Electronic stability control system - an indispensable safety feature.

What is an electronic stability control system?

Electronic Stability Control (ESC) is one of the important active safety solutions alongside Anti-lock Braking System (ABS), Electronic Brake-force Distribution (EBD), and Traction Control System (TCS)... Whenever the driver loses control of the steering wheel, ESC will intervene with the braking system to correct the steering direction, and at the same time automatically reduce engine power to give the driver time to regain control of the vehicle.

ESC works not only when the vehicle is operating on wet or icy roads, but also performs well during acceleration and cornering. The core element of ESC is its ability to detect the risk of wheel slippage before it becomes a real threat.

The technology behind ESC first appeared in Mercedes-Benz vehicles in 1987, originally as a traction control system. From the early 1990s to the present day, this technology has been developed and applied by many other automakers to most of their models.

The operating principles of these systems are quite similar, but each manufacturer has a different name based on their function and operating principle; they can all be collectively referred to as electronic balancing systems.

Structure of the electronic balance system

ESCs consist of five main components; signals from lateral acceleration sensors on the vehicle body, speed sensors on the wheels, and steering angle sensors are collected to determine the actual state of motion.

When the data is transmitted to the central control microprocessor, the computer compares the result with the steering wheel angle, and then issues commands to control the brakes or reduce power, helping the vehicle quickly return to the desired state as intended by the driver.

Electronic stability control systems use a hydraulic control module similar to ABS, but in addition to controlling or reducing the brake fluid pressure acting on the cylinders, this component can also increase the fluid pressure in the necessary area when required to create a differential braking force between the wheels.

In principle, the operation of ABS and ESC is inseparable; ABS allows ESC to effectively brake each wheel independently. However, the electronic stability control system works completely automatically when there is a discrepancy between the steering angle and the vehicle's turning angle, while the anti-lock braking system only activates when the driver applies the brakes and there is a risk of the wheels locking up.

Furthermore, ESC is closely integrated with the Traction Control System (TCS) and Electronic Brake-force Distribution (EBD). While ABS controls the braking process (longitudinal), TCS controls traction when the vehicle is moving forward (longitudinal), and EBD controls the braking force at each wheel, ESC functions to control the balance and stability of the vehicle when rear-end skidding, sideways sliding while cornering, or due to sudden steering at high speeds.

When a vehicle enters a corner at high speed and the driver fails to steer properly, it can lead to front wheel slippage (understeer), causing the vehicle to veer sideways off the intended path, thereby increasing the risk of rollover or accident.

If the vehicle is equipped with ESC, when it begins to skid sideways, the lateral skid sensor and steering angle sensor will send signals to the control unit. Based on these signals, the ESC will calculate and actively control the braking force on the wheel opposite the direction of skidding. This acts as a pivot point, creating a torque to compensate for the lateral skid, thereby keeping the vehicle stable and moving in the intended direction.

In the event of oversteer while cornering at high speed, the ESC (Emergency Stabilizer System) sends a control signal to apply the front brakes on the opposite side of the vehicle's direction of oversteer. This braking force creates a center of rotation, generating a compensating torque that keeps the vehicle balanced and moving steadily forward as intended.

If the road is too slippery, the tires are too worn, or the air pressure is incorrect, reducing traction, the ESC's operation may be affected or even completely ineffective. When the ESC is active, the warning light on the dashboard will flash.

All vehicles equipped with ESC have a switch to activate or deactivate the system, but for safety reasons, it's best to always leave it in the activated position.

Today, ESC has become a top-priority standard safety feature, with government studies in many countries demonstrating its contribution to increased road safety. According to the US National Highway Traffic Safety Administration (NHTSA), electronic stability control reduces the number of collisions by 35%, and the risk of fatal accidents in SUVs equipped with ESC is 67% lower than in vehicles without it. The number of fatalities could also be reduced by one-third if all vehicles were equipped with ESC.

The European vehicle safety rating program Euro NCAP has issued a strong message recommending that people buy cars equipped with ESC (Engineer, Electronic Stability Control).