What is ESP?

Maintaining a stable trajectory during our road trips is key to our safety. For this reason, stability control systems, known as ESP, have gained such importance that today they are mandatory in new vehicles.

If we take a look at the figures of road victims in Spain, we find a notable decrease in them in recent years. A reduction to which improvements have contributed, such as the latest safety developments that our cars incorporate.

Among these measures is the ESP system. Originally launched in 1995 in the Mercedes S-Class W140, this security system is of great help in maintaining control of our vehicle when its trajectory is not adequate. Its importance is so high that it is estimated that ESP is capable of saving around 2,500 lives a year.

For all these factors, ESP is mandatory in the standard equipment of all vehicles sold in the European Union. A measure that was adopted in 2014 and that, in view of the results, has been a good idea. So that you know more about this technology, we are going to analyze in detail how the car’s ESP works and what it contributes to your safety.

What are we talking about?

The acronym ESP corresponds to a system called Electronic Stability Program or Stability Control Program. Coincidentally, the initials also coincide with those of the initial name of this system in German, where it originally comes from. There it was called Elektronisches Stabilitätsprogramm.

As its name suggests, the system consists of a stability control, which is responsible for assessing at all times that the movement of the vehicle corresponds to the real direction in which the driver is steering the steering wheel. Should this not be the case, the system takes the necessary corrective action to safely return the car to its route.

This leads us to wonder if, just as the brakes are an active safety device, ESP is too. The answer is yes, since the main objective of this system is to correct those erroneous trajectories that can end up causing a collision with an object, with another vehicle or even end up off the road. Therefore, its preventive work is more than clear.

By the way, although it is known as ESP in the market, the truth is that this name varies depending on the vehicle manufacturer. In BMW cars, for example, this technology is called DSC or Dynamic Stability Control. For its part, in Alfa Romeo vehicles it is called VDC, an acronym for Vehicle Dynamic Control. But in the end, the system is always the same.

How does ESP work?

In order to determine the precise position of the vehicle at all times, the ESP system consists of control units located in different elements of the vehicle. One of these elements are the wheels, measuring the position, speed and precise angle of each one of them during the shooting. The same happens with the steering wheel, where another sensor is included with which to know both the angle of rotation and the speed at which those turns are made. With this data, the car evaluates at all times that the direction of the vehicle corresponds to what it should.

On the other hand, the system also has a sensor on the accelerator, which evaluates how much we are pressing on it, or a gyroscope, which reports whether the vehicle tries to turn on its axis, such as when it spins. The system is completed with lateral acceleration sensors, with which to verify if the turn of the steering wheel corresponds to the movement that it should execute. All these elements are connected to a control unit, responsible for interpreting the data and making decisions.

In the event of a discrepancy between the different sensors that we have mentioned, the ESP takes control of the vehicle. This is perceived because the ESP warning light comes on, although if it is necessary to brake we would see the ABS warning light active and ESP on. 

Let’s look at a couple of examples in this regard. If the vehicle were to understeer in a curve, that is, it turns less than it should turn, the ESP would release the accelerator and brake the inner rear wheel, so that we can take the curve correctly. On the contrary, if the car oversteers, turning more than we ordered, what it would do is brake the outer front wheel, to recover the trajectory and not completely close in said curve.

Disconnect the ESP

As crazy as it may sound, there may be times when ESP needs to be turned off. One of these is when we ride on snow and the wheels skid. If the ESP is activated, in this case we would not be able to move, since at the first skid the ESP would brake the wheels and prevent us from accelerating. Therefore, in situations such as the presence of snow, ice, sand or mud, it is obvious that we will have to deactivate the ESP , in order to be able to move. During this time we will see the ESP OFF message on the dashboard until we reactivate the system.

This brings us to a somewhat contentious issue regarding disconnecting the ESP. And it is that this system prevents the “more experienced drivers” from getting the most out of their sports cars and high-end cars. In this case, deactivating ESP gives a little more play when taking a curve with more force or speed, as long as control of the vehicle is maintained. However, the good news for these drivers is that, in the event of a loss of control, the ESP is usually not completely overridden, but remains dormant. Therefore, in case of extreme risk, it will probably take action.

We do not want to close this article without commenting on a couple of issues. One of them is that the ESP does not work miracles , so if we take a curve at excessive speed and at an impossible angle, we have a good chance of having a scare. The other is that ESP depends on the condition of the vehicle, so if the tires are not properly inflated or the brake pads are worn, we also increase our risk of an accident.

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