Conventional steering systems provide a mechanical link from the steering wheel to the front wheels, which is generally power-assisted via hydraulics on modern automobiles. For decades, this delivered a reasonable blend of handling and ride comfort, even if it came with certain trade-offs in performance.
Conventional steering systems develop hydraulic pressure via a belt-driven pump. This pump robs a minute amount of horsepower (and fuel economy) from the engine, which isn’t acceptable as manufacturers push for ever-higher fuel economy ratings. Instead, many have adopted electric steering, which gives good response and feel without robbing power.
Now Nissan has progressed electric steering to the next level, with its own version of steer-by-wire technology. The automaker claims its high-tech system can produce quicker steering response, improved feel and better car control over a wide variety of conditions and road surfaces.
The system consists of multiple components, including a steering force actuator, multiple electronic control units (ECUs), a steering angle actuator and a clutch to provide an emergency mechanical linkage between steering wheel and tires. There’s also a camera and processing module, which helps the system deliver better straight line control.
Driver steering input is measured by the steering force actuator, which sends its data to the primary ECU. The ECU then tells the steering angle actuator how much steering to provide, substantially quicker than a mechanical-based system can respond.
The steering angle actuator also keeps the front tires from “wandering” over grooved or rough pavement, which means the driver needs to make fewer minor steering corrections. The same holds true in crosswinds, as the steering angle actuator can help maintain lane position.
The camera system helps to further enhance on-center driving by monitoring the road ahead and detecting any minor deviations in lane position. When the car starts to wander (perhaps due to driver fatigue), Infiniti’s system will make the minor corrections necessary to maintain lane position.
If the thought of a potential steer-by-wire failure terrifies you, fear not: the system relies on three independent ECUs, and includes a clutch to provide a mechanical steering linkage in the (highly unlikely) event of a triple ECU failure.
While Nissan isn’t the first automaker to build steer-by-wire technology, it does lay claim to being the first with independent control technology (which controls tire and steering angle inputs separately) and the first to use accurate tracing technology (which helps maintain lane positioning).
Look for the system to debut on select (but yet unnamed) Infiniti models sometime next year.