June 29, 2016
MONTEREY, CA – I’ve taken and conducted a number of driving courses over the years, but none at a maximum speed of 30 km/h – until now. Mazda’s SkyActiv Driving Academy, at nearby Laguna Seca Raceway, rigorously limited top speed through a number of exercises to experience the latest addition to its suite of SkyActiv technologies – G-Vectoring Control.
What makes Mazda unique among manufacturers of affordable cars is the practice of challenging conventional thinking, sweating the details. This has resulted in a widely recognized ability to produce cars with the best driving dynamics in their classes, from the Mazda3 and CX3 to the Mazda6, and the vehicle many believe offers the best driving dynamics of any class and price – the MX5. Mazda calls it the tireless pursuit of Jinba-Ittai, a feeling of oneness between driver and vehicle.
We gathered at Mazda Raceway Laguna Seca to sample the latest product of this “sweat the details” philosophy. Subtle and difficult to describe and experience, G-Vectoring Control is the next building block in the SkyActiv program.
SkyActiv is not so much a technology as a philosophy – an ongoing series of engineering efforts and resultant technologies designed to deliver superior fuel economy, lower emissions and a natural, intuitive response to driver input.
G-Vectoring Control (GVC) falls into the latter area. In essence the concept is simple – a subtle transfer of weight to the front wheels and contact patches at the first millisecond of steering input. The result is more accurate and smoother steering.
But the execution of GVC is anything but simple. It has taken eight years of R&D and a new generation of powerful and fast processors to reach the stage where it can be included in a production vehicle.
An in-depth technical session headed by Dave Coleman, a well-known Mazda Vehicle Development Engineer who is also a racer, explained the development of GVC, covering some pretty esoteric concepts. It all started with the continued pursuit of smooth transitions between G-Forces when braking, turning and accelerating.
The development team began by studying the behaviour of the human body when subjected to movement. “We must tune our cars to please the driver’s subconscious. To do this we had to study the human body,” Coleman said.
That undertaking led to issues like “minimizing jerk theory” – the rate of change of acceleration. It turns out the “seat of our pants’ often referred to when describing our reaction to a vehicle is actually in our neck.
Studying head movement during dynamic situations from walking to driving or being a passenger allowed the engineers to develop a steering system that minimized vertical and lateral forces. Cameras, EKG sensors and various other technologies were used during development – and to effectively display the results – more on this point later.
Steering, brakes and engine involved
GVC involves not just the steering, but also the brakes, suspension and engine. Coleman says conventional brake systems and engines take too long to react, are too imprecise for GVC to work. The human brain can detect changes in G-forces within 250 milliseconds – one-quarter of a second. A new generation of faster and more powerful processors was required in order to put GVC into operation in a production vehicle.
“This latest generation of control computers allows more precise input, to combine a slight reduction in engine output at the first moment of steering input, shifting more weight unto the front tires. Everything has to happen within the first 50 milliseconds” Coleman said.
“The suspension was tuned so the front rolls slightly ahead of the rear and the inside goes down, rather than the outside going up. In tuning the steering, we want there to be direct feedback, the amount of turn or roll relating directly to the amount of steering input.”
Subtle, yet effective
The result is very subtle and yet very effective. To experience GVC we drove a fleet of Mazda6 sedans equipped with the system and an on/off button. Cameras mounted at several points in the interior recorded upper body movement and steering wheel movement. Sensors monitored steering angle and lateral forces. An engineer riding in the rear seat gathered all these inputs on a laptop computer as we drove a number of courses, all at a top speed of 30 km/h.
That task was difficult on closed courses around pylons in the infield and darn near impossible on the actual full road course including the famous corkscrew. For that session we were told to forget the racing line, but rather follow the white line on the outside of the track as closely and consistently as possible.
Each exercise was performed twice, once with GVC enabled and once without. At the conclusion of each exercise, the engineer showed us the traces of our steering wheel movement and G-Forces – dramatically pointing out the efficacy of GVC! The number and degree of steering corrections was emphatically greater without GVC.
The last session was a half-hour drive over twisting secondary public roads with an engineer sitting in the front passenger seat turning GVC on and off at different points, allowing the driver to experience the difference. It was difficult to detect in some instances, all but impossible in others – perhaps because the driver was trying so hard to be smooth he couldn’t tell the difference!
Most effective in poor conditions
Coleman and his crew said GVC will be most appreciated and effective in poor conditions. That certainly proved to be the case during the wet track and sandy-covered track exercises where it was obvious, by just watching the steering wheel movements that GVC smoothed things out considerably. I can’t wait to experience it on snow and ice!
GVC will be rolled out in production vehicles as the various vehicle systems are upgraded and engine control computers updated, starting with the 2017 Mazda6 this fall, followed by the Mazda3 then the CX3.
“Mazda is nuts!” Coleman said in conclusion. “But in the right kind of way. Nobody else would go to such lengths with the driver/vehicle interface. But, the more satisfying we can make the driving experience, the more likely we are to attract new customers.”
At the end of the day we were turned loose on the track with no restrictions in a fleet of bone stock Mazda3s and Mazda6s – proving just how good the current product is.
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