Whether you are on the highway on a dark and rainy night or driving up a snowy mountain road, Mazda’s new-generation all-wheel-drive system is designed to provide safety and comfort with fuel efficiency. Our engineers completely redesigned the system’s hardware and software, and by taking a proactive approach to controlling drive to all four wheels, have developed i-ACTIV AWD, a fully-autonomous AWD system that combines excellent all-road ability with outstanding fuel economy.
Torque is automatically distributed between front and rear wheels
i-ACTIV AWD is constantly monitoring road conditions in real-time and watching for tiny variations in wheel speed that a driver would never notice. Proactively controlling the distribution of torque, which can range from full front-drive through to full 4-wheel-drive, the system not only provides solid and predictable handling for all-road performance, it makes driving on poor road surfaces more efficient by all but eliminating wasteful tire-slippage.
Using a wide range of sensors to paint a highly accurate picture of the overall driving scene, including road conditions and the driver’s intentions, i-ACTIV continuously calculates and adjusts the amount of torque sent to the rear wheels. This enables secure take-off, acceleration, cornering and braking, without letting the tires slip in any direction—forward, backwards or sideways. The system minimizes torque sent to the rear wheels when on dry road surfaces with good traction. In this state, the car is working almost like a front-wheel-drive vehicle, which contributes to great fuel economy.
What are the sensors watching?
The system knows what the driver wants to do by monitoring factors such as accelerator position (the driver wants to start moving or accelerate), steering angle (the driver intends to turn) and brake fluid pressure (the driver wants to stop). It understands road surface conditions by watching a wide range of factors: Is it raining or snowing? Is it cold enough to freeze? i-ACTIV AWD knows by watching the wipers and the external temperature gauge. It can also measure how slippery the road surface is by comparing steering torque with the amount of current running through the electric power steering and the gradient of any slope by the degree of acceleration. In addition, the system precisely measures the speed of all four wheels and detects warning signs that indicate the wheels may be in danger of slipping. Along with engine driving force (applied to the front wheels), this is used to understand the driving conditions.
The perfect amount of torque is calculated and transferred to the rear wheels instantaneously
The AWD control module examines data from many sensor modules to analyze the driver’s intentions and the road conditions, calculates how much torque should be sent to the rear wheels in order to prevent slippage of the front tires, and almost instantaneously sends a command to the AWD coupling unit to send the appropriate drive force to the rear.
Cutting-edge technology in i-ACTIV AWD
i-ACTIV AWD uses a Front-wheel Slip-warning Detection System that makes it possible to control drive force with a high degree of accuracy. It also features a Torque Control System that allows a lag-free, near-instantaneous response.
The Front-wheel Slip-warning Detection system uses various sensors to accurately calculate ground speed and front wheel speed, making it possible to detect early the microscopic wheel slips that act as warning signs of potential tire spin.
In order to help the rear-wheel drive unit respond more quickly, the Torque Control System transfers a very small amount of torque to the rear even in front-wheel drive mode. This is known as “stand-by torque” and it helps the system make a smooth and instantaneous transition to AWD drive mode when the command is received to send torque to the rear wheels.