Patent Description:
Conventionally, magnetic marker systems for vehicles using magnetic markers laid in a road have been known (for example, refer to Patent Literature <NUM>). This magnetic marker system has an object of providing, by taking a vehicle with a magnetic sensor attached to a floor of the vehicle's body as a target, various driving assists using the magnetic markers laid along a lane, such as automatic steering control and lane departure warning.

<CIT> discloses a system for determining the position of a vehicle, the system comprising: a group of radio frequency identification tags spaced apart from one another in or around a work area for the vehicle, each of the tags having a corresponding unique identifier; a path planning module for establishing a path comprising a path segment between at least two of the radio frequency identification tags, the path segment comprising a least one of a distance between the tags, an angular heading between the tags, tag coordinates, and unique identifiers corresponding to the tags; a position estimator for determining an estimated position of the vehicle based on at least one of odometer data and inertial data; a vehicle controller for navigating between at least two of the radio frequency identification tags based on the estimated position, the distance and the angular heading; a reader for reading the tag identifiers of each tag to track the progress to facilitate execution of retrieval of any next path segment of the vehicle along the established path; a metal detector for detecting a change in a magnetic field associated with the proximity of a magnet or ferrous material co-located with the radio frequency identification tag; and a position verification module for determining whether or not the vehicle is co-located with or positioned over the read tag, as opposed to merely near the tag.

<CIT> discloses a marker system, comprising: a sensor array for detecting magnetic markers installed atop a roadway; a tag reader for acquiring marker position information, which represents the installation positions of the magnetic markers; an IMU for estimating the relative vehicle position by inertial navigation; and a control unit for executing a computation process to identify the vehicle position.

<CIT> discloses an abnormality determination device for a vehicle including a magnetic field intensity detection means for detecting the magnetic field intensity from magnetic markers disposed on the traveling road of the vehicle in the extended state in the right and left directions of the vehicle; and an abnormality determination means for determining whether at least either of the wheels of the vehicle and the traveling road is abnormal or not, based on comparison between a vertical component to the road surface of the magnetic field intensity detected by the magnetic field intensity detection means and a prescribed threshold.

<CIT> discloses a magnetic marker detection device.

However, the above-described conventional system has the following problem. That is, regular inspection work and maintenance work are required in order to enable avoidance of a trouble that can happen in the magnetic sensor on a vehicle side before it happens, quick handling after the trouble occurs, and so forth, thereby raising a possibility of increasing upkeep cost.

The present invention was made in view of the above-described conventional problem, and is to provide a vehicle and a vehicular diagnostic system that can suppress cost of inspection and maintenance of a magnetic sensor on a vehicle side.

The present invention provides a vehicle according to claim <NUM>, and a vehicular diagnostic system according to claim <NUM>. Further embodiments of the present invention are disclosed in the dependent claims.

The vehicle according to the present invention diagnoses the state of the magnetic detecting part by using marker state information indicating the state of the magnetic marker. According to this vehicle, with self diagnosis of the state of the magnetic detecting part, cost of inspection and maintenance can be suppressed, and upkeep cost can be reduced.

Modes for implementation of the present invention are specifically described by using the following embodiments.

The present embodiment is an example regarding vehicle <NUM> including a self diagnostic function of sensor array (magnetic detecting part) <NUM> for detecting magnetic marker <NUM>, and vehicular diagnostic system <NUM>. Vehicle <NUM> configuring this diagnostic system <NUM> diagnoses state of sensor array <NUM> by using marker state information distributed from server apparatus <NUM>. Details of this are described by using <FIG>.

Diagnostic system <NUM> of the present embodiment is configured of, as in <FIG>, a combination of vehicles <NUM> that can detect magnetic marker <NUM> and server apparatus <NUM> which distributes marker state information indicating state of magnetic marker <NUM>. This diagnostic system <NUM> is operated by taking a road (one example of a traveling road) where magnetic markers <NUM> which each integrally hold RFID (Radio Frequency IDentification) tag <NUM> (which will be described further below with reference to <FIG>) are laid as a target.

In the following, after (<NUM>) magnetic marker <NUM> is generally described, (<NUM>) vehicle <NUM> and (<NUM>) server apparatus <NUM> configuring diagnostic system <NUM> are described, and then details of (<NUM>) operation of diagnostic system <NUM> are described.

Magnetic marker <NUM> is a road marker including, as in <FIG>, a columnar-shaped magnet having a diameter of <NUM> and a height of <NUM> and having RFID tag <NUM> attached to its end face. This magnetic marker <NUM> is laid as, for example, being accommodated in a hole bored into a road surface. Magnetic markers <NUM> are arrayed, for example, at intervals of <NUM> meters along the center of a lane (one example of a traveling road) sectioned by left and right lane marks.

In magnetic marker <NUM>, as in <FIG>, sheet-shaped RFID tag <NUM> is laminated to the end face serving as an upper surface at the time of laying. RFID tag <NUM>, which is one example of a wireless tag, operates by wireless external power feeding, and externally outputs, by wireless communication, a tag ID as unique identification information, or the like.

RFID tag <NUM> is, as in <FIG>, an electronic component having IC chip <NUM> implemented on a surface of tag sheet <NUM> cut out from, for example, a PET (PolyEthylene Terephthalate) film. On the surface of tag sheet <NUM>, a printed pattern of loop coil <NUM> and antenna <NUM> is provided. Loop coil <NUM> is a receiving coil where an exciting current is generated by external electromagnetic induction. Antenna <NUM> is a transmission antenna for wireless transmission of position data and so forth.

Vehicle <NUM> includes, as in <FIG>, measuring unit <NUM>, tag reader <NUM>, main unit <NUM>, and a communication unit (omitted in the drawing) including a wireless communication function. Furthermore, vehicle <NUM> includes navigation device <NUM> which performs route guidance to a destination. Vehicle <NUM> can be connected to a public communication line via the communication unit. Vehicle <NUM> transmits and receives various information such as detection information, marker position information, and marker state information of magnetic marker <NUM> to and from server apparatus <NUM> via, for example, Internet <NUM> (<FIG>).

Measuring unit <NUM> is, as in <FIG> and <FIG>, a unit having sensor array (one example of the magnetic detecting part) <NUM> which detects magnetic marker <NUM> and IMU (Inertial Measurement Unit) <NUM> for achieving inertial navigation integrated together. Measuring unit <NUM> having a narrow rod shape is attached to, for example, the inside of the front bumper of vehicle <NUM> or the like, in a state of facing road surface <NUM> and along a vehicle-width direction. In the case of vehicle <NUM> of the present embodiment, attachment height of measuring unit <NUM> with reference to road surface <NUM> is <NUM>. Note that tag reader <NUM> may be integrally incorporated into measuring unit <NUM>.

Sensor array <NUM> includes fifteen magnetic sensors Cn (n is an integer of <NUM> to <NUM>, one example of the magnetic detecting part) arrayed on a straight line and detection processing circuit <NUM> having a CPU and so forth not depicted incorporated therein. In sensor array <NUM>, fifteen magnetic sensors Cn are equidistantly arranged with <NUM>-centimeter pitches. Magnetic sensors Cn are sensors which detect magnetism by using the known MI effect (Magneto Impedance Effect) in which impedance of a magneto-sensitive body such as an amorphous wire sensitively changes in response to an external magnetic field.

Detection processing circuit <NUM> (<FIG>) of sensor array <NUM> is an arithmetic circuit which performs marker detection process for detecting magnetic marker <NUM>, and so forth. This detection processing circuit <NUM> is configured by using a CPU (central processing unit) which performs various calculations as well as memory elements such as a ROM (read only memory) and a RAM (random access memory), and so forth. Detection processing circuit <NUM> acquires a sensor signal outputted from each of magnetic sensors Cn in a frequency of <NUM> to perform the marker detection process, and then inputs the detection result to main unit <NUM>.

IMU <NUM> incorporated in measuring unit <NUM> is an inertial navigation unit which estimates a relative position of vehicle <NUM> by inertial navigation. IMU <NUM> includes biaxial magnetic sensor <NUM> as an electronic compass which measures an azimuth, biaxial acceleration sensor <NUM> which measures acceleration, and biaxial gyro sensor <NUM> which measures angular velocity. Using the measured acceleration, the measured angular velocity, and so forth, IMU <NUM> calculates a relative position with respect to a vehicle position as a reference.

Tag reader <NUM> (<FIG>) included in vehicle <NUM> is a unit which wirelessly communicates with RFID tag <NUM> (<FIG>) arranged on a surface of magnetic marker <NUM>. Tag reader <NUM> wirelessly transmits electric power required for operation of RFID tag <NUM>, and receives information transmitted from RFID tag <NUM>. Note that transmission information of RFID tag <NUM> includes the tag ID, which is identification information of RFID tag <NUM>.

Main unit <NUM> (<FIG>) included in vehicle <NUM> is a unit which includes, in addition to a function of controlling (control part <NUM>) measuring unit <NUM> and tag reader <NUM> and a function of exchanging various information with server apparatus <NUM> (information exchanging part <NUM>, which is one example of an acquiring part), the self diagnostic function of diagnosing sensor array (magnetic sensors Cn) <NUM>. This self diagnostic function is implemented by diagnosing part <NUM> which diagnoses the state of sensor array <NUM>, history storage part <NUM> which stores history data, and so forth. As the history data, there are detection history data indicating history of detection of magnetic markers <NUM>, travel history data indicating a traveling route, which is a path through which vehicle <NUM> travels, and so forth.

Main unit <NUM> includes an electronic substrate (omitted in the drawing) having implemented thereon a CPU which performs various calculations, as well as memory elements such as a ROM and a RAM, and so forth. Main unit <NUM> uploads detection information of magnetic marker <NUM> to server apparatus <NUM> and, in response to uploading the detection information, receives a reply of marker position information from server apparatus <NUM>. Furthermore, main unit <NUM> acquires marker state information indicating the state of each magnetic marker <NUM> from server apparatus <NUM>. On a vehicle <NUM> side, by using this marker state information, self diagnosis of magnetic sensors Cn can be performed.

The detection information to be uploaded by main unit <NUM> includes a marker ID (marker identifying information) which can uniquely identify magnetic marker <NUM>, a vehicle ID as vehicle's identification information, and so forth. Note in a configuration of the present embodiment that the tag ID read from RFID tag <NUM> when magnetic marker <NUM> is detected is used as it is as the marker ID (marker identifying information).

Main unit <NUM> (<FIG>) identifies its own vehicle position by using the marker position information received from server apparatus <NUM>. When magnetic marker <NUM> is detected, server apparatus <NUM> takes a position indicated by the marker position information as a reference and identifies a position shifted by a lateral shift amount of vehicle <NUM> with respect to magnetic marker <NUM> as its own vehicle position. On the other hand, after magnetic marker <NUM> is detected and until new magnetic marker <NUM> is detected, a new own vehicle position is identified by using inertial navigation. Specifically, server apparatus <NUM> estimates the relative position of vehicle <NUM> by inertial navigation by taking the most recent own vehicle position as a reference. Then, the server apparatus identifies a position shifted by this relative position from the most recent own vehicle position as the new own vehicle position. Main unit <NUM> inputs the own vehicle position to navigation device <NUM> which performs, for example, route guidance to the destination and so forth. Note that navigation device <NUM> has map database (map DB) <NUM> storing map data and can perform process of mapping (process of associating) its own vehicle position on an electronic map based on map data. The map data of map DB <NUM> includes marker position data indicating positions of magnetic markers <NUM>.

Also, main unit <NUM> of the present embodiment can perform, based on the marker state information distributed from server apparatus <NUM>, self diagnostic process of diagnosing the state of sensor array <NUM> and magnetic sensors Cn forming one example of the magnetic detecting part.

Server apparatus <NUM> is, as in <FIG>, an arithmetic processing apparatus having main circuit <NUM> which includes an electronic substrate, not depicted, having implemented thereon a CPU, and so forth. In server apparatus <NUM>, storage device <NUM> such as a hard disk is connected to main circuit <NUM>. Main circuit <NUM> includes a communication function supporting a LAN (Local Area Network) not depicted. Server apparatus <NUM> can be connected to the public communication line such as Internet <NUM> (<FIG>) via a communication cable connected to a LAN port.

Connected to main circuit <NUM> are detection information acquiring part <NUM> which acquires detection information of magnetic marker <NUM> from vehicle <NUM>, position information providing part <NUM> which provides marker position information to vehicle <NUM> as a transmission source of the detection information, marker state information providing part <NUM> which distributes marker state information to each vehicle <NUM>, and so forth. Also, main circuit <NUM> includes functions such as state estimating part 11A which estimates the state of magnetic marker <NUM> and marker state information generating part 11B which generates marker state information indicating the state of magnetic marker <NUM>. These functions are achieved by processing a software program by the CPU or the like.

Server apparatus <NUM> is provided with marker database (marker DB) <NUM> using a storage area of storage device <NUM> connected to main circuit <NUM> to store data regarding magnetic markers <NUM>. Stored in marker DB <NUM> are installation data (<FIG>) of magnetic markers <NUM>, operation data (<FIG>) of magnetic markers <NUM>, state data (<FIG>) of magnetic markers <NUM>, and so forth.

The installation data of <FIG> includes marker position data indicating the position where each magnetic marker <NUM> is installed, flag data indicating a road type as a type of the road where it is installed, and so forth. To the marker position data or the like of each magnetic marker <NUM>, the marker ID (marker identifying information), which is identification information of magnetic marker <NUM>, is linked. Note that the road type of the present embodiment indicates a road classification based on the degree of volume of traffic. For example, magnetic markers <NUM> having the road type such as "road type <NUM>" in common have a similar number of vehicles passing thereover.

The operation data of <FIG> is data indicating an operation status of each magnetic marker <NUM> such as a marker-detected count of magnetic marker <NUM>, and has the marker ID linked thereto. The marker-detected count, which is an index indicating the operation status of magnetic marker <NUM>, is the number of times when magnetic marker <NUM> is detected by any vehicle <NUM>. This operation data is managed daily for each road type. For example, <FIG> depicts part of daily operation data regarding road type <NUM>. Based on the operation data, a daily marker-detected count of each magnetic marker <NUM> can be grasped. Furthermore, since the operation data is managed for each road type, statistical process on the marker-detected count of magnetic marker <NUM> can be performed for each road type.

The state data of <FIG> is flag data indicating a quality level (one example of a state) of magnetic marker <NUM>. To this state data, the marker ID is linked. In the example of <FIG>, as flag data indicating a quality level of magnetic marker <NUM>, three types of data are presented, for example, corresponding to a circle, a triangle, and a cross. The circle represents flag data indicating a good state with a low degree of possibility of trouble. The cross represents flag data with a high possibility of trouble, indicating that maintenance work is required. The triangle represents flag data indicating that maintenance work is not immediately required to be performed but there is a possibility of trouble and monitoring is required. The state data of <FIG> can be used as original data of maintenance information indicating whether to require maintenance work on each magnetic marker <NUM>. Also, the state data of the drawing can be used as marker state information indicating the state of each magnetic marker <NUM>.

As for details of operation of diagnostic system <NUM> configured as described above, first, with reference to <FIG> and <FIG>, (a) marker detection process by vehicle <NUM> is described. Subsequently, with reference to the flow diagram of <FIG>, (b) detection information uploading process by vehicle <NUM> and (c) marker position information distribution process by server apparatus <NUM> are descried. Furthermore, (d) marker state information generation process by server apparatus <NUM> is described and, subsequently, with reference to <FIG> and <FIG>, (e) self diagnostic process by the vehicle is described.

While vehicle <NUM> is traveling on the road, sensor array <NUM> (<FIG>) of measuring unit <NUM> repeatedly performs marker detection process for detecting magnetic marker <NUM>.

As described above, magnetic sensors Cn can measure magnetic components in a forwarding direction and the vehicle-width direction of vehicle <NUM>. For example, when these magnetic sensors Cn move in the forwarding direction to pass directly above magnetic marker <NUM>, magnetic measurement value in the forwarding direction has its sign reversed before and after passing magnetic marker <NUM> as in <FIG> and changes so as to cross zero at a position directly above magnetic marker <NUM>. Therefore, during traveling of vehicle <NUM>, when zero-cross Zc occurs in which the sign of the magnetic measurement value in the forwarding direction detected by any magnetic sensor Cn is reversed, it can be determined that measuring unit <NUM> is positioned directly above magnetic marker <NUM>. Detection processing circuit <NUM> (<FIG>) determines that magnetic marker <NUM> is detected when, as described above, measurement unit <NUM> is positioned directly above magnetic marker <NUM> and zero-cross Zc of the magnetic measurement value in the forwarding direction occurs.

Also, for example, as for a magnetic sensor with the same specification as that of magnetic sensors Cn, assume movement along a virtual line in the vehicle-width direction passing directly above magnetic marker <NUM>. In this case, the magnetic measurement value in the vehicle-width direction has its sign reversed on both sides across magnetic marker <NUM> and changes so as to cross zero at the position directly above magnetic marker <NUM>. In the case of measuring unit <NUM> having fifteen magnetic sensors Cn arrayed in the vehicle-width direction, the sign of the magnetic measurement value in the vehicle-width direction to be detected by magnetic sensor Cn varies depending on which side the unit is present with respect to magnetic marker <NUM>, as in the example of <FIG>.

Based on a distribution curve of <FIG> exemplarily depicting magnetic measurement values in the vehicle-width direction of respective magnetic sensors Cn of measuring unit <NUM>, it is possible to identify the position of magnetic marker <NUM> in the vehicle-width direction by using zero-cross Zc where the sign of the magnetic measurement value in the vehicle-width direction is reversed. When zero-cross Zc is positioned at an intermediate position (that is not limited to the center) between adjacent two magnetic sensors Cn, the intermediate position between the adjacent two magnetic sensors Cn across zero-cross Zc is the position of magnetic marker <NUM> in the vehicle-width direction. Alternatively, when zero-cross Zc matches the position of any magnetic sensor Cn, that is, when magnetic sensor Cn is present where the magnetic measurement value in the vehicle-width direction is zero and the signs of the magnetic measurement value of magnetic sensor Cn on both outer sides are reversed, a position directly below that magnetic sensor Cn is the position of magnetic marker <NUM> in the vehicle-width direction. Detection processing circuit <NUM> measures a deviation of the position of magnetic marker <NUM> in the vehicle-width direction with respect to the center position (position of magnetic sensor C8) of measuring unit <NUM> as the lateral shift amount of vehicle <NUM> with respect to magnetic marker <NUM>. For example, in the case of <FIG>, the position of zero-cross Zc is a position corresponding to C9. <NUM> in the neighborhood of a midpoint between C9 and C10. As described above, since the pitch between magnetic sensors C9 and C10 is <NUM>, the lateral shift amount of vehicle <NUM> with respect to magnetic marker <NUM> is (<NUM>-<NUM>)×<NUM>=<NUM> with reference to C8 positioned at the center of measuring unit <NUM> in the vehicle-width direction.

As in <FIG>, when sensor array <NUM> of vehicle <NUM> performs marker detection process P1 described above and detects magnetic marker <NUM> (S101: YES), tag reader <NUM> performs tag ID reading process for reading the tag ID of RFID tag <NUM> (S102). Tag reader <NUM> wirelessly transmits electric power required for operation of RFID tag <NUM> to start operation of RFID tag <NUM>, and receives transmission data (such as the tag ID) of RFID tag <NUM>. Then, tag reader <NUM> inputs the tag ID read by this tag ID reading process to main unit <NUM>. Main unit <NUM> handles this tag ID as the marker ID as marker identifying information, and generates detection information including this marker ID (S103). Then, the vehicle ID as identification information of vehicle <NUM> is linked to the detection information and main unit <NUM> transmits the detection information to server apparatus <NUM>.

Server apparatus <NUM>, as in <FIG>, when acquiring the detection information from the vehicle <NUM> side (S201), refers to marker DB <NUM> (<FIG>) which stores the marker position data of each magnetic marker <NUM> and so forth (S202) and then, from the inside of marker DB <NUM>, selects magnetic marker <NUM> corresponding to the detection information, that is, magnetic marker <NUM> regarding the marker ID of the detection information.

Server apparatus <NUM> refers to the installation data (<FIG>) in marker DB <NUM> and acquires the marker position data and so forth of the selected magnetic marker <NUM> (S203) and, furthermore, refers to the operation data (<FIG>) in marker DB <NUM> and increments the marker-detected count (refer to <FIG>) of the selected magnetic marker <NUM> by one (S204). Then, the server apparatus generates marker position information including the marker position data acquired at step S203, and transmits the marker position information to vehicle <NUM> as a transmission source of the detection information acquired at step S201 described above (S205).

Main unit <NUM> of vehicle <NUM>, when acquiring the marker position information (S104), identifies the vehicle position by taking the position indicated by this marker position information as a reference (S105). Specifically, the main unit performs calculation of shifting from the position of magnetic marker <NUM> as a reference by the lateral shift amount (one example of the relative position) measured by measuring unit <NUM> in a manner as described above and obtains the vehicle position. Navigation device <NUM> handles this vehicle position as the own vehicle position and performs route guidance and so forth.

Note that in a traveling section after magnetic marker <NUM> is detected and until new magnetic marker <NUM> is detected (S101: NO), main unit <NUM> estimates the relative position of vehicle <NUM> by inertial navigation by taking the vehicle position at the time of most recent magnetic marker detection as a reference position (S112). Specifically, IMU <NUM> (<FIG>) incorporated in measuring unit <NUM> calculates a displacement amount by double integration of acceleration measured by biaxial acceleration sensor <NUM> and performs calculation of integrating displacement amounts along a forwarding azimuth of vehicle <NUM> measured by biaxial gyro sensor <NUM>. With this, the relative position of vehicle <NUM> with reference to the above-described reference position is estimated. Then, a position obtained by moving by this relative position from the reference position is identified as the own vehicle position (S105).

Server apparatus <NUM> performs statistical process for calculating an average value, a standard deviation, or the like as for the marker-detected count of each magnetic marker <NUM> (operation data of <FIG>). Note in a configuration of the present embodiment that reliability of the statistical process is ensured by performing statistical process for each road type with the same degree of the volume of traffic.

For each magnetic marker <NUM>, server apparatus <NUM> calculates a deviation value of the marker-detected count and performs threshold process regarding this deviation value. For example, for magnetic marker <NUM> with its deviation value of the marker-detected count is below a predetermined threshold value, server apparatus <NUM> determines that the possibility of trouble is high. In this manner, server apparatus <NUM> generates state data (<FIG>) indicating the state of each magnetic marker <NUM>. This state data is quality information indicating the quality level of each magnetic marker <NUM>. This state data can be used as original data of maintenance information indicating whether to require maintenance work on each magnetic marker <NUM> and marker state information indicating the state of each magnetic marker <NUM>. Note in the present embodiment that, as in <FIG>, two-stage threshold values are set for the deviation value of the marker-detected count described above. And, with the two-stage threshold values, the quality levels of magnetic marker <NUM> are classified into three stages (circle, triangle, and cross in the drawing).

The state data of <FIG> can be used directly as maintenance information. According to the maintenance information based on the state data, it is possible to perform maintenance of magnetic markers <NUM> by, for example, a road administrator or the like at appropriate timing. For example, as for a magnetic marker with the cross, a determination can be made such as that in which the magnetic marker has a possibility of trouble and urgent maintenance is required. For example, as for a magnetic marker with the triangle, a determination can be made such as that in which maintenance is required in the next few days. Note that the state data of <FIG> may be processed. For example, as for magnetic marker <NUM> with its quality indicated by the circle, it is possible, for example, as maintenance information, to convert or process the state data to character information such as "a good state is being kept". Also, for example, as for magnetic marker <NUM> with its quality indicated by the cross, it is possible, for example, to convert or process the state data to maintenance information such as "immediate inspection is required".

Server apparatus <NUM> regularly distributes, as marker state information indicating the state of magnetic markers <NUM>, the state data of <FIG> to each vehicle <NUM>. On the vehicle <NUM> side, by using the marker state information acquired from server apparatus <NUM>, self diagnostic process of sensor array (magnetic sensors Cn) <NUM> is performed. Next, details of this self diagnostic process are described with reference to the flow diagram of <FIG>.

Main unit <NUM> first reads, from a storage area of history storage part <NUM> (<FIG>), travel history data and detection history data (S301). As described above, the travel history data is data indicating the traveling route of vehicle <NUM>. The detection history data is a history of magnetic markers <NUM> detected by vehicle <NUM> during traveling. Each magnetic marker <NUM> in the detection history data is identified with the marker ID, which is marker identifying information.

Main unit <NUM> reads, from map DB <NUM> of the navigation device, map data corresponding to the traveling route of the vehicle. Here, the map data of map DB <NUM> includes marker position data indicating the positions of magnetic markers <NUM>. By using this marker position data, main unit <NUM> maps the position of each magnetic marker <NUM> on the electronic map based on the map data (<FIG>).

Main unit <NUM> maps traveling route R of vehicle <NUM> based on the travel history data on the electronic map mapped with the position of each magnetic marker <NUM> (S302, <FIG>). Then, magnetic markers <NUM> on the traveling route R of vehicle <NUM> are identified. Note in <FIG> that the position of each magnetic marker <NUM> is indicated by a plot type (the circle, the triangle, the cross) representing the quality level based on the marker state information distributed from server apparatus <NUM> (<FIG>).

Main unit <NUM> performs process of comparing magnetic markers on the traveling route R (referred to as route markers) and magnetic markers in the detection history data (referred to as history markers) (S303). In this comparison process, of the above-described route markers, a route marker matching a corresponding history marker of the above-described history markers is converted to a detection point for scoring and added to an evaluation point (S304). Note that the point number of the detection point differs in accordance with the quality level of magnetic marker <NUM>. For example, a magnetic marker with the quality level indicated by the circle has <NUM> point, a magnetic marker with the triangle has <NUM> points, and a magnetic marker with the cross has zero point. In this manner, in a configuration of the present embodiment, in accordance with the quality level of the state of magnetic marker <NUM>, degree of reflection onto an index (for example, evaluation point, evaluation index value, which will be described further below, or the like) for use in diagnosis of sensor array <NUM> varies.

Main unit <NUM> performs the comparison process at the above-described steps S303→S304 for all route markers (S305: NO). Note that as for remaining magnetic markers <NUM> of the history markers that have not been able to be compared with corresponding route markers are treated as erroneously-detected magnetic markers <NUM>, and detection points of minus <NUM> points are added to the evaluation point.

Main unit <NUM> divides the above-described evaluation point by the number of magnetic markers <NUM> of the route markers with the quality level indicated by the circle or the triangle to calculate an evaluation index value (S306), and performs threshold process (S307). As a threshold value for this threshold process, for example, <NUM> point, <NUM> points, <NUM> point, or the like can be set.

When the evaluation index value is equal to or larger than the threshold value (S307: YES), main unit <NUM> determines that sensor array <NUM> is normal (S308). On the other hand, the evaluation index value is under the threshold value (S307: NO), it is determined that the state is such that inspection of sensor array <NUM> is required (S318, inspection-required determination), and notification as such is performed by displaying by a liquid-crystal display of the vehicle's interior or the like (S319, inspection-required display). With this notification, counter measures on a user side can be taken such as carrying the vehicle into a repair shop or the like, thereby allowing early counter measures before a critical trouble happens.

As described above, vehicle <NUM> in diagnostic system <NUM> of the present embodiment can perform self diagnosis of the state of sensor array <NUM> by using the marker state information indicating the state of magnetic marker <NUM>. In this vehicle <NUM>, since self diagnosis of the state of sensor array <NUM> can be performed, cost of inspection and maintenance can be suppressed, and upkeep cost can be reduced.

In the present embodiment, the configuration is exemplarily described in which the detection information of magnetic markers <NUM> is collected from general vehicle <NUM> and server apparatus <NUM> generates marker state information. In place of this configuration, an inspection vehicle may be caused to travel to collect detection information of magnetic markers <NUM> and server apparatus <NUM> may generate marker state information based on this detection information. In the case of this configuration, server apparatus <NUM> can generate marker state information even without acquiring the detection information uploaded by the general vehicle. For example, if this marker state information is distributed to each vehicle, self diagnosis of sensor array <NUM> on the vehicle side can be performed.

Note in the present embodiment that the configuration is exemplarily described in which server apparatus <NUM> generates state data of the magnetic markers by statistical process. The method of generating state data of the magnetic markers can be changed as appropriate.

The present embodiment is an example in which, based on diagnostic system of the first embodiment, a function of diagnosing a change in ground clearance of a vehicle is added. Details of this are described with reference to <FIG> and <FIG>.

In a diagnostic system of the present embodiment, a magnetic measurement value (peak value) when a magnetic marker is detected is added to detection information uploaded by the vehicle. To evaluate the quality of the magnetic marker, a server apparatus of the present embodiment evaluates the degree of magnetic intensity of the magnetic marker with ten-stage magnetic levels. The server apparatus calculates an average value of magnetic measurement values (peak values) included in the detection information acquired from each vehicle side, and allocates magnitude of that average value to any of ten-stage magnetic levels (refer to <FIG>). This magnetic level is distributed to each vehicle as part of the marker state information of the magnetic marker, together with information about a quality level (circle, triangle, cross).

For example, on the vehicle side receiving distribution of the marker state information based on the state data of <FIG>, in addition to diagnosis similar to that of the first embodiment regarding the state of the magnetic sensor, self diagnostic process of diagnosing the change in ground clearance of the vehicle is performed. Diagnosis of the change in ground clearance of the vehicle is diagnosis of detecting the change in ground clearance of the vehicle by using an index value indicating a correlation between the magnetic level of the magnetic marker and the magnetic measurement value (peak value) of the magnetic sensor.

Details of the process internally performed by the diagnosing part (reference sign <NUM> in <FIG>) of the vehicle can be described by using, for example, the graph of <FIG>. The graph of the drawing represents a relation between the magnetic measurement value (peak value) when a target vehicle detects a magnetic marker and the magnetic level of that magnetic marker (refer to <FIG>). The horizontal axis of the graph of the drawing represents ten-stage magnetic levels (marker state information) of the magnetic markers, and the vertical axis represents magnetic measurement values (peak values). On the graph of <FIG>, pieces of detection information uploaded by the target vehicle are sequentially plotted. Diagnosing part of the vehicle calculates, for a plotted point group, an approximate straight line by, for example, the least square method. Then, a gradient (coefficient) or an intercept of this approximate straight line can become the index value indicating the above-described correlation. Note that the intercept is the value at a point where the approximate straight line and the vertical axis cross.

The Diagnosing part sets a predetermined time, for example, one hour, two hours, one day, one week, or the like, and calculates approximate straight lines (for example, AP1 to AP3) of plotted point groups (for example, D1 to D3) for each predetermined time. For example, when the predetermined time is one hour, the approximate straight line is calculated for every one hour. For example, if sensitivity of magnetic sensors (magnetic detecting part) of the sensor array is not changed and mount height of the sensor array is not changed, the gradient and the intercept of the above-described approximate straight lines (for example, AP1 to AP3) are approximately constant with time. On the other hand, if the sensitivity of the magnetic sensors is not changed but a change occurs in the mount height of the sensor array, the gradient and so forth of the above-described approximate straight lines are changed with time.

With this temporal change being detected, the diagnosing part can detect the change in ground clearance of the vehicle. With the change in ground clearance of the vehicle being detected, the diagnosing part can detect, for example, a flat tire, overloading of loads, or the like, which is a cause for the change in ground clearance of the vehicle. When threshold process is performed regarding temporal changes of the gradient and so forth of the above-described approximate straight lines and a change exceeding a threshold value occurs, server apparatus <NUM> may generate vehicle information indicating that the change in ground clearance of the vehicle is large. In this case, server apparatus <NUM> may transmit this vehicle information to a corresponding vehicle to encourage caution. For example, if the vehicle information is presented to a passenger by using a display device, a loudspeaker, or the like, an occurrence of an accident due to the flat tire or overloading of loads can be prevented before it happens.

For example, a case in which a transition is made from point group D1→point group D2 is a case in which a change of the intercept hardly occurs but the gradient of the approximate straight line increases. In this case, the cause can be assumed such that the ground clearance of the vehicle is lowered due to, for example, overloading, the flat tire, or the like. With the ground clearance of the vehicle lowered, the mount height of the sensor array (magnetic sensors) is lowered, thereby increasing the magnetic measurement value (peak value) when the sensor array (magnetic sensors) detects the magnetic marker.

When the change in ground clearance of the vehicle is detected, in addition to or in place of notifying the passenger, there is a method of transmitting vehicle information to a terminal device of a vehicle's dealer which carries out maintenance of the vehicle or the like by using a public communication line such as the Internet, or the like. Furthermore, when the vehicle is a business vehicle such as a taxi or a truck, the vehicle information may be transmitted to a terminal device of a responsible section of an enterprise or a company which manages the business vehicle.

For example, a case in which a transition is made from point group D1→point group D3 is a case in which a change of the gradient of the approximate straight line is less but the intercept has been changed in a manner such that approximate straight line AP1 makes an upward translational movement to become approximate straight line AP3. In this case, there is a possibility that the sensitivity of the magnetic sensors has been changed and also there is a possibility that a change has occurred in the ground clearance of the vehicle. As with the case in which a transition is made from point group D1→point group D2, vehicle information such that there is the possibility that the change has occurred in the ground clearance of the vehicle is preferably presented to the passenger.

Note that a relation between a change in gradient and intercept of an approximate straight line of a point group or a change in distribution mode of the point group and a cause of occurrence may be subjected to machine learning or the like. According to this machine learning, the cause of occurrence can be estimated by an artificial-intelligence-like scheme. In this case, vehicle information indicating the cause of occurrence is preferably provided to the vehicle side.

Note that other configurations and operations and effects are similar to those of the first embodiment.

Claim 1:
A vehicle (<NUM>) including a magnetic detecting part (<NUM>) for detecting a magnetic marker (<NUM>) disposed in a traveling road of the vehicle (<NUM>), the vehicle (<NUM>) comprising
a diagnosing part (<NUM>) which diagnoses a state of the magnetic detecting part (<NUM>) as being normal or such that inspection is required by using marker state information indicating a state of the magnetic marker (<NUM>),
wherein the marker state information is information based on a result of statistical process of a marker-detected count, which is a count of detections of each magnetic marker by a plurality of vehicles.