HOW MAZDA DESIGNED I-ACTIV AWD TO ACT HUMAN

BASED on the human walk — that’s how Mazda describes its i-ACTIV AWD system. It’s a good thing though that the system wasn’t based on me; if it were, then it’d suck. The moment I stepped out of the bus and onto the Kenbuchi Proving Ground located north of Asahikawa in Hokkaido, Japan, I slipped and fell in full view of all the Mazda engineers and experts. It’s reassuring to everyone concerned that Mazda’s all-wheel drive system takes inspiration from more graceful humans.

Comparing its all-wheel drive system to how humans walk may sound like a stretch, but actually, it’s not. Born out of their Human Centric Design Philosophy, Mazda has made i-ACTIV AWD the world’s first predictive all-wheel drive system. Just as how humans will recognize a slippery road based on his senses, take judgement on what course of action to take, and to execute that action properly, Mazda’s system does something similar.

Since cars don’t have the traditional human senses, i-ACTIV AWD relies on a multitude of sensors (27 in all) to detect a slip, and then send power to the rear wheels even before the slippage actually occurs. The system monitors things like steering torque, steering angle, outside temperature, longitudinal g-forces, gas pedal position, wheel speed, engine rpm, vehicle incline angle, and even front and rear wiper speed 200 times a second.

These condition-biased sensors alert the car to obvious possibilities: cold weather could mean snow; wipers on means it’s probably raining, an uphill incline means weight has transferred from front to back equaling to the loss of traction, or amount of steering effort vis-àvis the angle of the steering wheel correlates to possibly slippery conditions. In other words, i-ACTIV AWD does recognition, judgement, and operation all on behalf of the driver.

By default, the system runs with 99 percent of power sent to the front wheels and one percent to the rear (Mazda calls this pre-torque and is done to avoid any jerky switchover). However, if the central control module predicts a slip, it sends up to 50 percent of the engine’s power to the rear wheels even before the front wheels begin to lose grip. Plus, by using an electromagnetic rather than hydraulic clutch, the torque split can exactly match what the central control module is dictating resulting in power at the right set of wheels at the right time.

While some would counter that such technology is frivolous in a country that doesn’t experience snow and ice, Mazda counters that i-ACTIV AWD is a safety system and is meant to add an extra layer of driver control on changeable road conditions. Measuring the coefficient of friction (mu), dry asphalt would be between 0.7 to 0.9 (the highest being 1), wet asphalt between 0.5 to 0.7, and snow between 0.1 to 0.2. Interestingly, standing water on asphalt is 0.3-0.4 — just a notch higher than driving on snow. And with 136 days out of 365 recorded as rainy in Manila, it does become an important safety feature.

The question now is: how does it compare to other all-wheel drive systems in the market today? Without having to prod it out of Mazda engineers, they were quick to volunteer that they’ve benchmarked Subaru in developing i-ACTIV AWD.

As with everything else Mazda has developed, i-ACTIV AWD is an integral ingredient into the whole Jinba-ittai experience. Labeling it as the most superior all-wheel drive system in the market today is still open to debate, but one thing is for sure: it sure is a simple and elegant solution. Having a “brain” process all of the available information generated by the car’s various systems doesn’t just cut the complexity of rolling out an allwheel drive system across Mazda’s entire line-up (all but the MX-5 is offered with i-ACTIV AWD as an option), but it also creates a fully unified and proactive system.

Driving on snow and ice here in Hokkaido does entail a measured quantity of slipping and sliding, but at the end of the day, I’ve always remained in control. During my time behind the wheel, it seems that the extension of my body — the car — is having an easier time adopting to the icy conditions than myself. And if it can perform beautifully in extreme conditions such as the ones here, imagine the amount of confidence it can inspire on our roads.