RESEARCH ANALYSIS: Electric steering creates opportunities for driver assistance
Ford is increasingly using electric steering in its models not just to enhance driving comfort and improve fuel economy, but also to allow driver-friendly features such as parallel parking assist, writes Matthew Beecham. Electric steering technology could act as catalyst for a number of other driver-enhanced features.
“Electrically Powered Steering (EPS) opens the door for many additional features that can be added via the steering system,” said Charlie Cregeur, director of product planning, TRW Automotive.
“Parallel park is one such feature and there are several others including Lane Keep Assist, Lane Guide, side wind compensation, nibble suppression and vehicle stability enhancements [in conjunction with the braking and in some cases passive restraints systems]. The market for these features is expected to grow as EPS fitment becomes more standard and certainly as fitment reaches into the high end cars and SUV markets.”
Laurent Bresson, Nexteer Automotive’s executive director in Europe and executive director of its global sales and marketing operations, agrees that there are a lot of benefits for drivers in pairing camera technologies with electric power steering systems. He told just-auto: “If you want to automate low-speed manoeuvres such as parallel or perpendicular parking, electric power steering is essential.”
Bresson believes that there is increasing demand for high-speed driver assistance, too. “Lane-keeping assistance, which uses a torque overlay from the electric motor, is just the first step in a direction that is leading us towards fully automated convenience and safety functions. Luxury manufacturers have introduced automated emergency braking and this will become mandatory in the next few years. If the car has electric power steering, then it will be eventually be possible to introduce evasive steering manoeuvres too.”
All this creates a lot of additional software development work for the OEM, however. “Nexteer has kept its software development in-house and this will be a considerable advantage, allowing OEMs’ own software engineers to focus on functions that are more visible to their customers.”
While some people see an even stronger link with advanced driver assistance systems, others believe that this may not be before the link braking, steering, and suspension is mature in production; developments are taking place for certain future cognitive safety features.
Cregeur says that there is progress in both areas. “Steering integration with Driver Assist Systems is progressing, albeit at a rate commensurate with radar and camera fitments and those are largely driven by net cost to the platform as well as what can be sold as marketable features. At the same time, steering integration with other chassis systems is also progressing. TRW’s advanced safety, algorithm expertise and integration capabilities allow us to participate in both areas. It comes as no surprise that the chassis integration part can go more rapidly because of the existence of the enabling hardware; and with the addition of smart algorithms in the braking controller it is quite practical to send signals to the steering system as part of an overall stability improvement solution.”
Meanwhile, steer-by-wire is still an advanced technology with limited application potential. Sure, you can prove and realise all sorts of advanced features with it but to bring it into the vehicle will cost the OEM an immense amount of money. So the question here is: will the end customer be willing to pay for it if he / she could get nearly the same functionality with an AFS and EPS combined?
“The challenge with steer-by-wire is the need for obsolescence in the system,” adds Bresson. “If you must fit a back-up system, you soon lose the packaging and cost advantages of steer-by-wire. I don’t see why the end-user would be willing to pay a premium to make packaging easier for the manufacturer. The benefits that they will be prepared to pay for come from linking EPS to other vehicle systems via the software functions that we can add.”
One alternative theory is that car manufacturers could use EPS systems’ torque overlay functions to provide active or artificial, instead of a natural return in their steering. Bresson believes that this could help them to take a more simplified approach to chassis development, where they spend less time on the architecture and the fine-tuning of the wheel and caster angles, resolving the issue in the software. OEMs haven’t explored this yet, but they will in time.