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Car and Driver explained the new Steer-By-Wire steering by Nissan/Infiniti that will most likely end up in our Infiniti Q50's, possibly making it the first Infiniti with Steer-By-Wire.
Ton's of benefits to a steering system like this, all explained below. Can't wait to get behind the wheel of an Infiniti Q50 to try it out
Ton's of benefits to a steering system like this, all explained below. Can't wait to get behind the wheel of an Infiniti Q50 to try it out
Electric Feel: Nissan Digitizes Steering, But the Wheel Remains - Feature - Car and Driver![]()
Steering-Force Sensor![]()
Playing two roles, this unit sends commands to the control modules and acts as the driver's feedback source by varying resistance to the wheel.
Clutch![]()
Most of the time it's open. Faults in the electronics force it closed, creating a solid mechanical connection between the steering wheel and the rack.
Control Modules![]()
This trio controls the electric-assist motors and the steering-force sensor. They also act as redundancies; you know, for safety.
Steering-Assist Motors![]()
Two of these smaller motors are cheaper than one large one. Plus, this arrangement frees some space for a low-slung longitudinal engine.
So-called “by-wire” controls, which replace a mechanical connection between driver and automobile with an electronic signal, have become commonplace. Electronic throttles are now ubiquitous, braking is increasingly dependent on electronic circuits, and even window switches have become computer controlled. Steering systems haven’t gone completely by-wire for good reason: It’s a little scary to imagine front wheels that may or may not respond to the driver’s inputs, depending on a computer’s whim.
But Nissan’s upcoming steer-by-wire (SBW) system includes a fail-safe clutch in its column. In *normal driving situations, this clutch is disengaged, but if one of the three control modules detects a fault, the clutch snaps shut and the steering acts as a conventional, electrically assisted rack-and-pinion system. The clutch also engages when the engine shuts off, so if one of the first SBW-equipped cars [likely the Infiniti Q50 (pictured below)] fails to start, the owner can still steer the car while pushing it.
Two assist motors mounted at 90 degrees at each end of the rack, plus a steering-force sensor, comprise the SBW’s other components. The steering-force *sensor reports the driver’s desired steering angle to the assist motors by way of the control modules.
Nissan’s stated benefits: Steer-by-wire eliminates steering-system flex and lash, so every driver input yields a direct action at the road. Also—and enthusiasts won’t love this part—SBW completely insulates the driver from road impacts. In a controlled demonstration, we hit a pothole at 30 mph in an SBW-equipped Infiniti G37 test mule. The steering wheel didn’t budge. No wiggle, no shimmy, not even a small jerk. Steering kickback, a common mid-corner occurrence on imperfect pavement, is also eliminated.
A by-wire column can infinitely vary the steering ratio, whereas conventional racks are limited in their variability. Increased safety is another potential benefit. Current stability-control systems yaw the car by slowing individual wheels with brake actuation. Varying the steering angle independently of the steering wheel is another means of stabilizing a slip-sliding car. And a by-wire system could automatically countersteer against a road crown, to make driving, as the Japanese might say, more pleasing to your life force.
While the electronic isolation increases comfort, SBW’s steering feedback redefines artificial, in that it is 100 percent replicated. On-center wander, however, is nil. Remember, electric-assist steering wasn’t all rainbows and lollipops when it rolled out a few years ago. Our December 2012 steering test [“Losing Touch?”] revealed how far electric power steering has advanced in driver satisfaction, and it might take *Nissan a few generations to produce SBW worthy of our approval.
Traffic Keeper
A year or so after Infiniti's steer-by-wire debuts, Volvo will introduce an addition to its electronic safety suite called Traffic Jam Assistance (TJA). In traffic and at speeds below 31 mph, a TJA-equipped Volvo will steer, brake, and accelerate on its own. This is enabled by already existing Volvo safety and convenience features (lane keeper and active cruise control). Switch on TJA, and data from the onboard cameras and radar sensors converges in a master control module, keeping the Volvo in its lane and following the car ahead at a safe distance. The convenience, which we predict will have a 100-percent take rate in Los Angeles, is limited to stop-and-go situations on the highway. So far, TJA can't recognize traffic lights and signs on city streets. Of course, any driver input overrides the system, just as with cruise control.
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