The name of German supplier Thyssenkrupp conjures images of raw steel and manufacturing equipment. But the company is also active in technology, including components for self-driving cars. Kristof Polmans, head of development for Thyssenkrupp's steering business, spoke with Staff Reporter Richard Truett about a technology that is playing an increasing role, electric powered steering assist.
Q: Electric powered steering assist systems have been far from trouble-free. What is Thyssen- krupp doing to improve reliability?
A: The failure rate of electric power assist steering, or EPAS, is a lot lower than hydraulic systems from the old days. When hydraulic systems failed, you would not lose the power assist immediately. There was always a transition phase, a warning. But the failure rate with EPAS is seen as more critical because from one second to the next, you don't have assist anymore.
There are some mechanical issues that cause failures, but the main reason for failures are torque sensors. So we are working very heavily on the software side to develop functions which allow you to have a certain amount of assist, even if certain failures happen. It might not give you the same steering feel, but it is a lot better than no support.
How do Thyssenkrupp's engineers work with automakers to create the software aspect of this technology?
The code and basic software come from us. However, we have a very flexible software architecture that allows OEMs to interface with us, so they can request a certain steering wheel torque or EPAS motor torque, or they request a certain requirement for automated parking and lane-keep assist and those kinds of functions.
How will electric powered steering assist change as we move into the autonomous vehicle era?
The big change of going to automated driving is the fail-operational state. Today, all steering operations are basically fail-safe. If you go to steer-by-wire in automated vehicles, we need a fail-operational EPAS system.
One global industry standard for redundancy in steer-by-wire systems would make things easier.
The big topic here is that all the OEMs don't have a clear answer yet on what the redundancy requirements are. But I agree. Having one standard would make everybody's life a lot easier. But standards are a tough topic. Standards don't tell you what the design looks like, just what requirements you have to fill.