Variable Gear Ratios Steering (VGRS) dapat merubah steering ratio untuk memperbaiki daya manuver di kecepatan rendah dan menjaga kendali di kecepatan tinggi. Steering ratio bervariasi dari 12.4-1 ke 18.0-1. Untuk membantu meningkatkan keselamatan, VGRS memilih steering ratio lebih tinggi bila Vehicle Stability Control (VSC) diaktifkan. Ini untuk mencegah sudut kemudi terlalu besar bila pengemudi berusaha menghindari sesuatu.
The ability to change a vehicle’s steering ratio has many advantages. A quicker ratio (fewer turns lock-to-lock) can give a vehicle a deft feel. At high speeds, switching to a slower ratio (more turns lock-to-lock) imparts a better sense of stability. Lexus is not alone in using a computer-controlled system to change ratios, but its approach is pretty trick. Note that this type of active steering is far more involved than the variable-ratio units with rack teeth cut at differing angles; they can’t make ratio changes on the fly over the full range of lock. The more complex Lexus (and Audi) approach is essentially a gearbox built into the steering column between the steering wheel and the pinion gear. Unlike BMW’s active steering system, which employs a planetary gearbox, Lexus’s Variable Gear Ratio Steering (VGRS) uses something called a wave generator and a flexible gear. Lexus claims its system is more accurate and quicker acting than others. VGRS can be found on the LS sedan, the LX SUV, and the new GS F Sport. We sliced into the unit to get an idea of how it works and because we wanted to find out what a wave generator is.
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