IMPORTANCE OF NON-LINEAR CONTROLLER IN IMPLEMENTING ANTI-LOCK BRAKING SYSTEM- A TECHNICAL REVIEW

Abstract

lock braking systems (ABS) is a safety and management devices enforced in ground vehicles that forestall the wheel lock-up throughout emergency braking. The most operate of ABS is to cut back the vehicle stopping distance and stopping time. Stopping distance is the distance travelled by the vehicle after applying the brake and time for the vehicle to reach to complete halt is stopping time. We can, in general consider a controller as a good controller if it helps to reduce both stopping distance and time. Under the influence of Drive torque, the vehicle moves and due to air drag, braking torque, surface friction and inertia, vehicle come to stop. A vibrant arrangement of all these torques and forces are accountable for motion of vehicle on a surface and coefficient of friction between tire and road-surface, amount of steering etc contribute further to vehicle dynamics. Due to drive torque obtained by engine, the wheels starts revolving and when brake applied it comes to arrest after sometime. Vehicle speed and wheel angular rapidity are relative in normal condition but when solid braking is made it is probable that vehicle speed is not drop down at the indistinguishable rate as wheel rotational speed, causing the slip. Slip is a condition created by locking of wheels, means wheels not rotating but vehicle is moving. This is a fatal driving condition and driver can lose the control of vehicle and the time to stop the vehicle increases. By controlling the Brake Pressure the Antilock Braking system matches the wheel speed and the vehicle speed, which intern results vehicle will be under stable zone. However, the ABS shows physically powerful nonlinear individuality in which the vehicles equipped with the accessible controllers can still have a predisposition to oversteer and become unbalanced. Many diverse control methods for ABS systems have been developed. These methods diverge in their hypothetical basis and performance under the changes of road circumstances. In this paper, an effort is made to evaluate the variety of nonlinear controllers used in the execution of ABS systems and also address the main difficulties concerned in designing such a systems and summarize the new modern developments in their control techniques.