The Direct Adaptive Steering (DAS) system introduced on the 2014 Infiniti Q50 is a game changer. Just as drive-by-wire controls transformed the aircraft industry, adaptive steering will replace the belts, pulleys, hydraulics and mechanical connections utilized in passenger vehicles.
Automotive steering systems have evolved over the years, from the early days of purely mechanical systems with big worm and sector gears to more compact, power-assisted rack-and-pinion systems. Electronics has enabled systems that vary the amount of assist and, more recently, electric motors have replaced hydraulic pumps and related hoses.
But the proprietary, industry-first system employed on the new Q50 changes the whole steering landscape.
Direct Adaptive Steering is the first steer-by-wire system employed in a production automobile. The result of 10 years of research, development and testing, DAS is a foundational change in the way we control the front tires. It eliminates any mechanical link between the steering wheel and the front wheels, translating steering wheel inputs to electronic signals.
As the driver moves the steering wheel, sensors report the change in angle to an electronic control unit (ECU) – which is programmed to translate that information to signals it sends to a steering angle actuator mounted on the front sub-frame, which adjusts the direction/angle of the front tires.
The amount of force necessary to turn the tires, dependent on a number of facts – including load, speed and available grip – is measured by a steering force actuator and the information sent back to the ECU and the steering wheel as feedback. The system is programmed to filter out unpleasant and unnecessary feedback.
Fear not, the system employs multiple ECUs and a degree of redundancy. If the system fails due to a power interruption, a clutch engages the steering shaft, resulting in conventional steering, albeit without any power assist.
The beauty of DAS is that it gives engineers an almost infinite ability for tuning. They can address the compromise between feedback and responsiveness and the issues of kickback, harshness, wandering and minor vibrations that come back through the steering wheel. For example, DAS removes the need for constant minor adjustments of the steering wheel on rough roads and uneven surfaces. The system has been programmed to deal with them. With no physical link between the steering wheel and road, the driver does not feel minor bumps and vibrations.
On the open highway, the system automatically makes the tiny adjustments necessary to maintain a true course, resulting in a more relaxed and refined experience.
DAS allows entirely new levels of adaptability, tuning and driver personalization through control of tire angle and steering inputs. The elapsed time between input and action is cut dramatically. The same is true of the reverse, what is happening at the front tires is reported to the driver through the steering wheel much more quickly through the steering wheel.
Instead of being filtered through a variety of mechanical and hydraulic devices, inputs and reactions are delivered in milliseconds. The system automatically varies the amount of assist and the ratio whether for parking in tight quarters or when running at high speeds.
The system incorporates a straight-line stability system. If the vehicle starts to stray from the straight and narrow, the system alerts the driver through subtle resistance through the steering wheel, and corrective action is taken. That feedback is so subtle you may not even notice it.
DAS provides drivers with the ability to customize the steering to their individual preference. They can change both the amount of assist and the ratio according to location and driving conditions.
Direct Adaptive Steering is a foundational change in the way we steer automobiles. While purists may bemoan the artificial feedback and lack of involvement, this is the future and can only become even more sophisticated as it evolves.
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