How Is ABS Related To Newtons Laws?

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How Is ABS Related To Newtons Laws?

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Answer 1

Newtons laws have to do with motion and inertia. ABS brakes work to control frictional forces between the tire and the road. So essentially ABS and Newtons laws have nothing to do with each other. As long as you leave out friction then you can state a few things.

Possibly the first law could be considered: Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.

ABS works by detecting that a tires rotation has slowed to a speed below that of the vehicals. An external force, that of the brake on that tire, has acted to slow the tire down too much and that tire is now skidding. In general a skidding tire does not supply as much deceleration to the car as would a non-skidding tire. So to maintain "Uniform motion" of that tire the ABS system will reduce the braking force on that tire.

You might also say that the third law: F=Ma also applies since the ABS computer is adjusting the braking force on the skidding wheel to keep the acceleration "a" of the car constant.

Answer 2

The basic idea behind Anti-lock Braking Systems (ABS) comes down to the difference between kinetic friction and static friction. Imagine you're trying to push a heavy box across a floor. You push it as hard as you can, and finally it budges. You notice that keeping the box moving requires much less force than it initially took to get the box to budge. This is the difference between static friction (friction between two objects that aren't moving relative to one another) and kinetic friction (sliding friction). The basic formula for friction force is:

where N is the normal force (basically any forces pushing an object toward the ground- weight, downforce, etc.) and mu is the friction coefficient. Static friction coefficients are larger than coefficients of kinetic friction. When you hit the brakes on your car, you therefore want your vehicles to roll to a stop so as to ensure that the wheels are slowing down due mostly to static friction (also called rolling friction), not purely kinetic friction (sliding friction). This often maximizes the friction force and can decrease stopping distances, especially on paved surfaces.

A standard Anti-lock Braking System uses four wheel speed sensors, a hydraulic pump, four hydraulic valves (assuming it is a 4 channel setup), and a controller. The controller in the ABS system monitors the speed of each wheel using the wheel speed sensors, which are usually hall effect sensors. If the controller sees that one wheel is decelerating at a rate that couldn't possibly correspond to the vehicle's rate of deceleration, it actuates the hydraulic valve in that wheel's brake line to reduce the brake pressure applied to that wheel. This allows the wheel to turn faster. Once the wheel is back up to speed, it uses the pump to introduce the pressure back into that brake line, applying that brake again. When the controller sees rapid deceleration again, it activates the valve and the cycle repeats about 15 times per second