CAR EXPLAINS
How Toyota and its premium brand have cracked the yoke.
Steer-by-wire tech is back with a vengeance. After its first production outing in the Infiniti Q50 was universally panned, causing the brand to return to a conventional steering rack, Toyota and Lexus are trying with the new bZ4X and RZ450e electric cars.
Here, it’s called One Motion Grip. The compact nature of the yoke-style steering ‘wheel’ that comes with it makes getting in and out easier as well as providing an unobstructed view of the dials. It’s the most visible part of a system that relies on software, sensors and a torque motor to communicate between driver and machine.
There’s a significant amount of ‘redundancy’ (belt-andbraces doubling up) in the system. That – combined with the torque motor – means the steer-by-wire system is 10kg heavier than the standard one. ‘We had to add a feedback motor onto that, and we also have a back-up system, an emergency power pack that we added,’ Lexus chief engineer Takashi Watanabe says. Even so, steer-by-wire reduces the number of mechanical parts, making maintenance simpler, and is considered crucial to the development of autonomous vehicles, as the car can relay steering inputs more accurately. One Motion Grip only requires 150º lockto-lock, making parking easier, with no arm-crossing.
‘Being able to go lock-to-lock without doing handover-hand was the first condition before we even thought about implementing a yoke,’ Lexus chief engineer Takashi Wa
