Is Lexus’ Steer By Wire A Yoke Done Right?
No More Hand Over Hand
In late 2021, Tesla made waves when it updated its Model S sedan and Model X SUVs with new interiors that featured a “yoke” instead of a steering wheel for directional control. Looking like something out of a science-fiction movie (or, for those of us that grew up watching Knight Rider, something David Hasselhoff would use), the yoke replaced a round wheel with a two-armed handle reminiscent of an aircraft control.
Why a yoke? In typical headline-seeking fashion, Tesla CEO Elon Musk suggested that with the increasing levels of automated driving coming from Tesla, drivers wouldn’t need to be steering as much as before. Switching to a yoke also freed up some interior space, making the Teslas’ interiors feel roomier and more open, especially when combined with the redesigned dashboard and central control screen.
But, the yoke has a problem: while it mostly worked fine to control the cars’ direction on highways, where lane changes and on- and off-ramps could be tackled without issue, low-speed maneuvering was a challenge. City streets, and especially parking, are a lot tougher when you don’t have a whole wheel to turn and find yourself fumbling for where the two grips are. Tesla would claim that its cars can park themselves, but you don’t always want to rely on the technology.
The problem with the yoke is that it’s still physically connected to a conventional steering system – which was always designed to have a wheel connected to it, which requires you to go hand-over-hand for tight turns. But now, Lexus thinks it has a better idea, combining a yoke-like control with steer-by-wire technology to eliminate the shortcomings of Tesla’ system.
Elevating The Human-Machine Connection
Introduced on the new Lexus RZ globally, and available in the U.S. at a future date, the Lexus steer by wire system enables the electronic exchange of steering and road surface information between the yoke-like steering control and tires via electrical signals, and not a mechanical linkage.
Eliminating the physical connection between the controls and front wheels and replacing it with sensors and an electric motor not enables the yoke-like control, but also reduces weight and complexity, as well as improving safety. If you’re in a frontal crash, there’s no heavy steering column that could potentially push into the cabin and cause injury.
The use of electronics to manage the interaction between the yoke and the front wheel allows for a variable steering ratio, which steers the wheels more aggressively at lower speeds and more gently at higher speeds – a half-turn in a parking lot can help you wheel it into a parking spot, where you’d normally need to go hand-over-hand with a conventional steering wheel.
The new yoke control’s steering angle is set at approximately 150 degrees, and thus reduces the driver’s workload and eliminates the need for hand-over-hand operation at intersections, U-turns, parking, winding roads and other driving situations. At higher speeds, the slower steering ratio makes lane changes and high-speed maneuvers more stable, inspiring greater driver confidence.
Steer by wire enables the electronic exchange of steering and road surface information between the steering wheel and tires via electrical signals instead of a physical connection. Lexus focused on the quality and transmission speed of important driving information, while eliminating vibrations – this improves the system’s refinement and adds to the feeling of luxury.
Unhindered by a sizeable standard steering wheel, Lexus’ designers redesigned the steering control’s compact shape and lowered the instrument cluster’s placement to encourage driver engagement and environmental awareness. Unlike the Tesla yoke, which has grips at the end of two spokes, the Lexus steering control has four spokes, making it easier to grip while still getting out of the way.
Part Of An Advanced Driver Assist System
Steer by wire is just one of many advanced driver assistance systems fitted to the all-electric Lexus RZ SUV. It comes standard with the latest Lexus “Safety System+ 3.0” set of driving aids, including standard pre-collision system, dynamic radar cruise control, lane departure alert and emergency driving stop system.
An available driver monitor system, which actively scans the driver’s face and eyes, enhances these features. It checks the driver’s condition, and if it is determined that the driver is distracted or drowsy – judged by how often the driver looks away from the road – the system will provide earlier alerts and braking to help avoid a collision and/or possible damage. This applies to the dynamic radar cruise control, the pre-collision system, and more.
The RZ also includes lane tracing assist, to help keep the vehicle centered in its lane. When activated, the wheels are controlled as needed, allowing for gentle steering and vehicle movement. Steer by wire enhances this function by allowing for an optimal steering ratio based on the driving conditions, making for smoother and less obtrusive interventions.
Lexus’ First All Electric SUV
The all-new 2023 RZ 450e is the luxury brand’s first global battery EV (BEV). It marks Lexus’ transition into a BEV-centered brand, and combines Lexus’ design and driving experience with advanced, electrified technology. With a 71.4-kWh battery and all-wheel drive, it is expected to deliver approximately 225 miles of range on a full charge. The 2023 Lexus RZ 450e is expected to go on sale towards the end of 2022.