Innovation in steering systems for light duty vehicles: OEM Focus
Brought to you by Automotive IQ
Nissan & Infiniti
Nissan was the first OEM to reveal a steer-by-wire system late last year, and it is due to go on the market in the Infiniti Q50 model later this year. The system assesses the driver’s intention by the torque applied to the steering wheel and controls tyre movement accordingly. Each wheel is controlled independently so the system is able to improve stability, while mitigating directional changes due to road surface or crosswind by reducing the amount of steering input required by the driver.
Source: Nissan: Fly-by-wire steering system
Actuating motors on the steering rack control the movement of the tyres, and as the driver steers, the current draw on these motors is analysed and calibrated to account for different road surfaces and driving conditions. This is then fed back to the driver via force applied to the steering wheel. This allows for a continuous closed loop feedback system, enabling the interaction between car and road surface to be ‘felt’ on the steering wheel by the driver.
The Infiniti Q50 will also incorporate a lane assistance system which will gradually move the car back into lane, rather than nudging it back into lane as on previous models, while a mechanical back-up system is also installed in case of a system failure.
Volvo
Volvo recently revealed a host of user-friendly, safety and support features which will be introduced in the new XC90 at the end of 2014, including road edge and barrier detection with steer assist, and Adaptive Cruise Control with steer assist.
Source: Volvo
Road edge and barrier detection with steer assist is designed to help the driver avoid accidentally departing the road. A forward-looking camera and radar work on conjunction to monitor the side of the road and different kinds of road barriers. The technology will act immediately if the driver shows signs of drifting off the road or into a barrier, and autonomously apply steering torque to bring the vehicle back onto the road.
Adaptive cruise control with steer assist uses electric power steering to help the vehicle stay in lane and follow the flow of traffic ahead. Data from a camera and radar is fed back to the ECU and the steering, along with the engine and brakes, reacts autonomously to keep the car in lane and maintain a set distance from the vehicle in front. This is another step towards autonomous driving, and further applications of the technology could see autonomous parking, whereby the driver could bring the vehicle to the entrance of a car park and allow it to locate and drive into a parking space by itself.
This is the second in a three part series on innovation in steering systems by Colin Pawsey. Part 3 focuses on future benefits of EPS.
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