Search schedule determining apparatus

In a search schedule determining apparatus, a target probability distribution showing a distribution of probabilities of positions of a target in a time zone is calculated based on target previous information. A search ability showing a quantitative evaluation of an ability to discover the target is calculated based on search vehicle previous information. A search effort distribution is calculated based on the target probability distribution and the search ability such that a combination of probabilities in which each of the search vehicles discovers the target has a maximum. A search schedule is automatically determined based on the target previous information and the search vehicle previous information such that the search vehicles are operated to realize the search effort distribution.

TECHNICAL FIELD

The present invention relates to a search schedule determining apparatus and a search schedule determining method, especially, to a search schedule determining apparatus and a search schedule determining method, by which a search schedule can be automatically determined.

BACKGROUND ART

A technique is known of searching ships which travel on very wide ocean from above by using various sensors installed in an artificial satellite or an aircraft as a search vehicle.

However, when the ground and ocean should be searched from the artificial satellite, the artificial satellite needs be arranged at so-called low orbit in hundreds kilometer from the ground in order to secure the resolution of the imaging sufficiently. In the artificial satellite which orbits the earth on such a low orbit, there is a limit in a time zone of staying above an area of a search object, unlike a case of the stationary satellite arranged at so-called geostationary orbit in about 36,000 kilometers from the ground.

Also, the regular replenishment of fuel is indispensable for the aircraft and there is a limit in the time of staying above the area of the search object. That is, the aircraft needs to repeat a routine of taking off from an airport or a base, flying to the area of the search object, carrying out a search operation, returning to the airport or the base, and then receiving various types of replenishment.

Moreover, an infrared sensor as an imaging unit used for a search vehicle cannot sometimes show the performance sufficiently in bad weather such as rain, and the imaging using a visible ray is unsuitable in night.

In addition to such a technical limitation, there is a limitation in the search vehicle usable in the actual search activity. That is, it is necessary to plan more effective search activity, in consideration of a limitation of the airport facilities near sufficiently from a predicted position of the target as the search object, a limitation of the search vehicles to be stood-by in the above airport facilities, and a limitation on the search vehicles actually usable in the range of the above limitations.

In conjunction with the above, Patent Literature 1 (JP H04-204187A) discloses an infrared-ray front monitoring apparatus. The infrared-ray front monitoring apparatus includes an infrared sensor, an image preprocessing section, a movement detecting section, a display section, a search schedule determining section, a sensor driving section and an operation section. Here, the infrared sensor images an infrared image. The image preprocessing section converts an image analog signal which is obtained from the infrared sensor into a digital signal. The movement detecting section detects a relative movement of an object in the image obtained from the image preprocessing section. The display section displays a position and a movement vector of the object obtained from the movement detecting section. The search schedule determining section generates a search pattern according to a relative movement quantity obtained from the movement detecting section. The sensor driving section turns the infrared sensor according to a visual axis drive angle which is instructed from the search schedule determining section. The operation section instructs the start-up and end of an automatic search mode.

Also, Patent Literature 2 (JP 2010-132073A) discloses a search work support system. This search work support system includes a navigation system, a radio receiver-transmitter, a database and an information processing unit. Here, in the navigation system, each of a plurality of rotorcrafts which carry out the search work measures a position and a speed of itself. The radio receiver-transmitter transmits and receives execution information of the search work by a radio signal to or from the other rotorcrafts. The database stores a search plan which contains position information of each of search areas of the rotorcrafts and the execution information of the search work of itself based on the search plan. The information processing unit plans a new search plan of itself based on the position and speed of itself measured by the navigation system, the execution information of the search work of the other rotor crafts received by the radio receiver-transmitter, and the search plan of the other rotor crafts stored in the database.

CITATION LIST

SUMMARY OF THE INVENTION

A search schedule is automatically determined to operate some finite search vehicles efficiently. The other problems and new features will become clear from the description and the attached drawing of this Specification.

A search schedule determining apparatus of the present invention includes a target probability distribution calculating section, a search ability calculating section, a search effort distribution calculating section, and a search calculating section. The target probability distribution calculating section calculates a target probability distribution showing a distribution of probabilities of positions where a target is predicted to exist in a predetermined time zone, based on target previous information collected previously for the target as a search object. The search ability calculating section calculates a search ability showing a quantitative evaluation of an ability to discover the target based on search vehicle previous information collected previously for each of search vehicles. The search effort distribution calculating section calculates a search effort distribution based on the target probability distribution and the search ability such that a combination of probabilities in which each of the search vehicles discovers the target has a maximum value. The search calculating section automatically determines a search schedule based on the target previous information and the search vehicle previous information such that the search vehicles are operated to realize the search effort distribution.

A search schedule determining method of the present invention includes collecting target previous information of a target as a search object by a target distribution probability calculating section; calculating a target probability distribution showing a distribution of probabilities of positions where the target is predicted to exist in a predetermined time zone, based on the target previous information by the target distribution probability calculating section; collecting search vehicle previous information of each of search vehicles by a search ability calculating section; calculating search ability showing a quantitative evaluation of ability to discover the target based on the search vehicle previous information by a search ability calculating section; calculating a search effort distribution based on the target probability distribution and the search ability by a search effort distribution calculating section, such that a combination of the probabilities in which each of the search vehicles discovers the target is maximum; and automatically determining a search schedule based on the target previous information and the search vehicle previous information by a search schedule calculating section such that the search vehicles are operated to realize the search effort distribution.

In the present invention, a non-transitory recording medium which stores a search schedule determining program to make a computer execute the search schedule determining program to implement functions of: collecting a target previous information of a target as a search object by a target distribution probability calculating section; calculating a target probability distribution showing a distribution of probabilities of positions where the target is predicted to exist in a predetermined time zone, based on the target previous information by the target distribution probability calculating section; collecting search vehicle previous information of each of search vehicles by a search ability calculating section; calculating search ability showing a quantitative evaluation of ability to discover the target based on the search vehicle previous information by a search ability calculating section; calculating a search effort distribution based on the target distribution probability and the search ability by a search effort distribution calculating section, such that a combination of the probabilities in which each of the search vehicles discovers the target is maximum; and automatically determining a search schedule based on the target previous information and the search vehicle previous information by a search schedule calculating section such that the search vehicles are operated to realize the search effort distribution.

According to the one embodiment, the search schedule can be automatically determined to make a probability of discovering a target with some finite search vehicles have a maximum.

DESCRIPTION OF EMBODIMENTS

Hereinafter, a search schedule determining apparatus and a search schedule determining method according to embodiments of the present invention will be described below with reference to the attached drawings.

First Embodiment

FIG. 1is a diagram showing an example of a position relation between a search target and search vehicles. InFIG. 1, a plurality of ships11to15invade from sea1toward a land2. A plurality of aircrafts31to33as the search vehicles take off from airports21and22and searches the positions of these ships11to15in search ranges311,321, and331, respectively.

In a conventional technique, the operation of the search vehicles was carried out in the following presupposition. That is, it is presupposed that a pattern of action in the search by aircrafts was previously determined. Also, it presupposed that search vehicles were sufficiently prepared. Moreover, it is presupposed that the search vehicles can search in an enough long time.

However, the aircraft as the search vehicle receives a constraint of endurance and so on in actual. That is, there is a limit in a loadable fuel amount for every aircraft, and the aircraft needs to carry out a flight for a destination, a search operation, and return to the airport, within a loaded fuel amount.

Also, as long as the aircrafts as the search vehicles cannot be inexhaustibly prepared, the efficiency of the search has to be considered. That is, an existence probability of a group of the ships as the search target is predicted with respect to a position and a time. In the search operation, the position having a high probability is searched with a priority, and the number of aircrafts is decreased for the position having a low probability.

When an action pattern of the aircraft as the search vehicle is presupposed without considering the above-mentioned constraints, the effective search operation cannot be expected in actual. Therefore, in order to improve the probability of discovering the ship group as the search target, an operation method of the aircrafts as some finite search vehicles needs to be reconsidered.

FIG. 2is a diagram showing an example of the definition of a probability distribution of discovering the search target. In this case, the search operation of the ship11as a representative of the ships11to15shown inFIG. 1will be described, but the description is applied to the other ships12to15.

In an example shown inFIG. 2, as target previous information about the ship11as the search target, a position of the ship11at a predetermined reference time, a movement speed of the ship11, possible movement routes110ato110cof the ship11, and a probability that each of the possible movement routes110ato110cis adopted by the ship11are collected and acquired previously. Note that a part of the target previous information may be estimated based on other collected information.

It is possible to calculate a distribution of of probabilities of a position where the ship11is predicted to exist in a time zone. In the example ofFIG. 2, this probability distribution is shown by three contour lines111ato111c. The ship11exists in the inner contour line111ain the highest probability, in the middle contour line111bin a next higher probability, and in the outer contour line111cin a next higher probability. Note that a probability that the ship11exists outside the outer contour line111cis not zero.

Moreover, it is possible to calculate a distribution of the probabilities of positions where the ship11is predicted to exist in a next time zone. In an example ofFIG. 2, the probability distribution is shown with three contour lines112ato112c. The meaning of these contour lines112ato112cis the same as that of the above-mentioned contour lines111ato111c. Of course, the distribution of calculated probabilities trends to spread on the ocean as time elapses. In more detailed, in the next time zone, the ship11is predicted to exist in the inner contour line112ain the highest probability, in the middle contour line112bin a next higher probability, and in the outer contour line112cin a next higher probability. Note that the probability that the ship11exists outside the outer contour line112cis not zero.

In the example ofFIG. 2, the probability distribution is expressed with a set of the contour lines for simplification of the description. However, another method may be used. For example, the ocean may be divided into a plurality of meshes and a probability of a position where the ship11is predicted to exist in a predetermined time zone may be calculated for every mesh.

Also, in the example ofFIG. 2, the probability distribution of the ship11as the representative of the ships11to15shown inFIG. 1is calculated. However, actually, the probability distribution of each of all the ships may be calculated, and the overall probability distribution of all the ships may be calculated from the calculated probability distributions. In the present example, only the probability distribution of the ship11is calculated and the calculation result is used as an approximation of the overall probability distribution of all the ships11to15.

FIG. 3is a diagram showing an example of a definition of the search ability. In this case, the aircraft31will be described as the representative of the aircrafts31to33shown inFIG. 1, but this description is applied to the other aircrafts32and33.

In the example ofFIG. 3, a search area (region)313is searched by the aircraft31flying along a search route312while searching a search range311on the ocean. Supposing that the length of the search route312is L and the width of the search range311in a direction orthogonal to the search route312is W, the total search area313is calculated approximately as L×W.

There is a possibility that the actual length of the search route312varies depending on the model of each of the aircrafts31to33, a kind and performance of search instruments loaded on the aircrafts31to33, a weather situation from around the airports21and22to the search areas, the distances from the airports21and22to the search areas, and other various conditions. However, the search area313to be possibly searched in once flight can be calculated approximately.

Also, by going and returning through the search route312, the search area313can be searched concentratedly.

The distribution of probabilities of discovering the search target can be calculated quantitatively by combining the above-mentioned conditions.

In the present invention, the quantitative estimation of the probability distribution to discover the target for every search vehicle is referred to as the “search ability” of the search vehicle. In the example shown inFIG. 3, it is easily expected that the discovery probability is higher in the inner portion of the search area313, and the discovery probability is lower in the peripheral portion of the search area313. Therefore, in the example shown inFIG. 3, the search ability is calculated to have a pattern similar to the probability distribution shown inFIG. 2.

FIG. 4is a diagram showing an example of the definition of search vehicle deployment. In the example shown inFIG. 4, in order to maximize the probability of discovering the search target with some finite search vehicles, the contour lines314ato314c,324ato324c, and334ato334cshowing distributions of the search target discovery probabilities are superimposed on the contour lines111ato111cshowing the distribution of the search target existence probabilities in the example shown withFIG. 2.

Here, the contour lines314ato314cwill be described. These contour lines314ato314cshow the search ability of the aircraft31in charge of the first target movement route110a. The probability of discovering the target when the aircraft31searches the target in an area shown by the contour line314cis the highest in the inner contour line314a, is next higher in the middle contour line314b, and is next higher in the outer contour line314c. Note that a probability that the target would exist outside the outer contour line111cis not zero.

In the same way, the contour lines324ato324cshow the search ability of the aircraft32in charge of the second target movement route110b, and the contour lines334ato334cshows the search ability of the aircraft33in charge of the third target movement route110c. Further detailed description of these contour lines324ato324cand334ato334cis the same as the above-mentioned description of the contour lines314ato314c. Accordingly, the description is omitted.

In the example ofFIG. 4, for simplification of the description, the search ability is shown by a set of the contour lines. However, like the case of the probability distribution of the target, the ocean is divided into a plurality of meshes which have a square shape or a hexagonal shape, and the probability of discovering the target by the search vehicle may be calculated for every mesh.

A probability to search and discover a target by a search vehicle in an area where the target is predicted to exist in a predetermined time zone can be determined as a product of the target existence probability and the target discovery probability. The integration of such a product over the whole search area gives a discovery probability of the whole search activity. In the present invention, the search vehicles are deployed so that the discovery probability of the whole search activity is maximized, and the deployment of the search vehicles is called a “search effort distribution”.

In the present invention, in order to operate the some limited search vehicles in the maximum efficiency, a search schedule is automatically determined such that the discover probability is maximized over the whole search activity. Conventionally, when the determination of the search schedule is automatically executed by a computer, an enormous amount of combinations needs to be calculated. In the present invention, the position of the target in a predetermined time zone and the search ability of each of the plurality of search vehicles are simplified as probability distributions. Moreover, an amount of calculation can be reduced greatly by using the search effort distribution calculated as middle data.

FIG. 5Ais a block diagram showing a configuration example of the search schedule determining apparatus according to the first embodiment of the present invention. The components of the search schedule determining apparatus in the configuration example shown inFIG. 5Awill be described.

The search schedule determining apparatus shown inFIG. 5Ahas a bus40, an operation section41, a storage section42, an input section43, an output section44and an external storage section45. Note that the search schedule determining apparatus may have a storage medium46. Also, a part or the whole of the components contained in the search schedule determining apparatus shown inFIG. 5Amay be configured by using a general-purpose computer.

The operation section41contains a target distribution probability calculating section411, a search ability calculating section412, a search effort distribution calculating section413and a search schedule determining section414. The storage section42contains a target database421and a search vehicle database422.

The connection relation of the components shown inFIG. 5Awill be described. The bus40is connected with the operation section41, the storage section42, the input section43, the output section44and the external storage section45. In other words, the operation section41, the storage section42, the input section43, the output section44and the external storage section45are mutually connected through the bus40.

The operation of each of the components shown inFIG. 5Awill be described.

The bus40mediates various types of signals which are transmitted and received by the operation section41, the storage section42, the input section43, the output section44and the external storage section45.

The operation section41has a CPU and executes various programs stored in the storage section42to realize various functions corresponding to the various programs. In more detailed, the operation section41executes corresponding programs to function as the target distribution probability calculating section411, the search ability calculating section412, the search effort distribution calculating section413and the search schedule determining section414. The operation section41may use a part of storage section42as a memory area for calculation when executing these programs. A set of these programs is a search schedule determining program in the present invention.

These programs are stored in the non-transitory storage medium46, and it is read by the external storage section45and may be stored in the storage section42.

Note that a part or the whole of the target distribution probability calculating section411, the search ability calculating section412, the search effort distribution calculating section413and the search schedule determining section414may be provided as operation circuits physically independent from the operation section41having general functions. In this case, it is desirable that the operation circuits provided independently are connected with the bus40.

The target distribution probability calculating section411calculates a target distribution probability. In more detailed, the operation section41executes a predetermined program to function as the target distribution probability calculating section411, to calculate a target distribution probability based on the target previous information stored in the target database421, and to store the result in the target database421.

The search ability calculating section412calculates the search ability. In more detailed, the operation section41executes a predetermined program to function as search ability calculating section412, to calculate the search ability based on the search vehicle previous information stored in the search vehicle database422and to store the result in the search vehicle database422.

The search effort distribution calculating section413calculates a search effort distribution. In more detailed, the operation section41executes a predetermined program to function as the search effort distribution calculating section413, and to calculate search effort distribution based on the target distribution probability stored in the target database421and the search ability stored in the search vehicle database422.

The search schedule determining section414automatically determines the search schedule. In more detailed, the operation section41executes a predetermined program to function as the search schedule determining section414based on the target previous information stored in the target database421, the search vehicle previous information stored in the search vehicle database422and the search effort distribution calculated by the search effort distribution calculating section413, to automatically determine the search schedule, and to output the result from the output section44.

The storage section42stores the target database421and the search vehicle database422so that the operation section41is possible to read and write. Also, a part of the storage section42may function as the memory area for the calculation, as mentioned above.

It is desirable that the target database421and the search vehicle database422in the storage section42are configured of a non-volatile storage device. The storage section used as the memory area for the calculation may be non-volatile or volatile.

The target database421stores the target previous information. Also, after the target distribution probability calculating section411calculates a probability distribution of the target, the target database421stores the calculated target distribution probability.

The search vehicle database422stores the search vehicle previous information. Also, after the search effort distribution calculating section413calculates the search effort distribution, the search vehicle database422stores the calculated search effort distribution.

The input section43inputs various signals externally. Especially, the input section43inputs a start signal requesting the operation start of the search effort distribution calculating section413and the search schedule determining section414from outside, for example, through the operation of buttons (not shown).

Besides, the input section43may be used for the input of information to be stored in the target database421and the search vehicle database422.

The output section44outputs various signals for the outside. For example, the output section44outputs the determined search schedule from a display section (not shown). Besides, the search schedule may be stored in the storage section42and may be preserved in a storage medium through the external storage section45.

The external storage section45reads and writes various data from and to the storage medium46. The external storage section45reads the various programs stored in the storage medium46and stores them in the storage section42through the bus40.

The storage medium46stores various data and the various programs in readable and writable manner. The storage medium46stores the search schedule determining program of the present invention executed by the search schedule determining apparatus of the present invention, to realize the search schedule determining method of the present invention.

FIG. 5Bis an example of a time chart showing each of steps executed in the search schedule determining method in the present invention. The time chart shown inFIG. 5Bcontains a first step S1to a tenth step S10.

At the first step S1, the target distribution probability calculating section411refers to the target database421. More specifically, the target distribution probability calculating section411requests necessary information to the target database421, and the target database421supplies the requested information to the target distribution probability calculating section411. The information requested by the target distribution probability calculating section411contains target previous information about the ships as the search target. After the first step S1, a second step S2is executed.

At the second step S2, the target distribution probability calculating section411calculates a target distribution probability and stores the result in the target database421. More specifically, the target distribution probability calculating section411calculates the target distribution probability based on the target previous information read at the first step S1.

The first and second steps S1and S2are executable independently from the other steps. In other words, a routine of calculating the target distribution probability may be repeatedly executed at any time every time the target previous information is updated.

At a third step S3, the search ability calculating section412refers to the search vehicle database422. More specifically, the search ability calculating section412requests necessary information to the search vehicle database422, and the search vehicle database422supplies the requested information to the search ability calculating section412. The information requested by the search ability calculating section412contains the search vehicle previous information about the aircrafts as the search vehicles. After the third step S3, a fourth step S4is executed.

At the fourth step S4, the search ability calculating section412calculates the search ability and stores the result in the search vehicle database422. More specifically, the search ability calculating section412calculates the search ability based on the search vehicle previous information read at the third step S3.

The third and fourth steps S3and S4are executable independently from the other steps. In other words, a routine of calculating the search ability is updated may be repeatedly executed at any time every time the search vehicle previous information.

At a fifth step S5, the input section43transmits a start instruction signal to the search effort distribution calculating section413. After the fifth step S5, a sixth step S6is executed.

At the sixth step S6, the search effort distribution calculating section413refers to the target database421and the search vehicle database422. More specifically, the search effort distribution calculating section413requests necessary first information to the target database421, and the target database421supplies the requested first information to the search effort distribution calculating section413. The first information contains the target distribution probability calculated at the second step S2. Also, the search effort distribution calculating section413requests necessary second information to the search vehicle database422, and the search vehicle database422supplies the requested second information to the search effort distribution calculating section413. The second information contains the search ability calculated at the fourth step S4. After the sixth step S6, a seventh step S7is executed.

At the seventh step S7, the search effort distribution calculating section413calculates the search effort distribution and supplies the result to the search schedule determining section414. After the seventh step S7, an eighth step S8is executed.

At the eighth step S8, the search schedule determining section414refers to the target database421and the search vehicle database422. More specifically, the search effort distribution calculating section413requests the necessary first information to the target database421, and the target database421supplies the requested first information to the search effort distribution calculating section413. The first information contains the target previous information. Also, the search effort distribution calculating section413requests necessary second information to the search vehicle database422, and the search vehicle database422supplies the requested second information to the search effort distribution calculating section413. The second information contains the search vehicle previous information for every search vehicle. After the eighth step S8, a ninth step S9is executed.

At the ninth step S9, the search schedule schedule determining section414automatically determines the search schedule and supplies the result to the output section44. After the ninth step S9, a tenth step S10is executed.

At the tenth step S10, the output section44outputs the search schedule determined at the ninth step S9. When the tenth step S10completes, the search schedule determining method and the search schedule determining program of the present invention are ended. However, after the search schedule is determined and outputted, the first to fourth steps S1to S4may be repeatedly executed appropriately, as mentioned above.

FIG. 6is an example of the search schedule obtained by the search schedule determining apparatus and the search schedule determining method in the present invention.FIG. 6shows a combination of the target movement routes110ato110ccorresponding to the search areas and the search schedules showing the time zones until return to the airports after taking off from the airports, for each of the used search vehicles which are the five aircrafts31,310,32,320and33.

In the example shown inFIG. 6, the aircraft31takes off from the airport at time t1, carries out the search operation in the search area corresponding to the target movement route110a, and then returns to the airport at time t3. The aircraft310takes off from the airport at time t2, carries out the search operation in the search area corresponding to the target movement route110a, and then returns to the airport at time t5. The aircraft32takes off from the airport at the time t1, carries out the search operation in the search area corresponding to the target movement route110b, and then returns to the airport at the time t5. The aircraft320takes off from the airport at the time t1, carries out the search operation in the search area corresponding to the target movement route110b, and then returns to the airport at a time t4. The aircraft33takes off from the airport at the time t2, carries out the search operation in the search area corresponding to the target movement route110c, and then returns to the airport at the time t4.

Note that a more specific flight route of each of the aircrafts31,310,32,320, and33as the search vehicles may be calculated as a part of a search schedule by the search schedule determining section414based on the target movement routes110ato110cto the search areas, the probability distribution of the ships11to15as the target at a time zone for the search operation to be carried out, and the positions of the airports21and22where each of the aircrafts stands-by.

The embodiments have been described in which the search schedule shown inFIG. 6is automatically determined from the examples shown inFIG. 1toFIG. 4about the target and the search vehicles.

As above, the present invention has been described with reference to the embodiments. However, the present invention is not limited to the embodiments. The present invention may be changed or modified in a range which does not deviate from the spirit of the present invention. Also, the features of the embodiments described above can be freely combined in a range which does not cause any technical contradiction.