RO127555A2 - Vehicle navigation system - Google Patents

Abstract

The invention relates to a vehicle navigation system for autonomous vehicles piloted by a human operator in order to reduce the travel time, to avoid traffic congestions and minimize the fuel consumption. According to the invention, the system comprises two subsystems, one being placed on the ground and comprising a pheromone server (11) running a software application meant to ensure the communication with some vehicles and to update a map (13) of the environment wherein there is integrated some information about the current position of the vehicles; the ground subsystem also comprises wireless communication equipments (12); the second subsystem is placed on the board of the vehicle and comprises a location module (23), a microcontroller data processing unit (24), a wireless communication equipment (22) and a pilot (21) which may be a human operator.

Description

Technical field of the invention

The present invention relates to the problem of selecting and following a route for autonomous vehicles, or piloted by a human operator, in order to reduce the journey time, to avoid traffic congestion and to minimize fuel consumption.

The proposed solution aims to create a system that will provide the rider with real-time synthetic information about the available routes, as well as the degree of traffic flow on these routes. In essence, the proposed solution can be described as a device _> THE STATE OF THE INVENTION

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Portable Navigation Assistant (PNA) with improved functionality due to communication facilities with a server on the ground.

The state of the art in the field of vehicle navigation systems / devices

Given the huge number of vehicles of all types in circulation, their impact on the environment and on the daily lives of billions of people, it is natural interest to find technical solutions that can optimize the various aspects related to vehicle traffic, from the definition and selection of optimal routes, reduction of fuel consumption, detection and signaling of traffic congestion, until the creation of autonomous vehicles, capable of building an internal representation of the environment based on the information provided by a set of sensors and navigating "intelligently" through the environment .

Of the thousands of solutions proposed, one of the most widespread and well-known is the navigation device based on the GPS location of the vehicle in traffic, commonly called PNA (Portable / Personal Navigation Assistant).

In this approach, the GPS locator provides the position information to a microcontroller, which extracts from its own memory and displays on a local display a predefined map of the geographical area, corresponding to the current position of the vehicle.

The main disadvantage of this solution derives from the fact that the maps used are static and do not contain information about the extent to which the roads are practicable, if they are affected by traffic restrictions (one-way traffic, road work, speed restrictions or access at certain time intervals. , etc.) nor about the degree of traffic flow on these roads.

To overcome this limitation, numerous solutions have been proposed. For example, in patent US2006 / 0094443, a device is proposed that uses the information provided by the GPS locator to select and display on a local display a series of web pages, the continuation of which is related to the current geographical position of the vehicle (for example tourist objectives , shops, etc., located nearby), accessed through a mobile internet connection.

A similar solution is presented in WO2010 / 073053, notwithstanding that the information accessed by the PNA (Portable Navigation Assistant) device through the internet connection is provided by a central server, which collects and processes updated traffic conditions data.

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The solution proposed by the patent US2004 / 0249569, adds an input device in the system, by which the user can define a route by marking the starting and destination points, after which the system automatically loads, from an external source, information characteristic of the selected route.

In patent GB2431261 it is proposed to supplement the geographic information stored in the maps used by the PNA device with information on possible speed limits and a method of selecting the optimal route is described, by minimizing a "cost" associated with each possible route.

The solution proposed by the patent US2010 / 0057334 is based on the communication between the PNA and a computer located in a base station, which centralizes the information from a plurality of mobile phones equipped with GPS. The base station computer estimates the traffic density and communicates it to the PNA devices upon request.

The patent US2009 / 0063045 proposes a solution of route selection according to the criterion of the minimum fuel consumption, taking into account the information on the state of the road, the state of the weather, the parameters of traffic lights, traffic jams, provided by a plurality of devices interconnected in the network. All data processing is done at the PNA device level.

All the solutions mentioned above have a common disadvantage in that the knowledge base about traffic conditions, located in one or more external devices to the NAP is difficult and expensive to build and to update.

The solution proposed by the present invention eliminates this disadvantage, because the knowledge base on traffic conditions is built ad-hoc, even in the communication process between the PNA-type devices on board the vehicles and a server located on the ground.

The central element of the solution is the concept of "virtual pheromones", defined by analogy with natural pheromones, volatile chemicals, dispersed in the environment by some species of insects for inter-individual coordination within complex activities at the level of the river.

Natural pheromones have been discovered! by Karlson and Luscher in 1959 ([1]), and Grasse ([2]) described the mechanism of indirect communication through pheromones (stigmergy) in some insect species.

Further Dorigo et al. ([3]) described the mechanism for selecting the optimal routes between the nest and the food source in the ant colonies, which they called "ant colony optimization" (ACO). The optimization process is explained by the fact that the longer routes

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1 -10- 2010 ^ύ It requires a longer time to travel, during which time the pheromone evaporation process becomes predominantly compared to the process of accumulating new quantities of pheromones as new agents travel the respective route. Finally, short routes are preferred by more and more agents, and long routes are completely abandoned.

Following ACO discovery, numerous attempts have been made to create artificial pheromones for coordinating agents, from simply detecting accidentally dispersed polluting chemicals in the environment ([4]), to exchanging infrared-encoded messages between agents ([5] ). Susnea et. described in ([6]) an experiment in which simple data structures, called "digital pheromones", are stored in RFID tags distributed in the environment and used to drive mobile robots.

A definition of the concept of "virtual pheromones", in an acceptance close to the one used in the present invention, was given by Susnea et al ([7]).

In this sense, virtual pheromones are frames left by agents not in the environment, but in a map of the environment, stored and updated by a pheromone server, in communication with the agents. In the process of communication between agents and the pheromone server, the map incorporating pheromone distribution information is constituted in a common memory, shared by all agencies.

In this way, each agent has access to a synthetic and dynamically updated information about the traffic through the geographical area represented by the common map, and the "pheromone tracks" left by the agents that previously crossed the area represent possible routes to follow.

Brief description of the invention

The present invention describes a navigation system for vehicles (autonomous or driven by a human operator), hereinafter referred to as "agents", based on the concept of "virtual pheromones".

The system is composed of two subsystems, one of which is located on board the vehicle and comprises a location module (23), for example GPS, a local microcontroller data processing unit (24), wireless communication equipment (22), for example, mobile equipment for connecting to the interior and a pilot (21), who, in the particular case of non-autonomous agents, can be a human operator.

A second subsystem, located on the ground, is composed of the "pheromone server (11), implemented by a computer, running a software application designed to ensure communication with the agencies and to update an environmental map (13), in which they are information about the current position of the agents. The ground subsystem may, V

Page Description ¢ ^ -2 0 1 0 - 0 0 9 6 0 -1 1 -10- 2010 includes adequate wireless communication equipment (12), which ensures real-time communication with distributed agents! in the environment.

Periodically, at predetermined time intervals, each agent sends to the server a data package containing the following information:

a unique identification code. In the particular case of internet communication, this may even be the IP of the communication node corresponding to the vehicle.

b. The geographical coordinates of the agent's current position, as reported is the localization subsystem (23).

c. The orientation (heading) determined by the microcontroller processing unit (24) based on the information about the successive positions occupied by the vehicle.

d. Travel speed calculated based on information on the successive positions occupied by the vehicle.

Upon receiving the data packet, the server performs the following operations:

a. Locate the agent on an internal grid map (13), associating it with a cell corresponding to the geographical position reported by the agent.

b. Calculate for each cell of the map a coefficient, called "virtual pheromone concentration", according to a formula that takes into account the number of vehicles crossing the cell in the unit of time, their average speed and the time since the last update of the data about that cell.

c. Forward to the agent that issued the query a response data packet, which, besides the identification code of the agent receiving the message, contains the pheromone concentrations calculated for the cells near the agent's current position.

Upon receiving the response from the server, the local data processing unit superimposes the information about pheromone concentrations over the static geographic map it has in its own memory and presents the result information, in an appropriate format, to the pilot.

Brief description of the drawings

Figure 1 shows the general structure of the system.

Subsystem 1 is located on the ground and is composed of:

- PS pheromone server (11)

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- EM environment map (13), in which a dedicated software application incorporates information about the spatial distribution of vehicles in communication with the server

- CE wireless communication equipment (12), for example specific equipment for making mobile internet connections, or other wireless communication equipment compatible with that on board the vehicles.

Subsystem 2, located on board the vehicle, composed of:

- A local LPU data processing unit (24)

- The locating subsystem, LS (23), which may be, for example, a GPS locator, or other locating device suitable for the type of vehicle

- The CE wireless communication subsystem (22), for example, equipment capable of providing a mobile internet connection, or other wireless communication equipment, compatible with the communication subsystem (12) for the server (11).

Pilot (21) - who can be a human operator, or, in the case of autonomous agents, a device capable of ensuring the management of the agent without a human operator.

Figure 2 is a graphical representation of a portion of the grid map of the environment (13). The pheromone concentration determined for each cell of the map is represented in this case by shades of gray, in which the white color corresponds to a zero concentration (complete lack of pheromones), and black corresponds to a maximum possible concentration.

In this example, the driver of a vehicle that has the route between points A and F of the map is informed that the traffic flow is reduced on the section between B and E, so it might be preferable to follow the detour route ABCDEF, instead of choosing the route in short, ABEF.

Figure 3 describes the internal structure of the local LPU processing unit (24), in which the following functional blocks are present:

- A MCU microcontroller (31)

- RAM (32)

- NVM non-volatile memory (33) for data storage, for example static maps of the crossed geographical area,

- At least one RS232 serial interface (34) for connecting to the location device (23)

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- USB USB interface (35) for connecting to data storage media, or communication interfaces,

- An LCD display, or touchscreen (36) for local display of text or graphic messages,

- An ETH network communication interface (37) required for connection to the wireless communication equipment (22).

Detailed description of the preferred implementation

In the preferred implementation, the pilot (21) is a human operator, and the vehicle can be any road vehicle. Wireless communication using devices (12) and (22) is ensured by a mobile internet connection.

The pheromone server (11) is a conventional computer running a dedicated software application, having the following functions:

- To ensure the bidirectional transfer of data packets between the server and the agents in the environment, encapsulating the packets in TCP / IP packets.

- To create and update a data structure corresponding to the 2D grid (two-dimensional) representation of a geographical region, (map (13)) representation composed of a number of square cells with the side 'a' (cf. Fig. 2 ). The value of parameter 'a' is determined according to the processing power of the server, the resolution of the location devices (23), the average speed of the vehicles in the geographic area of interest, as well as the time interval between which the data packets between agents follow. and server. A reasonable value for this parameter is in the range 50-100 meters.

- Calculate for each map cell (13) a variable, called "virtual pheromone concentration, P", so that a higher value of this parameter indicates that the associated cell is flowing through vehicles, and a value close to zero to indicate difficult traffic, few vehicles in the area, or lack of information about the area. A possible formula for calculating the variable P is given by the relation (1):

Λ / ”'(1)

Where N / j is the number of vehicles leaving the Cjj cell in the unit of time, v is the average speed of the vehicles passing through the Cij cell, t is the elapsed time

cv-2 Ο 1 Ο - Ο Ο 9 6 0 - 1 1 -10- 2010 since the last update of Cy cell data, and τ is the "evaporation time constant" of virtual pheromones.

The variable Ρ- _ν is updated for cell C _,; each time a new agent sends a request for access to the pheromone map to the server, specifying that the same agent cannot change the pheromone concentration of a cell several times, when moving slowly or stationary.

It is observed that, in case of traffic congestion, the average speed of the agents is reduced, and the number of agents leaving the cell in the unit of time is also small, which leads to a low value of P, j.

The communication between the devices on board the vehicles and the pheromone server proceeds as follows:

- At predetermined time intervals (depending on the performance of the internet communication and the computing power of the server), the agents issue data packets (queries) to the server, which contain information on the identification, location, speed and orientation of the respective agent.

- Based on the position reported by the agent, the server locates it in a cell of the internal pheromone map, recalculates the pheromone concentration for the respective cell and sends a response packet, which contains the pheromone concentrations calculated by the server for the cells adjacent to the cell in which it is located. there is the agent who sent the query. With reference to figure 2, if, for example, we consider that the value of parameter 'a' is 100 meters, for an agent located in the cell indicated by point A, the reception of a package of 100 values of the concentration of virtual pheromones corresponding to the cells represented in fig. 2, allows to evaluate the traffic conditions on a distance of 1Km before and 500 meters laterally, which is sufficient for the traffic conditions in cities and leads to relatively small volumes of data transferred between the server and the agents.

Upon receiving the response packet from the server, the processing unit (24) extracts from its own non-volatile memory (33) a map of the geographical area in which it is located, quite similar to the existing PNA devices, over which it overlaps, for example by a color code, traffic flow information, contained in pheromone concentrations and displays the modified map on the local display (36).

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The solution described in the present invention has the following obvious advantages over any of the solutions currently known:

Solve with minimal costs the problem of creating and updating dynamic maps, updated in real time with traffic information, for personal navigation devices.

- Is "backwards compatible" with existing devices in operation. In the absence of a pheromone server in the crossed area, the allied device on board the vehicle behaves like a conventional NAP.

- All components of the system can be easily implemented with commercially available standard equipment.

- At the pheromone server level, simulations of special traffic situations (eg "rush hour" situations) with simulated vehicles can be run. Following these simulations, pheromone distributions obtained through an “Ant Colony Optimization-ACO” process can be saved, which can then be offered to physical agents for navigation.

- The system is compatible with both autonomous agents and agents operated by a human operator.

- The system allows the inclusion in the traffic of "virtual agents" - simulated software vehicles, to mark convenient routes in various situations when it is desired to direct traffic on certain routes, for example indicating bypass routes in the event of an accident blocking a crowded artery.

- The information about the traffic flow accumulated at the server level can be easily adapted and transmitted to "intelligent traffic lights", able to dynamically adjust their switching times, favoring the movement on the crowded arteries.

Description

Claims (7)

1. A vehicle navigation system consisting of: - a subsystem for data processing located on the ground (outside vehicles), called "pheromone server", or "server", - a plurality of vehicles, each of them having on board a subsystem, capable of determining the position, orientation and speed of the vehicle, referred to as a "navigation device", characterized in that: - the on-board navigation devices are in wireless data communication with the server, - the server creates and updates a data structure, in correspondence with a certain geographical space, the data structure called a "map", organized in the form of a set of adjacent cells, in which each cell corresponds to a certain surface in the considered geographical space, - the navigation devices on board the vehicles periodically report to the server the position, speed and orientation of the vehicles in traffic, - the server locates each vehicle in a cell of the internal map, calculates for each cell a numerical coefficient, called "virtual pheromone concentration", the value of which is proportional to the number of vehicles crossing the cell in the unit of time and speed. average, and transmits to each navigation device with which there is in communication a data pack containing pheromone concentrations calculated for Neighboring cells with the cell in which the respective vehicle is located, - the navigation devices present to the drivers of the vehicles, in an appropriate form, the synthetic information about the distribution of the virtual pheromone concentrations obtained from the server. 2. A system as in claim 1, wherein the pheromone concentrations calculated for each cell of the map are variable, decreasing in time, similarly to the evaporation of natural pheromones. 3. A system as in claim 1, wherein the functions of a part of the navigation devices are software simulated to influence in a certain programmed way the distribution of the virtual pheromone concentrations presented by the server to the navigation devices with which it is in communication. £ ^ -201 0-00960-- Μ 1 1 -10- 2010 4. A system as in claim 1, which uses predefined static distributions of pheromone concentrations to direct vehicle traffic on certain routes. 5. A system as in claim 1, wherein the server is equipped with hardware and software interfaces to ensure its communication with intelligent traffic lights, capable of adjusting its switching times according to traffic density, as reflected by the concentration distribution. of virtual pheromones. 6. A system as in claims 1 and 4, characterized in that it can switch between dynamic distributions of virtual pheromone concentrations, as in claim 1 and their static distributions, as in claim 4, in a programmed manner, or according to a command. issued by a human operator. 7. A system as in claim 1, characterized in that the drivers of the vehicles are automatic devices, for example of the type of those that ensure the driving of the mobile robots.