The new electromechanical steering system, celebrating its premiere in the luxury vehicle segment with the CLS, is a radical step forward in the relationship between driver, car and road. This is because for the first time engineers have the freedom to choose and program freely a wide variety of parameters which can influence feeling experienced when steering.
The driving dynamics experts at Mercedes-Benz are making the most of this opportunity to thoroughly examine which steering characteristics are preferred both by professionals as well as regular customers when at the wheel of their cars. Extensive trials conducted in Europe and the USA using around 100 sample drivers from both camps have tested which steering behaviour is considered to be the most ideal. Initial results are already very surprising: customers on both sides of the Atlantic showed almost exactly the same preferences.
Using test vehicles in which the steering moments can be freely programmed, the engineers tested for what was perceived to be the most comfortable steering in all conceivable driving conditions.
For example, tests were conducted for:
steering response: the time delay between turning the steering wheel and the reaction of the vehicle being felt. If this period is too short, the steering is perceived as being too jumpy. If it is too long then the steering is considered to be sluggish.
feedback: results showed that all drivers would like to feel immediate resistance when they turn the wheel, as well as a defined increase in steering moments at increased speed and lateral acceleration.
centre alignment and damping: this provides the feeling of secure straight-line stability at higher speeds.
response rate: how dynamically does the steering wheel respond in returning to the straight-line position after cornering?
physical effort: what is perceived as comfortable and appropriate when manoeuvring, driving in urban traffic, along winding country roads or on the motorway?
the turning circle diameter and the necessary steering-wheel turns from lock to lock.
The bottom line is that Mercedes customers want precise steering which, on the one hand, offers relaxed driving at speed, and therefore high levels of stress-free comfort on the motorway; while on the other hand, features such as high manoeuvrability with few turns on winding roads are also appreciated as being highly comfortable.
A total of around 250 parameters were recorded. Their assessment has been used to define the Mercedes-Benz steering characteristics, which in future will form the basis for tuning all vehicles with electromechanical steering. The underlying feature is that the steering is perceived as comfortable across all model series, and translates well into refined sportiness.
As part of this, individual tuning according to vehicle class remains one of the core competences of the development engineers: ultimately the expectations of drivers at the wheel of an M-Class are different to those at the wheel of an SLS AMG, something which also emerged as a clear factor when developing the Mercedes-Benz steering characteristics.