JP5403428B2 - ITS simulation system - Google Patents

Description

  The present invention relates to a technique suitable for application to simulation of an ITS system.

In recent years, various applications such as road-to-vehicle communication and vehicle-to-vehicle communication have been studied as an ITS system (Intelligent Transport System). As an example of an ITS application, the vehicle position obtained by the GPS device is exchanged with surrounding vehicles, and when a danger such as an encounter collision or a rear-end collision occurs, the driver is warned or the driving is intervened to avoid the danger. To do.

  In order to verify the operation of an ITS application, it is necessary to conduct a demonstration experiment using several tens to several hundreds of vehicles in an actual traffic environment, but such an experiment is very large and requires time and cost. . Although verification by such a method is necessary at the final stage of development, it is not realistic to frequently perform such verification from the initial stage of development. Therefore, verification of the ITS application by simulation using a computer is indispensable.

  In order to evaluate an ITS application that uses communication, an ITS application simulation includes a micro-traffic flow simulation that determines the vehicle position at each time, a radio wave propagation simulation that evaluates the communication possibility between the transmitting and receiving nodes, and communication information. It is necessary to combine network simulation to evaluate whether it is possible. The present inventors have developed an integrated platform that communicates with each element simulator, and has developed an integrated simulation system of a loosely coupled architecture that allows easy selection and exchange of each element simulator.

Toshiro Hamada et al., “Vehicle-to-vehicle communication simulation simulating real city environment with integrated simulator”, Dicomo 2008.

  In an actual ITS system, each vehicle acquires position information by a GPS device mounted on its own vehicle, and transmits the position information to surrounding vehicles and roadside devices by wireless communication. Then, the ITS application compares the received position information of the other vehicle with the position information of the host vehicle, determines the risk of a collision and issues a warning or intervenes in driving. In the conventional integrated simulation, the operation of the ITS application is simulated using position information obtained by the traffic flow simulation.

However, the position information obtained from the GPS device includes a positioning error, and only estimates the current position. The ITS application operates based on position information including such positioning errors. As in the prior art, when the operation of the ITS application is simulated using position information obtained by traffic flow simulation, that is, position information that does not include an error, the reality cannot be reproduced. For example, consider a case where two vehicles 100 and 101 that are executing an ITS application for preventing collision enter an intersection as shown in FIG. When the actual position of the vehicle 101 is a place indicated by 101a, it is assumed that the position information obtained from the GPS device is the position 101b due to the influence of the positioning error. When the collision prevention application uses position information including an error, it should be a collision, but it is determined that these vehicles do not collide due to the influence of the error, and the collision prevention function does not work. In the development of ITS applications, it is necessary to design so that collisions do not occur even when positioning information includes positioning errors, but conventional simulation methods cannot realize simulations that take into account errors included in positional information. .

  The present invention has been made in consideration of the above-mentioned problems, and an object thereof is to enable an ITS simulation that is closer to reality.

  In order to achieve the above object, the present invention simulates the operation of the ITS system by the following means or processing.

The ITS simulation system according to the present invention includes:
A traffic flow simulator that simulates vehicle motion and determines the vehicle position at each time;
A position information simulator for obtaining position information obtained by the GPS device at the position, using as input the position of the vehicle obtained by the traffic flow simulator;
An ITS application simulator that simulates the operation of the ITS application using the position information obtained by the position information simulator as input, and determines the influence of the ITS application on the vehicle operation;
Is provided.

  As described above, in the ITS simulation system according to the present invention, the position information simulator obtains the position information obtained by the GPS device in the vehicle position information obtained by the traffic flow simulator, and the ITS application simulator is obtained by the position information simulator. The ITS application operation is simulated using the position information. Therefore, it is possible to simulate a case where a positioning error is included in the position information obtained by the GPS device.

  There are several methods for calculating the position information obtained by the GPS device using the position information simulator.

  The first method is a method for obtaining, as position information obtained by the GPS device, a position obtained by adding a random error according to a normal distribution to the position of the vehicle obtained by the traffic flow simulator. This method is effective because it can simulate the operation of the ITS application in accordance with position information including an error, while the calculation process is the simplest.

  The second method prepares a database for storing map information and a predetermined GPS positioning error distribution at each position on the road, and adds the error at this position to the position of the vehicle determined by the traffic flow simulator. This is a technique for obtaining a position to which a GPS positioning error according to the distribution is added as position information obtained by a GPS device. As the error distribution stored in the database, for example, a distribution based on actual measurement can be adopted. According to this method, a more realistic GPS positioning error is added, so that GPS positioning information closer to reality can be obtained. The distribution may be such that a certain value is given as an error.

In the third method, a database storing road and feature information is prepared, GPS positioning error is obtained from the shape of the feature at the position of the vehicle obtained by the traffic flow simulator, and the obtained GPS positioning error is added. This is a technique for obtaining a position as position information obtained by a GPS device. More specifically, the shape of the surrounding feature is classified into several patterns (profiles), and it is determined to which pattern the shape of the feature around the vehicle position belongs, and an error corresponding thereto is added. It is possible. Again, the error to be added may be a constant value or a random error according to a certain distribution.

  The fourth method prepares a database that stores information on the position of roads, features, and GPS satellites, and determines the number of GPS satellites that can be captured at the positions determined by the traffic flow simulator, as well as vehicle position and feature information. And based on the position of the GPS satellite. Then, a GPS positioning error corresponding to the number of GPS satellites that can be captured is obtained, and a position obtained by adding the obtained GPS positioning error to the vehicle position is obtained as position information obtained by the GPS device. Again, the error according to the number of satellites that can be captured may be a constant value or a random error according to a certain distribution.

  The present invention can also be understood as an ITS simulation method including at least a part of the above processing, or a program for realizing these methods. Each of the above means and processes can be combined with each other as much as possible to constitute the present invention.

  According to the present invention, it is possible to perform an ITS simulation closer to reality in consideration of a positioning error by a GPS device.

It is a figure which shows the outline | summary structure of an ITS integrated simulator. It is a figure explaining cooperation of each element simulator in an ITS integrated simulator. FIG. 3A is a functional block diagram of a position information simulator and FIG. 3B is a diagram for explaining an error distribution in the first embodiment. It is a figure explaining the error distribution stored in (A) functional block diagram of a position information simulator, and (B) positioning error DB in a 2nd embodiment. It is a figure explaining the error distribution stored in (A) position information simulator and (B) positioning error DB in a 3rd embodiment. In the fourth embodiment, (A) a functional block diagram of a position information simulator, and (B) a flowchart showing a flow of error addition processing. It is a figure explaining the problem of a prior art.

  Hereinafter, some preferred embodiments of the present invention will be described in detail with reference to the drawings. First, a configuration common to a plurality of embodiments will be described.

  FIG. 1 is a diagram showing a functional configuration of an integrated simulator (ITS simulation system) capable of evaluating an ITS application using communication by linking element simulators. When simulating a phenomenon consisting of a plurality of elements, there is a method in which each element simulator is closely combined inside, but in this embodiment, a method in which element simulators that operate individually are loosely coupled is adopted. . In the loosely coupled architecture, an integrated simulation platform (hereinafter also referred to as ISP) 1 is prepared, and each element simulator is coupled by communication. The reason for adopting such a method is that the element simulator can be appropriately selected and exchanged according to the evaluation purpose.

The integrated simulator according to the present invention uses the traffic flow simulator 9, the communication simulator 10, the position information simulator 11, and the ITS application simulator 12 as element simulators by the ISP 1. The traffic flow simulator 9 is a micro traffic flow simulator that determines the vehicle at each time by simulating the movement of the vehicle. The communication simulator 10 evaluates whether or not communication is possible between vehicles or between a vehicle and a roadside communication facility at each time when the position of the vehicle changes every moment, and evaluates whether information can be transmitted by communication. . The position information simulator 11 obtains positioning information acquired by the GPS device at the time of each vehicle. The ITS application simulator 12 evaluates the influence on the vehicle operation by simulating the ITS application of the in-vehicle device or the roadside equipment. Note that these element simulators may be configured by a plurality of simulators. For example, the communication simulator may include a radio wave propagation simulator and a network simulator.

  The ISP 1 includes an overall management module 2 that manages the cooperation of each element simulator, and various controllers (traffic flow controller 3, communication controller 4, position information controller 5, and ITS application controller 6) that control each element simulator. The ISP 1 stores a state data storage unit 7 that stores the state of each element simulator at each time step, and an event that occurs in the simulation (for example, sudden braking by a driver, start of collision avoidance control by an ITS application, occurrence of communication, etc.) An event data storage unit 8 is provided.

  The integrated simulator according to the present embodiment includes a central processing unit (CPU), a main storage device such as a RAM, an auxiliary storage device such as an HDD and a CD-ROM, an input / output device, and the like from the viewpoint of hardware. Consists of a computer. Each of the above functional units is realized by such a computer executing a program, but some or all of these functional units may be realized by a dedicated circuit. Note that it is also preferable that the integrated simulator is constituted by a plurality of computers or computers including a plurality of processors, and each element simulator is executed in parallel.

  The overall management module 2 receives the simulation parameters 13 including the simulation start time, end time, time of 1 time step, and the like, and starts the simulation. The overall management module 2 uses the state data stored in the state data storage unit 7, the event data stored in the event data storage unit 8, and the map / terrain data stored in the map / terrain database 14 as a controller. The result is passed to each element simulator via, and the element simulation is executed, and the result is received. The calculation result by the element simulator is stored in the state data storage unit 7 and the event data storage unit 8. Interfaces 9a, 10a, 11a, and 12a for absorbing differences between element simulators are provided between the controller and each element simulator, and can be used without correcting the element simulator.

The overall flow of the simulation in such an integrated simulator will be described with reference to FIG. First, the traffic flow simulator 9 simulates the vehicle operation based on the initial state, thereby calculating the position of each vehicle in the next time step. The position of each vehicle determined in this way represents the exact position of the vehicle in the simulation and does not include errors. Next, the communication simulator 10 determines whether or not communication is possible between vehicles based on the accurate position of each vehicle. The position information simulator 11 obtains GPS positioning information obtained by the GPS device of each vehicle based on the accurate position of each vehicle. This GPS positioning information includes positioning errors in the GPS device. Position information including this error is position information exchanged by communication between vehicles. The ITS application simulator 12 simulates the operation of the ITS application between communicable vehicles. Here, the ITS application simulator 12 simulates the operation of the ITS application using the vehicle position information including the error obtained by the position information simulator 11. Then, in consideration of the influence of the ITS application operation on the vehicle operation, the position of the vehicle at the next time step is calculated by the traffic flow simulator 9. Thereafter, the simulation of the ITS system is executed by repeating the above processing. Here, the description has been made so that the element simulators directly cooperate with each other. However, as described above, in the present embodiment, all data linkage is performed through the ISP 1.

  Thus, in this integrated simulator, since the GPS positioning error is taken into consideration, it is possible to execute a simulation of an ITS system closer to reality.

  In the embodiment of the present invention, there are several methods for adding a GPS positioning error in the position information simulator 11. Hereinafter, each method will be described.

(First embodiment)
In the first embodiment, a random error is given as a GPS positioning error regardless of the position of the vehicle. FIG. 3A shows a functional configuration of the position information simulator in the present embodiment. As described above, the position information simulator 11 generally includes the vehicle position input unit 111 and the error addition unit 112. The vehicle position input unit 111 acquires the position of the vehicle that does not include the error obtained by the traffic flow simulator 9. The error adding unit 112 determines and outputs a position obtained by adding a GPS positioning error to an accurate vehicle position as position information obtained by the GPS device.

  As described above, in the present embodiment, the error adding unit 112 adds a random error. FIG. 3B shows a probability distribution (probability density function) of random errors added by the error adding unit 112. Here, an error according to a normal distribution is given. The normal distribution is considered to have an average of 0 and a variance of several centimeters to several tens of meters.

  In FIG. 3B, only the error distribution in the one-dimensional direction is shown, but errors according to the normal distribution may be given for all directions. Moreover, you may give a different error by the advancing direction (or direction along a road) of a vehicle, and the direction orthogonal to this. For example, an error according to the normal distribution may be given only in the traveling direction of the vehicle. This is not limited to the first embodiment, and the same applies to other embodiments.

  According to such a method, the GPS positioning error can be simulated by a simple method.

(Second Embodiment)
In the second embodiment, an error distribution for each position is obtained and stored in advance, and an error according to the error distribution at the position of the vehicle is given. FIG. 4A shows a functional configuration of the position information simulator in the present embodiment. As described above, the position information simulator 11 generally includes the vehicle position input unit 111, the positioning error database 113, and the error adding unit 112. The positioning error DB 113 stores a positioning error distribution for each position on the road. FIG. 4B shows a positioning error distribution for each area stored in the positioning error DB 113. This distribution of positioning errors may be based on actual measurement, or may be an error distribution obtained by numerical calculation or other methods. Since the positioning error is expected to be different for each measurement, it is preferably stored in the form of a probability distribution. However, the error does not necessarily have to take a plurality of values, and a constant error may be given. Even when a constant error is given, it is considered that the positioning error DB 113 stores a distribution in which the probability of taking this constant error is 100%.

  The error adding unit 112 receives an accurate position of the vehicle from the vehicle position input unit 111, adds a positioning error according to the distribution at the position with reference to the positioning error DB 113, and outputs it as position information obtained by the GPS device. To do.

According to such a method, since a positioning error according to the characteristics for each position can be given, a more accurate simulation can be executed. When the error distribution is determined based on the actual measurement value, a simulation closer to reality can be executed.

(Third embodiment)
In the third embodiment, several error distributions are defined according to the situation of buildings and the like located in the vicinity, and an error according to the error distribution corresponding to the situation of the buildings and the like at the vehicle position is given. FIG. 5A shows a functional configuration of the position information simulator 11 in the present embodiment. Thus, the position information simulator 11 generally includes the vehicle position input unit 111, the positioning error DB 113, and the error adding unit 112.

  The positioning error DB 113 stores an error distribution according to the surrounding situation (profile). FIG. 5B shows a positioning error distribution for each profile stored in the positioning error DB 113. Here, three profiles are prepared: “A place with a good view”, “A place between high-rise buildings”, and “A place with a high-rise building on one side”, but the profiles may be defined in more detail. . In a place where the line of sight is good, the positioning error is small, and the error is not biased in a specific direction. Therefore, a normal distribution with zero average and small variance (about several centimeters) is given as the error distribution. In addition, when both sides of the road are sandwiched between high-rise buildings, the error will increase, but the error will not be biased in a specific direction, so the average error distribution is zero and the variance is large (about a dozen or so meters) ) Gives a normal distribution. In addition, when there is a high-rise building on only one side of the road, the error may be biased in a specific direction. In this case, a normal distribution with a non-zero average is given as the error distribution, or a constant value error is given. It is possible. But the distribution for every profile mentioned here is an illustration, and you may make it give other distribution.

  The error adding unit 112 determines what profile the vehicle position belongs to from the accurate position of the vehicle received from the vehicle position input unit 111 and the feature data around the vehicle position obtained from the map data. Then, an error corresponding to the vehicle position profile is determined with reference to the positioning error DB 113, added to the exact position of the vehicle received from the vehicle position input unit 111, and output as position information obtained by the GPS device. In order to avoid determining which profile the vehicle position belongs to each time, it may be stored in advance in the map data to which profile each position belongs.

  In this way, error distribution is defined by dividing each point on the road into several profiles according to the surrounding situation, so it is a simpler configuration than defining error distribution individually for all points Thus, the same effect as that of the above-described embodiment can be obtained.

(Fourth embodiment)
In the fourth embodiment, an error corresponding to the number of GPS satellites that can be captured at the vehicle position is given. FIG. 6A shows a functional configuration of the position information simulator 11 in the present embodiment. As described above, the position information simulator 11 generally includes the vehicle position input unit 111, the GPS satellite position DB 114, the captureable satellite number calculation unit 111, and the error addition unit 112.

  The GPS satellite position DB 114 holds orbit data of GPS satellites. Therefore, the GPS satellite position at an arbitrary time can be calculated by referring to the GPS satellite position DB 114. The captureable satellite number calculation unit 115 calculates the number of GPS satellites that can be captured by the vehicle based on the positional relationship between the GPS satellites, the vehicle, and the feature. Since the GPS signal has strong straightness, it can be determined whether or not the GPS satellite can be captured based on whether or not a building exists on the line connecting the vehicle and the GPS satellite.

FIG. 6B is a flowchart showing the flow of error addition processing in the present embodiment. First, the vehicle position input unit 111 receives an accurate position of the vehicle (step S61). Then, the number of captureable satellites calculation unit 115 receives GPS satellite positions obtained from the GPS satellite position DB 114,
The number of GPS satellites that can be captured by the vehicle is calculated with reference to the position of the vehicle received from the vehicle position input unit 111 and the shape of the surrounding features obtained from the map data (step S62). Then, the error adding unit 112 adds an error corresponding to the number of GPS satellites that can be captured to the vehicle position, and outputs the result as position information obtained by the GPS device (step S63). Note that an error distribution that gives a larger error as the number of GPS satellites that can be captured is determined in advance, and the error adding unit 112 adds a positioning error according to the error distribution according to the number of GPS satellites that can be captured.

  In this way, the GPS positioning error in the vehicle can be taken into account based on the positional relationship between the GPS satellite and the vehicle. Therefore, an ITS simulation that is close to reality is possible.

(Other)
The calculation method of the error added as the GPS positioning error is not limited to the method described above, and various modifications can be considered based on the above description. For example, the positioning error may be calculated by arbitrarily combining the above methods. For example, the error relating to the traveling direction of the vehicle (or the direction along the road) and the error relating to the direction orthogonal thereto may be calculated by different methods. Moreover, you may add an error with a different method for every position on a road. Further, the method based on the number of GPS satellites that can be captured can be combined with other methods to increase the error (variance of error distribution) as the number of satellites that can be captured is small.

11 Position Information Simulator 111 Vehicle Information Input Unit 112 Error Addition Unit 113 Positioning Error DB
114 GPS satellite position DB
115 Number of satellites that can be captured

Claims (6)

A traffic flow simulator that simulates vehicle motion and determines the vehicle position at each time;
A position information simulator for obtaining position information obtained by the GPS device at the position, using as input the position of the vehicle obtained by the traffic flow simulator;
An ITS application simulator that simulates the operation of the ITS application using the position information obtained by the position information simulator as input, and determines the influence of the ITS application on the vehicle operation;
ITS simulation system. The position information simulator obtains, as position information obtained by a GPS device, a position obtained by adding a random error according to a normal distribution to the position of a vehicle obtained by a traffic flow simulator. The described ITS simulation system. A database for storing map information and a predetermined GPS positioning error distribution at each position on the road;
The position information simulator obtains, as position information obtained by a GPS device, a position obtained by adding a GPS positioning error according to a distribution at the position to a position of a vehicle obtained by a traffic flow simulator. 2. The ITS simulation system according to 1. A database that stores road and feature information;
The position information simulator obtains a GPS positioning error from the shape of the feature at the position of the vehicle obtained by the traffic flow simulator, and adds a position obtained by adding the GPS positioning error to the vehicle position obtained by the traffic flow simulator. The ITS simulation system according to claim 1, wherein the ITS simulation system is obtained as position information obtained by an apparatus. A database further storing information on the location of roads, features, and GPS satellites;
The position information simulator obtains the number of GPS satellites that can be captured at the position of the vehicle determined by the traffic flow simulator based on the feature information and the information on the position of the GPS satellites, and determines the number of GPS satellites that can be captured. The ITS simulation system according to claim 1, wherein a position obtained by adding a corresponding GPS positioning error to the position of the vehicle obtained by the traffic flow simulator is obtained as position information obtained by the GPS device. Computer
A traffic flow simulation process for simulating vehicle operation and obtaining the vehicle position at each time,
A position information simulation step for obtaining the position information obtained by the GPS device at the position, using the vehicle position obtained by the traffic flow simulation step as an input,
ITS application simulation process for simulating the operation of the ITS application using the position information obtained in the position information simulation process as input, and determining the influence of the ITS application on the vehicle operation;
The ITS simulation method characterized by performing this.

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