New “RZ” (prototype)
Another notable point of Lexus’ new “RZ” is steer-by-wire. An innovative steering system that does not have a steering shaft that physically connects the wheels and the steering wheel, and uses only electrical signals to steer. It will be the world’s first mass-produced vehicle.
This steer-by-wire equipped vehicle is scheduled to be introduced later, and the RZ used for the test drive is also a prototype under development.
Sitting in the seat, you can immediately tell that it is steer-by-wire due to the unique shape of the steering wheel. It has an oblong shape, and I can no longer have the image of turning it. In fact, the steering angle of the steering wheel is as small as 150 degrees, and the tires are fully cut before the arms are completely crossed. Normally, the amount of steering wheel operation is 2.5 to 3 turns, so the amount of steering is overwhelmingly small.
In addition, the design of the cockpit also changes greatly by changing the shape of the steering wheel from a circle to an oval. RZ’s steer-by-wire specification is a shared instrument panel with a normal steering wheel. Even so, the meters that were seen through the steering wheel can now be seen from above the steering wheel, and the view in front of the driver becomes more open.
The new RZ steer-by-wire equipped model (prototype) adopts a horizontally elongated steering wheel
The test ride included narrow cranks and slalom set in the paddock, reverse parking, and passing over bumps for ride comfort.
As someone who is used to turning a round steering wheel, the control stick (?) in front of me is new and arouses great curiosity.
When the driving position is matched, the hip point is high, and the shape of the steering wheel also gives good forward visibility. The A-pillar is thick and strongly slanted, so there are parts that are hidden, but the part that can be seen through the triangular window is large, making it easy to check the pylon course.
Enter the crank course first. Normally, you have to cut the steering wheel a lot, but with steer-by-wire, the amount of steering wheel operation is overwhelmingly small. I was puzzled how far the tire would cut because it was different from the feeling so far. I thought that I might step on the pylon with an inner ring difference.
Steer-by-wire also has a speed parameter, so it cuts sharply at low speeds, and at medium and high speeds, the tire turning angle becomes smaller even with the same amount of steering. It doesn’t make the most of your experience so far, but you’ll definitely get used to it as you use it. At low speeds like this time, it seems to be compatible with the combination of rear wheel steering that does not care regarding the inner wheel difference, but the priority was to proceed with the development of the prototype and improve the perfection of the steer-by-wire.
In low-speed slalom, the amount of turning back of the steering wheel was small, and it was easy to clear. If the turning angle of the tire and the amount of steering wheel operation match, it seems to be able to run more agilely. Until now, humans had operated the steering wheel according to the mechanism of the car, but it made me feel that we have entered an era where the car adapts to the driver.
I haven’t been able to grasp the relationship between speed and the amount of steering wheel operation yet, and I was confused at low speeds, but if I continue to mature how steer-by-wire can respond to human reactions, I’m sure I can build a good relationship.
Kickback is almost zero when passing over a bump road, and eliminating the shock from the road surface also helps reduce driver fatigue. It’s a feeling I’ve never felt before.
It was my first experience with slalom and crank, which was often confusing, but my impression changed completely when I ran a circuit at a pace like running on a public road. At around 60km/h, the tension eases and the steering feels smoother than the normal steering wheel. When it comes to medium-speed corners, the steering wheel operation and the tire turning angle are perfectly matched and it feels good.
The usability of the peculiar steering wheel is still unknown, and there are still many unknowns, such as whether the driver will not be burdened even if driving for a long time, and how far the road surface conditions can be felt by the palm of the hand.
In addition, being able to actively control the steering angle of the tires means that the car can steer according to the driver, and the possibilities for future autonomous driving will greatly expand.
