VEHICLE POSITION ESTIMATION DEVICE

There is provided a vehicle position estimation device, including: a first boundary-line calculation determination unit that calculates a first distance between the vehicle and a boundary line, and determines whether or not the vehicle has crossed the boundary line; a second boundary-line calculation determination unit that calculates a second distance between the vehicle and the boundary line, and determines whether or not the vehicle has crossed the boundary line; a traveling lane matching unit that adjusts at least one of the first and second distances for matching, based on whether or not the vehicle has crossed the boundary line, determined by the first boundary-line calculation determination unit and the second boundary-line calculation determination unit; and a position estimation unit that estimates a position of the vehicle, based on the first or second distance adjusted by the traveling lane matching unit.

TECHNICAL FIELD

The present application relates to a vehicle position estimation device.

BACKGROUND ART

During travel of a vehicle on a road, it is important to estimate the accurate position of the vehicle. Heretofore, a technique that estimates the position of the vehicle on the basis of observed data of multiple detection means has been known. Here, although the detection means may be sensors that are mounted on the vehicle and detect an external environment thereof, they may be sensors that are provided outside the vehicle and detect motion-related elements such as a position, a speed, etc. of the vehicle.

There is disclosed a technique of accurately estimating the position of the vehicle in such a manner that a position of the vehicle is calculated using a Global Navigation Satellite System (GNSS); then the position of the vehicle is identified on a map and a distance between the vehicle and its nearby object is calculated; in addition, a distance between the vehicle and the nearby object is detected using an on-vehicle sensor; and thereafter, the position of the vehicle is estimated so that its deviations from the distances calculated by such two different means are minimized (for example, Patent Document 1).

CITATION LIST

Patent Document

The technique disclosed in Patent Document 1 is based on the assumption that the nearby objects observed by the respective detection means are the same object. If multiple objects having similar shapes and colors are present around the vehicle, a case is conceivable where the respective means detect distances from such mutually different objects to the vehicle. In that case, when the position of the vehicle is adjusted so that its deviations from the calculated two different distances are minimized, a case may arise where the accuracy of vehicle position estimation is degraded.

This problem occurs, particularly in cases where a distance to a boundary line on the road during travel is used to estimate the position of the vehicle. This problem emerges remarkably when the vehicle makes a movement of crossing the boundary line in order to change the lane (traveling lane). This is because the shapes and colors of respective boundary lines are similar to each other and thus, at the time of lane change of the vehicle, it may be highly likely that confusion will occur between “boundary lines on right and left sides viewed from the vehicle” acquired by the respective detection means.

SUMMARY

This application has been made to solve the problem as described above. An object thereof is to provide a vehicle position estimation device which, at the time of estimating the position of a vehicle by using a distance from the vehicle to a boundary line, can accurately estimate the current position of the vehicle by restricting the accuracy of vehicle position estimation from being degraded, even when the vehicle makes a lane change.

Solution to Problem

A vehicle position estimation device according to this application comprises:a first boundary-line calculation determination unit that detects a position of a boundary line on a road to thereby calculate a first distance between a vehicle and the boundary line, and that determines whether or not the vehicle has crossed the boundary line, on a basis of the first distance;a second boundary-line calculation determination unit that detects a position of the boundary line on the road to thereby calculate a second distance between the vehicle and the boundary line, and that determines whether or not the vehicle has crossed the boundary line, on a basis of the second distance;a traveling lane matching unit that adjusts at least one of the first distance and the second distance for matching, on a basis of: whether or not the vehicle has crossed the boundary line, determined by the first boundary-line calculation determination unit; and whether or not the vehicle has crossed the boundary line, determined by the second boundary-line calculation determination unit; anda position estimation unit that estimates a position of the vehicle on a basis of the first distance or the second distance adjusted for matching by the traveling lane matching unit.

Advantageous Effects

By the vehicle position estimation device according to this application, at the time of estimating the position of the vehicle by using the distance from the vehicle to the boundary line, it is possible to accurately estimate the current position of the vehicle by restricting the accuracy of vehicle position estimation from being degraded, even when the vehicle makes a lane change.

DESCRIPTION OF EMBODIMENTS

<Configuration of Vehicle Position Estimation Device>

FIG.1is a configuration diagram of a vehicle position estimation device100according to Embodiment 1. The vehicle position estimation device100has a first boundary-line calculation determination unit101, a second boundary-line calculation determination unit102, a traveling lane matching unit113and a position estimation unit114. The first boundary-line calculation determination unit101is connected to a first sensor201, and the second boundary-line calculation determination unit102is connected to a second sensor202.

The first sensor201and the second sensor202both observe a position of a boundary line on a road on which an object vehicle1travels, and transfer signals related to their observed data to the first boundary-line calculation determination unit101and the second boundary-line calculation determination unit102, respectively. The first sensor and the second sensor each output the observed data that indicates a relative positional relationship between the object vehicle1and the boundary line. When there are multiple boundary lines on the right or left side of the object vehicle1, the first sensor201and the second sensor202may each observe the positions of these boundary lines.

Here, each of the first sensor201and the second sensor202may be of any type so long as it has a function of acquiring a relative positional relationship between the object vehicle1and the boundary line. The first sensor201and the second sensor202may be sensor devices each provided with a function of acquiring a relative positional relationship between the object vehicle1and the boundary line, on the basis of a visible-light image or an image of light other than visible light acquired by an imaging element. Further, for example, they may be sensor devices each provided with a function of radiating electromagnetic waves in a specified frequency range and then receiving reflected electromagnetic waves from an object, to thereby acquire a relative positional relationship between the object vehicle1and the boundary line. Further, for example, they may be sensors each provided with a function of combining: the latitude and longitude information of the object vehicle1calculated on the basis of signals received from satellites; continuous relative-movement information calculated through measurement of the movement distance, the movement speed and the acceleration rate of the object vehicle1; and map information, together, to thereby acquire a relative positional relationship between the object vehicle1and the boundary line. In this case, such a positional relationship between the object vehicle1and the boundary line may be used as input information, that has been calculated from information of satellite signals and information from a wheel rotation sensor, an acceleration sensor, a rotational acceleration sensor, map data, etc. Further, the first sensor201and the second sensor202may be sensor devices of mutually different types, or may be sensors that are of the same type but are mutually different in characteristic such as measurement sensitivity or the like.

The vehicle position estimation device100outputs an estimated position of the object vehicle1. Here, the estimated position of the object vehicle1may be defined as a relative position of the object vehicle1with respect to the right or left boundary line of a lane (traveling lane) on which the object vehicle1is traveling. Further, a value indicative of a distance with reference to the position of the object vehicle1and up to a boundary line, may be used as information that defines the position of the object vehicle1in the lane. Hereinafter, with respect to the estimated position of the object vehicle1, such cases will be described as examples where a value of the relative distance between the vehicle and a right or left boundary line in a coordinate system using the object vehicle1as the origin point is regarded as an estimated position of the object vehicle1.

The estimated position of the object vehicle1outputted by the vehicle position estimation device100may be used as an input to a display device and a vehicle control device. By use of the observed data of the first sensor201and the second sensor202detected at a time t, the estimated position of the object vehicle1at the time t can be outputted in real time.

The first boundary-line calculation determination unit101uses, as its input, signals related to the observed data from the first sensor201, to thereby calculate a first distance between the object vehicle1and a boundary line. The first boundary-line calculation determination unit101determines whether or not the object vehicle1has crossed the boundary line, on the basis of the thus-calculated first distance. The first boundary-line calculation determination unit101outputs the determination result, together with the calculated first distance, to the traveling lane matching unit113.

The second boundary-line calculation determination unit102uses, as its input, signals related to the observed data from the second sensor202, to thereby calculate a second distance between the object vehicle1and the boundary line. The second boundary-line calculation determination unit102determines whether or not the object vehicle1has crossed the boundary line, on the basis of the thus-calculated second distance. The second boundary-line calculation determination unit102outputs the determination result, together with the calculated second distance, to the traveling lane matching unit113.

The traveling lane matching unit113receives, as its inputs, the outputs from the first boundary-line calculation determination unit101and the second boundary-line calculation determination unit102. There are cases where the traveling lane matching unit113transfers the first distance calculated by the first boundary-line calculation determination unit101and the second distance calculated by the second boundary-line calculation determination unit102as they are without being adjusted for matching, to the position estimation unit114. Further, there are cases where the traveling lane matching unit113transfers the first distance and the second distance after adjusting one or both of them for matching, to the position estimation unit114.

The traveling lane matching unit113makes a determination about matching of the first distance or the second distance, on the basis of: whether or not the object vehicle1has crossed the boundary line, determined by the first boundary-line calculation determination unit101; and whether or not the object vehicle1has crossed the boundary line, determined by the second boundary-line calculation determination unit102. The position estimation unit114uses, as its input, the output from the traveling lane matching unit113, to thereby estimate and output the position of the object vehicle1based on the observed data of the first sensor201and the second sensor202.

<Hardware Configuration of Vehicle Position Estimation Device>

FIG.2is a hardware configuration diagram of the vehicle position estimation device100. AlthoughFIG.2may be applied also to vehicle position estimation devices100a,100bto be described later, description is herein made about the vehicle position estimation device100as a representative. In this Embodiment, the vehicle position estimation device100is an electronic control device for estimating the position of a vehicle by using a distance from the vehicle to a boundary line. The respective functions of the vehicle position estimation device100are implemented by a processing circuit included in the vehicle position estimation device100. Specifically, the vehicle position estimation device100includes as the processing circuit: an arithmetic processing device90(computer) such as a CPU (Central Processing Unit) or the like; storage devices91that perform data transactions with the arithmetic processing device90; an input circuit92that inputs external signals to the arithmetic processing device90; an output circuit93that externally outputs signals from the arithmetic processing device90; and the like. The respective pieces of hardware, such as the arithmetic processing device90, the storage devices91, the input circuit92, the output circuit93, etc. are connected to each other by way of a wired network such as a bus, or a wireless network.

As the arithmetic processing device90, there may be included an ASIC (Application Specific Integrated Circuit), an IC (Integrated Circuit), a DSP (Digital Signal Processor), a GPU (Graphics Processing Unit), an FPGA (Field Programmable Gate Array), any one of a variety of logic circuits, any one of a variety of signal processing circuits, or the like. Further, multiple arithmetic processing devices90of the same type or different types may be included so that the respective parts of processing are executed in a shared manner. As the storage devices91, there are included a RAM (Random Access Memory) that is configured to allow reading and writing of data by the arithmetic processing device90, a ROM (Read Only Memory) that is configured to allow reading of data by the arithmetic processing device90, and the like. As the storage device91, a non-volatile or volatile semiconductor memory, such as a flash memory, an SSD (Solid State Drive), an EPROM, an EEPROM or the like; a magnetic disc; a flexible disc; an optical disc; a compact disc; a mini disc; a DVD; or the like, may be used. The input circuit92includes A-D converters, a communication circuit, etc. to which output signals of a variety of sensors and switches including the first sensor201and the second sensor202, and a communication line, are connected, and which serve to input these output signals of the sensors and switches, and communication information, to the arithmetic processing device90. The output circuit93includes a driver circuit, a communication circuit, etc. which serve to output control signals from the arithmetic processing device90. The interfaces of the input circuit92and the output circuit93may be those based on the specification of CAN (Control Area Network) (Registered Trademark), Ethernet (Registered Trademark), USB (Universal Serial Bus) (Registered Trademark), DVI (Digital Visual Interface) (Registered Trademark), HDMI (High-Definition Multimedia Interface) (Registered Trademark) or the like.

The respective functions that the vehicle position estimation device100includes, are implemented in such a manner that the arithmetic processing device90executes software (programs) stored in the storage device91such as the ROM or the like, to thereby cooperate with the other hardware in the vehicle position estimation device100, such as the other storage device91, the input circuit92, the output circuit93, etc. Note that the set data of threshold values, determinative values, etc. to be used by the vehicle position estimation device100is stored, as a part of the software (programs), in the storage device91such as the ROM or the like. Although each of the functions that the vehicle position estimation device100has, may be established by a software module, it may be established by a combination of software and hardware.

<Lane Change of Vehicle>

FIG.3is a diagram showing a lane change of the vehicle1, according to Embodiment 1.FIG.4is a graph showing a distance to a boundary line during the lane change of the vehicle1, according to Embodiment 1. As shown inFIG.3, a case will be described where the object vehicle1changes the traveling lane from the left lane to the right lane. Here, the description for that case will be made using, as a value indicative of the position of the object vehicle1in the lane, a distance to the nearest lane on the left side of the object vehicle1(hereinafter, referred to as “a distance to a left-side boundary line”). The distance to the left-side boundary line of the object vehicle1varies as in the graph shown inFIG.4.

The ordinate of the graph shown inFIG.4represents a distance to the left-side boundary line. With respect to the distance to the left-side boundary line, a distance in the leftward direction with reference to the center line of the object vehicle1and relative to the traveling direction of the object vehicle1, is regarded as positive. In the case shown inFIG.3, because of the traveling lane change, the line nearest and left next to the object vehicle1, is changed from a boundary line A to a boundary line B. Thus, as shown inFIG.4, the distance to the left-side boundary line varies abruptly and non-continuously at a certain time (boundary-line crossing determination time).

As shown inFIG.3, the value indicative of the position of the object vehicle1may also be indicated by use of a distance to the nearest lane on the right side of the object vehicle1(hereinafter, referred to as “a distance to a right-side boundary line”). With respect also to the distance to the right-side boundary line, because of the traveling lane change, the line is changed from the boundary line B to a boundary line C. Accordingly, the distance to the right-side boundary line also varies abruptly at the timing at which the object vehicle1crosses the boundary line.

FIG.5is a set of graphs showing distances to the boundary line according to the first sensor201and the second sensor202during the lane change of the vehicle1, according to Embodiment 1. InFIG.5, with respect to the case of the traveling lane change shown inFIG.3, exemplary observed data is shown that is related to distances to the left-side boundary line and outputted from the first sensor201and the second sensor202. As aforementioned, the distance to the left-side boundary line observed by each of the first sensor201and the second sensor202shows a non-continuous change at a crossing time T1or a crossing time T2.

The crossing time T1at which the non-continuous change emerges in the observed data of the first sensor201and the crossing time T2at which the non-continuous change emerges in the observed data of the second sensor202, do not necessarily coincide with each other. This is thought to be due to a difference between these sensors in mounted position or observation method, or a sensor-to-sensor error, or the like.

For example, the first sensor201is a sensor that detects a boundary line on the basis of an image acquired by an imaging element, so that a time at which the object vehicle1is determined to make a lane change on the basis of the field of the image, corresponds to the crossing time T1. Further, for example, the second sensor202is a sensor that calculates the positions of the boundary line and the object vehicle1through position determination with the satellites and collation with a map, so that the latitude and longitude of the object vehicle1is determined as its position and a time at which this position crosses a boundary line on the map, corresponds to the crossing time T2. In the mentioned case, the first sensor201and the second sensor202differ significantly from each other in measurement method, so that the crossing time T1and the crossing time T2do not necessarily coincide with each other. Further, even if the first sensor201and the second sensor202have ever been pre-calibrated so that the crossing time T1and the crossing time T2coincide with each other, when an error included in each of the sensors may vary by time, it can't be said that the crossing time T1and the crossing time T2constantly coincide with each other.

InFIG.5, a mismatch occurs in an interval between the crossing time T1and the crossing time T2because the first sensor201and the second sensor202indicate the position of the object vehicle1individually by using distances to the different boundary lines. Because of the mismatch, a sensor-to-sensor difference in distance to the boundary line increases significantly.

According to the case ofFIG.5, description will be further given as follows. In the time range between the crossing time T1and the crossing time T2, the first sensor201recognizes the left-side boundary line after the lane change of the object vehicle1(boundary line B) as the nearest left-side boundary line, whereas the second sensor202recognizes the left-side boundary line before the lane change of the object vehicle1(boundary line A) as the nearest left-side boundary line. Accordingly, in the interval between the crossing time T1and the crossing time T2, the difference increases significantly between the distances to the left-side boundary line according to the first sensor201and the second sensor202. Thus, degradation occurs in the accuracy of position estimation for the object vehicle1based on information from these sensors.

FIG.6is a set of graphs showing matching between distances to the boundary line according to the first sensor201and the second sensor202during the lane change of the vehicle1, according to Embodiment 1. “Matching” is to make adjustment so as to avoid a trouble, namely, it means to adjust the value to that assumed to be correct. Here, the traveling lane matching unit113performs matching between the distances to the left-side boundary line. As shown inFIG.6, it performs processing so that the times according to the first sensor201and the second sensor202at which the distance to the left-side boundary line varies abruptly, are matched therebetween.

Specifically, following processing is performed. First, on the basis of the input from the first sensor201, the first boundary-line calculation determination unit101determines that the object vehicle1has crossed the boundary line at the crossing time T1. On the basis of that determination, the traveling lane matching unit113assumes that an inconsistency occurs between the traveling lanes on which the object vehicle1is traveling, according to the first sensor201and the second sensor202. Then, it performs conversion of the traveling lane according to the observed data of the second sensor202so that it is matched with the traveling lane according to the observed data of the first sensor201. Namely, distances to the left-side boundary line according to the second sensor202are substituted with distances to the left-side boundary line according to the first sensor201. The traveling lane matching unit113outputs to the position estimation unit114, the distance to the left-side boundary line according to the first sensor201and the distance to the left-side boundary line according to the second sensor202after being adjusted for matching.

Thereafter, on the basis of the inputted observed data of the second sensor202, the second boundary-line calculation determination unit102determines that the object vehicle1has crossed the boundary line at the time T2. On the basis of that determination, the traveling lane matching unit113assumes that the difference between the traveling lanes according to the first sensor201and the second sensor202has been resolved. Then, it terminates matching processing of the distance to the left-side boundary line according to the sensor202, that was performed in the interval between the crossing time T1and the crossing time T2.

According to such processing, as shown inFIG.6, the respective observed data of these sensors to be inputted to the position estimation unit114are matched with each other so that, totally, the distances to the boundary line A both change abruptly to the distances to the boundary line B at the same crossing time T1.

<Processing by Vehicle Position Estimation Device>

FIG.7is a first flowchart showing processing by the vehicle position estimation device100according to Embodiment 1.FIG.8is a second flowchart showing processing by the vehicle position estimation device100, which shows steps subsequent toFIG.7.

FIG.7andFIG.8are flowcharts in which shown are operations of the first boundary-line calculation determination unit101, the second boundary-line calculation determination unit102, the traveling lane matching unit113and the position estimation unit114, from when the signals of the observed data at the current time are inputted from the respective sensors until when the estimated position of the object vehicle1at the current time is outputted. The processing of the flowchart ofFIG.7is executed every fixed period of time (for example, every 10 ms). It is allowed that the processing of the flowchart ofFIG.7is not executed every fixed period of time but executed in response to an occurrence of an event, such as, at every time the vehicle travels a fixed distance, at every time the sensor acquires new information, or at the time an instruction is given from the outside.

After the processing of the flowchart ofFIG.7is started, in Step ST101, the first boundary-line calculation determination unit101calculates the first distance between the object vehicle1and the boundary line on the basis of the observed data of the first sensor201. Then, it determines whether or not the object vehicle1at the current time has crossed the boundary line, on the basis of the thus-calculated first distance. When it determines that the vehicle has crossed the boundary line, a first crossing flag is set.

This determination of boundary-line crossing may be made using, for example, variation in the value of the distance between the boundary line and the object vehicle1. The occurrence of the boundary-line crossing may be determined when the first distance varies more than a predetermined crossing determination distance within a predetermined crossing determination time.

In another manner, a distance between the boundary line and the object vehicle1according to the observed data of the first sensor201at a time at which that data is last valid (a past time closest to the current time), is compared with a distance between the boundary line and the object vehicle1according to the observe data at the current time at which that data is valid. If a difference from the comparison result exceeds a fixed value, it is determined that the vehicle has crossed the boundary line. Here, “the observed data is valid” can be defined as a situation in which the reliability of the observed data of the first sensor201is a specified value or more. For example, when the first sensor201is a sensor of such a type that measures a distance between a boundary line and the object vehicle1by using an imaging element, if the boundary line is blurred or the noise from the imaging element is large, it may be assumed that the reliability of the observed data is low and thus the observed data is invalid. In this manner, by the comparison between the last-valid observed data and the valid current observed data, it is possible to determine that the object vehicle1has crossed the boundary line. This makes it possible to avoid a situation where erroneous boundary-line crossing determination is made, even when the accuracy of the observed data is reduced temporarily.

Further, other than the determination method exemplified above, such a method may be employed in which boundary-line crossing is determined using observed data special to the first sensor201. For example, when the first sensor201is a sensor of such a type that calculates the distance between the boundary line and the object vehicle1by using collation between a result of position determination by the satellites and a map, whether the traveling lane is changed may be judged.

This makes it possible to make the determination of the boundary-line crossing according to whether or not the lane on which the object vehicle1has traveled at a time at which that data is last valid, is the same as the lane on the map on which the object vehicle1is currently traveling. When the sensor is of this type, whether “the observed data is valid” or not can be determined depending on the reliability indicative of the quality of the position-determination signals of the satellites. According also to this exemplary determination method, by the comparison between the last-valid observed data and the current observed data, it is possible to avoid a situation where erroneous crossing determination is made, even when the accuracy of the observed data is reduced temporarily.

Further, in the above determination, an angle of the traveling direction of the object vehicle1with respect to the boundary line may be used in combination. For example, the determination may be made in such a manner that as the traveling direction angle with respect to the boundary line becomes closer to the right angle, the conditions for the boundary-line crossing determination are relaxed.

Further, in each determination method described above, the observed data that is related to both of the nearest left-side boundary line and the nearest right-side boundary line, or that is related to only one of them, may be used. For example, when the crossing determination is made on the nearest right-side boundary line on the basis of the observed data related to the nearest right-side boundary line, the observed data related to the nearest left-side boundary is not necessarily used. Note that, in this step, whether the vehicle has crossed the right-side boundary line or the left-side boundary line is determined additionally.

In Step ST102, in response to the determination result in Step ST101, the first boundary-line calculation determination unit101makes conditional branching of processing. In Step ST102, whether the first crossing (determination) flag is being set or not is determined. If the first crossing (determination) flag is not being set (judgement is NO), the flow moves to Step ST201.

In Step ST102, if it is determined that the first crossing (determination) flag is being set (judgement is YES), the flow moves to Step ST103. In Step ST103, the first boundary-line calculation determination unit101stores the crossing time T1of the object vehicle1determined to have crossed the boundary line on the basis of the first distance calculated using signals from the first sensor201. Note that the crossing time T1is given as a value that is kept without being erased even after the completion of the entire processing ofFIG.7andFIG.8. Further, an observation start time of the first sensor201is set as the initial value of the crossing time T1.

In Step ST201, the second boundary-line calculation determination unit102calculates the second distance between the object vehicle1and the boundary line on the basis of the observed data of the second sensor202. Then, it determines whether or not the object vehicle1at the current time has crossed the boundary line, on the basis of the thus-calculated second distance. When it determines that the vehicle has crossed the boundary line, a second crossing flag is set.

Like in Step ST101, the determination of boundary-line crossing in Step ST201may also be made using, for example, variation in the value of the distance between the boundary line and the object vehicle1. Further, like in Step ST101, the determination of boundary-line crossing may be made by the comparison of the latest observed data that is valid. Further, like in Step ST101, the determination of boundary-line crossing may be made using observed data special to the second sensor202. Note that, in this step, whether the vehicle has crossed the right-side boundary line or the left-side boundary line is determined additionally.

In Step ST202, in response to the determination result in Step ST201, the second boundary-line calculation determination unit102makes conditional branching of processing. In Step ST202, whether the second crossing (determination) flag is being set or not is determined. If the second crossing (determination) flag is not being set (judgement is NO), the flow moves to Step ST204.

In Step ST202, if it is determined that the second crossing (determination) flag is being set (judgement is YES), the flow moves to Step ST203. In Step ST203, the second boundary-line calculation determination unit102stores the crossing time T2of the object vehicle1determined to have crossed the boundary line on the basis of the second distance calculated using signals from the second sensor202. Note that the crossing time T2is given as a value that is kept without being erased even after the completion of the entire processing ofFIG.7andFIG.8. Further, an observation start time of the second sensor202is set as the initial value of the crossing time T2.

In Step ST204, the first crossing (determination) flag and the second crossing (determination) flag are cleared. Then, the flow moves to Step ST301inFIG.8.

In Step ST301inFIG.8, the traveling lane matching unit113determines whether or not the first boundary-line calculation determination unit101has made the determination of boundary-line crossing, at a time near the current time, earlier than the second boundary-line calculation determination unit102. Specifically, this determination is deemed true if the difference between the current time and the crossing time T1is less than a matching duration time TP1(meaning that the crossing time T1has been updated recently) and the value resulting from subtracting the crossing time T2from the crossing time T1is more than a matching prohibition time TP2(meaning that, unlike the crossing time T1, the crossing time T2has not been updated from the matching prohibition time TP2before).

In Step ST302, the traveling lane matching unit113determines whether or not the second boundary-line calculation determination unit102has made the determination of boundary-line crossing, at a time near the current time, earlier than the first boundary-line calculation determination unit101. Specifically, this determination is deemed true if the difference between the current time and the crossing time T2is less than the matching duration time TP1(meaning that the crossing time T2has been updated recently) and the value resulting from subtracting the crossing time T1from the crossing time T2is more than the matching prohibition time TP2(meaning that, unlike the crossing time T2, the crossing time T1has not been updated from the matching prohibition time TP2before).

In this Step ST302, if the determination is true (judgement is YES), the flow moves to Step ST402. In Step ST302, if the determination is false (judgement is NO), the flow moves to Step ST403.

In Step ST401, the traveling lane matching unit113adjusts for matching, the second distance based on the observed data of the second sensor202, by using the first distance based on the observed data of the first sensor201. Accordingly, the traveling lane of the object vehicle1based on the observed data of the second sensor202is adjusted so as to be the same as the traveling lane of the object vehicle1based on the observed data of the first sensor201. The first distance based on the observed data of the first sensor201is not adjusted for matching.

Because the matching processing is applied to the second distance based on the observed data of the second sensor202, the second distance after the crossing time T1is substituted with the first distance as exemplified inFIG.6. According to this matching, in the observed data of all of the sensors, the traveling lanes of the object vehicle1are uniformized to have the boundary line that the vehicle has crossed at the crossing time T1. Similar matching processing is also applied when the object vehicle1is determined to have crossed the left-side boundary line. According to this Step ST401, the second distance adjusted for matching and the first distance not adjusted for matching are transferred to the position estimation unit114.

In Step ST402, the traveling lane matching unit113adjusts for matching, the first distance based on the observed data of the first sensor201, by using the second distance based on the observed data of the second sensor202. Accordingly, the traveling lane of the object vehicle1based on the observed data of the first sensor201is adjusted so as to be the same as the traveling lane of the object vehicle1based on the observed data of the second sensor202. The second distance based on the observed data of the second sensor202is not adjusted for matching.

Because the matching processing is applied to the first distance based on the observed data of the first sensor201, the first distance after the crossing time T2is substituted with the second distance. According to this matching, in the observed data of all of the sensors, the traveling lanes of the object vehicle1are uniformized to have the boundary line that the vehicle has crossed at the crossing time T2. Similar matching processing is also applied when the object vehicle1is determined to have crossed the left-side boundary line. According to this Step ST402, the first distance adjusted for matching and the second distance not adjusted for matching are transferred to the position estimation unit114.

In Step ST403, the traveling lane matching unit113executes neither the matching processing of the first distance nor that of the second distance. The first distance that is based on the observed data of the first sensor201and not adjusted for matching, and the second distance that is based on the observed data of the second sensor202and not adjusted for matching, are transferred to the position estimation unit114.

In Step ST501, the position estimation unit114receives the first distance and the second distance that are based on the observed data of the respective sensors and are each being adjusted or not adjusted for matching in one of Step ST401, Step ST402and Step ST403. The matching processing in Step ST401and Step ST402is applied to the first distance and the second distance to be transferred to the position estimation unit114. In contrast, the calculation of the first distance and the determination on whether or not the vehicle has crossed the boundary line, to be executed by the first boundary-line calculation determination unit101, as well as the calculation of the second distance and the determination on whether or not the vehicle has crossed the boundary line, to be executed by the second boundary-line calculation determination unit102, are continued without being affected by the matching processing.

Using the first distance and the second distance, the position estimation unit114calculates the estimated position of the object vehicle1. For this calculation of the estimated position, an already-existing technique of sensor fusion is employed. For example, such weights each corresponding to the accuracy of each of the sensors may be set to the respective observed data, to thereby determine, using these weights, a weighted average value of the first distance according to the observed data of the first sensor201and the second distance according to the observed data of the second sensor202, as the estimated position of the object vehicle1. For further example, as disclosed in Patent Document 1, such processing may be performed that estimates the position of the vehicle so that its deviations from the first distance according to the observed data of the first sensor201and the second distance according to the observed data of the second sensor202become minimum.

By the thus-configured vehicle position estimation device100according to Embodiment 1, it is possible to achieve a following effect. In the vehicle position estimation device100, whether or not the object vehicle1has crossed the boundary line is determined on the basis of the distances calculated in the first boundary-line calculation determination unit101and the second boundary-line calculation determination unit102by using the observed data of the respective sensors. Then, in the traveling lane matching unit113, on the basis of the determination on whether or not the object vehicle1has crossed the boundary line, it is possible to perform matching processing by which the traveling lanes of the object vehicle1based on the distances calculated using the observed data of the respective sensors, are uniformized. Thus, the different boundary lines are restricted from being erroneously regarded as the same boundary line by the observed data of the respective sensors. Further, the position estimation unit114estimates the position of the object vehicle1on the basis of the first distance or the second distance adjusted for matching. Accordingly, there is achieved an effect of restricting the accuracy of position estimation of the object vehicle1from being degraded, even when the object vehicle1makes a traveling lane change.

In another aspect, in the first boundary-line calculation determination unit101/the second boundary-line calculation determination unit102, whether or not the object vehicle1has crossed the boundary line is determined by the comparison between the observed data at the time signals inputted from the first sensor201/the second sensor202were last valid, and the valid observed data at the current time. This makes it possible, when the observed data of the first sensor201or the second sensor202becomes temporarily invalid, to prevent the object vehicle1from being erroneously determined to have crossed the boundary line.

In the traveling lane matching unit113, it is possible to perform matching processing for uniformizing: the respective determination timings of the first boundary-line calculation determination unit101and the second boundary-line calculation determination unit102at which the object vehicle1is determined to have crossed the boundary line; and their recognized traveling lanes on which the object vehicle1is traveling. As a result, there is achieved an effect of restricting the accuracy of position estimation of the object vehicle1from being degraded, even when the object vehicle1is crossing the boundary line.

<Configuration of Vehicle Position Estimation Device>

A vehicle position estimation device100according to Embodiment 2 corresponds to that obtained by changing the processing details of the vehicle position estimation device100according to Embodiment 1 through software change. With respect to the hardware, the configuration ofFIG.1can be employed because no change is necessary.

FIG.9is a set of graphs showing distances to boundary lines according to the first sensor201and the second sensor202during a lane change of the vehicle1, according to Embodiment 2.FIG.10is a first set of graphs showing matching between the distances to the boundary lines according to the first sensor201and the second sensor202during the lane change of the vehicle1, according to Embodiment 2.FIG.11is a second set of graphs showing matching between the distances to the boundary lines according to the first sensor201and the second sensor202during the lane change of the vehicle, according to Embodiment 2.

Description will be made about a case where the object vehicle1changes the traveling lane from the left lane to the right lane as shown inFIG.3. The ordinate of the upper-side graph shown inFIG.9represents a distance to the left-side boundary line according to the first sensor201. The ordinate of the lower-side graph shown inFIG.9represents a distance to the right-side boundary line according to the second sensor202.

With respect to the distance to the left-side boundary line, a distance in the leftward direction with reference to the center line of the object vehicle1and relative to the traveling direction of the object vehicle1, is regarded as positive. With respect to the distance to the right-side boundary line, a distance in the rightward direction with reference to the center line of the object vehicle1and relative to the traveling direction of the object vehicle1, is regarded as negative. In the case shown inFIG.9, because of the traveling lane change, the line nearest and left next to the object vehicle1, is changed from the boundary line A to the boundary line B. Because of the traveling lane change, the line nearest and right next to the object vehicle1, is changed from the boundary line B to the boundary line C.

The distance to the right-side boundary line B according to the second sensor202shown on the lower side inFIG.9reaches zero at a time T2and thereafter, its sign is reversed. Namely, this means that, although the distance taken up to the boundary line B was a distance in the rightward direction relative to the traveling direction of the object vehicle1, the boundary line B has moved to be located on the left side of the object vehicle1after the time T2.

Since the position of the boundary line is switched from right to left, the second boundary-line calculation determination unit102can recognize that the time T2is the crossing time. The traveling lane matching unit113adjusts for matching, the distance to the left-side boundary line according to the first sensor201, on the basis of the crossing time T2.

As shown inFIG.10, using distances to the right-side boundary line from the time T2to a time T1according to the second sensor202, the distance to the left-side boundary line according to the first sensor201is adjusted for matching. According to this matching, as shown inFIG.11, the distance to the left-side boundary line according to the first sensor201can be matched with such data in which the distance changes abruptly at the time T1.

Further, as shown inFIG.11, the distance to the right-side boundary line according to the second sensor202may also be adjusted for matching by using the distance to the boundary line C right next to the crossed boundary line B. According to this matching, the distance to the right-side boundary line according to the second sensor202can be matched with such data in which the distance changes abruptly at the time T2.

According to the above processing, even when the object vehicle1makes a traveling lane change, it is eliminated, before the input stage to the position estimation unit114, that mutually different boundary lines are erroneously regarded as the same boundary line by the first sensor201and the second sensor202. More detailed processing will be described later. Note that, in the above example, the description has been made assuming that the time T2<the time T1(the time T2comes earlier); however, this is not limitative. Namely, an effect similar to the above can be exhibited even when the boundary-line crossing of the object vehicle1is determined firstly by using the first distance according to the first sensor201.

<Processing by Vehicle Position Estimation Device>

FIG.12is a first flowchart showing processing by the vehicle position estimation device100according to Embodiment 2.FIG.13is a second flowchart showing processing by the vehicle position estimation device100, which shows steps subsequent toFIG.12.

FIG.12andFIG.13are flowcharts in which shown are operations of the first boundary-line calculation determination unit101, the second boundary-line calculation determination unit102, the traveling lane matching unit113and the position estimation unit114, from when the signals of the observed data at the current time are inputted from the respective sensors until when the estimated position of the object vehicle1at the current time is outputted. The processing of the flowchart ofFIG.12is executed every fixed period of time (for example, every 10 ms). It is allowed that the processing of the flowchart ofFIG.12is not executed every fixed period of time but executed in response to an occurrence of an event, such as, at every time the vehicle travels a fixed distance, at every time the sensor acquires new information, or at the time an instruction is given from the outside.

The flowchart ofFIG.12according to Embodiment 2 corresponds to that obtained by changing Step ST101and Step ST201in the flowchart ofFIG.7according to Embodiment 1 to Step ST111and Step ST211. The flowchart ofFIG.13corresponds to that obtained by changing Step ST401and Step ST402in the flowchart ofFIG.8according to Embodiment 1 to Step ST411and Step ST412. In the following, description will be made focusing on the different portions of processing.

InFIG.12, after the processing is started, in Step ST111, the first boundary-line calculation determination unit101calculates the first distance between the object vehicle1and the boundary line on the basis of the observed data of the first sensor201. Then, it determines whether or not the object vehicle1at the current time has crossed the boundary line, on the basis of the thus-calculated first distance. When it determines that the vehicle has crossed the boundary line, a first crossing flag is set.

This determination of boundary-line crossing may be made using, for example, variation in the value of the distance between the boundary line and the object vehicle1. The occurrence of the boundary-line crossing may be determined when the first distance varies more than a predetermined crossing determination distance within a predetermined crossing determination time. Further, it is allowed to determine that the object vehicle1has crossed the boundary line, when the position of the boundary line is switched between right and left with respect to the object vehicle1.

For example, the first boundary-line calculation determination unit101may execute calculation of a first right-side distance between the object vehicle1and a boundary line on the right side of the object vehicle1, and determination based on the first right-side distance on whether or not the object vehicle1has crossed the boundary line on the right side thereof.

Instead, the first boundary-line calculation determination unit101may execute calculation of a first left-side distance between the object vehicle1and a boundary line on the left side of the object vehicle1, and determination based on the first left-side distance on whether or not the object vehicle1has crossed the boundary line on the left side thereof. Further, instead, the first boundary-line calculation determination unit101may execute both of: the calculation of the first right-side distance and the determination on whether or not the object vehicle1has crossed the boundary line on the right side thereof; and the calculation of the first left-side distance and the determination on whether or not the object vehicle1has crossed the boundary line on the left side thereof.

In Step ST211, the second boundary-line calculation determination unit102calculates the second distance between the object vehicle1and the boundary line on the basis of the observed data of the second sensor202. Then, it determines whether or not the object vehicle1at the current time has crossed the boundary line, on the basis of the thus-calculated second distance. When it determines that the vehicle has crossed the boundary line, a second crossing flag is set.

Like in Step ST111, the determination of boundary-line crossing in Step ST211may also be made using, for example, variation in the value of the distance between the boundary line and the object vehicle1. The occurrence of the boundary-line crossing may be determined when the second distance varies more than a predetermined crossing determination distance within a predetermined crossing determination time. Further, it is allowed to determine that the object vehicle1has crossed the boundary line, when the position of the boundary line is switched between right and left with respect to the object vehicle1.

For example, the second boundary-line calculation determination unit102may execute calculation of a second right-side distance between the object vehicle1and a boundary line on the right side of the object vehicle1, and determination based on the second right-side distance on whether or not the object vehicle1has crossed the boundary line on the right side thereof. Instead, the second boundary-line calculation determination unit102may execute calculation of a second left-side distance between the object vehicle1and a boundary line on the left side of the object vehicle1, and determination based on the second left-side distance on whether or not the object vehicle1has crossed the boundary line on the left side thereof. Further, instead, the second boundary-line calculation determination unit102may execute both of: the calculation of the second right-side distance and the determination on whether or not the object vehicle1has crossed the boundary line on the right side thereof; and the calculation of the second left-side distance and the determination on whether or not the object vehicle1has crossed the boundary line on the left side thereof.

In Step ST411inFIG.13, with respect to the first distance based on the observed data of the first sensor201and the second distance based on the observed data of the second sensor202, the traveling lane matching unit113starts adjusting the first distance and the second distance for matching, each by using a distance to a different boundary line. Specifically, it executes matching processing by using a distance to the adjacent boundary line, as described usingFIG.11. In Step ST412, with respect to the first distance based on the observed data of the sensor201and the second distance based on the observed data of the second sensor202, the traveling lane matching unit113starts adjusting the first distance and the second distance for matching, each by using a distance to a different boundary line.

For example, in the case where one of the first boundary-line calculation determination unit101and the second boundary-line calculation determination unit102determines that the object vehicle1has crossed a boundary line from left to right, the traveling lane matching unit113may start adjusting the first right-side distance and the second right-side distance for matching, by using a distance between the object vehicle1and a boundary line right next to the boundary line that the object vehicle1has crossed. Instead, in this case, the traveling lane matching unit113may start adjusting the first left-side distance and the second left-side distance for matching, by using a distance between the object vehicle1and the boundary line that the object vehicle1has crossed.

Further, in the case where one of the first boundary-line calculation determination unit101and the second boundary-line calculation determination unit102determines that the object vehicle1has crossed a boundary line from right to left, the traveling lane matching unit113may start adjusting the first right-side distance and the second right-side distance for matching, by using a distance between the object vehicle1and the boundary line that the object vehicle1has crossed. Instead, in this case, the traveling lane matching unit113may start adjusting for matching, the first left-side distance and the second left-side distance, by using a distance between the object vehicle1and a boundary line left next to the boundary line that the object vehicle1has crossed.

By the thus-configured vehicle position estimation device100according to Embodiment 2, it is also possible to achieve an effect similar to that in Embodiment 1. The position estimation unit114estimates the position of the object vehicle1on the basis of the first distance and/or the second distance adjusted for matching. Accordingly, there is achieved an effect of restricting the accuracy of position estimation of the object vehicle1from being degraded, even when the object vehicle1makes a traveling lane change.

<Configuration of Vehicle Position Estimation Device>

FIG.14is a configuration diagram of a vehicle position estimation device100aaccording to Embodiment 3. The configuration diagram ofFIG.14according to Embodiment 3 differs from the configuration diagram of the vehicle position estimation device100ofFIG.1according to Embodiment 1 only in that an input signal from a traveling-lane-change operation information acquisition unit213is added.

In Embodiment 1, the first boundary-line calculation determination unit101and the second boundary-line calculation determination unit102are configured to determine whether or not the object vehicle has crossed a boundary line, on the basis of the signals of the first sensor201and the second sensor202, respectively. However, such an error may occur in which, even though the object vehicle1actually makes no lane change, the vehicle is determined to have crossed the boundary line because of noise or the like in the observed data of the sensor. When such a determination error occurs, the accuracy of the estimated position of the object vehicle1to be outputted by the position estimation unit114is degraded significantly.

For that reason, in the vehicle position estimation device100aaccording to Embodiment 3, the traveling-lane-change operation information acquisition unit213that acquires information of an operation at the time the object vehicle1makes a lane change is provided, and its output is used to make the determination. Examples of the information to be acquired by the traveling-lane-change operation information acquisition unit213may include: information about whether a winker lamp of the object vehicle1is lit or not; a steering angle of the object vehicle1; a yaw rate of the object vehicle1; biological data of the driver of the object vehicle1; and the like. According to this configuration, it is possible to reduce the frequency of occurrence of the error in which, even though the object vehicle1actually makes no lane change, the vehicle is determined to have crossed a boundary line. As a result, it is possible to restrict the accuracy of position estimation of the object vehicle1from being degraded.

A first boundary-line calculation determination unit101aand a second boundary-line calculation determination unit102ause, as their inputs, the lane-change operation information outputted from the traveling-lane-change operation information acquisition unit213. The first boundary-line calculation determination unit101auses, as its inputs, the observed data from the first sensor201and the lane-change operation information from the traveling-lane-change operation information acquisition unit213, and then outputs to the traveling lane matching unit113, the first distance from the object vehicle1to a boundary line and the determination result on whether or not the object vehicle1has crossed the boundary line.

The second boundary-line calculation determination unit102auses, as its inputs, the observed data from the second sensor202and the lane-change operation information from the traveling-lane-change operation information acquisition unit213, and then outputs to the traveling lane matching unit113, the second distance from the object vehicle1to a boundary line and the determination result on whether or not the object vehicle1has crossed the boundary line.

<Processing by Vehicle Position Estimation Device>

FIG.15is a first flowchart showing processing by the vehicle position estimation device100aaccording to Embodiment 3. Processing subsequent to the flowchart ofFIG.15is shown inFIG.8.

FIG.15andFIG.8are flowcharts in which shown are operations of the first boundary-line calculation determination unit101a, the second boundary-line calculation determination unit102a, the traveling lane matching unit113and the position estimation unit114, from when signals at the current time are inputted from the first sensor201, the second sensor202and the traveling-lane-change operation information acquisition unit213until when the estimated position of the object vehicle1at the current time is outputted. The processing of the flowchart ofFIG.15is executed every fixed period of time (for example, every 10 ms). It is allowed that the processing of the flowchart ofFIG.15is not executed every fixed period of time but executed in response to an occurrence of an event, such as, at every time the vehicle travels a fixed distance, at every time the sensor acquires new information, or at the time an instruction is given from the outside.

The flowchart ofFIG.15according to Embodiment 3 corresponds to that obtained by changing Step ST101and Step ST201in the flowchart ofFIG.7according to Embodiment 1 to Step ST121and Step ST221. In the following, description will be made focusing on the different portions of processing.

InFIG.15, after the processing is started, in Step ST121, the first boundary-line calculation determination unit101acalculates the first distance between the object vehicle1and the boundary line on the basis of the observed data of the first sensor201. Then, it determines whether or not the object vehicle1at the current time has crossed the boundary line, on the basis of the thus-calculated first distance and the lane-change operation information from the traveling-lane-change operation information acquisition unit213.

This determination of boundary-line crossing is performed using the determination method described in Embodiment 1 provided that a situation that a winker lamp is lit by the object vehicle1, for example, is added to the conditions for determining the boundary-line crossing. That is, when the object vehicle1is assumed to have crossed the boundary line on the basis of the first distance and further, the winker lamp in the same direction as the crossing direction of the object vehicle1is lit, the object vehicle1is determined to have crossed the boundary line. When it is determined to have crossed the boundary line, a first crossing flag is set.

Note that, as another type of lane-change operation information, such a situation that steering by a specified angle or more is made toward the crossing direction, may be added to the conditions for determining the boundary line crossing of the object vehicle1, by use of the steering angle sensor of the object vehicle1. Further, when the yaw rate of the object vehicle1is to be used, such a situation that the absolute value of the yaw rate of the object vehicle1is a fixed value or more, may be added to the conditions for determining the boundary line crossing of the object vehicle1. Further, when the biological data of the driver of the object vehicle1is to be used as another type of lane-change operation information, such a situation that, from the biological data, the driver of the object vehicle1is determined to have an intention to make a lane change, may be added to the conditions for determining the boundary line crossing of the object vehicle1.

In Step ST221, the second boundary-line calculation determination unit102acalculates the second distance between the object vehicle1and the boundary line on the basis of the observed data of the second sensor202. Then, it determines whether or not the object vehicle1at the current time has crossed the boundary line, on the basis of the thus-calculated second distance and the lane-change operation information from the traveling-lane-change operation information acquisition unit213.

Like in Step ST121, this determination of boundary-line crossing is performed by adding the situation that a winker lamp is lit by the object vehicle1, for example, to the conditions for determining the boundary-line crossing. That is, when the object vehicle1is assumed to have crossed the boundary line on the basis of the second distance and further, the winker lamp in the same direction as the crossing direction of the object vehicle1is lit, the object vehicle1is determined to have crossed the boundary line. When it is determined to have crossed the boundary line, a second crossing flag is set. In addition, like in Step ST121, the other type of lane-change operation information may be used as the lane-change operation information.

By the thus-configured vehicle position estimation device100aaccording to Embodiment 3, the determination of boundary-line crossing is performed using the lane-change operation information outputted from the traveling-lane-change operation information acquisition unit213. With this configuration, it is possible to reduce the occurrence of error in which, even though the object vehicle1actually makes no lane change, the vehicle is determined to have crossed the boundary line because of noise or the like in the observed data of the sensor. Accordingly, there is achieved an effect of restricting the accuracy of position estimation of the object vehicle1from being degraded.

<Configuration of Vehicle Position Estimation Device>

FIG.16is a configuration diagram of a vehicle position estimation device100baccording to Embodiment 4. In Embodiment 1, such a configuration is employed in which the position of the object vehicle1is estimated on the basis of the observed data of the first sensor201and the second sensor202. However, there is conceivable a case where the sensor201and the sensor202both become unusable due to an internal factor in the observation environment or the device. In addition, such a case may arise where the first sensor201and the second sensor202are both degraded in observation accuracy, significantly.

For these reasons, the vehicle position estimation device100baccording to Embodiment 4 has a configuration in which the position of the object vehicle1is estimated on the basis of the observed data of N-number of sensors (N denotes an integer of three or more) and using N-number of boundary-line calculation determination units. With this configuration, it is possible to achieve an effect of improving tolerability to the degradation in accuracy and the failure of each of the sensors.

InFIG.16, the observed data outputted from the Nth sensor20N (N denotes an integer of 1 to NS) is used as the input. Here, like the first sensor201and the second sensor202described in Embodiment 1, the Nth sensor20N may be of any type so long as it has a function of acquiring a relative positional relationship between the object vehicle1and a boundary line.

The Nth boundary-line calculation determination unit10N calculates a distance to a boundary line on the basis of the observed data from the Nth sensor, and determines whether or not the object vehicle1has crossed the boundary line, on the basis of the thus-calculated distance. It outputs the calculated distance and the determination result to a traveling lane matching unit113a. Further, it may add, as its input, lane-change operation information from a traveling-lane-change operation information acquisition unit213(not illustrated).

With respect to the respective outputs from the N-number of boundary-line calculation determination units, the traveling lane matching unit113amakes adjusting one or more calculated distances for matching so that the respective crossing times of the object vehicle1are matched with each other and the respective traveling lanes on which the object vehicle1is traveling are matched with each other, and then it outputs the thus-adjusted distance and the distance not adjusted for matching, to a position estimation unit114a.

Whether or not each calculated distance is to be adjusted for matching, is determined in the traveling lane matching unit113a. With respect to the output from the traveling lane matching unit113a, the position estimation unit114acalculates the estimated position of the object vehicle1on the basis of the respective distances calculated from the observed data of the first to Nth sensors and the distance adjusted for matching.

<Processing by Vehicle Position Estimation Device>

FIG.17is a flowchart showing processing by the vehicle position estimation device100baccording to Embodiment 4. The processing of the flowchart ofFIG.17is executed every fixed period of time (for example, every 10 ms). It is allowed that the processing of the flowchart ofFIG.17is not executed every fixed period of time but executed in response to an occurrence of an event, such as, at every time the vehicle travels a fixed distance, at every time the sensor acquires new information, or at the time an instruction is given from the outside.

In Step ST601inFIG.17, the integer N (counter N) indicative of the Nth sensor is initialized to 1. In Step ST602, the Nth boundary-line calculation determination unit10N calculates the distance to the boundary line on the basis of the observed data of the Nth sensor20N. Then, the Nth boundary-line calculation determination unit10N determines whether or not the object vehicle1at the current time has crossed the boundary line, on the basis of the thus-calculated distance. This determination of boundary-line crossing is established by processing similar to that described at Step ST101or Step ST201in Embodiment 1. When it determines that the vehicle has crossed the boundary line, an Nth crossing flag is set.

In Step ST603, whether the Nth crossing flag is being set or not is determined. If it is being set (judgement is YES), the flow moves to Step ST604. If the Nth crossing flag is not being set (judgement is NO), the flow moves to Step ST605.

In Step ST604, the Nth boundary-line calculation determination unit stores a crossing time TN (N denotes an integer of 1 to NS) of the object vehicle1determined to have crossed the boundary line on the basis of the calculated distance. The crossing time TN is given as a value that is kept without being erased even after the completion of the entire processing ofFIG.17. Further, an observation start time of the Nth sensor is set as the initial value of TN. In Step ST610subsequent to Step ST604, the Nth crossing flag is cleared.

In Step ST605, whether or not the integer N (counter N) indicative of an Nth order is equal to the total number NS of the sensors, is determined. If this determination is true, the loop related to the sensor N is terminated and the flow moves to Step ST607. If this determination is false, the loop is to be continued and the flow moves to Step ST606.

In Step ST606, the integer N (counter N) indicative of an Nth order is incremented by one. Thereafter, the flow moves to Step ST602, so that the calculation and the determination by the next Nth boundary-line calculation determination unit are executed.

In Step ST607, the traveling lane matching unit113aextracts every sensor number M of the sensor with which the vehicle is already determined to have crossed the boundary line. Here, M is given as an integer not less than 1 and not more than NS. Note that the total number of extracted M may be zero or plural number. Specifically, every sensor number M of the sensor with which the difference between the current time and the crossing time TM is less than the matching duration time TP1, is extracted. The sensor number M extracted in this step will be used in the next Step ST608.

In Step St608, the traveling lane matching unit113executes matching processing of the distance to the boundary line based on the observed data of each of the sensors other than a sensor having the sensor number M. This makes it possible to cause the traveling lanes (on which the object vehicle1is traveling) based on the observed data of the sensors other than the sensor having the sensor number M, to be matched with each other. Here, the sensor number M means every sensor number M extracted in Step ST607. The matching processing of the distance is the same as the processing described at Step ST401and Step ST402inFIG.8according to Embodiment 1. The matching target distance may be set to a representative value of the distances calculated from the observed data of the sensors having the sensor number M, or a most frequent value thereof, or an average value thereof.

In Step ST609, the position estimation unit114aestimates the position of the object vehicle1by using the distance calculated using the observed data of the respective sensors, and adjusted for matching or not adjusted for matching in Step ST608. This processing is the same as the processing described at Step ST501inFIG.8according to Embodiment 1. For the processing by the position estimation unit114a, an already-existing technique of sensor fusion may be employed.

Note that, in this example ofFIG.17, a case is described where the integer N is incremented one by one from1to NS. However, inFIG.17, it is not necessarily required to increment (or decrement) the integer N in this manner. It suffices to design so that the integer N can take every value from1to NS.

By the thus-configured vehicle position estimation device100baccording to Embodiment 4, although the observed data of the N-number of sensors is used, it is possible to restrict the accuracy of position estimation of the object vehicle1from being degraded at the time the vehicle makes a lane change. Further, since the position of the object vehicle1is calculated on the basis of the observed data of the N-number sensors, there is achieved an effect of improving tolerability to the degradation in accuracy and the failure of each of the sensors.

When there is disagreement between the outputs of two sensors, namely, the first sensor201and the second sensor202, and between the calculation results and determination results of the first boundary-line calculation determination unit101and the second boundary-line calculation determination unit102, a case is conceivable where one of them is failed. In this occasion, a case may arise where it is difficult to determine which one of the results is to be used. Even in that case, when there are provided three or more sensors and three or more boundary-line calculation determination units, it is possible to obtain reliable calculation result and determination result by majority decision, to thereby improve the reliability of the vehicle position determination device100b.

In this application, a variety of exemplary embodiments and examples are described; however, every characteristic, configuration or function that is described in one or more embodiments, is not limited to being applied to a specific embodiment, and may be applied singularly or in any of various combinations thereof to another embodiment. Accordingly, an infinite number of modified examples that are not exemplified here are supposed within the technical scope disclosed in the present description. For example, such cases shall be included where at least one configuration element is modified; where at least one configuration element is added or omitted; and furthermore, where at least one configuration element is extracted and combined with a configuration element of another embodiment.