JP2010079521A - Traffic statistical information generation device, on-vehicle traffic information processor and traffic information processing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a traffic statistical information generation device reducing capacity of a memory or storage capacity of an on-vehicle traffic information processor, and speeding up processing in the device. <P>SOLUTION: This traffic statistical information generation device has a time-classified statistical processing part 2 for calculating a time zone-classified statistic of each time zone by performing day average processing of history data of a prescribed plurality of days of history data of each day and each time zone accumulated as traffic information history data 1. The traffic statistical information generation device has a data compression-storage part 3 generating a compression value by compressing the time zone-classified statistics of the plurality of time zones calculated in the time-classified statistical processing part 2 within a range of a prescribed compression allowable error, and storing the compression value as traffic statistical information data 4. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a traffic statistics information generating device, an in-vehicle traffic information processing device, and a traffic information processing system, and in particular, a technique for generating a compressed value of a statistical value for each time zone, and processing the generated compressed value It relates to in-vehicle traffic information processing technology.

  A conventional in-vehicle traffic information processing apparatus included in a traffic information processing system uses an estimated time (hereinafter also referred to as a link travel time) required when a road section unit called a link travels temporarily. The invention described in Patent Document 1 includes statistical value storage means for counting past link travel times and storing them as link travel time statistics for each time zone.

Japanese Patent No. 2927204

  As described above, in the statistical value storage means provided in the in-vehicle traffic information processing device, for each time zone obtained by counting the link travel time (for example, if the segment interval is 5 minutes, one day consists of 288 time zones). Store link travel time statistics. However, the number of links to all over Japan, the North American continent, and the whole of Europe is enormous, so there is a problem that a large amount of memory is required to store link travel time statistics and memory to process them. was there. In addition, when the memory for processing the link travel time statistics is constrained, it is necessary to classify the link travel time statistics from the storage device and sequentially store them in the memory, and to sequentially process them. There was a problem that it took.

  The present invention has been made in order to solve the above-described problems, and reduces traffic capacity and memory capacity of an in-vehicle traffic information processing apparatus, and traffic statistics information capable of speeding up the processing of the apparatus. An object of the present invention is to provide a generation device, an in-vehicle traffic information processing device, and a traffic information processing system.

  The traffic statistics information generating device according to the present invention performs daily average processing of the history data for a predetermined plurality of days among the history data for each day and time zone accumulated as traffic information history data, and thereby for each time zone. An hourly statistical processing unit for calculating the statistical value for each time zone is provided. Then, by compressing the time zone statistical values of the plurality of time zones calculated by the hour time statistical processing unit within a range of a predetermined compression tolerance, a compressed value is generated, and the compressed value is traffic statistics information A data compression / storage unit for storing data is provided.

  According to the traffic statistics information generating device of the present invention, the data used in the in-vehicle traffic information processing device is compressed within a predetermined compression tolerance by the data compression / storage unit. As a result, the storage capacity and memory capacity of the in-vehicle traffic information processing apparatus can be reduced, and the processing of the apparatus can be speeded up.

<Embodiment 1>
FIG. 1 is a diagram showing a configuration of a traffic information processing system according to the present embodiment. As shown in FIG. 1, the traffic information processing system according to the present embodiment includes a traffic statistics information generation device 5 and an in-vehicle traffic information processing device 9. The traffic statistical information generating device 5 is installed in a center or the like and creates traffic statistical information data. The in-vehicle traffic information processing device 9 is provided in a navigation device, and the traffic statistics created by the traffic statistical information generating device 5 Store information data. Note that both the traffic statistics information generating device 5 and the in-vehicle traffic information processing device 9 may be provided in the navigation device. First, the traffic statistical information generation device 5 and the in-vehicle traffic information processing device 9 will be briefly described with reference to FIG.

  The traffic statistics information generating device 5 includes traffic information history data 1, a time-by-hour statistical processing unit 2, a data compression / storage unit 3, and traffic statistical information data 4. In the traffic information history data 1, history data of the past (for example, about several weeks to several years) for each link, day, and time zone is accumulated. The history data according to the present embodiment includes a link travel time and a congestion degree. The hourly statistical processing unit 2 and the data compression / storage unit 3 read a plurality of historical data from the traffic information historical data 1 for each link, compress the historical data to generate a compressed value, and use the compressed value as traffic statistics. Store as information data 4.

  The in-vehicle traffic information processing device 9 includes traffic statistics information data 6, a data reading / decompression unit 7, and an application 8. The traffic statistical information data 4 generated by the traffic statistical information generation device 5 is copied to the in-vehicle traffic information processing device 9 as traffic statistical information data 6. The data reading / decompression unit 7 decompresses / extracts the compressed data required by the application 8 from the compressed data composed of the compressed values stored as the traffic statistics information data 6.

  FIG. 2 is a flowchart showing the operation of the traffic statistics information generating apparatus 5 according to the present embodiment. FIG. 2A is a flowchart showing the overall operation of the traffic statistics information generating apparatus 5, and FIG. 2B is a flowchart showing the operation of the data compression / storage unit 3 in step S2 of FIG. 2A. is there. The operation of the traffic statistics information generating device 5 will be described with reference to FIG.

  After the start of FIG. 2A, the hourly statistical processing unit 2 performs daily average processing of history data for a predetermined number of days among the history data for each day and time zone accumulated as the traffic information history data 1. Thus, the statistical value for each time zone is calculated (step S1). When the hourly statistical processing unit 2 according to the present embodiment reads history data Xi (j) of a certain time zone j at a certain date i for a certain link from the traffic information history data 1, the date according to the following equation (1) is obtained. Averaging processing is performed to calculate a statistical value A (j) for each time zone. In the following formula, avg means that an average process is performed for a lowercase value written below.

  In this statistical process, the days i (= 1 to M) to be counted are included in a predetermined plurality of days. The predetermined multiple days referred to here are, for example, multiple days classified into days of the week, weekdays, holidays, and the like. In this way, by performing daily average processing on the history data of a predetermined number of days i (= 1 to M), it is possible to calculate the time zone statistical value A (j) for various types of days.

  The time zone j of the time zone statistical value A (j) is a value obtained by dividing one day by a predetermined data update unit. If the data update unit of the time zone statistical value A (j) is 5 minutes, the time zone j is j = 1,. In the following description, the data update unit is described as being 5 minutes. However, the data update unit is not limited to this, and may be divided into, for example, 10 minutes, 15 minutes, and 30 minutes. For example, when the update time of the history data in the traffic information history data 1 is 5 minutes, the time for classifying the statistical value A (j) by time zone is set to 30 minutes, and the time zone j = 1,. When it is desired to do so, the average time of six consecutive history data may be set as Xi (j) in the equation (1). Alternatively, the history data every 30 minutes (every 6 history data) may be Xi (j) in the formula (1), and the 5 data in between may be discarded.

  Further, the daily average processing of the hourly statistical processing unit 2 represented by the formula (1) may use not only a simple (arithmetic) average but also a harmonic average or a geometric average. If the harmonic average calculated by the following equation (2) is used, fluctuations in historical data (for example, link travel time) that have become large under traffic conditions in which sudden events such as accidents have occurred will be mitigated. The statistical value A (j) for each time zone can be obtained.

Next, as shown in FIG. 2 (a), the data compression / storage unit 3 stores the time zone statistical values A (j) of the plurality of time zones j calculated by the hour time statistical processing unit 2 in a predetermined range. A compressed value is generated by compression within the range of the allowable compression error W (step S2). In the present embodiment, this compressed value is a representative value D (s) that represents a plurality of time zone statistical values A (j). Therefore, hereinafter, the representative value D (s) may be referred to as a compressed value D (s). The data compression / storage unit 3 according to the present embodiment is an information presence / absence flag for associating the compressed value D (s) with each time zone j in parallel with the generation of the compressed value D (s). An information presence / absence flag compressInfo [j] is generated. The operation of step S2 of the data compression / storage unit 3 will be described with reference to FIG. Hereinafter, the maximum value of the time zone j of the statistical value A (j) by time zone may be written as jmax, and may be written as j = 1,..., Jmax. In the following description, the reference time zone is defined as k, the reference value is defined as X ₀ (= A (k)), the survey time zone is defined as p, and the survey value is defined as c (= A (p)).

First, as initialization processing, the hourly information presence / absence flag compressInfo [1] = ture (1) is set. Further, when the head of the time zone statistics A series of (1) to set the reference value X _0, survey values the next time zone statistics A (2) of the time zone statistics A (j) c is set (step S21). That is, the reference time zone k = 1 and the survey time zone p = 2 are set.

Then, the absolute value (= | X ₀ −c |) of the difference between the reference value X ₀ and the survey value c is compared with half of the predetermined compression allowable error W, and the absolute value of the difference (= | X ₀ It is determined whether -c |) is smaller than half of the predetermined compression allowable error W (step S22). As described above, the data compressing / storing unit 3 calculates the time zone statistical value A (k) (= X ₀ ) corresponding to the first time zone (reference time zone k) and the reference time zone k. The absolute value of the difference from the time zone statistical value A (p) (= c) corresponding to the second time zone (survey time zone p) after the above time zone is from half of the predetermined compression tolerance W Is also determined to be small.

Wherein a predetermined compression tolerance W of the amount of fixed preset (e.g., 30 seconds) may be set to an amount that varies depending on the magnitude of the reference value X ₀ (e.g., X ₀ 10%). If, as in the latter case, if set to vary in accordance with the magnitude of the reference value X _0, if there is a need to deal with various data types and units, compressed tolerances every time data type or unit is changed There is no need to set W one by one. Therefore, the versatility of the apparatus is enhanced, the maintenance is excellent, and the development cost can be reduced.

In step S22, the data compression / storage unit 3 according to the present embodiment has the absolute value of the difference smaller than half of the predetermined compression tolerance (that is, | X ₀ −c | <W / 2). Is determined, the hourly information presence / absence flag compressInfo [p] = false (0). At the same time, the data compression / storage unit 3 advances the investigation time zone p determined in step S22 by one time zone, and sets p = p + 1 (step S23). Thereafter, the process proceeds to end determination (step S26).

In step S22, the data compression / storage unit 3 according to the present embodiment determines that the absolute value of the difference is equal to or greater than half of the predetermined compression tolerance (| X ₀ −c | ≧ W / 2). In this case, the hourly information presence / absence flag compressInfo [p] = ture (1) is set. At the same time, the data compression / storage unit 3 sets the compression interval (k˜) between the investigation time zone p−1 obtained by returning the investigation time zone p determined in step S22 by one time zone and the reference time zone k. p-1), and one value based on a plurality of time zone statistical values A (j) (j = k,..., p-1) in the compression interval is determined as the compression value D (s). (Step S24).

  Here, s is a compression section number. The initial value of the compression section number s is s = 1, and 1 is added every time the compression section is determined (s = s + 1). In this embodiment, one value based on a plurality of time zone statistical values A (j) (j = k,..., P−1) in the compression interval, that is, the compressed value D (s) Calculated by (3).

  The averaging process of the data compression / storage unit 3 represented by the expression (3) may use not only a simple (arithmetic) average but also a harmonic average or a geometric average. In the present embodiment, an arithmetic average is used for this averaging process. Thus, by calculating the compression value D (s) by the averaging process, the error (| D (s) −A (j) |) (j = k,..., P−1) after compression is reduced to a predetermined compression. It can always be smaller than the allowable error W. Conventionally, unless the execution of compression processing and the evaluation of compression error are repeated a plurality of times, traffic statistical information data that falls within the allowable compression error range cannot be created. According to the present invention, since the upper limit of the error can be guaranteed, traffic statistical information data can be created by a single compression process if an allowable compression error is determined. Therefore, an effect that the calculation amount (compression processing and error evaluation) of the traffic statistics information generating device 5 can be greatly reduced is obtained.

Next, before describing the step S25 after the step S24, if the reference value X _0, the investigation time period p from the same value (reference time zone k and compression values D (s) described in the explanation of step S24 Consider the case where the time period is changed to the average value of the time zone statistical value A (j) until the survey time zone p-1 returned by one time zone, and step S22 is performed. In this case, the reference value X ₀ = D (s) itself follows the survey value c = A (p). Therefore, when the survey value c increases asymptotically monotonously (or decreases) within a range equal to or less than half of the predetermined compression tolerance W, the reference value A (k) and the survey value c Although the absolute value of the difference is larger than the predetermined compression tolerance W, the process cannot proceed to step S24. For this reason, there arises a problem that the temporal variation feature of the time zone statistical value A (j) cannot be expressed after compression.

Therefore, the data compression and storage 3 according to the present embodiment, after the step S24, changes the survey value c the reference value X ₀ (X ₀ = c) to. That is, the time zone statistical value A (k) corresponding to the reference time zone k is changed to the time zone statistical value A (p) corresponding to the latest survey time zone p determined in step S22. After this change, the data compression / storage unit 3 advances the investigation time zone p determined in step S22 by one time zone, and sets p = p + 1 (step S25).

  After step S23 or step S25, the data compression / storage unit 3 determines whether the investigation in all time zones j is completed, that is, p = jmax + 1 (step S26). If it is determined in step S26 that p = jmax + 1, the data compression / storage unit 3 ends the process of step S2. If it is not determined in step S26 that p = jmax + 1, the process returns to step S22, and S23, S24, or S25 is repeated.

  By performing the above operation, the data compression / storage unit 3 included in the traffic statistical information generation device 5 according to the present embodiment has a fluctuation of the compression value D (s) that is more than half of the predetermined compression allowable error W. The compression value D (s) is generated so that As a result, the number of compressed values D (s) can be suppressed to the minimum necessary number. Note that the maximum value of the compression section number s last determined in step S2 may be referred to as smax hereinafter.

  After performing step S2 as described above, the data compression / storage unit 3 uses the hourly information presence / absence flag compressInfo [j] generated in step S2 as traffic statistics information data 4 as shown in FIG. Store. At the same time, the data compression / storage unit 3 stores the compressed value D (s) generated in step S2 as traffic statistics information data 4 (step S3).

  FIG. 3 shows an example of the storage configuration (overall) of the traffic statistics information that the data compression / storage unit 3 stores as the traffic statistics information data 4 in step S3. FIG. 3 shows an example in which traffic information related to VICS links throughout Japan is stored in units of day types and secondary meshes.

  FIG. 4 shows an example of the storage configuration (details) of information by link / time. As described above, the history data according to the present embodiment includes the degree of congestion indicating the degree of congestion (standardized link travel time) related to the VICS link, and the link travel time. FIG. 4 shows an example in which a compressed value D (s) related to history data (congestion level and link travel time) is stored as hourly traffic statistical information. 4 corresponds to the hourly information presence / absence flag compressInfo [j], and the hourly information update unit shown in FIG. 4 corresponds to the data update unit described above. Therefore, hereinafter, the hourly information presence / absence flag may be referred to as compressed information compressInfo [j], and the data update unit may be referred to as an hourly information update unit. 3 and FIG. 4 are stored in a standard format of data structure, ASN. 1 (ITU-T Rec. X.680) notation.

  Here, an example in which the time information of the compressed value D (s) is stored using the hourly information presence / absence flag compressInfo [j] is shown, but the time information of the compressed value D (s) is directly stored in the time of FIG. It may be included in the separate traffic statistics information. For example, if one expiration date (valid for hh (s) hour mm (s)) is stored for one compression value D (s), the in-vehicle traffic information processing apparatus 9 uses the previous compression value D. The effective time range of the compression value D (s) is hh (s-1) from the relationship with the expiration date of (s-1) (effective until hh (s-1) hours mm (s-1) minutes). It can be determined from the time mm (s-1) minutes to hh (s) hours mm (s) minutes.

  FIG. 5 shows a table created when the storage configuration shown in FIG. 4 is performed. FIG. 5 shows a case where the hourly information update unit is 5 minutes. The data compression / storage unit 3 according to the present embodiment includes the compression information compressInfo [j] (j = 1,..., 288) generated in step S2 and the compressed value D (s) (s = 1,. Are stored as traffic statistics information data 4. Thereby, a table as shown in FIG. 5 is created.

  Since the compression information compressInfo [j] is 1-bit information, even if 288 items are stored, it can be stored in a storage capacity of 288 bits, that is, 36 bytes. In addition, 288 statistical values A (j) for each time zone had to be stored before compression, but after compression, smax (≦ 288) compressed values D (s) were stored. The number of powers can be reduced. In this way, by using the compression information compressInfo [j], the compressed value D (s) is associated with each time zone j, so that the above-mentioned storage capacity and the number of time-based statistical values A (j), that is, The data size can be suppressed. Next, these effects will be described in detail when the above-described compression is actually performed when the hourly information update unit is 15 minutes and the time zone j takes a value of 1 to 96.

  First, the effect obtained by using the compression information compressInfo [j] will be described. The difference between the data size when the time information is given to each of the smax compression values D (s) and the data size when the compression information compressInfo [j] is used will be described.

  In order to represent one time zone according to time information, 5 bits are necessary to represent the time (0 to 23:00), 6 bits are necessary to represent the minutes (0 to 59 minutes), and a total of 11 bits are required. Therefore, 132 bytes (= 96 × 11/8) are required to represent 96 time zones according to time information. On the other hand, the compression information compressInfo [j] is 1-bit information. Therefore, only 12 bytes (= 96/8) are required to represent 96 time zones by the compressed information. Thus, the data size can be reduced by using the compression information compressInfo [j].

  Next, taking as an example the case where the history data is the degree of congestion on a road link, the number of data before compression (the number of statistical values A (j) by time zone) and the number of data after compression (compression value D) (Number of (s)). FIG. 6 is a diagram showing the data before and after the compression for each time zone j (= 1 to 96) regarding the degree of congestion. A solid line indicates data before compression, and a staircase line formed by a square plot indicates data after compression. The number of data before compression, that is, the number of values different from each other in the vertical direction in FIG. 6 was about 50, but the number of data after compression was 10 and the compression rate was 20%. . FIG. 7 is a diagram showing compression ratios (solid lines) in various road links and approximation errors (square plots) generated by the compression. As shown in the figure, it is understood that a low compression ratio of 5 to 30%, that is, highly efficient compression can be achieved while suppressing the approximation error to 5% (predetermined allowable compression error) or less.

  Since the traffic statistical information data 4 generated by the traffic statistical information generating device 5 is copied as the traffic statistical information data 6 to the in-vehicle traffic information processing device 9, the compressed value D (s) and the compressed information as described above are used. compressInfo [j] is stored as traffic statistics information data 6. Therefore, according to the traffic statistics information generation device 5 according to the present embodiment, it is possible to reduce the storage capacity and memory amount of the statistical value storage means of the in-vehicle traffic information processing device 9 and to speed up the processing of the device. can do.

  The traffic statistics information generation device 5 has been described above in the traffic information processing system according to FIG. Next, the in-vehicle traffic information processing device 9 will be described. FIG. 8 is a flowchart showing the operation of the in-vehicle traffic information processing apparatus 9. The data reading / decompression unit 7 reads the compressed value D (s) and the compressed information compressInfo [j] stored as the traffic statistics information data 6 (step S100). Next, the data reading / decompression unit 7 decompresses the compressed data composed of the read compressed value D (s) using the compression information compressInfo [j], and obtains traffic statistics information Y (m) for each data update period. Generate (step S101).

  FIG. 9 is a diagram showing details of the operation of the data reading / decompression unit 7 in step S101. Thus, as long as the compression information compressInfo [m] continues to take a value of false (0), the traffic statistical information Y (m) takes a compression value D (s) that does not change s. On the other hand, when the compression information compressInfo [m] takes a value of true (1), the traffic statistical information Y (m) takes a compression value D (s) where s = s + 1. Here, m is a value obtained by dividing one day by the data update cycle. When the data update cycle is 15 minutes, N = 96.

  Thereafter, the data reading / decompression unit 7 gives the generated traffic statistics information Y (m) to the application 8. In this way, the data reading / decompression unit 7 which is a data decompression unit included in the in-vehicle traffic information processing device 9 decompresses the decompressed data by decompressing the compressed data composed of the compressed value D (s) stored by the traffic statistics information generating device 5. (Traffic statistics information Y (m)) is given to the application 8. In the present embodiment, as described above, the data reading / decompression unit 7 decompresses the above-described compressed data using the hourly information presence / absence flag compressInfo [j] stored in the traffic statistics information generating device 5. The data reading / decompressing unit 7 does not need to provide all the traffic statistics information Y (m) to the application 8, but may provide only the traffic statistics information Y (m) required by the application 8. .

  When the application 8 is, for example, a route search application, the in-vehicle traffic information processing device 9 uses the traffic statistical information Y (m) corresponding to the link travel time and the degree of traffic congestion at each time for each link. Search for a route. When the application 8 is, for example, a map display application, the in-vehicle traffic information processing device 9 displays the traffic statistical information Y (m) corresponding to the link travel time and the degree of congestion at each time of each link on the map. And present it to the user.

  According to the vehicle traffic information processing apparatus 9 according to the present embodiment as described above, the compressed data composed of the compressed value D (s) is expanded. Therefore, it is possible to reduce the storage capacity and memory amount of the statistical value storage means of the in-vehicle traffic information processing device 9, and to speed up the processing of the device.

It is a figure which shows the structure of the traffic information processing system which concerns on Embodiment 1. FIG. 4 is a flowchart showing the operation of the traffic statistics information generating device according to the first embodiment. It is a figure which shows the storing operation | movement of the traffic statistics information generation apparatus which concerns on Embodiment 1. FIG. It is a figure which shows the storing operation | movement of the traffic statistics information generation apparatus which concerns on Embodiment 1. FIG. It is a figure which shows the storing operation | movement of the traffic statistics information generation apparatus which concerns on Embodiment 1. FIG. It is a figure which shows the effect of the traffic statistics information generation apparatus which concerns on Embodiment 1. FIG. It is a figure which shows the effect of the traffic statistics information generation apparatus which concerns on Embodiment 1. FIG. 3 is a flowchart showing an operation of the in-vehicle traffic information processing apparatus according to the first embodiment. It is a figure which shows operation | movement of the vehicle-mounted traffic information processing apparatus which concerns on Embodiment 1. FIG.

Explanation of symbols

  1 traffic information history data, 2 hourly statistical processing unit, 3 data compression / storage unit, 4, 6 traffic statistical information data, 5 traffic statistical information generating device, 7 data reading / decompression unit, 8 application, 9 in-vehicle traffic information processing apparatus.

Claims (7)

By calculating the statistical value for each time zone by time averaging the history data for a predetermined plurality of days among the history data for each day and time zone accumulated as traffic information history data A statistical processing unit;
A compressed value is generated by compressing the statistical value for each of the plurality of time zones calculated by the statistical processor for each time within a predetermined compression tolerance, and the compressed value is used as traffic statistical information data. A data compression / storage unit for storing,
Traffic statistics information generator. The daily average processing of the hourly statistical processing unit uses a harmonic average,
The traffic statistics information generation device according to claim 1. The data compression / storage unit
(A) The time zone statistical value corresponding to the first time zone and the time zone statistical value corresponding to the second time zone after the time zone of one or more from the first time zone. Determining whether the absolute value of the difference is less than half of the predetermined compression tolerance;
(B) If it is determined that the absolute value of the difference is smaller than half of the predetermined compression tolerance, the determined second time zone is advanced by one time zone, and Return to processing
(C) When it is determined that the absolute value of the difference is not less than half of the predetermined compression tolerance, the time zone obtained by returning the determined second time zone by one time zone and the first time zone The time corresponding to the first time zone is determined after the time zone is determined as a compression interval, and one value based on the plurality of time zone statistical values in the compression interval is determined as the compression value. Changing the statistical value by band to the statistical value by time zone corresponding to the second time zone determined to be half or more, and returning to the process of (a),
The traffic statistics information generation device according to claim 1 or 2. The data compression / storage unit
Generating an information presence / absence flag for associating the compressed value with each of the time zones, and storing the information presence / absence flag as the traffic statistics information data;
The traffic statistics information generating device according to any one of claims 1 to 3. A data decompression unit that decompresses compressed data composed of the compressed values stored by the traffic statistics information generating device according to any one of claims 1 to 4, and provides the decompressed data to an application.
In-vehicle traffic information processing device. Data that decompresses the compressed data composed of the compressed value stored by the traffic statistics information generation device according to claim 4 using the information presence flag stored by the traffic statistics information generation device and gives the decompressed data to an application With an extension,
In-vehicle traffic information processing device. The traffic statistics information generating device according to claim 1;
The vehicle-mounted traffic information processing device according to claim 6,
Traffic information processing system.

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