DAC and Attention Assist fatigue control systems monitor the physical condition of the driver and, if necessary, signal that it is time for the driver to stop and rest. Such a check is carried out by three control options:
Attention Assist and DAC are fatigue control systems that monitor the driver's ability to physically control the vehicle and, if necessary, give a signal to stop driving for rest. The check is carried out by three types of control, which depend on the following behavioral factors:
1.
Driver behavior is assessed;
2.
The driver's gaze is fixed;
3.
The movement of the vehicle is monitored.
The Attention Assist device, which monitors the driver's behavior, has been produced by Mercedes-Benz since 2011. This device is guided by the following motivations: way of driving, steering, driver's actions while driving and some other parameters.
Schematically, the fatigue monitoring system consists of a steering sensor, a control indicator and an audible alert that alerts the driver.
A sensor mounted on the steering wheel monitors the change in the force exerted on the steering wheel as it rotates. The system also takes into account information received from other control sensors: driving stability, braking system, visibility restrictions and engine parameters.
The signals received by the device are processed, defining the following parameters:
a) within half an hour from the beginning of the movement, the speed and lateral acceleration of the vehicle are analyzed (driving style);
b) the condition under which the movement occurs (here both the time of day and the duration of the trip are taken into account);
v) the control of the following units is analyzed: buttons located on the steering wheel and below it switches and the brake system;
G) the force of influence on the steering wheel is analyzed;
e) road surface condition and vehicle behavior while driving (lateral and longitudinal acceleration).
By analyzing all these parameters, the system detects violations in the actions of the driver and changes in the direction of the vehicle. After that, a signal with sound accompaniment is sent to the screen located on the dashboard, so that the driver stops to rest. If the driver in a drowsy state ignores the signal and continues driving, the system continues to remind him of this every 15 minutes. It should also be recalled that control over the driver's condition begins to work at a speed of more than 80 km / h.
At Volvo, the driver's control Driver Alert Control (or DAC) differs from Attention Assist in that it monitors only the trajectory of movement along the highway, and video monitoring, following in the direction of the vehicle's path, determines its location in the lane of the roadway. If suddenly the car starts to move beyond the established limits, the system reacts to this as if the driver is tired and issues two warning signals: "soft" and "hard" Both of these signals depend on the general well-being of the driver and differ from each other in volume and tone. The DAC system is activated, working in conjunction with the system elements Lane Departure Warning, when the vehicle speed reaches 60 km / h.
A special built-in unit, which is installed by General Motors, where the already tested Seeing Machines method, which assesses the state of the driver's gaze, is the base, is installed not only on cars, but also on railway transport. The task of the unit is to monitor the openness of the driver's eyes and their concentration, and when it detects signs of fatigue or loss of alertness and sleepiness, the system immediately gives a command to stop the vehicle.
Also, the driver fatigue tracking system can control other functions of the car, for example, the direction of gaze, you can enable or disable certain options on the dashboard. Or, when making a maneuver, notify the driver that he forgot to look in the mirror.
It's no secret to her that falling asleep while driving is the cause of many serious accidents. If the duration of the trip exceeds 4 hours, then the driver's reaction time increases several times, and the dark time of the day can also play a role. Let's look at what solutions to this issue are offered by auto manufacturers.
One of the simplest devices that monitor the driver's condition (whether he fell asleep) is attached to the auricle and looks like a bluetooth headset. If you have ever fallen asleep while standing or sitting, then you know that when you fall asleep, your head tilts forward a little. If the device detects that the forward tilt angle has changed by a certain degree, then it beeps. The volume of the signal is limited so as not to frighten the sleeping driver, and at the same time make him wake up. The angle at which the device will wake up the driver can be adjusted and there are some reasons for that, for example, so that the device does not work if the driver likes to shake his head to the beat of the song that sounds from the radio, or the driver's head deviates very slightly when he falls asleep.
We examined the most primitive anti-sleep system, I think many will be interested in how advanced auto manufacturers solve this problem.
Have Mercedes-Benz such a system is called Attention Assist, it, using the vehicle engine control unit and the steering wheel angle sensor, determines the driver's driving style and, accordingly, if it changes, gives a sound and light signal.
Let's list what kind of information the system analyzes:
- Times of Day;
- duration of the trip;
- the frequency of using the buttons on the control panel;
- steering wheel speed and acceleration;
- using the brake pedal;
Lexus they mount a camera in the dashboard, which does not monitor the behavior, but the driver's face and warns him if he falls asleep.
Volvo- system Driver Alert Control, with the help of the camera, monitors that the car moves strictly in the lane and, in the event of a wobble, corrects the car's course and warns the driver.
Saab uses two cameras that track the movement of the driver's eyes and warns him with a message on the dashboard if the driver does not respond, a beep sounds.
Despite the fact that the price for these systems is high, especially in those systems where video cameras are used, their benefits overshadow their price. In principle, such a system will be useful to every driver making a long trip, whether it is a truck driver, an intercity bus driver, or just a car enthusiast who decides to go to a neighboring city. By the way, in some systems where a camera is used that monitors the driver's behavior, you can look at the camera to turn on the high beam, for example, or some other device, the functionality depends on the manufacturer.
The most effective driver monitoring systems are Attention Assist, Driver Alert Control and Seeing Machines. Their goal is to detect and report changes in the human body in time.
The content of the article:
A monotonous road or long car journeys, especially at night, lead to driver fatigue. As a result, his reaction is reduced, and fatigue increases. This leads to the fact that the body cannot withstand the load, and the driver simply falls asleep. This leads to numerous serious accidents.
In order to avoid such cases, they came up with systems that monitor and control the level of driver fatigue. This can be done using 3 indicators. In the first case, the actions of the driver are observed, then the movement of the car, and finally the look of the driver.
Attention Assist
The Attention Assist system performs control using several parameters and elements. This system is built into the car of the German Mercedes-Benz brand. The Attention Assist system consists of several sensors, each of which is responsible for a specific indicator of fatigue. These are sensors such as the steering wheel, engine or brake system. One of the main ones is the control unit sensor.
He monitors the physical condition of the driver for many indicators. First of all, he controls the driving style, namely the speed. The next indicators are the conditions in which the car is moving. Here we mean the duration of the trip and when it takes place, at what time of day.
The braking system and the steering column switches belong to the control system, which is also controlled by the system. Finally, the acceleration is controlled, namely lateral and longitudinal.
Monitoring the current state, the system compares it with the original. If the indicators signal a significant deviation from the norm, a sound signal is turned on and the message "Attention Assist: Pause" is displayed on the screen panel, warning the driver to stop.
An alarm is signaled every 15 minutes if the warning is ignored. The system is activated from a speed of 80 km / h. The analysis of speed, maneuverability and the removal of other parameters occurs 30 minutes after the start of the movement, since most often this is exactly how much time is required to move over long distances.
Driver Alert Control (DAC)
The next control system Driver Alert Control was created by the Swedish car company Volvo. Here, the principle is based on monitoring the driver's condition through the manner in which the car is moving. For this, a special video camera is built into the Volvo car, which monitors the driving behavior on the road. The trajectory is assessed and changed using the steering wheel sensor and lane monitoring. The second video camera monitors the external state of the driver, namely the movement of the eyes.
If an overwork condition is detected, the system alerts the driver with a signal and the message “Driver Alert. Time for a break ". The system starts to operate at a speed of 60 km / h.
Seeing Machines
The latest system that monitors the driver's condition is the Seeing Machine, implemented in the British brand Jaguar. It is noteworthy that this technology is used not only in the case of driving a car, but in other areas. The system is built exclusively on monitoring the external physical condition of the driver. The built-in camera records the position of the eyes and their direction.
If the indicator deviates from the norm, the system notifies of fatigue and the likelihood of falling asleep while driving with a signal and a special message.
The perfection of this technology is that it is activated even if the driver is wearing sunglasses. This system also includes additional parameters. For example, the system detects lack of attention to the rearview mirror. In this case, the driver receives a reminder of this action.
Video of the driver tracking system:
Topic 6. Fatigue and performance
Fatigue and tiredness. Signs, causes and process of fatigue development.
Types of fatigue
Health phases
Overwork
Fatigue and tiredness. Signs and causes of driver fatigue.
The reliability of drivers depends to a large extent on their performance. High efficiency ensures the execution of work with high productivity and high quality indicators. When driving in a state of reduced performance, drivers make mistakes that sometimes lead to accidents.
Fatigue is one of the reasons for the decline in driver performance.
There are concepts such as fatigue, tiredness and overwork.
Fatigue- This is a natural process of a temporary decrease in working capacity that occurs as a result of activities. This is an objective process characterized by changes in the human body that can be established by objective methods.
Fatigue- This is a subjective experience of fatigue by a person. The physiological essence of fatigue is to signal the body to stop or reduce the intensity of work in order to avoid disturbances in the functions of nerve cells.
At the same time, the feeling of fatigue does not always correspond to the degree of fatigue. A person in a state of fatigue may not feel tired under the influence of emotional excitement, danger, interest in the work being performed, a sense of duty, responsibility for the assigned task. It is for this reason that the driver experiences less fatigue on a long journey than the passenger sitting next to him, although prolonged driving naturally leads to more driver fatigue than the inactive passenger.
For the optimal course of mental processes, an optimal level of information load is required. The excess and lack of information contribute to the development of fatigue. In addition, the nature of the incoming information is also important.
When driving in conditions when there are no other road users on the road, the driver will feel fatigue faster in a monotonous landscape than when driving in heavy city traffic. In a monotonous environment, with a lack of information or in a state of forced inactivity, a feeling of fatigue can arise faster than with active strenuous work, although there may still be no objective signs of fatigue.
Domestic physiologists have found that brain cells get tired much faster than working muscles. The nerves, along which nerve impulses are transmitted, have the least fatigue.
This was first proved by the physiologist I.M.Sechenov in an original experiment. The subject, when bending the index finger in a given rhythm, lifted the weight to a certain height. As a result of developing fatigue, the height of lifting the load decreased after a while, and then a moment came when the subject could not lift the load at all. At the same time, he felt a strong fatigue in the muscles of the working finger and, naturally, believed that fatigue had developed in them. Further, at the moment when he could not lift the load, an electric current was passed through the muscles of the working finger, which caused the muscles to contract in the same rhythm, which led to the lifting of the load. Naturally, one could assume that after turning off the current, the muscles that have worked additionally will not contract as a result of even greater fatigue. However, when the current was turned off, the subject again began to easily lift the load at the same pace. This is explained by the fact that during work, fatigue developed faster not in the muscles themselves, but in the nerve centers that sent impulses to these muscles. During muscle contraction by electric current, the nerve cells of these centers rested, their working capacity was restored, and they again began to send impulses to the muscles. Thus, the nerve cells of the cerebral cortex are fatigued the fastest, then muscles are fatigued and the nerves along which nerve impulses are transmitted are the least fatigued.
As a result of more rapid fatigue of the nerve cells of the brain, first of all, there are disturbances in the course of mental processes - perception, thinking, memory and attention. In addition, visual acuity decreases, the field of vision becomes narrower, depth vision deteriorates, accuracy and coordination of movements are impaired, reaction time increases, the degree of automation of skills decreases, heart rate increases, blood pressure rises, a sense of speed is lost, apathy, lethargy appear, and readiness for action is impaired. in case of an unexpected change in the traffic situation.
Fatigue manifests itself in the form of a gradual decrease in the body's performance. At the same time, auditory, visual and tactile sensitivity decreases, reaction time increases, the number of errors increases, and productivity decreases.
Signs of coming fatigue:
• feeling tired;
· The appearance of minor erroneous actions;
• desire to straighten up, change posture;
· A noticeable decrease in the intensity and stability of attention;
· Involuntary distraction by thoughts not related to driving;
· Increasing volitional effort required to overcome the listed negative phenomena.
The first signs of fatigue that appear after several hours of driving are not dangerous for the driver and can be easily eliminated with a short rest.
The degree of fatigue depends on the duration of the work. The longer the driver's working day, the more pronounced the fatigue, the more likely mistakes are. Statistics have established a direct relationship between the time of driving and the number of accidents.
Drivers, driving a car for 7-12 hours, commit an accident 2 times, and with a driving duration of more than 12 hours, 9 times more often than with a duration of up to 7 hours. According to other sources, drivers who work more than 7 hours make 1/3 of all road accidents. Accidents resulting from driver errors as a result of long-term driving lead to more serious consequences. Thus, for drivers who work more than 12 hours, fatal accidents occur 1.5 times more often.
With fatigue, simple, well-automated skills can be retained, which allow one to act correctly in well-known, standard situations. However, complex types of mental activity are disrupted, which reduces the readiness for action in case of an unexpected and unusual change in the traffic situation. All this reduces the reliability of drivers, leads to errors and accidents.
Visual fatigue is of particular importance to the driver. After 8 hours of continuous operation, he sees a road sign no longer 100 m, but only 80 m.The fatigue of vision is facilitated by insufficient contrast between the background and the object, which occurs when driving a car in conditions of limited visibility, as well as when drivers are blinded by the headlights of oncoming cars by night and by the sun by day. Visual fatigue affects the performance of the driver. The tired muscular system of the eyes does not provide a clear spatial perception. Even experienced drivers, when tired, look more often to the side of the road and from a distant perspective to a near one, which makes it difficult to perceive and predict the development of the road situation.
Possible reasons contributing to the development of driver fatigue:
Uncomfortable seat,
Low air temperature,
Frequent changes in temperature in the car cabin,
· bad visibility,
Frequent changes in illumination and insufficient illumination of the road at night,
Vibration,
· Getting into the cab of vapors of gasoline or exhaust gases.
The process of developing fatigue goes through the following stages:
1) Stage of no fatigue. The work is not tired yet, the person can continue to work further or do something else;
2) The first stage of fatigue. There is a feeling of work-induced fatigue. But after an hour of active or passive rest, freshness of thoughts and feelings is regained, a person becomes energetic again.
3) The second stage of fatigue. The volitional effort, which forces the brain to strain to solve complex issues, decreases.
4) The third stage of fatigue. A person no longer wants to dwell on anything, even in the lightest work, but still retains the desire to eat and sleep;
5) The fourth stage of fatigue. It is characterized by insomnia. At the same time, there are signs of neurasthenia, headaches, a feeling of fatigue after a night of half-sleep and half-wakefulness, irritability, excessive sensitivity in communicating with other people, irascibility, and sometimes depression.
According to statistics, up to a third of accidents on the roads are due to the negligence of drivers, caused by physical exhaustion or falling asleep while driving. The greatest risk group includes those motorists who professionally engage in freight and passenger transportation over long distances, for a long time without interruption. Monotonous road markings and nighttime contribute to falling asleep while driving.
The need for a fatigue recognition system
When, in order to avoid a road accident, the response time of the brake mechanism will be one of the factors in the timely stopping of transport. Other similar factors include: the speed with which the driver will react to the changed situation, and the time it will take him to make a decision and activate the corresponding actuator.
As a result of the research, it was found that constant traffic management for 4 hours reduces the speed of response of a motorist to a change in the road situation by 2 times, and within 8 hours - up to 5-7 times.
The driver fatigue recognition system monitors certain parameters of a person's physical condition, which are stable when a person is sleeping and vigorous behind the wheel. In the case when the mechanism notices deviations from the basic standards laid down by the settings, it notifies of the need with various types of signals and notifications, having paused for rest.
Control methods
Driver fatigue can be controlled by several methods. The safety device is based on three ways to determine the fatigue of a person driving a vehicle:
- A method based on the assessment of the trajectory of traffic.
- A method based on the assessment of the actions of the driver of a road vehicle.
- A method based on assessing the trajectory of a person's head movement while driving.
The existing today, as well as early detection of signs of fatigue of the driver of a vehicle, function based on several nuances: driving style, driving behavior, the use of control mechanisms, conditions and driving environment. Structurally, such devices can combine a control device, a rudder controller, light and sound warning signals.
Operating principle
How the driver fatigue sensor works: the steering wheel angle sensor statistically evaluates the intensity, the frequency of the wheel turns over the past four hours from the start of the movement, and if a statistical error is found above the permissible level, it sends a signal to the control unit, which activates the hazard alarm elements.
The control complex receives a large number of signals informing about different parameters:
- Driving style - different types of acceleration in half an hour after the start of the movement, speed estimation.
- Driving conditions - duration of the trip, estimate of the time of day.
- Operation of actuators - assessment of the intensity of using switches under the steering wheel, braking system, devices on the control panel.
- Intensity of steering wheel turns - estimate of speed and acceleration.
- Road surface condition - control of acceleration modes.
- The direction of movement of the road vehicle - control of various types of acceleration.
Constantly carrying out complex calculations according to certain algorithms, the device detects deviations in the direction of vehicle movement and human actions. What is reported on the control panel display, signaling by sound. If the driver ignores the signals, continues to drive the car while sleepy, then the notification resumes at intervals of a quarter of an hour. The safety system is activated when the vehicle reaches a speed of 80 km / h.
Australia's latest development in testing, the DAS Driver Fatigue Management System, helps vehicles maintain road safety through stringent compliance requirements. Such a device is able to read the established signs, and also monitor the implementation of the norms prescribed by them. Such a tool is able to provide the police with detailed information about where the vehicle was, what its speed was on certain sections of the road.
The DAS complex is equipped with three video cameras, one of which looks forward, and the rest are focused on the position of the driver's head. The recording device of the computer records the traffic situation and the position of the head, and the smart device, highlighting the desired one, understands the purpose of the traffic signs.
If the vehicle approaches road signs, such as speed limits, too quickly, the system alerts the driver with a signal. If the warning is ignored, the violation is entered into the computer's memory. The same mechanism for preventing and fixing violations is provided for other groups of road signs.
The DAS Driver Fatigue Monitoring System is Volvo's newest safety device on the market. The device is equipped with video recording, the task of which is to control the evenness of the vehicle running relative to the road markings. When periodic deviations from the trajectory of movement and wobbling are detected, a warning signal is issued by the notification organs. For the driver, this can symbolize a kind of red line, which is not worth crossing, but you need to make a stop to rest. For a detailed acquaintance with such a system, the manufacturer provides an operating manual written in more than 400 pages.
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