An anti-lock braking system (ABS) is a standard feature in most modern vehicles, and for good reason. ABS prevents accidents caused by loss of steering control during braking by allowing drivers to steer their vehicles properly while reducing the braking distance. In this article, we will explore how ABS works, its principles of steering and braking, and how it can prevent accidents.
When you press the brake pedal, the brake pads on the wheel disks are activated and press against the disks, stopping the wheels’ rotation. This causes slippage between the road and wheels, and the vehicle stops due to this friction. On the other hand, the whole steering mechanism is dependent on the wheels rolling. The wheels have two kinds of motion, rotational and translational. For non-slip rolling conditions, the sum of the translational and rotational velocities at the contact point should be zero.
All four wheels should be rolling at all times in an automobile to avoid the vehicle slipping, and this simple rolling principle is why your car turns when you turn the front wheels. However, when the brake pads are activated, the wheels stop spinning, and there will be no rotational velocity at all. This can cause the car to slip, losing control of the steering, and sliding in a straight line, which can cause an accident.
ABS solves these issues by preventing the wheels from completely locking up. The ABS system includes speed sensors attached to all of the wheels. When the sensors detect that a wheel is about to lock up, a modulator unit partially releases the brake pad on that wheel. This way, the wheels will be allowed to spin intermittently during braking. This intermittent wheel rotation allows the steering to function, and the driver will be able to steer the vehicle even during braking.
Moreover, ABS reduces the braking distance by adjusting the brake pressure to keep the slip ratio near 12%, where the frictional value is at the maximum. During breaking without ABS, the frictional coefficient that comes into effect is predominantly sliding friction. But in ABS braking, the clever algorithm adjusts the brake pressure to keep the slip ratio near 12%, which significantly reduces the braking distance.
In summary, ABS prevents accidents caused by loss of steering control during braking, reduces the braking distance, and allows drivers to steer their vehicles properly during braking. Additionally, modern ABS includes electronic braking distribution (EBD), which measures the yaw rate of the car and the relative slip of each wheel to reduce the brake pressure on the wheels with higher grip, keeping the yaw torque and the whole car under control. It is crucial to understand how ABS works to maximize its benefits and improve road safety.