Driving assistance devices

Abstract

A driving assistance device (3) comprises: an other-vehicle information storage unit (32) storing other-vehicle time series information about another vehicle; a state-of-motion estimation unit (34) that estimates the state of motion of the other vehicle; a correction interval detection unit (33) that detects a correction interval on the basis of confidence information included in the other-vehicle time series information; and a state-of-motion correction unit (35) that simulates and outputs a travel trajectory on the basis of the state of motion of the other vehicle. The state-of-motion correction unit corrects the state of motion by generating a correction candidate for each piece of information included in the state of motion of the other vehicle, calculates an evaluation value for the degree of agreement between the travel trajectory of the other vehicle, as simulated on the basis of the corrected state of motion, and map information that includes lane information, and outputs the travel trajectory with the highest degree of agreement with the map information on the basis of the calculated evaluation value for the degree of agreement.

Description

[Technical Field]

[0001] The present application relates to a driving assistance device. [Background technology]

[0002] There is a technology called V2X (Vehicle to Everything) that can improve the safety of automobile driving. V2X is a technology that allows mutual communication between vehicles and devices that may affect the vehicle. In particular, driving assistance devices that exchange information between vehicles equipped with communication devices are being developed to improve safety while driving.

[0003] A conventional driving assistance device has disclosed a technology that receives position information of another vehicle, performs map matching of the current position of the other vehicle based on this information and map information, and determines the possibility of a collision based on the map-matched current position of the other vehicle and the current position of the vehicle itself (see, for example, Patent Document 1). Note that map matching means that, since the received position information contains errors, the position information is corrected to a position that is thought to be optimal using map information to identify the current position. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-352610 Summary of the Invention [Problem to be solved by the invention]

[0005] Conventional driving assistance devices have the problem that they can only perform map matching to identify the current location of other vehicles on a road-by-road basis, and are unable to perform map matching to identify the lane in which the other vehicle is traveling.

[0006] The present application has been made to solve the above-mentioned problems, and aims to provide a driving assistance device that can perform map matching to identify the lane in which other vehicles are traveling. [Means for solving the problem]

[0007] The driving assistance device of the present application includes an other vehicle information storage unit that acquires and stores other vehicle time-series information of other vehicles traveling within a communication range with the host vehicle via an inter-vehicle communication device, a motion state estimation unit that estimates a motion state of the other vehicle based on the other vehicle time-series information stored in the other vehicle information storage unit, and a motion state correction unit that simulates a travel trajectory of the other vehicle from the motion state of the other vehicle estimated by the motion state estimation unit and outputs the simulated travel trajectory of the other vehicle. The motion state includes time-series direction information, speed information, acceleration information, and angular velocity information of the vehicle orientation of the other vehicle in a horizontal plane of the other vehicle, and the motion state correction unit generates correction candidates for each piece of information included in the motion state of the other vehicle to correct the motion state, calculates a matching evaluation value between the simulated travel trajectory of the other vehicle from the corrected motion state and map information including lane information, and outputs the travel trajectory that most closely matches the map information based on the calculated matching evaluation value. [Effects of the Invention]

[0008] In the driving assistance device of the present application, the motion state correction unit generates correction candidates for each piece of information included in the motion state of the other vehicle to correct the motion state, calculates a matching evaluation value between the simulated driving trajectory of the other vehicle from this corrected motion state and map information including lane information, and outputs the driving trajectory that has the highest matching degree with the map information based on the calculated matching evaluation value, thereby making it possible to perform map matching to identify the lane in which the other vehicle is driving. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a configuration diagram of a vehicle equipped with a driving assistance device according to a first embodiment. [Figure 2] 1 is a configuration diagram of a driving assistance device according to a first embodiment. [Figure 3]5 is a flowchart showing a method for outputting a travel trajectory of another vehicle in a motion state correction unit of the driving assistance device according to the first embodiment. [Figure 4] 4 is a diagram showing an evaluation function for calculating a coincidence evaluation value in the motion state correction unit of the driving assistance device according to the first embodiment. FIG. [Figure 5] 1 is a diagram illustrating an example of a hardware configuration of a driving assistance device according to a first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, a driving assistance device according to an embodiment of the present invention will be described in detail with reference to the drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.

[0011] Embodiment 1 Fig. 1 is a configuration diagram of a host vehicle equipped with a driving assistance device according to embodiment 1. As shown in Fig. 1, a host vehicle 10 is equipped with a positioning device 1, an inter-vehicle communication device 2, a driving assistance device 3, an alarm device 4, and a cruise control device 5.

[0012] The positioning device 1 measures the position, traveling direction, etc. of the vehicle 10 using a GNSS (Global Navigation Satellite System) receiver, various sensors, etc. mounted on the vehicle 10. The positioning device 1 outputs vehicle information such as the position and traveling direction of the vehicle 10 that has been positioned to the inter-vehicle communication device 2 and the driving assistance device 3. The positioning device 1 corrects the positioning results by referring to map information as necessary.

[0013] The inter-vehicle communication device 2 adds the vehicle identification information of the subject vehicle 10 to the subject vehicle information of the subject vehicle 10 input from the positioning device 1 and transmits the information to the multiple other vehicles 11. The inter-vehicle communication device 2 also receives other vehicle information such as the position, speed, and traveling direction of the other vehicle 11, including the vehicle identification information, from the multiple other vehicles 11. The inter-vehicle communication device 2 then outputs the received vehicle identification information and other vehicle information to the driving assistance device 3. Note that the other vehicles referred to here are multiple vehicles that are present within a range in which the inter-vehicle communication device 2 can communicate with the subject vehicle.

[0014] The subject vehicle information and other vehicle information include not only information on the position, speed, and direction of travel of the vehicle, but also reliability information that numerically represents the reliability of the information.

[0015] The driving assistance device 3 determines the possibility of a collision between the subject vehicle and another vehicle based on the subject vehicle information input from the positioning device 1 and the other vehicle information input from the vehicle-to-vehicle communication device 2, following the determination steps described below. If collision avoidance action is required based on the possibility of a collision between the subject vehicle and another vehicle, the driving assistance device 3 outputs an alarm command to the alarm device 4 and the cruise control device 5. Note that the driving assistance device 3 does not necessarily have to determine the possibility of a collision between the subject vehicle and another vehicle. As described below, the driving assistance device 3 may simply simulate the driving trajectory of the other vehicle based on the other vehicle information input from the vehicle-to-vehicle communication device 2, and perform map matching to identify the lane in which the other vehicle is traveling based on a matching evaluation value with map information including lane information.

[0016] The warning device 4 issues a warning to the driver of the host vehicle 10 when a warning command is input from the driving assistance device 3. The cruise control device 5 causes the host vehicle 10 to take action to avoid a collision when a warning command is input from the driving assistance device 3. It is sufficient that at least one of the warning device 4 and the cruise control device 5 is installed in the host vehicle 10.

[0017] 2 is a configuration diagram of a driving assistance device according to this embodiment. The driving assistance device 3 according to this embodiment includes an other vehicle identification unit 31, an other vehicle information storage unit 32, a correction target section detection unit 33, a motion state estimation unit 34, a motion state correction unit 35, and an alarm instruction determination unit 36. The driving assistance device 3 also stores map information 37. Note that the map information 37 does not necessarily have to be stored inside the driving assistance device 3. The map information 37 may be stored in the positioning device 1, or may be stored in another device, such as a navigation device.

[0018] The other vehicle identification unit 31 identifies multiple other vehicles based on the vehicle identification information included in the input other vehicle information. Furthermore, the other vehicle identification unit 31 outputs other vehicle information such as position information, speed, and traveling direction for each identified other vehicle to the other vehicle information storage unit 32.

[0019] The other vehicle information storage unit 32 stores the other vehicle information for each other vehicle input from the other vehicle identification unit 31 together with the acquisition time information as other vehicle time-series information. Then, the other vehicle information storage unit 32 outputs the stored other vehicle time-series information for each other vehicle to the correction target section detection unit 33 and the motion state estimation unit 34.

[0020] The correction target section detection unit 33 determines that the position information needs to be corrected if the reliability information related to the position information included in the input other vehicle time-series information for each other vehicle is smaller than a preset threshold and this state continues for longer than a preset time.The correction target section detection unit 33 then outputs the section in which the reliability information continues to be smaller than the preset threshold as a correction target section to the motion state estimation unit 34.

[0021] Furthermore, the correction target section detection unit 33 can compare the location information included in the input other vehicle time-series information for each other vehicle with the map information 37, and detect whether or not the section requires correction of the location information. For example, when the other vehicle is traveling through a tunnel, the reliability of the location information obtained by the GPS (Global Positioning System) decreases. Based on the map information 37, the correction target section detection unit 33 outputs, for example, a section traveling through a tunnel as a correction target section to the motion state estimation unit 34.

[0022] When the correction target section is input from the correction target section detection unit 33, the motion state estimation unit 34 estimates the time-series motion state of each other vehicle from the other vehicle time-series information of each other vehicle input from the other vehicle information storage unit 32. Here, the motion state includes, for example, the vehicle direction in the horizontal plane representing the vehicle's travel at each time, the vehicle's longitudinal speed, the vehicle's longitudinal acceleration, the vehicle's lateral acceleration, and the angular velocity of the vehicle direction. The motion state is also assumed to be n pieces of time-series information at regular time intervals. The motion state can be estimated by interpolating the latitude and longitude series included in the other vehicle time-series information using a spline curve or the like, and estimating the time-series motion state from the curve. This calculation method is an inverse calculation method of the calculation used in the conventionally known autonomous navigation method.

[0023] The motion state correction unit 35 corrects the time-series motion states estimated by the motion state estimation unit 34 using parameters that become error factors. Parameters that become error factors include, for example, the offset of the angle sensor of the vehicle direction, the offset of the acceleration sensor, and the gain of the speed sensor. The motion state correction unit 35 simulates the travel trajectory of the other vehicle based on the corrected time-series motion states, and calculates a matching evaluation value by comparing the simulated travel trajectory of the other vehicle with map information 37. Then, the motion state correction unit 35 outputs the travel trajectory of the other vehicle that has the smallest matching evaluation value to the warning instruction determination unit 36.

[0024] FIG. 3 is a flowchart showing a method of outputting the traveling locus of another vehicle in the motion state correction unit. In step S01, the motion state correction unit 35 generates correction candidates. Hereinafter, a case of correcting the angular velocity included in the motion state will be described assuming the offset of a gyro sensor that detects the angle of the vehicle orientation as a correction target.

[0025] In step S01, the motion state correction unit 35 generates correction candidates. For example, a set of constants for correction is set as (a i , b j ), and this is used as a set of correction candidates. Let m and l be arbitrary integers of 3 or more, i be an integer from 0 to m - 1, and j be an integer from 0 to l - 1. a i is changed by dividing the range between a preset minimum value and maximum value into m - 1 equal parts, and b j is changed by dividing the range between a preset minimum value and maximum value into l - 1 equal parts.

[0026] In step S02, the motion state correction unit 35 selects one unevaluated correction candidate from the correction candidates. Then, in step S03, the motion state correction unit 35 performs the following correction of the motion state for the selected correction candidate (a i , b j ). Assume that there are n angular velocities included in the motion state at regular intervals in the time axis direction. When correcting for the angular velocity ω k (0 ≤ k < n), let the corrected angular velocity be Ω k . For example, the correction is performed as Ω k = ω k + a i × k + b j . The motion state after replacing ω with Ω in the motion state before correction is taken as the corrected motion state. In this way, in step S03, the motion state correction unit 35 corrects the motion state. Then, the motion state correction unit 35 proceeds to step S04.

[0027] In step S04, the motion state correcting unit 35 simulates the travel trajectory of the other vehicle based on the corrected motion state. As a method for simulating the travel trajectory of the vehicle from the motion state, for example, a self-contained navigation technique can be used. Then, in step S05, the motion state correcting unit 35 calculates an evaluation value of the degree of coincidence between the simulated travel trajectory of the other vehicle and the map information. The calculation of the evaluation value of the degree of coincidence between the travel trajectory of the other vehicle and the map information in step S05 can be performed by the following method.

[0028] There are n time-series motion states at regular time intervals. The travel trajectory of other vehicles based on the time-series motion states is defined as P k (x k , y k ) where k is an integer between 0 and n-1, and x k , y k are the longitude and latitude, respectively.

[0029] It is assumed that the other vehicle is traveling on a road with two lanes on each side. It is also assumed that the two lanes are formed by three dividing lines on the road, and that walls are installed on both sides. Figure 4 is a diagram showing an evaluation function for calculating a matching evaluation value in the motion state correction unit 35. Figure 4 corresponds to a cross section in a direction perpendicular to the lanes of the two-lane road. In Figure 4, L indicates the position of the dividing line, and W indicates the position where the vehicle contacts the walls on both sides. X k is the position perpendicular to the lane, Y k Let denote the position along the lane.

[0030] The motion state correction unit 35 uses the map information 37 to k (x k , y k ) represents the position on the road. k (X k , Y k ) as shown in FIG. 4. k Evaluation function f in kThis evaluation function is set so that it is 0 in the center of the lane, gradually becomes larger than 0 in the direction crossing the dividing line L, and suddenly becomes a larger value at the position W where it contacts the wall. In other words, this evaluation function is set based on the structure of the road on which the other vehicle is traveling. The motion state correction unit 35 uses this evaluation function to calculate the degree of coincidence evaluation value V shown in the following equation (1). Here, X k is P k (x k , y k ) to Q k (X k , Y k ) is the position of the other vehicle in the direction perpendicular to the lane, which is obtained by converting

[0031]

number

[0032] The motion state corrector 35 stores the calculated coincidence evaluation value in association with the correction candidate selected in step S02. Next, in step S06, the motion state corrector 35 determines whether or not all correction candidates have been selected. If all correction candidates have not been selected in step S06 (NO), the motion state corrector 35 returns to step S02. If all correction candidates have been selected in step S06 (YES), the motion state corrector 35 proceeds to step S07.

[0033] In this embodiment, the evaluation function used to calculate the evaluation value of the degree of match between the travel path of another vehicle and map information has been described using an example of a two-lane road as shown in Fig. 4. This evaluation function can be set appropriately depending on the number of lanes, the width of the lanes, etc.

[0034] In step S07, the motion state correction unit 35 outputs the stored travel trajectory with the smallest coincidence evaluation value as the travel trajectory of the other vehicle with the highest degree of coincidence to the warning instruction determination unit 36. Note that in the driving assistance device of this embodiment, the travel trajectory with the smallest coincidence evaluation value is determined to be the travel trajectory of the other vehicle with the highest degree of coincidence. Depending on the method of calculating the coincidence evaluation value, the travel trajectory with the smallest coincidence evaluation value is not necessarily the one with the highest degree of coincidence.

[0035] The warning instruction determination unit 36 compares the travel trajectory of the other vehicle input from the motion state correction unit 35 with the host vehicle information and determines the possibility of a collision between the host vehicle and the other vehicle. The warning instruction determination unit 36 can determine the possibility of a collision, for example, using the time-to-collision (hereinafter referred to as TTC). The TTC is a value (unit: time) obtained by dividing the inter-vehicle distance between the host vehicle and the other vehicle by the relative speed between the host vehicle and the other vehicle. If the TTC is shorter than a preset time, the warning instruction determination unit 36 determines that collision avoidance action is necessary and outputs a warning command to the warning device 4 and the driving control device 5. Note that the possibility of a collision may be determined using a method other than the method using the TTC, or a combination of the method using the TTC and another method.

[0036] The driving assistance device 3 configured in this manner calculates the degree of match evaluation value between the driving trajectory of another vehicle and map information by setting an evaluation function that includes lane information, so that map matching can be performed to identify the lane in which the other vehicle is driving.

[0037] The warning instruction determination unit 36 does not necessarily have to be included in the driving assistance device 3. The driving assistance device may simply output the travel trajectory of the other vehicle. For example, the driving assistance device outputs the travel trajectory of the other vehicle to a driving control device. The driving control device may determine the possibility of a collision based on the travel trajectory of the other vehicle input from the driving assistance device and the host vehicle information, and may cause the host vehicle to take collision avoidance action based on the determination result.

[0038] As shown in FIG. 5 , an example of hardware of the driving assistance device 3 is configured with a processor 40 and a storage device 50. Although not shown, the storage device 50 includes a volatile storage device such as a random access memory and a non-volatile auxiliary storage device such as a flash memory. Alternatively, a hard disk auxiliary storage device may be included instead of the flash memory. The processor 40 executes a program input from the storage device 50. In this case, the program is input to the processor 40 from the auxiliary storage device via the volatile storage device. The processor 40 may output data such as calculation results to the volatile storage device of the storage device 50, or may store the data in the auxiliary storage device via the volatile storage device.

[0039] Although the present application describes exemplary embodiments, the various features, aspects, and functions described in the embodiments are not limited to application to a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not illustrated are contemplated within the scope of the technology disclosed in the present specification, including, for example, modifying, adding, or omitting at least one component. [Explanation of symbols]

[0040] 1 Positioning device, 2 Vehicle-to-vehicle communication device, 3 Driving assistance device, 4 Warning device, 5 Driving control device, 10 Own vehicle, 11 Other vehicle, 31 Other vehicle identification unit, 32 Other vehicle information storage unit, 33 Correction target section detection unit, 34 Motion state estimation unit, 35 Motion state correction unit, 36 Warning instruction determination unit, 37 Map information, 40 Processor, 50 Storage device.

Claims

1. an other vehicle information storage unit that acquires and stores other vehicle time series information of other vehicles traveling within a range in which communication with the own vehicle is possible via an inter-vehicle communication device; a motion state estimation unit that estimates a motion state of the other vehicle based on the other vehicle time-series information stored in the other vehicle information storage unit; a correction target section detection unit that, when reliability information included in the other vehicle time-series information stored in the other vehicle information storage unit is smaller than a predetermined threshold and this state continues for longer than a predetermined time, detects the section in which the reliability information is smaller than the predetermined threshold as a correction target section and outputs the correction target section to the motion state estimation unit; a motion state correction unit that simulates a travel trajectory of the other vehicle from the motion state of the other vehicle estimated by the motion state estimation unit, and outputs the simulated travel trajectory of the other vehicle, the motion state includes time-series direction information, speed information, acceleration information, and angular velocity information of the vehicle direction of the other vehicle in a horizontal plane; the motion state estimation unit estimates the motion state of the other vehicle traveling in the correction target section input from the correction target section detection unit; the motion state correction unit generates correction candidates for each piece of information included in the motion state of the other vehicle to correct the motion state, calculates a coincidence evaluation value between the travel trajectory of the other vehicle simulated from the corrected motion state and map information including lane information, and outputs the travel trajectory that has the highest coincidence with the map information based on the calculated coincidence evaluation value.

2. 2. The driving assistance device according to claim 1, wherein the motion state correction unit sets an evaluation function based on a structure of a road on which the other vehicle is traveling, and calculates the degree of coincidence evaluation value based on the set evaluation function.

3. The driving assistance device according to claim 1 or 2, characterized in that the correction target section detection unit detects the correction target section by comparing the location information included in the other vehicle time-series information stored in the other vehicle information storage unit with the map information.

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