Tesla is developing a variable steering ratio for models fitted with its controversial yoke steering wheel but as it turns out, Lexus has beaten it to the punch.
The all-electric Lexus RZ will be offered with a yoke steering wheel that includes a steer-by-wire system and variable steering ratio. As such, steering inputs are sent electronically and controlled by software. The wheel has a steering angle of 150 degrees lock-to-lock, dramatically less than the near-800 degree angle of Teslas with a yoke.
Importantly, this means drivers of the RZ will be able to keep two hands on the steering wheel no matter the driving maneuver, eliminating the need to endlessly spin the wheel like in a Tesla.
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Speaking with Auto News, chief engineer of Lexus Electrified Takasahi Watanabe said a steer-by-wire system like that of the RZ is a key technology for electrification.
“This is a very effective feature for electrification,” Watanabe said. “It has a deep connection with the kind of electrification we are trying to achieve. It increases the connection between the car and driver by blending the steering, braking and acceleration all together with the same taste.”
Lexus has also ditched any mechanical redundancy with the system. Whereas the steer-by-wire system of cars like the Infiniti Q50 also have a mechanical steering shaft as a fail-safe, Toyota, JTEKT, and Denso developed two electronic control units that back up each other. One of these motors is located behind the yoke and inputs steering torque signals while the other is on the steering rack and turns the wheels. These motors can be powered by the car’s battery pack, the normal 12-volt battery, and an emergency lithium-ion battery pack.
Lexus says the yoke steering wheel will be offered in the United States, in contrast to Toyota which has yet to confirm which markets the yoke wheel for its bZ4X will be offered. Lexus expects roughly a quarter of RZ customers will go with the yoke.
