Often abbreviated as AYC, the Active Yaw Control uses an active differential to transfer torque to the wheels that have the most grip on the road. Unlike a pair of traditional mechanical limited-slip differentials and center differential, an AYC is electronically controlled.
The effects of active yaw control include better handling, improved accelleration on loose surfaces (like gravel and snow), better corner exit speeds, and more stability. The system also makes the vehicle safer due to how difficult it is to lose control and spin out.
The AYC Computer
An essential part of the Active Yaw Control is its computer. A number of factors need to be considered in order for it to get the most grip onto the driving surface.
A vehicle equipped with AYC has sensors that detect driving surface conditions, steering wheel angle, and lateral acceleration.
After the computer knows what's going on (from information gathered from the sensors) around the vehicle, it can apply changes to the differential to improve grip and turning performance, and adjust according to changes at a very rapid rate (the exact rate depends on the model).
When entering a curve, the power is applied to the wheels on the outside of the curve, which improves maneuverability. When accelerating out of a curve, the power is transferred back to the outside wheels and reduces understeer. In addition, power is transferred from the wheels, regardless of side, on slippery or rough surfaces to the wheels that are on a surface with more drip. This improves both stability and acceleration from a standstill.
Vehicles With AYC
Active Yaw Control was first found on the Mitsubishi Lancer Evolution Rally Car, and made its way into the Lancer Evolution IV production model. Starting in 1996, the Mitsubishi Galant VR-4 Type-V came equipped with it, as well as a number of Mitsubishi's concept cars.