Co-developed with Hitachi Automotive and Kanagawa Institute of Technology, Mazda's GVC monitors the speed of steering-wheel inputs then signals the engine to reduce torque to a minute degree. The resulting deceleration is nearly imperceptible to the driver and without drama, delicately loads the front axle and thus tightens up compliance in the car's steering and front suspension.
The basic premise is this: G-Vectoring activates only when the car's on-board computer reads simultaneous steering and throttle input. The data — including throttle position, steering angle, and, crucially, how quickly you're adjusting the steering angle — are then funneled through an algorithm to reduce engine torque, which transfers vehicle weight, adding more grip to the wheels that need it.
The physics behind GVC are pretty simple: To achieve the car's natural cornering posture, you increase the vertical load on the front tires by triggering a slight deceleration. Done right, this forward pitch (longitudinal g-force), is very natural and something you may already do on a race track or canyon road—breathe the throttle to prepare for a fast corner, help the front tires get the car into the corner more smoothly. Breathing the throttle or brushing the brakes will create noticeable longitudinal g-force. You and your passengers can feel the car pitch forward.
But what if that longitudinal g-force was more subtle and happening nearly every time you turned the wheel?
That's what Mazda asked. And kept asking for the past eight years while hunting an answer. Engineers initially went down the path of lightly—very lightly—applying brakes every time the driver turned the wheel, but that was an impossible solution: too slow to react and not natural, mainly. There were other issues. It was a dead end.
Then it chased development work on an electric Mazda2 (known as a Demio in Japan), creating a way to slightly reduce torque output of the electric motor with each steering input, neatly marrying longitudinal g-force (created by torque reduction) with lateral g-force (created by steering input). And that was the breakthrough: using the powertrain to improve chassis dynamics.
In the 2017 Mazda6 and Mazda3, the GVC system is essentially monitoring three parameters: vehicle speed, throttle position, and rate of steering wheel rotation. Turn the steering wheel even the smallest amount and the system goes to work, reacting in less than 50 milliseconds, minutely reducing engine torque by retarding spark timing. The result is an increased vertical load on the front tires.
At maximum, the system will deliver .05 g of deceleration, enough to generate a measure of longitudinal g-force but generally below the threshold of human perception. (F1 driver Lewis Hamilton, a super human, may feel it.) This moment of longitudinal g-force, married to the lateral g-force created by steering input, is where Mazda says the magic happens. The result: a more natural vehicle cornering posture for improved turn-in performance.
Does it work? Well, yes. But you have to go to the data to see it.
Mazda let us drive a Mazda6 rigged with a GVC "on-off" switch. (In production, the system will be invisible, part of the software package and with no "off" switch.) We drove a number of different scenarios including a simple parking-lot oval—two tight, constant-radius turns connected by short straights—at speeds between 20 and 35 mph with cruise control switched on to deliver a constant speed.
With the GVC system on, the data showed less steering wheel movement, indicating the initial turn-in moment for each maneuver was more precise and needed less mid-maneuver correction. And that's the goal: improved steering performance at nearly all speeds and in nearly every condition. On slippery surfaces, the difference is more noticeable.
Mazda is quick to point out GVC is not a torque vectoring system. Technically, torque vectoring from Acura, Audi, Ford, and the like are "active yaw control" systems. They help a car rotate by altering torque delivered to a single wheel. In a left-hand turn, for example, the hybrid Acura NSX will instruct the electric motor powering its front-right wheel to add more torque, pushing the vehicle to the left and into the corner.
Done correctly, torque vectoring can be wonderful. But Mazda does not embrace the solution, as it finds it unnatural and disruptive to the purity of their driving dynamics. Further, torque vectoring systems are often set up to help only at higher speeds. This is not to discount torque vectoring—not at all. It's just not a solution Mazda loves. It went its own path.
G-Vectoring Control, Mazda believes, is a pure solution and can improve dynamic feel with every steering input at nearly ever speed. The only time G-Vectoring Control is not activated by steering movement is when the driver is completely off throttle.
Devamını Oku G-vector control