In addition to ABS, TSC, ESP, there is also an electronic program called EBD - electronic brake force distribution. This system usually acts as a "makeweight" to ABS, TSC and ESP, optimizing primarily the braking forces on the rear wheels.
When is EBD in demand? Under normal conditions, the main load falls on the brakes of the front wheels, which have better contact with the road, because when braking, the car seems to “bite” with its nose, redistributing the weight to the front. But imagine that you need to slow down when the car is going uphill - the main load now falls on the rear wheels. The EBD system is designed for such cases.
How Brake Assist works
There was a system designed to improve the performance of the brakes - Brake Assist System (BAS). BAS is activated by a sensor that registers too fast movement of the brake pedal, indicating the beginning of emergency braking, and ensures that the maximum possible fluid pressure is created in the brakes. In vehicles with ABS, the fluid pressure is limited to prevent the wheels from locking up.Therefore, BAS is designed to create maximum pressure in the braking system only at the initial moment of an emergency stop of the car. But even this is enough to reduce the braking distance by 15% when braking from a speed of 100 km/h. This shortening of the stopping distance can be decisive: the BAS system can save someone's life.
The potential for auto-braking is huge. Even the simplest systems save lives: if the speed before impact is reduced by 5%, the probability of a fatal outcome is reduced by 25%. And according to real accident statistics in six European countries, auto-braking systems reduce the risk of injury in an accident by 40%.
Unlike BAS, and contrary to common misconception, ABS and ESP do not reduce the braking distance, but, on the contrary, often increase it.. Ultimately, traction is determined by tread pattern, profile width and tire characteristics, and ABS and ESP do not allow the tread to show "character". On asphalt, the increase in braking distance turns out to be insignificant (or does not appear), but on loose snow, gravel, loose soil, the loss in the length of the braking distance can reach 20%.
However, on slippery ice surfaces, ABS support, on the contrary, provides a reduction in the distance to a complete stop by 15% compared to a car without ABS, the wheels of which were braked "in the skid". The main thing is that ABS in a critical situation retains the ability to drive a car, and ESP also helps to return the car to a safe trajectory.
How VSC works
Another novelty in brake technology is the VSC system. It combines the advantages and capabilities of ABS, traction control and vehicle side slip control. It also compensates for some of the shortcomings inherent in each of the systems, which ensures confident movement even on winding slippery roads.VSC sensors monitor engine and transmission operating modes, rotational speed of each of the wheels, brake pressure, steering angle, lateral acceleration and yaw, and the resulting data is transmitted to the electronic control unit. The VSC microcomputer, having processed the information from the sensors and assessing the situation, makes the only correct decision for a particular situation and issues a command to the actuators. In situations that could become emergency due to excessive confidence or due to insufficient driver experience, the VSC system will correct his actions, fix the error and prevent the car from getting out of control.
Suppose the car enters a turn at too high speed, and the driver, realizing that he made a mistake with her choice, makes another mistake - he brakes sharply or turns the steering wheel excessively in the direction of the turn. Having received information from the sensors, the VSC system instantly registers that the car is in a critical position, and without allowing the wheels to lock up to skid, it redistributes the braking forces on the wheels to counteract the car's rotation around a vertical axis.
Why do owners of high-end cars need to have important safety components? They must be installed on all vehicles to protect the driver and passengers. In the near future, VSC will become a private, as will ABS.
Today we will try to explain and answer the question: What is VSC in a car? In fact, Vehicle Stability Control, or in the abbreviation VSC, is a vehicle stability control system.
Check VSC is installed in the car in order to constantly monitor its speed and direction of movement. This electronic system continuously compares the parameters actually produced during the maneuvers of the machine with the acceleration or deceleration set by the driver. VSC helps replace lost traction to help prevent skidding.
The stability control system is a necessary assistance to the driver in maintaining control of the vehicle when driving under normal conditions and during difficult weather situations. However, the presence of VSC in the car is not a panacea and one hundred percent protection against
The safety of the driver by and large depends on him: on his experience and driving style, compliance with traffic rules and keeping the car in proper order. You can not rely on the system, ignoring elementary safety rules. The degree to which VSC is effective in preventing loss of control is directly related to the amount of speed, the driver's reaction, the condition and quality of the tires on the wheels, as well as the availability and quality of the road surface.
The system allows you to control the stability when maneuvering the car. Check VSC using electronic sensor data to manage over or under maneuverability in critical situations. Insufficient maneuverability contributes to the loss of traction of the car on the front wheels, causing the front axle to shift. Excessive maneuverability leads to a loss of traction by the rear wheels and, accordingly, the rear axle moves away from the vehicle's trajectory.
By braking with one wheel or several at once, the system limits the thrust of the car engine in order to prevent skidding or overshooting. However, the driver should remember that VSC is not omnipotent and cannot, violating the laws of physics, provide proper grip in critical situations.
Conducted independent international studies have proven the invaluable benefits and effectiveness of the electronic VSC system in providing real assistance to the driver in maintaining control of the car, minimizing the risk of car collisions and thereby saving human lives. Provided that this system would function in every car, then 10,000 people would not die in accidents every year.
However, the opinions of the direct users of this electronic system were divided into opposite ones. Some consider it the most important means of safety (like the belts of the same name). Others claim that "guaranteed safety" only encourages the driver - the reckless driver to make daring decisions and risky maneuvers when driving a car. And in general, such "electronic things" indulge in aggressive and absent-minded driving.
Some experienced drivers refuse to use the stability control system, claiming that it deprives them of the opportunity to experience the real dynamics of the purchased car. And in general, the "electronic nanny" spoils all the pleasure derived from independent driving.
Therefore, in order to please all customers at once, some manufacturers, when installing the VSC system in a car, also provide a button to turn it off. And in some cars there is a function to change the settings of the electronic system so that it works only with a significant skid or drift.
Another important claim to the VSC is the permission to "reckless drivers" at a fairly high speed to drive a car steadily. And when the unfortunate racer “crosses the line”, the collision occurs at “cosmic” speed and entails dire consequences.
However, the reasonable use of the VSC system can improve the comfort and safety of driving a car, significantly reduce the number of deaths during accidents.
29.02.2016
Modern cars are "stuffed" with electronics, which take on many different functions - engine control, brakes, fuel supply system, and so on. In turn, car owners do not always know what tasks a particular system performs. In this article, we will pay attention to such popular devices as VSC, BAS and EBD.
EBD system
1. Appointment. The abbreviation EBD stands for Electronic Brake Force Distribution or, translated into Russian, “Brake Force System”. The main task of the system is to prevent the rear wheels from locking by controlling the brakes on the rear axle of the car. This feature is easy to explain. Most of the machines are built in such a way that the rear axle takes on less of the load. Therefore, to improve the stability of the car on the road, the front wheels should be blocked before the rear ones.
When hard braking occurs, the load on the rear wheels is reduced due to a shift in the center of gravity. As a result, instead of effective braking, you can get wheel lock. The task of the EBD system is to eliminate such a problem. At the same time, the operation algorithm itself is set programmatically and is a kind of addition to the ABS system.
Thus, the brake force system is assembled on the basis of a standard ABS, but at the same time it performs a wider function. Common names for these systems are Elektronishe Bremskraftverteilung or Electronic Brake Force Distribution. Different manufacturers may have different names for the system, but the principle of operation remains the same.
2. Features of construction. If we consider the system in more detail, then its work is based on the cyclic execution of tasks. In this case, several main phases are included in one cycle:
- maintaining the pressure level;
- resetting the pressure level to the required level;
- rise in pressure level.
The ABS control unit collects data from sensors that control wheel speed, and then compares the efforts of the rear and front wheels. If the difference is greater than a predetermined value, then the principle of the distribution of forces of the brake system is started.
Based on the current difference in the signals from each of the sensors, the control unit decides on the exact moment of locking the rear wheels. At the same time, he gives the command to close the intake valves in the circuits of the brake cylinders (of course, for the rear axle). At this stage, the pressure is maintained at a given level and remains unchanged. In turn, the front wheel intake valves open and remain in that position. The pressure in the front circuit continues to increase until the wheels are blocked.
In the case when the rear wheels are further blocked, the exhaust valves open. As a result, the pressure in the brake cylinders of the rear wheels is reduced to the required limit. If the angular velocity of the rear axle wheels begins to grow and exceeds a certain parameter, then the pressure in the circuit will increase and the wheels will brake.
As a rule, the force distribution system stops working at the moment the front wheels lock. At the same time, the ABS system is connected to work, which does not allow the wheels to lock up and allows the driver to maneuver even when the brake pedal is pressed sharply.
BAS system
1. Appointment. Among the auxiliary systems of modern cars, one cannot fail to note the Brake Assist System or BAS for short. This system is an algorithm that provides assistance in the event of an emergency pressing the brake pedal. Compared to the BAS system discussed above, it is easier to operate. Its task is to assist the driver and "squeeze" the maximum out of the vehicle's braking system.
We can cite the following situation. The driver cannot “push” the brake to the limit (for example, the pedal is pressed too poorly or a bottle has fallen under it). As a result, the brake system worked, but not 100 percent. In the presence of the BAS system, the “brains” do everything on their own and give the command to increase the braking speed.
A feature of the Brake Assist System is the full automatism of work and independence from the actions of the driver. Electronics analyzes when it is necessary to help the driver and increase the brakes. In this case, the decision is made after analyzing the information from a whole group of different sensors.
2. History of appearance. The history of the emergence of this algorithm, which was created as an auxiliary system for a standard ABS, deserves special attention. The first "swallows" on cars have appeared since the beginning of the 70s of the last century. Chrysler was the pioneer.
At the present stage, everything has changed. If earlier the Brake Assist System was mounted only on expensive cars and was presented as an exclusive algorithm, then at the present stage such systems are mounted on almost all classes of cars. So, recently the Euro NCAP committee summed up the results of installing BAS systems on cars from different manufacturers. Almost immediately after that, it was decided to implement this device as a mandatory installation. In particular, a car does not receive a five-star safety test if it does not have a similar system on board. Such a revolutionary innovation has pushed manufacturers to create even safer and more efficient cars.
There is confidence that after some time, BAS systems will become mandatory and will be installed on all production models. Already today they are on such popular cars as the Ford Focus or Chevrolet Aveo, the cost of which ranges from half a million to a million rubles. Despite the fact that previously such systems were mounted only on Volvo or Mercedes cars.
3. Working principle. A feature of the BAS system is the ability to work with different brake systems, both hydraulic and air. To recognize the situation, various measuring devices are used (installed at different points in the car):
- a sensor that controls the speed of the wheels;
- a sensor that records the speed of movement of the amplifier rod; the task of this device is to record the force of pressing the accelerator pedal;
- a sensor that controls the level of pressure in the brake system; here the principle is similar to the previous device; the difference is that this unit is used for hydraulics, and not for a vacuum booster as in the previous case.
According to the principle of operation, BAS controls the fluid pressure. It's easy to explain. The hydraulics are configured in such a way that the entire mechanism is controlled by a hydraulic drive. In this case, the brake pedal only transfers force from the foot to the brake cylinder. Due to the pressure created, the piston begins to move, and the brake system mechanism is compressed. The BAS algorithm takes control of the pressure of the brake fluid in the cylinders, adding or subtracting the force of the brake system.
4. Views. Such systems are conditionally divided into several categories and may vary:
- by the number of sensors that are used to take readings;
- by functionality.
The most reliable systems are mounted on Mercedes and BMW cars. The peculiarity of the products is taking into account a number of factors - the condition of the road, the force on the brake pedal, the distance to the car that is moving in front, and so on.
If in the car the main emphasis is on the pneumatic drive, then the compressed air is adjusted. The latter moves the piston and improves the quality of the brakes. This function is due to the possibility of regulating the air pressure.
VSC system
In the automotive world, the stability control system has been known for a long time. At the same time, many motorists are still confused in the designations. The reason is simple - almost every manufacturer of this system has some name of its own. For example, in Volvo cars it is called VSA, in Hyundai, Kia and Honda - ESC, in Jaguar, Rover and BMW cars - DSC, on almost all brands of cars made in the USA and EU countries - ESP, on Toyota - VSC and so on. . At the same time, regardless of the name, the principle of operation remains the same.
1. Appointment. The stability control system is mounted to improve the overall drivability of the machine by identifying and correcting certain functions in critical situations. Since 2011, this system has become mandatory for installation on cars in the EU countries, Canada and the USA. With the help of the system, you can keep the car within the boundaries of a given trajectory.
2. Principle of action. A feature of the VSC system from the manufacturer TRW is a combination of all the positive qualities and functionality of the ABS, a new control system, as well as traction control of the side slip of the machine. In addition, the exchange rate stability system takes on the functions of a spotter and eliminates the problems of each of the above systems. This is especially noticeable when operating the machine on slippery sections of the road.
The VSC sensor monitors the modes of operation of the gearbox and power unit, the pressure in the brake system and the rotation of the wheels. After collecting the data, it transmits the information to the control unit. The computer receives and processes information. After assessing the situation, he decides which command to give to the actuators. The level of performance largely depends on the capabilities of the electronics, therefore, in critical situations, the system secures the self-confident driver and corrects obvious errors in control.
The principle of operation of the device can be described with an example. The car moves at speed and makes a turn. In this case, the resulting force tries to move the car off the road - to the outside of the turn or throw it to the side. If the turn occurs at high speed, then there is a great risk of drift into a ditch. The driver understands the mistake and begins to act completely inadequate - he presses the brake and turns the steering wheel in the direction he is turning. This is where the VSC system makes a lightning-fast decision and prevents the wheels from locking up. In this case, the redistribution of braking forces occurs and the car is leveled. All this work of the system takes no more than a few seconds.
In an effort to make cars as safe as possible, manufacturers equip them with all kinds of assistance systems designed to help the driver avoid danger at the right time. One of them is the stability control system. On cars of different brands, it can be called differently: ESC for Honda, DSC for BMW, ESP for the vast majority of European and American cars, VDC for Subaru, VSC for Toyota, VSA for Honda and Acura, but the purpose of the exchange rate stabilization system is the same - prevent the vehicle from deviating from a given trajectory in any driving mode, whether it is acceleration, braking, driving in a straight line or in a turn.
The operation of ESC, VDC, and any other can be illustrated as follows: the car is moving into a corner with a set of speed, suddenly one side hits a sandy area. The traction force changes dramatically, and this can lead to skidding or drifting. To prevent departure from the trajectory, the dynamic stabilization system instantly redistributes torque between the drive wheels, and, if necessary, brakes the wheels. And if the car is equipped with an active steering system, the angle of rotation of the wheels changes.
For the first time, the car's stability control system appeared back in 1995, then called ESP or Electronic Stability Program, and since then has become the most common in the automotive industry. In the future, the device of all systems will be considered on its example.
Design of ESC, DSC, ESP, VDC, VSC, VSA systems
The stability control system is a high-level active safety system. It is a composite, consisting of simpler ones, namely:
- brake force distribution systems (EBD);
- electronic differential lock (EDS);
This system consists of a set of input sensors (pressure in the brake system, wheel speed, acceleration, turning speed and steering angle, etc.), a control unit and a hydraulic unit.
One group of sensors is used to evaluate the driver's actions (data on the steering wheel angle, brake pressure), the other helps to analyze the actual parameters of the car's movement (the wheel speed, lateral and longitudinal acceleration, car turning speed, brake pressure are estimated).
The ESP ECU, based on the data received from the sensors, issues the appropriate commands to the actuators. In addition to the systems that make up the ESP itself, its control unit interacts with the engine control unit and the automatic transmission control unit. From them, he also receives the necessary information and sends them control signals.
The dynamic stabilization system works by means of an ABS hydraulic unit.
The principle of operation of the ESC, DSC, ESP, VDC, VSC, VSA systems
The stability control ECU operates continuously. Receiving information from sensors that analyze the actions of the driver, it calculates the desired parameters of the car's movement. The results obtained are compared with the actual parameters, information about which comes from the second group of sensors. The mismatch is recognized by ESP as an uncontrollable situation, and it is included in the work.
The movement is stabilized in the following ways:
- certain wheels are braked;
- engine torque changes
- if the car has an active steering system, the angle of rotation of the front wheels changes;
- if the car has an adaptive suspension, the degree of damping of the shock absorbers changes.
Motor torque is changed in one of several ways:
- throttle position changes;
- fuel injection or ignition pulse is skipped;
- the ignition timing changes;
- gear shifting in automatic transmission is canceled;
- in the case of all-wheel drive, the torque is redistributed on the axles.
How necessary is the dynamic stabilization system
There are many opponents of any auxiliary electronic systems in cars. All of them, as one, argue that ESC, DSC, ESP, VDC, VSC, VSA and others only discourage drivers and, moreover, are just a way to get more money out of the buyer. They support their arguments by the fact that even 20 years ago, there were no such electronic assistants in cars, and, nevertheless, drivers did an excellent job of driving.
We must pay tribute to the fact that there is some truth in these arguments. In fact, many drivers, believing that the help of ESC, DSC, ESP, VDC, VSC, VSA gives them almost unlimited possibilities on the road, start driving, neglecting common sense. The result can be very sad.
However, one cannot agree with the opponents of active safety systems. The system of exchange rate stability is necessary, at least as a safety measure. Studies show that a person spends much more time assessing the situation and responding correctly than an electronic system. ESP has already helped save the lives and health of many road users (especially novice drivers). If the driver has perfected his skills to such an extent that the system, although it works, does not interfere with the actions of a person, he can only be congratulated.
Additional features of ESC, DSC, ESP, VDC, VSC, VSA systems
The course stability system, in addition to its main task - the dynamic stabilization of the car, can also perform additional tasks, such as preventing the car from tipping over, preventing collision, stabilizing the road train and others.
SUVs, due to the high center of gravity, are prone to tipping over when entering a turn at high speed. To prevent such a situation, a rollover prevention system, or Roll Over Prevention (ROP), is designed. To increase stability, the front wheels of the vehicle are braked and engine torque is reduced.
To implement the collision avoidance function, the ESC, DSC, ESP, VDC, VSC, VSA systems additionally require adaptive cruise control. First, the driver is given audible and visual signals, if there is no reaction, the pressure in the brake system is automatically increased.
If the stability control system performs the function of stabilizing the road train on vehicles equipped with a towing device, then it prevents the trailer from yawing by braking the wheels and reducing engine torque.
Another useful feature that is especially needed when driving on serpentine roads is to increase the effectiveness of the brakes when they heat up (called Over Boost or Fading Brake Support). It works simply - when the brake pads are heated, the pressure in the brake system automatically increases.
Finally, the dynamic stabilization system can automatically remove moisture from the brake discs. This function is activated when the wipers are on at speeds above 50 km/h. The principle of operation is a short-term regular increase in pressure in the brake system, as a result of which the pads are pressed against the brake discs, they heat up and the water that has fallen on them is partially removed by the pads, and partially evaporates.
