Electrically powered steering (EPS) systems save manufacturers money, reduce customers’ fuel bills and save designers valuable space. Continuing just-auto’s series of interviews with leading players in the steering market, Matthew Beecham talked with executives of ZF Lenksysteme about active front steering, steer-by-wire systems, EPS market and fine tuning ‘steering feel’.
Generally speaking, in the early days of EPS the system had its faults. How does the latest generation EPS compare and what could we expect?
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The early problems are definitely overcome. EPS has become mainstream. Current quality levels with EPS are much better than with the previous HPS technology. With HPS a major concern was always with oil leakages.
OEMs talk about ‘steering feel’. Can it be tuned depending on the brand? And if so, what needs to happen to achieve that?
EPS tuning is very flexible and many parameters can be adjusted depending on the requirement of the OEM and the characteristic of the car model to be equipped with. Although steering feel is difficult to measure and is to some extent a subjective criteria there is definitely a lot of know-how required to design the mechanical parts and the electronics to achieve the targeted performance.
We are also hearing a lot about the ‘autonomous car’. To what extent can EPS assist such a vehicle? And what other areas need to be developed in order to achieve it?
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By GlobalDataAlready the currently used EPS systems basically are capable to provide the interface for autonomous driving. The key for this technology are the sensors which must enable the system to digitally evaluate the complete environment of the car in the short and long range distance. Problems to be resolved are to eliminate potential safety issues and related legal requirements.
Steer-by-wire systems have also been talked about for years. But there are signs that they are about to become a reality. What’s your view on its prospects?
The functionality of steer-by-wire can be achieved already today for example with an active front steering system. The additional advantage would be to get rid of most of the packaging issues in the engine compartment and at the dashboard. Steer-by-wire systems call for many redundant components to ensure the safety requirements. That makes these systems very expensive.
To what extent does active front steering (AFS) influence driving performance?
Active front steering contributes to enhance the agility and lateral dynamics of a car, but stabilises on the other hand steering at high speeds on highways for example. By applying a superimposed angle on the steering the gear ratio can be adjusted very flexible according to the driving conditions. In connection with other car systems (e.g. ESP, ABS) the system can support to stabilise a car in critical driving conditions.
AFS is said to make steering more comfortable and safer. Yet do you think that such steering technology and associated systems will become a necessity rather than a luxury?
This depends on how the system is valued by the end customer and whether regulations will be implemented to make such systems mandatory.
We are trying to get a feel for the pace of market growth of AFS. What are your thoughts on, say, the proportion (fitment percentage) of cars fitted with AFS today and the pace of growth over the next few years?
The system is currently offered mainly by premium car manufacturers. The fitment rate depends a lot on how they promote it in their cars.
EPS has followed a growth path over the past decade, gradually permeating across all vehicle segments. What are its continued prospects for its application in emerging markets?
We see the trend to change to EPS in emerging markets faster than forecasted a few years back. With higher volumes the prices for EPS come down and car drivers in emerging markets appreciate the benefit of EPS like lower fuel consumption, additional functions even more.
In terms of EPS technologies fitted to passenger cars, is there a dominant technology emerging (i.e. rack drive EPS) or does it depend on the vehicle application?
The remainder of this interview is available on just-auto’s QUBE research service
