SI22722A - Electronic toll map - Google Patents

Abstract

The invention introduces an electronic toll map, which includes a multitude of virtual toll stations covering the complete toll area where each of the virtual toll stations includes one or several geographic areas represented by any polygon with the toll map defined as a tree structure consisting of cells, which are defined as rectangles featuring exactly defined coordinates and sides parallel to the geographic meridians and parallels of latitude, where the quantity of data inside the individual cell is smaller from the OBU memory capacity. Each specified cell includes all toll stations or geographic areas, which are at least partly inside the area covered by the cell, while for paying toll only those cells are taken into consideration, which represent the branches of such a tree structure. The invention provides a minimum data exchange volume between DM and OBU, which reduces the communication channel load and consequentially reduces the cost and/or time required for updating.

Description

Electronic toll map

FIELD OF THE INVENTION

The present invention relates to an electronic toll map used in electronic toll collection at a distance. The Toll Road Map is an organized set of virtual toll booths and covers the entire toll area, which can be country, region, continent or the whole world, and besides the entire road network (roads of all categories) are parking lots, tunnels, bridges, city centers and the like.

More specifically, the invention deals with the organization of a plurality of captured data within a toll folder as efficiently as possible.

BACKGROUND OF THE INVENTION

Electronic toll collection has been known in the art for a long time. One of the most advanced remote toll collection systems is designed to be a territory where toll collection takes place, where said territory may be smaller (eg part of a city) or larger (eg entire country, multiple countries, continents or the whole world) divided into geographical areas.

These areas are defined as arbitrary polygons that are adapted to the shape and the course of the roadway, and their nodes are specified by GPS coordinates containing latitude and longitude (no altitude).

One or more of these geographical areas constitutes a virtual toll station.

In addition to the nodes that define the spatial placement, the virtual toll stations also contain an identification code, the type of toll station, the toll picker identifier, and an indication of the layers of the folder in which the toll station is located, which is necessary if the areas of the virtual toll stations overlap .

The type of toll station determines how the toll is carried out, which can be segmented (motorway sections, tunnels, bridges ...), based on the time the vehicle is located inside the toll station (city centers, parking lots ...) or based on the length of the road within the toll station (regional road network).

Toll collection is carried out so that each vehicle has a communication unit that communicates wirelessly (eg via the GPRS network) with the folder distributor (DM).

In English, the OBU code (abbreviated as "on board unit") has been applied to this unit, so we will continue to use the OBU code below.

The list of all virtual toll stations with coordinates represents the toll map of the toll area. The toll station folder is located and maintained by the folder distributor (DM), who is also responsible for distributing OBU map information to devices.

The OBU must be familiar with the type of toll station in order to be able to produce relevant information on vehicle movement and transit from one geographical area to another. An additional type of toll station is defined as the "toll area", which represents the geographical area (for example, national borders) within which the OBU device tolls by default. When leaving the OBU toll area, the device switches to compatible mode of operation, depending on the tolling arrangements it enters.

A technical problem

In the described toll collection method, the amount of data collected is extremely large, which causes problems in processing them, updating the status of each vehicle and, consequently, delays or errors in the calculation of tolls.

As the OBU needs to know the geographical areas in which the vehicle is moving or located, it must contain information about those areas, which in practice is a problem as the memory in the OBU is limited and cannot accept the entire toll map.

BRIEF DESCRIPTION OF THE INVENTION

The present invention solves the described technical problem by introducing a toll map which is defined as a tree structure consisting of cells defined as rectangles with well-defined coordinates and having sides parallel to geographical meridian and parallel.

Short description of the pictures

Hereinafter, the present invention is described by way of the accompanying drawings, in which:

Figure 1: tree structure of the toll map,

Figure 2: Marking of new cells in cell division,

Figure 3: Marking paths in a tree by stringing 2-bit blocks,

Figure 4: Examples of cell identification codes.

DETAILED DESCRIPTION OF THE INVENTION

The following facts must be taken into account when organizing the toll map:

• Space constraint:

o The OBU in the vehicle is limited by the size of the memory, while the toll map of the entire tolling area is arbitrarily large, so transferring the entire folder to the OBU is impracticable.

• Minimum data exchange:

o The basic prerequisite for proper toll charging is the consistency of toll station allocations between the OBU vehicle and the map distributor (DM). Any changes to the folder (adding new virtual stations, changing the geographical location, or terminating existing stations) must be timely transmitted to all OBUs in order to process captured vehicle positions using valid data. Communication between the device and the Folder Distributor (DM) while updating data should be minimal due to restrictions on the communication channel and reduced cost and / or updating time.

o Therefore, it is important to ensure that when updating, only those changes to the folder that the OBU really needs are transferred.

Particular attention must be paid to the fact that the processing of covered points is not always immediate. In the case of unstable GPRS communication, the updating of the toll map is disabled, which can cause the processing of the covered points to be stopped while the OBU continues to keep a record of new vehicle positions. As soon as communication is established (and thus the folder is updated), the processing of captured points will resume. If there is an interruption of communication between the DM and the OBU at the end of the journey, it is very likely that the driver will turn off the vehicle before the last points captured are processed. If the vehicle is parked for a long time (for example, over the weekend or even a few days), there may be changes in the electronic folder in the meantime. When the driver restarts the vehicle, processing of covered points will resume at the point where it stopped earlier. In order for the toll to be calculated correctly, it is necessary to upload to the OBU a map of the toll area that was valid at the time of data collection, but not one that was valid at the time of processing these points.

A toll map is defined as a tree structure consisting of cells. Cells are defined as rectangles with well-defined coordinates. The sides of the cells are parallel to the geographical meridian and parallel.

Each cell contains all toll stations or geographical areas that are at least partially within the area covered by the cell.

The tree structure is built according to the following principles:

• The entire toll area should be covered by a baseline that represents the root of the tree structure. We call this cell the "base cell".

• The maximum amount of data a cell contains is defined, otherwise it must be broken down into four equal parts by halving its length and width. The newly formed cells represent the leaves of the broken cells. The partitioning process is repeated until all the sheets contain the permissible amount of data per cell.

• For tolling, only cells that are leaves of a tree structure are considered.

The recursive procedure described above enables the automatic creation of a toll map. The end result is a hierarchical structure of cells that completely cover the entire toll area, with no cells overlapping. The amount of data in individual cells is limited upwards (by a system parameter), which is very useful for scheduling minimal OBU memory capacities and managing communication constraints.

Figure 1 shows the tree structure of the toll map, where the top shows the starting cell 1, which in the next level 2 is divided into four cells 2a, 2b, 2c, 2d, and one of the cells, in this case 2b, is in the next level (3) divided into four new cells 3a, 3b, 3c, 3d, within which division is shown in two more levels.

The cells after the last division are the leaves of a tree structure. Cell division is continued until all the sheets contain the amount of data allowed.

Toll map cells are assigned identification tags that illustrate in binary form the path from the root of the tree structure to the corresponding cell. In the cell division process, four new cells are generated, for which the labeling requires 2 bits, as schematically shown in Figure 1, which shows the labeling of new cells in cell division.

By stringing 2-bit blocks, we can mark the path in the tree down the hierarchy. To determine the cell uniquely, we need the depth of the cell in the tree.

The number of bits for displaying the depth of a cell depends on the desired maximum depth of the tree structure that represents the toll map (reducing the maximum amount of data within each cell increases the maximum depth of the folder).

An example is the use of 32 bit identification tags organized in the manner shown in Figure 3. Bits 31 to 28 determine the depth of the cell, and bits 27 to 0 (in blocks of two bits) determine the path from the root of the tree to the cell. This marking method allows the toll folder to be made up of a maximum of 16384 cells.

Figure 4 shows an example of the source cell and post-cell identification tags, where the cells to which the tag refers are shaded.

With the help of the dimensions of the base cell (the root cell of the tree structure), it is possible to determine unequivocally for each observed cell, based on its identification code:

• spatial placement of the observed cell (we can calculate the geographical coordinates of the area covered), • adjacency relation (we can construct identification tags of all adjacent cells at the same depth of the tree structure, or simply check whether the cells are adjacent), • hierarchical content relation (we can construct identification codes of all cells of the toll sub-tree with the root in the observed cell).

Each OBU must know the dimensions of the starting cell. The minimum requirement for performing the toll collection process is the presence of at least one cell in OBU (a cell that geographically corresponds to the captured point in processing). To calculate the toll, the OBU must have a loaded cell containing the station traveled and representing a leaf of the tree structure of the folder. An OBU can calculate which cell it needs based on the dimensions of the starting cell, the division rules, and its position. An updated version of it may already be loaded in its memory or may be requested from a distributor (DM). In case the requested cell is not a tree structure sheet, the distributor will send a new configuration and the process will be repeated until the OBU requests a tree structure sheet.

The loaded cells are stored in the OBU memory until it is filled. When the OBU memory is full, the longest unused cell is deleted and replaced with a new one. In this way, a working set of the most needed cells is built, according to standard driver paths, which further complicates communication with the distributor (DM).

Claims (1)

Patent claims An electronic toll map containing a plurality of virtual toll stations covering the entire toll zone, each containing in the plurality of virtual toll stations one or more geographical areas that are arbitrary polygons, characterized in that it is defined as a tree structure consisting of cells , defined as rectangles with well-defined coordinates and having sides parallel to geographical meridian and parallel, where the amount of data in an individual cell is less than the memory capacity of the OBU. Electronic toll map according to claim 1, characterized in that each cell contains all toll stations or geographical areas that are at least partially within the area covered by the cell. An electronic toll map according to claim 2, characterized in that, when the amount of data in an individual cell is too large, the cell is divided into four new cells, where each of the newly created cells contains an amount of data less than the memory capacity of the OBU, where each cell is identified by a unique identifier. An electronic toll map according to claim 3, characterized in that only those cells representing the leaves of the tree structure are taken into account in the toll collection. Electronic toll map according to claims 3 and 4, wherein the data exchange between the DM and the OBU is carried out wirelessly, characterized in that the OBU knows the dimensions of the starting cell and that only those cells in the OBU are updated and / or modified The OBU needs it at some point. Electronic toll map according to claim 5, characterized in that when the memory in the OBU is filled, it deletes the cells that have not been used for the longest time and replaces them with those cells that the OBU needs.