On the Path to Automated Driving Lexus Integrates Steer-by-Wire System in the RZ

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FAULHABER Drive Systems

In the Lexus RZ, a steer-by-wire system makes the driving task easier and offers a number of impressive advantages. It is not only intuitive to operate, but also improves visibility and space in the cockpit thanks to the innovative yoke steering wheel. At the same time, it provides precise, fast and reliable feedback. Unwanted vibrations are also filtered out.

In contrast to a classic steering system, steer-by-wire has no mechanical connection between the steering wheel and the front wheels. Instead, the driver's steering movements are transmitted to the front axle as an electronic signal. The response is quick and direct. If the electronic steering system should ever have problems, a backup system takes over and guarantees uninterrupted operation.

However, the steering control actuator not only receives electronic signals from the steering wheel, but also detects the forces emanating from the road surface. Unwanted vibrations, for example from the brakes or from sudden tire movements on uneven surfaces, can be filtered out. At the same time, steer-by-wire reduces the risk of the wheels not reacting as desired by the driver - for example when driving uphill or downhill.

Better Visibility of the Road Increases Safety

Steering is via the yoke steering wheel: it dispenses with the upper and lower sections of traditional steering wheel rims and is visually more reminiscent of the steering wheel of an airplane. The compact dimensions ensure a clear view of the road and increase the space between the steering wheel and the driver's legs. The yoke steering wheel thus also contributes to the "Tazuna" concept in the cockpit: The controls, instruments and displays are arranged in such a way that the driver can operate them with minimal hand movements and thus concentrate fully on what is happening on the road.

Steering itself is also easier, as the increased steering angle means that a small movement is enough to steer the vehicle in the desired direction, making over-reaching unnecessary, for example.

Another advantage is the variable steering ratio, which is automatically adjusted depending on the driving speed. At low speeds, the steering operates with a lower ratio, which simplifies maneuvering at junctions or when parking. At medium speeds, for example on winding country roads, only minimal steering movements are required to achieve agile and dynamic handling. On freeways, on the other hand, the transmission ratio is automatically increased to improve stability and safety.

Combined with the Electric Direct4 All-Wheel Drive

The steer-by-wire system not only adapts to the current driving situation, but also works together with the Lexus DIRECT4 electric all-wheel drive system. The interplay between the two technologies enables the vehicle to follow driving commands even more directly.

The steer-by-wire system comes as standard on board the new Lexus RZ 550e F SPORT with DIRECT4 electric all-wheel drive and Interactive Manual Drive, which simulates a classic eight-speed automatic transmission in an electric car. The steer-by-wire system is optionally available for the Lexus RZ 500e Luxury in conjunction with the new all-wheel drive. (se)