ABS (Anti-Lock Braking System)
As we all know, vehicles move because of friction between tires and the road.
When we brake, the brake applies a torque in the opposite direction of the friction and the wheel gradually stops turning.
That's how normal brakes work.
Now, when we're moving on a smooth surface like snow, the coefficient of friction is low, so there's less friction.
Braking in this case, even hard on a regular road surface, causes the wheels of the vehicle to stop turning and start to slide because of the torque.
This is known as wheel locking.
Unless you're a skilled drifter, this is a potentially dangerous situation because you can't control the wheels.
The function of the ABS is to prevent the wheels from locking up under very hard brakes or on low friction surfaces such as snow or wet roads.
A typical ABS consists of the following parts
1. ECU
2. Four sensors for monitoring wheel speed
3. A pair of valves in each brake unit.
The ECU monitors the speed of each wheel.
If it detects that any wheel rotating at a slower speed than others (this indicates an imminent wheel lock) it redirects the valves to reduce brake pressure. Conversely if it detects a wheel faster than the others it instructs the valves to increase brake pressure. All of this helps us maintain control of our car even in extreme situation.
EBD (Electronic BrakeForce Distribution System)
EBD is basically a subsystem of ABS and it always works in conjunction with an ABS system. There main job of EBD is to optimise brake force on each wheel individually so to get maximum breaking power without losing control. It can alter braking pressure on each wheel individually depending on the conditions and weight distribution of the vehicle at that moment.
As you can see ABS coupled with EBD is a very useful feature and a big improvement over normal brakes.