Component supplier ZF says it has made dramatic advances in its steer-by-wire (SbW) technology that overcomes problems of steering feel and fail-safe redundancy.
In the meantime, The Peugeot Inception prototype it showcased that company’s “Hypersquare,” a rectangular device that provides steering input when the car is being driven manually and stows away in the dash when the car is self-driving.
Self-driving cars will obviously be driven by wire, but the technology must be mature for use in that application. Even if self-driving cars are further in the future than previously believed, separating the steering wheel from the steered wheels has benefits in human-driven cars.
ZF previously announced a deal with Chinese electric vehicle company Nio to provide that company with SbW systems for its cars. At CES, ZEF introduced a racing simulator for drivers to try out a virtual version of the system for themselves.
Indeed, no less an authority than Lamborghini Chairman and CEO Stephan Winkelmann stopped by the ZF stand to test drive the simulator, as evidenced by a photo of a smiling Winkelmann that ZF board member Martin Fischer ZF, posted on LinkedIn. “The future of mobility will be software-driven and that means that steer-by-wire and brake-by-wire technologies like those produced by ZF will become a big part of future functionality that will help make mobility safer, cleaner, more comfortable and more affordable for everyone, everywhere. ”Fischer wrote in that post.
In an interview at the show, Fischer explained that ZF will start manufacturing its steering-by-wire system this year and that Nio plans to deliver cars using the system from 2025.
Eliminating the physical connection between the steering wheel and the road wheels provides a host of potential benefits. Removing the steering column from the front of the car is safer in a crash. In addition, the crash structure can be installed without providing clearance for the steering rack shaft, making it easy to reinforce the front end of vehicles.
With no hub, the steering wheel can be located anywhere, on the left, as in the US, on the right, as in the UK, or in the center, as on some race cars and the McLaren Speedtail supercar. While center-mounted steering may be a niche product, the ability for automakers to place the steering wheel on either side of the dash is an obvious benefit to automakers globally.
The response to steering input can vary based on the needs of the situation, so steering is slow and steady at highway speeds, but while parallel parking, drivers can get a large steering angle with very little input. . “That’s a huge advantage for city driving,” Fischer said.
According to Fischer, the powerful electrical architecture being installed in new cars along with their fast data networks make SbW truly practical for the first time. “That power allows us to do things we couldn’t do in the past,” he said.
The absence of a steering axis raises concerns about emergency backup control in case of failure. ZF’s solution is redundancy throughout the system, with all redundant components powered by separate circuits, according to Christophe Marnat, Executive Vice President Active Safety Systems at ZF. “The power pack in the flywheel is two motors in one, with two separate power supplies and also two actuators.”
In addition to providing a fail-safe solution, having dual actuators on the steering wheel is also key to solving concerns about quality of feel and steering response. “How do you control the steering wheel in your hand?” Marnat asked.
“The actuator needs the software to do that for very fine management of that feedback,” he said. But even with smart programming and fast network communications, there is still a fractional delay in steering wheel response if you use a single actuator, since that device must reverse direction when changing steering direction.
Having dual actuators allows ZF to apply both of them, even in opposition to each other, so the transfer from one turning in one direction to the other pulling in the opposite direction is instantaneous, without the inertia of one actuator being reversed. . “You can make the actuators play against each other,” Marnat explained.
As a safety system, electronic steering can directly block steering commands that would crash the car, rather than using the brakes and throttle to minimize the effect as current electronic stability control systems do. That could mean slowing down the response to a harsh input that could induce a spin on slippery surfaces, for example.
ZF says it has “significant multi-customer contracts with steer-by-wire launches scheduled in all major regions,” so we may not have to wait for the Nio in 2025 to see steer-by-wire in action.