Electronic balance system - indispensable safety feature

What is electronic balance system?

The electronic stability control system (ESC) is one of the important active safety solutions along with the anti-lock braking system (ABS), electronic brake force distribution (EBD) and anti-slip system (TCS). Whenever the driver loses control of the steering wheel, the ESC will act on the braking system to help readjust the steering direction, and automatically reduce engine power to help the driver regain control of the vehicle.

ESC not only works when the car is operating on wet or icy roads, but also works well when the car is accelerating and cornering. The core element of ESC is to detect the risk of wheel slip before it becomes a real threat.

The technology behind ESC first appeared on Mercedes-Benz vehicles in 1987 as a traction control system. Since the early 1990s, this technology has been developed and applied by many other car manufacturers on most of their car models.

The operating principles of the systems are quite similar, but each company has a separate name based on the function and operating principle, which can be generally called an electronic balance system.

Structure of electronic balance system

ESC consists of 5 main parts, signals from lateral acceleration sensors on the vehicle body, speed sensors on the wheels and steering angle... are collected to determine the actual movement state.

When transmitted to the central control microprocessor, the computer will compare the results with the steering wheel angle, thereby issuing braking or power reduction commands to help the vehicle quickly return to the state desired by the driver.

The electronic balance system uses a hydraulic control module similar to ABS, but in addition to controlling or reducing the brake fluid pressure acting on the cylinder, this part can also increase the oil pressure to the required area when required to create a differential braking force between the wheels.

In principle, the operation of ABS and ESC cannot be separated from each other, ABS allows ESC to brake independently on each wheel effectively. However, the electronic balance system works completely automatically when there is a discrepancy between the steering angle and the vehicle body rotation angle, while the anti-lock braking system only works when the driver steps on the brake and the wheel is at risk of locking.

In addition, ESC is also closely linked to the anti-slip system TCS and electronic brake force distribution EBD. If ABS controls the braking process (longitudinal), TCS controls the traction when the vehicle moves forward (longitudinal), EBD controls the braking force at each wheel, ESC has the function of controlling the balance and stability of the vehicle when the tail occurs, skidding sideways when cornering or due to sudden steering at high speed.

When the car enters a corner at high speed and the driver lacks steering, the front wheels will slip (Understeer), causing the car to veer off the expected path, leading to the risk of overturning or causing an accident.

If the vehicle is equipped with ESC, when it starts to have a tendency to slide sideways, the sideslip sensor and steering angle will send a signal to the control box, based on which the ESC will calculate and control to actively create a braking force on the wheel opposite the direction of the vehicle sliding, acting as a center of rotation to create a torque to compensate for the sideslip force, thereby keeping the vehicle in a stable state and moving in the expected direction.

In case the car enters a corner at high speed and steers too much, causing the rear of the car to slip out of the intended steering direction (Oversteer). Upon receiving the information, the ESC control box also sends a control signal to brake the front wheel in the opposite direction of the rear of the car being skidded, the braking force creates a center of rotation that generates a compensating torque to keep the car in a balanced state and move steadily forward as desired.

If the road is too slippery, the tires are too worn or the air pressure is not up to standard, reducing traction, the ESC operation may be affected or even not work. When ESC is working, the warning light on the clock will flash.

All cars equipped with ESC have a switch that activates or deactivates the operation, but for safety it is best to leave it activated at all times.

Nowadays, ESC has become a top priority standard safety feature, even government studies in many countries have proven that ESC helps increase road safety. According to the US National Highway Traffic Safety Administration (NHTSA), electronic stability control reduces the number of collisions by 35%, the risk of death in SUVs equipped with ESC is 67% lower than in the case of not having it, the number of fatalities can also be reduced by a third if all vehicles are equipped with ESC.

The European car safety assessment program Euro NCAP has sent out a strong message advising people to buy cars equipped with ESC systems.