Active yaw control
Encyclopedia
Active Yaw Control is an automobile
feature that uses an active differential to transfer torque
to the wheels that have the best grip on the road. Unlike traditional mechanical limited slip differential
s, an AYC is electronically controlled.
AYC was designed by Mitsubishi Motors
, first introduced in the Mitsubishi Lancer Evolution IV. It has been included in certain models of every subsequent generation, and was also used in the VR-4
variant of the eighth generation Mitsubishi Galant
sedan and Legnum wagon
. Later developments led to S-AYC (Super-Active Yaw Control), first introduced on the Evolution VIII, utilizing a planetary gearset which could support an even greater torque bias than the previous system. AYC and S-AYC have also been seen in several Mitsubishi concept car
s based on the underpinnings of the Lancer Evo, such as the CZ3 Tarmac and Tarmac Spyder, the Montero Evolution
, the RPM 7000
, and the Concept-X.
Active yaw control is based on a computer
-controlled rear differential
which can actively split torque
based on input from various accelerometer
s in the vehicle measuring longitudinal and lateral g forces
, steering, brake
s and throttle
position. Where ABS brakes
are fitted they too are included in the input parameters. It accomplishes this via two hydraulic clutch
es which can limit torque on individual axle
s. This system should not be confused with stability control systems which utilize the braking system of a vehicle by individually braking certain wheels to rotate and slow the car (such as Electronic Brakeforce Distribution
). AYC is a performance-oriented system which aims to increase cornering speeds.
Automobile
An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...
feature that uses an active differential to transfer torque
Torque
Torque, moment or moment of force , is the tendency of a force to rotate an object about an axis, fulcrum, or pivot. Just as a force is a push or a pull, a torque can be thought of as a twist....
to the wheels that have the best grip on the road. Unlike traditional mechanical limited slip differential
Limited slip differential
A limited slip differential is a type of differential gear arrangement that allows for some difference in angular velocity of the output shafts, but imposes a mechanical bound on the disparity...
s, an AYC is electronically controlled.
AYC was designed by Mitsubishi Motors
Mitsubishi Motors
is a multinational automaker headquartered in Minato, Tokyo. In 2009 it was the fifth-largest Japan-based automaker and the 17th-largest in the world measured by production...
, first introduced in the Mitsubishi Lancer Evolution IV. It has been included in certain models of every subsequent generation, and was also used in the VR-4
Mitsubishi Galant VR-4
The Mitsubishi Galant VR-4 was the range-topping version of Mitsubishi Motors' Galant model, available in the sixth , seventh and eighth generations of the vehicle...
variant of the eighth generation Mitsubishi Galant
Mitsubishi Galant
The first generation of the car, initially known as the Colt Galant, was released in December 1969. The design was dubbed "Dynawedge" by Mitsubishi, referring to the influence of aerodynamics on the silhouette. Three models were available, powered by the new 'Saturn' engine in 1.3 or 1.5 L ...
sedan and Legnum wagon
Station wagon
A station wagon is a body style variant of a sedan/saloon with its roof extended rearward over a shared passenger/cargo volume with access at the back via a third or fifth door , instead of a trunk lid...
. Later developments led to S-AYC (Super-Active Yaw Control), first introduced on the Evolution VIII, utilizing a planetary gearset which could support an even greater torque bias than the previous system. AYC and S-AYC have also been seen in several Mitsubishi concept car
Concept car
A concept vehicle or show vehicle is a car made to showcase new styling and or new technology. They are often shown at motor shows to gauge customer reaction to new and radical designs which may or may not have a chance of being produced....
s based on the underpinnings of the Lancer Evo, such as the CZ3 Tarmac and Tarmac Spyder, the Montero Evolution
Mitsubishi Pajero
The Mitsubishi Pajero is a sport utility vehicle manufactured by Mitsubishi Motors. It was named after Leopardus pajeros, the Pampas Cat which is native to the Patagonia plateau region of southern Argentina. However, since pajero is an offensive term for "wanker" in Spanish, alternative names have...
, the RPM 7000
Mitsubishi RPM 7000
The Mitsubishi RPM 7000 is a concept car designed by the Cypress, California Design Studio of Mitsubishi Motors and exhibited at the 2001 North American International Auto Show. Displayed alongside the Mitsubishi ASX, the two vehicles represented the company's vision for sporty, stylish crossover...
, and the Concept-X.
Active yaw control is based on a computer
Computer
A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...
-controlled rear differential
Differential (mechanics)
A differential is a device, usually, but not necessarily, employing gears, capable of transmitting torque and rotation through three shafts, almost always used in one of two ways: in one way, it receives one input and provides two outputs—this is found in most automobiles—and in the other way, it...
which can actively split torque
Torque
Torque, moment or moment of force , is the tendency of a force to rotate an object about an axis, fulcrum, or pivot. Just as a force is a push or a pull, a torque can be thought of as a twist....
based on input from various accelerometer
Accelerometer
An accelerometer is a device that measures proper acceleration, also called the four-acceleration. This is not necessarily the same as the coordinate acceleration , but is rather the type of acceleration associated with the phenomenon of weight experienced by a test mass that resides in the frame...
s in the vehicle measuring longitudinal and lateral g forces
G-force
The g-force associated with an object is its acceleration relative to free-fall. This acceleration experienced by an object is due to the vector sum of non-gravitational forces acting on an object free to move. The accelerations that are not produced by gravity are termed proper accelerations, and...
, steering, brake
Brake
A brake is a mechanical device which inhibits motion. Its opposite component is a clutch. The rest of this article is dedicated to various types of vehicular brakes....
s and throttle
Throttle
A throttle is the mechanism by which the flow of a fluid is managed by constriction or obstruction. An engine's power can be increased or decreased by the restriction of inlet gases , but usually decreased. The term throttle has come to refer, informally and incorrectly, to any mechanism by which...
position. Where ABS brakes
Anti-lock braking system
An anti-lock braking system is a safety system that allows the wheels on a motor vehicle to continue interacting tractively with the road surface as directed by driver steering inputs while braking, preventing the wheels from locking up and therefore avoiding skidding.An ABS generally offers...
are fitted they too are included in the input parameters. It accomplishes this via two hydraulic clutch
Clutch
A clutch is a mechanical device which provides for the transmission of power from one component to another...
es which can limit torque on individual axle
Axle
An axle is a central shaft for a rotating wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to its surroundings, with the wheels rotating around the axle. In the former case, bearings or bushings are provided at the mounting points where the axle...
s. This system should not be confused with stability control systems which utilize the braking system of a vehicle by individually braking certain wheels to rotate and slow the car (such as Electronic Brakeforce Distribution
Electronic brakeforce distribution
Electronic brakeforce distribution ', Electronic brakeforce limitation ' is an automobile brake technology that automatically varies the amount of force applied to each of a vehicle's brakes, based on road conditions, speed, loading, etc...
). AYC is a performance-oriented system which aims to increase cornering speeds.