Electromechanical servo-steering can lead to transmission rattle, which can disturb the driving experience severely. We use the combination of vehicle road trials, test bench trials for full vehicles and components, and simulations to find out, where the noise arises and how to get rid of it.

First, we analyze the occurring noise or vibration in road trials. Therefore, the vehicle is equipped with sensors for air- and structure-borne noise and sent over appropriate road surfaces to excite the noise phenomenon.

With the help of a transmission path analysis, we then examine how the noise or vibration moves from its source to recipient.

Furthermore, the entire vehicle is tested in our servo-hydraulic test center. Here, we reproduce the excitation from the road-tire-contact measured during the road trials and vary its spatial direction in order to identify the relevant spatial directions.

Ideally, we then continue the root cause analysis and optimization of steering varieties on system and component level. Therefore, we construct a customized testing setting based on the full vehicle testing results and use simulations to identify its eigenfrequencies.

These results then are transferred with the help of a transmission path analysis to the full vehicle and used to demonstrate the inside sound. Finally, a variety of steering systems can be built into the vehicle to validate the used methodology.