Safety Systems s in Modern Cars

 

Safety Systems s in Modern Cars

Introduction 

The most common cause of road accidents is the reduction in driver's attention due to fatigue or simply because the driver is devoted to other tasks such as tuning the radio, phone use and communication with traveling companions. Using qualified estimate it can be assumed that with the application of "intelligent" systems in vehicles, over 50% of human lives could be saved. In recent years the most attention was given to improving the passive safety of vehicles, making vehicles of today four times safer than they were in the 1970s [29,32,33]. Vehicle safety is also an element of competitiveness; therefore vehicle manufacturers are paying increased attention to this issue when developing new cars. The modern car is designed with particular emphasis to ensure a high level of safety of passengers and other road users. To ensure a high level of security, vehicles are fitted with systems that support certain conducting activities, and in some cases they can replace the driver, for example in a traffic accident the system could report the location of the vehicle and call for help (eCall). Progress in measurement techniques and information systems opened up new possibilities for automation of the vehicle control process. It is now technically possible to build fully automated vehicles, but the user problems arise from the technical difficulties that have arisen in the course of testing in urban conditions and also the applicable laws that fail to address the legal responsibility for driving intelligent vehicle without a driver and causing an accident [30,38].

1.    Vehicle safety

When developing new vehicles i tis emphasized that the vehicle meets the safety requirements. These requirements are set by valid regulatory acts, but also by customer’s needs. In addition, vehicle manufacturers themselves are developing a variety of safety features that are intended to increase the safety of the vehicle [34,40,43]. The main purpose of vehicle safety is life and health of the vehicle crew, but also other road users (pedestrians, cyclists, other vehicles, etc.). In general, the goal is to minimize the likelihood of an accident and if this occurs, to ensure protection of health and life. To achieve this goal it is possible to apply different features that can be called safety of the vehicle. The term safety of the vehicle means two basic categories of safety: active and passive safety.

1.    Integrated intelligent safety systems

Development in vehicle safety focuses on linking of pre-existing systems, streamline their operations and lower their prices, which allows the application of these systems within the lower price categories of vehicles. Intelligent vehicle will also need support intelligent road network. The road network must be integrated with telematics applications; transport management systems and equipped with communication systems [36,35,44]. Categories of integrated safety systems:

1.    Autonomous active safety systems;

a.    systems continuously supporting the activity of the driver;

b.    the systems active at the time of the expected impact;

2.    Systems of active safety cooperating;

a.    with the other vehicles;

b.    with the infrastructure;

3.    Systems active at the moment of impact;

4.    Systems active after the crash - autonomous;

5.    Systems active after the crash - cooperating.

Integrated intelligent safety systems are results of the evolution of the automotive industry and various technologies of competing vehicle manufacturers. Their deployment in vehicles is partly voluntary (competitive advantage in terms of security) and partly compulsory due to the legislation for vehicle type approval for operation in road traffic.

 

     2.1     Autonomous active safety systems

The best way to reduce road accidents is to prevent them. Active safety systems can be classified in terms of function over time into continuously operating systems, and systems that act at the moment of potential danger (the chance of a traffic accident). Active safety systems ensuring its continuous support for the driver are also called "driver assistance systems" also known as ADAS (Advanced Driver Assistance Systems) or DSS (Driver Support System)

 

     2.2     Systems continuously supporting the activity of the driver

The systems continuously supporting the activity of the driver should be able to adapt to the current situation anticipate needs and, if necessary, take the initiative. The systems continuously supporting the activity of the driver include the following technologies:

 

1.    1. Anti-lock braking system (ABS) –

Anti-lock brakes, preventing the wheels from locking during braking, allowing the driver to maintain control of the vehicle. Locked wheels cannot transmit lateral guidance forces. The control unit controls the ABS wheel-speed sensors through a number of revolutions of all-wheel vehicles. If there is a blockage of a single wheel, the solenoid valve will reduce the anti-skid control unit for brake pressure to that wheel until the same does not rotate freely. The pressure is then increased again to limit blocking. The vehicle retains stability and manoeuvrability. The driver feels the intervention of the anti-lock system, a light pulse in the brake pedal. On dry surfaces may slightly lengthen braking distances. Its main task is, especially on slippery road surfaces while at the same time enable the driver to brake and change direction of the vehicle.

 

1.    2. Anti-Slip Regulation system (ASR) or Traction Control System (TCR) 

prevents wheel spinning on slippery surface, changing direction on acceleration; Smarter systems are capable on one axle torque split, if one wheel is on a slippery surface and one on the hard disk.

3. Electronic Stability Program (ESP) or Electronic Stability Control (ESC) –

 Improves management control and automatically stabilizes the vehicle in all situations. Electronic Stability Program identifies critical situations and prevents the fact that the vehicle is deviating from the track. It should actively prevent uncontrolled skidding of the vehicle and assist the driver to stabilize the vehicle if it gets to skidding. It directly cooperates with ABS and ASR. It compares the behavior of the vehicle with calculated values. It checks the desired direction of travel based on the steering angle; the actual speed based on the wheel speed. Compares lateral acceleration and vehicle rotation around the vertical axis with calculated values. The vehicle may become unstable when cornering with excessive speed, or when the road surface unexpectedly changes (water, ice, pollution), or during an unexpected evasive manoeuvre. The controlling unit in Electronic Stability Program recognizes the kind of volatility based on data from sensors and intervenes in the engine management and brake control. When the vehicle understeer, it’s entering the bends by front wheels, while it’s not turned enough. ESP targeted brakes at the rear wheel, on the inside of the bend and if necessary, simultaneously reduces engine power. If the driver begins to brake, ESP also hits and reduces the braking force on the outside of the bend. We must emphasize that electronic stability program cannot overcome the boundaries of physical laws. If the driver overestimates the possibilities of chassis the Electronic Stability Program fails to prevent an accident.

 

 

1.    4. Brake Assistant System (BAS) –

assistant braking action; in crisis situations and in cases where ABS regulates brake pressure, brake pedal may begin to vibrate, which can lead the driver to release the pedal to avert these vibrations, which however will reduce braking effectiveness. Brake Assist is activated in case of the critical braking. When the driver breaks suddenly, in most cases, will strongly hamper with some delays. BAS evaluate rapid responses by the driver and automatically define the will of the braking system and increases braking pressure in the system, thereby shortens the braking distance by up to 2 m. If the driver does not increase the pressure on the brake control system pressure in the system is released again.

1.    5. Blind Spot Monitoring (BLIS)

 or Blind Spot Detection – the blinds spot monitoring system is checking the blind spot on both sides of the vehicle, where the vehicle in the rear-view mirrors is difficult to see; so called blind spot, using audio and visual alerts for the driver when moving into an occupied lane; more modern systems are able to alert even of an rapidly approaching vehicle (from rear).

 

Conclusion

Currently, vehicles are packed with smart technology solutions for active safety, which should avoid the risks associated with driving. Improving the control of the vehicle in different driving situations, increasing the safety and passenger comfort, facilitating of communication and controlling the situation on the road. The active lighting systems provide better visibility for the driver and a faster reaction to emerging obstacles along the way. These vehicles are equipped with a large number of sensors, receivers, actuators and control units whose task is to coordinate cooperation of all electronic and mechanical components of the vehicle and to communicate between other road users. Safe and intelligent vehicles characteristic not only by innovative energy sources for propulsion, but also the ability to interact with intelligent infrastructures. The main advantages of moving vehicles in automatic mode are:

•road safety;

•lower fuel consumption;

•improves traffic flow due to the communication between vehicles;

•reduction of congestion in urban areas.

The big challenge for intelligent transport systems is to reduce the dangerous human behavior on the road. This relates to the decision of the driver (respecting traffic laws and safe driving) and the behavior of other road users.