Car2x Communication-Virtual Sensors
Dept. of Computer Science
Chair of Computer Engineering
Submitted by: Bhalgama Nitin Narasinhbhai
Student ID: 469601
Supervising tutor: Prof. U. Tudevdagva
AbstractThe number of vehicles on the road is increasing day by day which causes more accidents, more traffic jams, etc. To avoid these situations as well as to handle them better, vehicles should get road information (e.g. accident, jam, road surface condition) in a detailed way. The new concept Car2X communication has been introduced to solve these difficulties, where cars can communicate with other cars or infrastructures also known as C2C (Car to Car) and C2I (Car to Infrastructure) communication. The higher-level engineering system for assuring Car2x communication is known as the Intelligent Transport System (ITS). In Car2X communication information is exchanged through wireless technology between cars and roadside units. The communication is possible in both directions, e.g. Car2Roadside and Roadside2Car. Roadside units can send several information to the cars like traffic congestions, slippery road condition, accident, incident, and road work ahead. Cars can broadcast received information from the roadside unit to other cars within their range. Vice versa, cars also can send received messages from other cars to a roadside unit through sensors and network.
Keywords: Car2X communication, Road safety, ITS, Sensors
Content TOC o “1-3” f h z u Abstract PAGEREF _Toc517383004 h 1Content PAGEREF _Toc517383005 h 2List of Figures PAGEREF _Toc517383006 h 4Figure 1. PAGEREF _Toc517383007 h 4List of Abbreviations PAGEREF _Toc517383008 h 51Introduction PAGEREF _Toc517383009 h 62Car2X communication PAGEREF _Toc517383010 h 73Virtual sensor: PAGEREF _Toc517383011 h 93.1When Do You Need Virtual Sensors? PAGEREF _Toc517383012 h 93.2Advanced driver assistance systems (ADAS): PAGEREF _Toc517383021 h 113.2.1Classification PAGEREF _Toc517383022 h 113.2.2Information and warning PAGEREF _Toc517383023 h 123.2.3Function specific automation PAGEREF _Toc517383024 h 123.2.4Combined function automation PAGEREF _Toc517383025 h 123.2.5Limited self-driving automation PAGEREF _Toc517383026 h 123.3Active Cruise Control (ACC) PAGEREF _Toc517383027 h 133.3.1Classification PAGEREF _Toc517383028 h 134CAR2X Application PAGEREF _Toc517383029 h 154.1CAR-2-CAR Application: PAGEREF _Toc517383030 h 154.1.1Traffic Safety PAGEREF _Toc517383031 h 154.1.2Traffic Efficiency PAGEREF _Toc517383032 h 174.1.3Infotainment and Payment PAGEREF _Toc517383033 h 174.1.4Other Applications PAGEREF _Toc517383034 h 174.2CAR-2-Infrastructure Application: PAGEREF _Toc517383035 h 194.2.1Safety PAGEREF _Toc517383036 h 194.2.2Efficiency PAGEREF _Toc517383037 h 194.2.3Payment and Information PAGEREF _Toc517383038 h 20
List ofFiguresFigure 1.Car to Car City scenario07
Figure 2. Sensor devices around the vehicle10Figure 3. Advance driver assistance11Figure 4. Adaptive cruise control12Figure 5. Hazardous location warning14Figure 6. Privileging fire truck15Figure 7. Reporting accidents:15Figure 8. Intelligent intersection16Figure 9. V2V based Cooperative-adaptive Cruise Control test vehicle PAGEREF _Toc516520274 h 17Figure 10.Safety applications with the integration of DSRC and roadside sensors PAGEREF _Toc516520279 h 18Figure 11. Dynamic traffic control supported by DSRC PAGEREF _Toc516520280 h 19
TOC h z c “Abbildung”
List of AbbreviationsIntroductionCar2x communication, in which “x” represents a various kind of things such as Car2Car (C2C), Car2Pedestrian (C2P), and Car2Object (C2O) Car2Infrastrucutre (C2I). The system is working on sensors and it is useful for the communication. It connects all other vehicles and surrounding objects so that they can receive the information simultaneously. This communication system is very precisely focusing on time critical applications like collision avoidance, pedestrian information, speed limit indication, car breakdown warning in nearby area.
Physical sensors play an important role in control systems and communication system, as they provide information about system state and malfunctions of monitored entities. Currently, these systems depend on sensor data to actuate on their components in order to provide a safe and enjoyable driving experience. Consequently, modern vehicles have hundreds of embedded sensors to monitor their performance and, with recent advances, their drivers.
Given the importance of sensors to a vehicle’s operation, new models embed numerous high-quality sensors to get more reliable and diverse information about the vehicle. All data outputted from sensors in a vehicle is delivered to its Engine Control Unit (ECU) through an internal network, which is accessible using the vehicle’s On-Board Diagnostic (OBD) system. Virtual sensors are very useful and important alternatives to monitor aspects, variables, and events for which there are no physical sensors. There are cases where physical sensors are unavailable for a particular phenomenon and a virtual sensor can replace them, given that the variable they monitories precisely described or highly correlated to other monitored variables. In fact, a virtual sensor may be obtained from several physical sensors, used to monitor a single aspect for which there is no physical sensor, by gathering their information using models and output information. At the end of this process, a virtual sensor can produce new and possibly more valuable information.
Car2X communicationCar-to-X (C2X) is nothing but a means of communication that includes exchange of data and information between a vehicles and the transport infrastructure (C2I) or between vehicles (C2C/V2V). The basic goal is to give the driver an early and effective notice about any critical or dangerous situations along the road. Furthermore, increasing the traffic efficiency through a method of co-operative assistance. This type of communication is thus considered as the future of road transport throughout the world. In Europe, for example, there are different projects that essentially look to increase the safety in traffic as well as finding solutions to optimizing the road traffic. This is achieved by using C2X communication within the context of seeking applications with Intelligent Transport Systems (ITS). The information exchange takes place by a communication within the vehicle ad hoc networks (VANETs) on Dedicated Short Range Communication (DSRC). In Europe, the term ITS-G5 is used to avoid the confusion between the US and the Japanese version of DSRC ETS 12. The communicating nodes represent the ITS-S stations (ITS-S), where vehicles are referred to as Vehicle ITS-S and the infrastructure as Roadside ITS-S2 ETS-10a.
The infrastructure represents static road facilities and facilities on traffic routes that actively process and disseminate information. This is done by sending messages that can be received and expanded by the car. The car on the other hand processes the application data from the Adaptive Driver Assistance Systems (ADAS) and communicates with nodes in their environment. Car-2X communication thus represents the highly dynamic topology of the network which consists of short connection times, changing environmental conditions and directions of movement of vehicles. This forms the basis for the underlying communication system.
The C2X technology also offers new possibilities to enhance road traffic safety and traffic efficiency at a large scale. In figure 1.3, the car is seen to be able to connect with cars beyond its horizon. This extended horizon means the potential limit on the area of coverage for the communication can be effectively extended as a network. It can no longer be limited to the horizon of the camera active in the car. This involves the usage of Radar and Lidar technologies. With the help of these technologies, when a dangerous situation is detected along the road, the cars can send signals via hops. This allows the drivers behind to react on time and adapt their driving behavior accordingly.
Figure 1. Car to Car City scenario
C2X communication is based on the IEEE 802.11p standard which will be detailed in the following chapter. It is a standard that allows time critical safety applications at a very low data transmission delay. The European commission, in this context has agreed and initiated an allocation of the 30 MHz spectrum, from 5.875 to 5.905 GHz respectively. According to the European profile for safety related communications, two channels with 20 MHz each are assigned within the 802.11p standard. One channel is dedicated to network control and safety purposes and the second for safety applications 9.
Virtual sensor:A Virtual Sensor estimates product properties or process conditions using mathematical models. These mathematical models use other physical sensor readings to calculate the estimated property or condition.
When Do You Need Virtual Sensors?The Property or State Cannot be measured by a Physical DeviceA Physical sensor is too slowA Physical sensor is too far downstreamImplementing a Physical sensor is too expensiveThere is no means to install a physical sensorThe sensor environment is too hostileA physical sensor is inaccurateA physical sensor is expensive to maintainPhysical sensors are an important part of control systems, especially vehicular control systems. Sensor readings help drivers to control their vehicles as well as their internal systems while keeping a vehicle stable and running. Currently, a modern luxury car carries hundreds of diverse and precise sensors and not all of them are visible to the driver. However, there are phenomena and aspects for which there are no physical sensors available. Virtual sensors combine readings from multiple sensors in order to develop their own output values based on conditions and models, and, eventually, substitute and monitor failing physical sensors, as well as sense complex variables. Designing a virtual sensor is usually a difficult process due to the complexity of the different processing stages it comprises. This work studies the process of creating and prototyping vehicular virtual sensors, describing the development stages and presenting examples of virtual sensors created with a framework developed to facilitate the design process.
There are different types of sensors installed all around the vehicle that deliver information from near, medium and distant ranges. The following figure shows the elements of the environment sensing around the vehicle.
Figure 2. Sensor devices around the vehicle.
Types of vehicle sensor devices:
Examples of vehicle technologies (Virtual Sensors)
Electronic stability control
Blind Spot Monitoring
Lane Departure Warning
Obstacle And Collision Warning
Advance hazard warning
Advanced driver assistance systems (ADAS) and Active Cruise Control (ACC) technology that use most of virtual sensor and by using that, it create one complete autonomous vehicle.
Advanced driver assistance systems (ADAS):Advanced driver assistance systems (ADAS) are defined here as vehicle-based intelligent safety systems which improve road safety in terms of crash avoidance, crash severity mitigation and protection and post-crash phases.
Figure 3. Advance driver assistance
ADAS technologies exist at different levels of active assistance and are being introduced in overlapping stages. Driver information systems, such as simple rear-view cameras, surround-view displays, and blind spot and lane departure warnings, provide information but leave the driver in full control at all times. Partially autonomous systems, such as lane keep assistance and active cruise control, enable the vehicle to control itself briefly in carefully defined situations, but with the driver ready to override automatic control at all times. Highly autonomous systems, including automatic parking valet or impaired driver monitoring and override, will take full control of the vehicle at specific times. These higher levels of assistance employ the technologies used in the more basic levels, paving the way to self-driving, fully autonomous cars. At this level, the car can operate on its own, with or without someone in the driver’s seat.
ClassificationTypically ADAS can be broadly classified in 3 groups:
– Passive system.
– Active system.
– Co-operative system.
Passive systems are the most conventional systems, where the corrective measures are taken to minimize the effects of a crash. These systems do not in themselves are capable of avoiding an accident, thus come into picture only once the event has occurred. Some of the examples of passive system are such as airbags, seat belts and so. Hence, these systemsFall into a very preliminary category of safety requirement, which minimize the effects, but cannot avoid it in any way.
Active systems on the other hand, aim at preventing the accident itself. Active systems are capable of proactively detecting a probable cause of accident and avoid it by notifying the driver.
Co-operative systems communicate with the central information system, which exchanges information with relevant sources like inputs from sensors and GPS. This information is thus notified to the driver, to take corrective action and prevent any accident. Co-operative systems are also capable of taking preventive measures automatically in adverse conditions, where the chances of accident are high and in events of sudden occurrence of an adversary.
Information and warning• Side and rear cameras with driver displays
• Back-up assistance
• Warning of oncoming cross-traffic
• Ultrasound sensing of areas in front and behind the car obstructed from driver view
• Traffic sign recognition
• Detection of lane markings
• Blind spot warning
• Night vision
• Ranging of objects ahead in conditions of poor visibility
• Vehicle-to-vehicle and vehicle-to infrastructure communication
• Dynamic display image of the entire car and surrounding space
• In-cabin monitoring and warning to a distracted driver
Function specific automation• Lane keep assistance to stay in the center of the lane
• Active cruise control for changing traffic conditions
• Collision avoidance by automatic braking
• Automated emergency brake
Combined function automation• Adaptive cruise control with lane centering
• Traffic jam assist
Limited self-driving automation• Automated parking/valet parking
• Highway auto pilot
Active Cruise Control (ACC)Adaptive cruise control (ACC) is a system which regulates the cruising speed of the vehicle. Once the driver sets the ACC to a prescribed speed, the systems regulates the throttle valve of the engine. In ACC, the system takes control of the engine throttle to maintain the speed and is released only when the driver represses the Brake/Clutch. This system is very useful for long stretches of straight roads, where continuous driver control induces fatigue in the driver leading to tiredness. ACC also maintains a predetermined distance from the vehicle driving ahead to avoid collision and adapts speed accordingly. Sensors used in ACC are radar, LIDAR and ultrasound 10.
Figure 4. Advance cruise control
Classification:ACC can be classified as:
? Assisting system
? Multi-sensor system
? Predictive system.
This system usually incorporates forward looking radar, featuring a situation prior to a crash. The system detects collision probability, issues alert notice to the driver and if required assists in braking in case of high risk of collision. A few systems also incorporate steering assistance to accommodate the lane maintaining system.
Multi sensor system works in conjunction with other sensors to provide better driving safety. It allows the vehicle to maintain existing speed in case of lane diversion indicator is notified by the vehicle moving ahead. The indicator is detected by the camera and notified to ACC, which does not reduce the speed despite the front vehicle moving at a reduced speed. Another example can be in a situation related to traffic crossing, where in case the frontvehicle violates red light, the car will take the traffic light recognition and adapt ACC accordingly 7.
This system adapts the vehicle cruise based on the behavior of the accompanying cars in the vicinity. This behavior prediction allows the car to beforehand adapt to the speed and distance. Typical example of this nature is the lane change situation, where a car while overtaking other car remains in the high speed lane for lesser time as compared to controlled speed lane 8.
CAR2X ApplicationCAR-2-CAR Application:C2C communication enables a great number of use cases mostly in relation to improve driving safety or traffic efficiency and provide information or entertainment to the driver. The definitions of the below mentioned use cases are based on CAR 2 CAR Communication Consortium Manifesto.
Traffic SafetySafety use cases are those where a safety benefit exists when the vehicle enters into a scenario applicable to the use case. The following safety applications can be relevant with the help of C2C communication.
Warnings on entering intersections or departing highways
Figure 5. Hazardous location warning
Sudden stop warnings: forward collision warning, pre-crash sensing or warning
Lane change/keeping warnings/assistance
Privileging ambulances, fire trucks, and police cars
Figure 6. Privileging fire truck
Hazardous location warning: obstacle discovery, reporting accidents
Figure 7. Reporting accidents
Traffic EfficiencyTraffic Efficiency use cases are those meant to improve efficiency of the transportation network by providing information either to the owners of the transportation network or to the drivers on the network.
Enhanced Route Guidance and Navigation
Intelligent intersections: Adaptable traffic lights, Automated traffic intersection control, Green Light Optimal Speed Advisory
Merging Assistance: enters an on-ramp to a limited access roadway (it is also a safety application)
Variable speed limits
Figure 8. Intelligent intersection
Infotainment and PaymentThis category does not contain direct traffic related applications, rather comfort services. Many of these use cases interact more directly with the vehicle owner on daily basis providing entertainment or information on a regular basis. Others are transparent to the driver but still perform a valuable function such as increasing fuel economy.
The electronic payment applications result in convenient payments and avoiding congestions caused by toll collection and makes pricing more manageable and flexible.
Other ApplicationsThe V2V communication system can support the currently available driver assistance systems. With help of the broadcasted vehicle parameters the adaptive cruise control and park pilot functions can be improved.
Figure 9. V2V based Cooperative-adaptive Cruise Control test vehicle
With special low-cost roadside units (RSU) the road sign recognition function can be supported and the reliability can be improved. In special cases it could offer safety functions in case of bridge or tunnel height or gate width.
Another important field of usage could be the policing and enforcement. Police could use the V2V communication in several ways especially checking the traffic rules such as:
Surveillance (e.g. finding stolen vehicles)
Red light drive through
CAR-2-Infrastructure Application: SafetyThe safety applications aim to decrease the number of accident by prediction and notifying the drivers of the information obtained through the communications between the vehicles and sensors installed on the road.
Figure 10.Example safety applications with the integration of DSRC and roadside sensors.
The typical safety applications could be the following:
Warning for hazardous situations (congestions, accidents, obstacles etc.)
rail crossing operations
Priority assignment for emergency vehicles
EfficiencyThese applications can support the better utilization of the roads and intersections. These functions can operate locally at an intersections or a given road section, or in an optimal case on a large network, such as a busy area of city. It is important to note that the efficiency applications also have a beneficial effect on safety in most cases.
The following typical applications can enhance the traffic efficiency:
traffic jam notification,
prior recognition of potential traffic jams,
dynamic traffic light control,
dynamic traffic control,
Figure 11. Dynamic traffic control supported by DSRC
Payment and InformationThe number plate recognition serves as base for the payment applications, which is well-tried and reliable camera-based technology. The payment applications could be the following:
Highway toll control.
This information services can be typically the traffic signs or temporary road signs with a DSRC beacon.
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