You were traveling at a high velocity when you hit a curb. You tried to turn the steering wheel, but your vehicle started to skid instead of turning. Due to this, you lost control of your car, but don’t worry; Electronic Stability Control (ESC) is there to keep you safe.
So, what is ESC, and how does it help you regain control of your vehicle when you turn at high velocities? Well, let’s find out.
What Is Electronic Stability Control, and Why Is It Needed?
Invented by Frank Werner after skidding off an icy road in Sweden, ESC is the most significant safety invention after the seatbelt. In fact, according to this PDF from the National Highway Traffic Safety Administration (NHTSA), Electronic Stability Control has saved more than 7,000 lives from 2011-2015.
Also known as dynamic stability control, ESC is a safety feature that helps drivers regain control of their vehicles while turning at high velocities. In addition to this, ESC also prevents slipping while cornering on wet surfaces, but why is slipping so dangerous?
You see, your steering wheel can only control the movement of your car when the wheels are rotating. Once the tires start sliding, your steering inputs do not affect the car’s motion.
To understand why your tires skid in the first place, you need to understand the first law of motion. According to this law, a body in motion will remain in the same state until and unless an external force is applied. Therefore, the first law of motion prevents the car from changing its course when you try to turn a vehicle skidding in a straight line. That’s because if your tires are skidding, they don’t have any grip, so they’re applying little to no external force that will affect your car’s direction.
To prevent this issue, the Electronic Stability Control applies an external force on the car by leveraging the Antilock Braking System.
Understanding the Moving Parts of ESC
Now that we know why ESC is needed, we can look at the components which make it possible.
- Wheels speed sensor: Every wheel on your car comes with a wheel speed sensor. This sensor consists of a perforated magnetic ring and a Hall effect sensor. As the wheel rotates, the magnetic field created by the ring changes periodically. The Hall effect sensor collects this data enabling the sensor to calculate the speed of the wheels.
- Yaw rate sensor: The yaw rate sensor monitors the vehicle’s rotation. To measure this rotation, the yaw rate sensor uses a micro-electromechanical gyroscope. This gyroscope measures the Coriolis force acting on the vehicle to estimate how much the car has rotated about its center of gravity.
- Steering angle sensor: As the name suggests, the steering angle sensor determines the steering wheel’s rotation angle. Mounted on the steering wheel shaft, the sensor uses magnetic gears and a Hall effect sensor to detect the rotation angle.
- ECU: Just like a CPU is the brains of a personal computer, an ECU is a computer that monitors the critical operations of your car. This includes tasks like tracking the amount of fuel and air entering your engine, but unlike personal computers, a car has several ECUs. These computing devices communicate with one another to enable features like Automatic emergency braking, Adaptive cruise control systems, and Lane-keeping assist.
- Antilock Braking System: Although the driver controls the brakes using the brake pedal, ABS controls the amount of pressure applied to the tires. In emergencies, the ABS handles the hydraulic braking system to stabilize the vehicle.
- Engine control module: Also known as the ECM, the engine control module is an ECU that monitors a series of sensors and actuators in the engine bay. This enables the ECM to control the power delivered by the engine.
In addition to the sensors and ECUs given above, the ESC uses the CAN protocol for communication. This communication between the sensors and ECUs enables the ESC to monitor vehicle conditions on a real-time basis making the system robust.
How Does ESC Work?
Now that we understand the components that make ESC possible, we can look at how it works.
It all starts with the steering angle sensor, which monitors the steering wheel’s rotation angle. This data and inputs from the yaw rate sensor are sent to the ECU. The ECU analyzes this data to check if the vehicle is turning according to the users’ inputs. If that is not the case, the ECU activates the Electronic Stability Control system.
Once enabled, the ESC tries to understand if the wheels on the car are slipping. To do this, it compares the data from all the wheel speed sensors. If the angular velocity of one of the wheels is more when compared to the others, the ESC concludes that it is slipping.
To prevent this slipping phenomenon, the ESC enables the ABS. Once the ABS is enabled, it applies the brakes rapidly to the skidding wheel. This application of brakes exerts an external force on the car, stabilizing it.
In addition to reducing the speed of the wheels using ABS, the ESC also controls the power delivered to the wheels. To do this, the ESC communicates with the ECM and reduces the power delivered from the engine. This reduction in power and the Antilock Braking System prevents the car from oversteering or understeering while cornering or swerving in emergency situations.
Not only this, but the enhanced stability also protects vehicles like trucks and tractors from toppling over while turning
Is ESC All for the Good?
The Electronic Stability Control system comprises several components, and if one of the sensors malfunctions, it can cause the vehicle to behave abnormally.
Although the Electronic Stability Control offers a lot of safety to its users, it prevents your car from reaching its limits. Due to the throttle limiting capabilities of ESC, it reduces the power delivered to the tires preventing high-performance cornering. Also, if you take your car to a racetrack and want to burn some rubber, the ESC will prevent the car from drifting.
That being said, users can disable ESC if they are looking to push their vehicles to the limit.
Is ESC Making the World Safer?
The Electronic Stability Control is a safety feature that provides control to the driver while cornering. To provide this stability, the ESC monitors the yaw rate and steering wheel sensors to detect a lack of steering control. Once detected, the ESC activates the ABS and ECM to reduce the vehicle’s speed.
This system stabilizes the car enabling the driver to regain control of the vehicle when turning at high velocities. In terms of safety, ESC can make a difference between life and death. Due to this reason, the NHTSA made this feature compulsory for all cars sold after 2012. As proven by data, ESC has saved countless lives from certain tragedy.
Read the full article here