Continuing just-auto/QUBE's series of interviews with tier one suppliers, we spoke to Dr Marcus Parche, executive vice president, Robert Bosch Automotive Steering about steering technologies for different levels of driver autonomy, user experience test results, steer-by-wire and further market potential for electric power steering.
In terms of the near future, what will be the next steps in terms of steering technology?
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Our fail-operational steering system will enter production in 2019.
The most advanced engineering systems are for highly automated driving. We have SAE Levels 3, 4 and 5 systems coming up. That means the driver will not be constantly surveying the driving situation. So if something occurs while driving and the driver cannot correct it in time then it needs a steering solution that can intervene. We are going into production in 2019 with our fail-operational steering system. And this is for highly automated driving situations.
How does a Level 3 steering system differ from a Level 5?
So, if we talk about level 3 then that is more or less a standard which we offer fail-operational steering system. It incorporates a mitigation strategy should the need arise. And then if we talk about a certain time, from just a couple of seconds to even minutes, then the steering system must operate without human interference. That means the solution is a redundant steering system. That means the system must bridge the driving situation until the driver is back in control. If we then go to a Level 5 situation then I would liken it to a robot-taxi. In that situation, no human is operating the car. So there is an even longer time that we need to bridge between machine failure and when a human can interfere.
We understand that Bosch has carried out user experience tests in order to design steering systems. Could you tell us more about that?
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By GlobalData
In a highly automated driving situation, an important consideration is how the driver perceives the car and its steering. Today, when you are driving you can completely feel the steering and how it reacts to any shocks in the chassis and as you change direction.
The next step is hands off. But even if you do not steer with your hands on the wheel, you still have a perception of when the vehicle is changing direction. That is something that nobody can tell you. So what we did is undertake a user experience approach. In this situation, we brought people into controlled situations to observe how they reacted. So it was not about testing technical solutions but rather asking: what is the user experience in the simulator? And from that, we developed a requirement and a technical solution.
Moving ahead to a Level 5 car, you may not sit behind the wheel of a car but the passenger still needs to have a sense if the car changes direction. That is again what we are doing with our user experience research programme.
Could you give us a historical perspective on how your steering business has evolved since its separation from ZF?
So from the business data, we have doubled our revenue over the past ten years because we gained a lot of market share with the new electric power steering. Since we are Bosch, which is now more than two and a half years ago, we are now very much more integrated. We had a team of around 50 specialised people who were tasked with facilitating this integration. We used joint purchasing processes and development on things like motion control together with Bosch. And this time was around for two years as a project. It finished successfully hence we are now fully integrated with Bosch.
Steer-by-wire systems have also been talked about for years. What's your view on its prospects?
We see that as the next step. The fail-operational steering system represents practically the base of a fully redundant system. The motivation for SBW is packaging. Everybody wants that space in the cockpits for things like interior componentry, third living space parts, etc. The other thing is that the driving behaviour is currently fixed on the transmission between the steering wheel and the gear. With one push of a button, we can move from sports to comfort mode. This would pave the way for an individual steering feel. So imagine the vehicle has learnt what you like in your environment. So it knows what you like and your preferences for steering feel in that situation. That is the second driver for SBW.
We are trying to get a feel for the pace of market growth of EPS in China. Any thoughts on that market?
In three or four years, we will have a very high penetration of EPS in China.
In respect of the market, we see in Europe we are almost completely up to electric steering. It is nearly finished in North America. In China, they have used hydraulic power steering systems for some time but now have a market surge that tells us that China is going completely towards electric power steering completely. So I would say in three or four years, we will have a very high penetration of EPS in China.
What about other BRIC countries like Russia and India?
In India, we are just changing over. So the modern small vehicles also go for electric power steering. In Brazil, it is also just changing over to electric power steering.
Could you tell us what you see as the advantages of dual pinion steering?
There are two factors why OEMs might choose dual pinion over single. First of all, it is to do with the size the car and the load of the steering. So from a packaging point of view it is very difficult to have very high loads. So that means light commercial vehicles, pick-up trucks and big premium cars typically use a belt drive steering system. And that is very hard to do with [single] pinion steering. The second advantage of dual pinion is that dynamics of the gear ratio may be adopted to the need.
See also Global light vehicle steering market – forecasts to 2032
