Top Tech Cars 2013: Infiniti Q50
Today, drive by wire; tomorrow, drive by robot
Many cars already apply their own brakes and adjust their own throttles to avoid collisions. Now Infiniti has taken the next big leap toward cars that can drive themselves, with steer by wire. The Infiniti Q50 changes direction without any mechanical connection between the steering wheel and the front wheels. The system uses sensors to measure how much the driver has turned the steering wheel, then calculates the desired amount of vehicle turn and relays the appropriate commands to a pair of actuators. The actuators are what actually pivot the car’s steering rack, which in turn angles the front wheels.
For easier low-speed maneuvers or high-speed stability, sensors can instantly vary power-steering assist and even the degree to which the steering wheel must be turned to effect a certain change in the car’s direction. With no physical connection, Infiniti says, the system can better filter out unwanted noise, such as rough-road vibration and impacts, sending only desirable feedback to the driver. It can account for any tendency for tires to wander off-line and thus requires fewer steering corrections from the driver.
Nissan says the system can be faster and feel more responsive because it doesn’t waste time and energy on mechanical connections. The lane-departure system gains as well: Instead of using brake interventions to crudely adjust the car’s attitude, the windshield-mounted camera can alert the steering to keep the car centered.
When fly-by-wire airplanes were introduced, some pilots worried that a haywire computer might run away with things, HAL 9000–style. So the industry included redundant systems. Nissan has done the same thing by providing three independent electronic controllers. There’s even a physical backup: Under a failure, a clutch engages to restore a driver’s mechanical control. But in the future, Infiniti acknowledges, those training wheels will likely come off, because eliminating the bulky steering linkage entirely would save weight and complexity.
Steering: Steer by wire Price (estimated): US $39 000 Power plant: 3.7-L V-6, 245 kW (328 hp); gas-electric hybrid option