero-emission mobility: "EasyTurn is suitable for vehicles with rear-wheel drive, the usual setup in electric cars. And it is ideally suited for volume segments because the MacPherson axle is compatible with around 80 percent of today's common platforms," says Knut Heidsieck, Head of Axle System Development in the Vehicle Motion Control System House.
The driver in the EasyTurn car also benefits from ZF's extensive systems expertise. The axle concept works even better when combined with the steer-by-wire system (SbW). Since SbW dispenses with the mechanical connection between the steering wheel and the steering gear, the steering angle of the wheels is always independent of the steering wheel movement. "Because EasyTurn offers an extremely high steering angle, a small steering wheel movement would cause a large deflection with a classic steering system. With SbW, we can allow the steering to react differently depending on the driving speed so that the steering is less sensitive at high speed than when maneuvering," explains Heidsieck.

AKC rear axle steering: Better maneuverability in all driving situations

AKC rear axle steering: Better maneuverability in all driving situations

At the other end of the vehicle, a classic from the ZF portfolio innovatively plays to its strengths to improve maneuverability: The Active Kinematics Control (AKC) rear axle steering system stabilizes the vehicle not only at high speed with improved driving dynamics, but also reduces the turning radius at low speeds and enables the car to move sideways. When maneuvering in a small space, this offers an unbeatable advantage that assistance systems can exploit. ZF demonstrates one potential scenario with "Zig-Zag Motion": The smart maneuvering assistant for electric cars connects AKC, the electric front axle steering system from ZF (EPS) and the electric drive with an algorithm that can reposition the vehicle sideways in record time – for example, when the rear end of the vehicle protrudes into the road from the roadside parking space. "We have identified 32 maneuvers altogether where Zig-Zag Motion can easily resolve a tricky driving situation. These maneuvers not only help the driver enter and exit parking spaces but also make it easier to move to an emergency lane during traffic jams or help the driver reach an awkwardly positioned parking garage barrier," says Volker Vogel, the project manager in charge of development of Zig-Zag Motion.
At the same time, ZF is constantly fine-tuning the AKC to make it even more efficient. While the current volume production version of the rear axle steering enables a steering angle of up to four degrees, the prototype installed in the "Zig-Zag Motion" innovation vehicle already reaches eight degrees. Over the long term, engineers are looking at up to 10 degrees. They are also focusing on the efficiency of the AKC specifically for use in electric vehicles. For safety reasons, the AKC has been designed as a self-locking system, resulting in up to 80 percent of the required energy being lost through friction. To reduce these losses, the AKC will use a fail-safe solution similar to that developed by ZF for SbW front axle steering systems.

Ready for the mobility of the future

Ready for the mobility of the future

Overall, it is clear that ZF's overriding aim is to integrate these innovative actuators into the overall vehicle control system and network them with other subsystems to fully leverage their advantages. Thanks to standardized, open interfaces, EasyTurn and AKC can be easily integrated into different platforms and control systems, for example in ZF's Vehicle Motion Control Platform cubiX, as well as into proprietary solutions. If necessary, a Zig-Zag Motion app could be developed that allows the driver to enter and exit a parking space using a smartphone – maneuverability at the tap of a finger.

Related Content