Route estimation device and collision determination device

Abstract

To curb a decrease in estimation accuracy of a travel route for a four-wheel steering vehicle.SOLUTION: A route estimation device 210, which estimates a travel route PA1 for a vehicle VM constituted as a four-wheel steering vehicle, comprises: an acquisition part 212 that acquires rear wheel steering information on a steering angle of a rear wheel possessed by the vehicle; and a driver's own vehicle route estimation part 213 that estimates the travel route by making use of a time change rate of the steering angle of the rear wheel identified by making use of the rear wheel steering information.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a path estimation device and a collision determination device. [Background technology]

[0002] Conventionally, a technology is known in which the possibility of a collision between a vehicle and a target is determined based on the predicted movement path of the vehicle and the movement paths of targets around the vehicle, and if there is a possibility of a collision, a braking operation is performed to slow down the vehicle, thereby reducing the possibility of a collision (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-172144 Summary of the Invention [Problem to be solved by the invention]

[0004] The estimation of the host vehicle's path described in Patent Document 1 utilizes the yaw rate of the host vehicle detected by a yaw rate sensor. The detected yaw rate includes a revolution component of the yaw rate resulting from the turning motion of the host vehicle and a rotation component resulting from the yaw rotational motion of the host vehicle. However, in a four-wheel steering vehicle, because rear wheel steering control is also performed, the influence of the rotation component of the yaw rate on the detected yaw rate is stronger than in a two-wheel steering vehicle. For this reason, if the detected yaw rate is used directly to estimate the host vehicle's path in a four-wheel steering vehicle, there is a problem in that the estimation accuracy of the path decreases. This problem is not limited to path prediction for collision detection, but is common to various path predictions for vehicle control. [Means for solving the problem]

[0005] The present disclosure can be realized in the following forms.

[0006] According to one aspect of the present disclosure, there is provided a path estimation device (210) that estimates a driving path (PA1) of a vehicle (VM) configured as a four-wheel steering vehicle. The control device includes an acquisition unit (212) that acquires rear wheel steering information, which is information related to the steering angle of the rear wheels of the vehicle, and a host vehicle path estimation unit (213) that estimates the driving path using a time rate of change of the steering angle of the rear wheels identified using the rear wheel steering information.

[0007] According to this type of control device, the driving route is estimated using the time rate of change of the steering angle of the rear wheels of a vehicle configured as a four-wheel steering vehicle, so that the influence of the time rate of change of the steering angle of the rear wheels, i.e., the yaw rate of the rotation component, on the route estimation can be suppressed, and a decrease in the accuracy of the estimation of the driving route can be suppressed. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is an explanatory diagram showing a schematic configuration of a vehicle control system according to an embodiment of the present invention; [Figure 2] FIG. 2 is an explanatory diagram of a vehicle presence region on an XY plane of a two-dimensional coordinate system. [Figure 3] FIG. 2 is an explanatory diagram of a target existence region on an XY plane of a two-dimensional coordinate system. [Figure 4] FIG. 2 is an explanatory diagram of a vehicle solid and a target solid in a three-dimensional coordinate system. [Figure 5] 10 is an explanatory diagram showing collision determination between the host vehicle and a target based on the host vehicle solid and the target solid; FIG. [Figure 6] 1 is a first flowchart showing the procedure of a collision determination process according to the present embodiment. [Figure 7] 10 is a second flowchart showing the procedure of the collision determination process according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] A. First embodiment: A-1. System Configuration: A vehicle control system 10 including a collision determination device 200 of this embodiment is applied to a vehicle. The vehicle to which the vehicle control system 10 is applied may be configured to be capable of autonomous driving. The vehicle control system 10 shown in FIG. 1 includes a target detection device 110 and a collision determination device 200.

[0010] The target detection device 110 transmits millimeter waves and detects the positions of targets around the vehicle and the relative speed of the targets with respect to the vehicle from the reflected waves generated when the transmitted millimeter waves are reflected by the targets TG. The target detection device 110 includes a millimeter-wave radar sensor 111 and a radar ECU 112.

[0011] The millimeter-wave radar sensors 111 are attached, for example, to the front and rear of the vehicle, emit millimeter waves around the vehicle, receive the reflected waves, and output reflected wave signals related to the received reflected waves to the radar ECU 112.

[0012] The radar ECU 112 calculates the position of a target around the vehicle and the relative speed of the target with respect to the vehicle from the reflected wave signal output from the millimeter-wave radar sensor 111. The radar ECU 112 outputs the calculated position of the target and the relative speed of the target with respect to the vehicle to the collision determination device 200. The radar ECU 112 is configured by a computer including, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input / output interface, etc. Note that ECU is an abbreviation for Electronic Control Unit.

[0013] The collision determination device 200 is connected to a yaw rate sensor 120, a wheel speed sensor 130, and a collision suppression device 300. The yaw rate sensor 120 is provided, for example, at the center of the vehicle, and outputs a yaw rate signal corresponding to the rate of change in the steering amount of the vehicle to the collision determination device 200. The wheel speed sensor 130 is attached, for example, to a wheel of the vehicle, and outputs a wheel speed signal corresponding to the wheel speed of the vehicle to the collision determination device 200.

[0014] The collision suppression device 300 is a device that suppresses a collision of a target with the vehicle, and in this embodiment, includes a braking device 310 and a seatbelt actuator 320.

[0015] The braking device 310 controls braking by the brake actuator. Specifically, it controls the braking force of the brake actuator in accordance with the deceleration signal output from the collision determination device 200. The amount of deceleration of the vehicle is adjusted by controlling the braking force of the brake actuator. The seatbelt actuator 320 operates a seatbelt retractor in accordance with the activation signal output from the collision determination device 200, and retracts and tensions the seatbelt.

[0016] The collision determination device 200 determines whether or not the host vehicle will collide with the target, based on the target position and the target's relative speed with respect to the host vehicle output from the target detection device 110. Specifically, the collision determination device 200 calculates a host vehicle solid, which is a solid that indicates the transition of the host vehicle's existence area on the host vehicle's estimated path, in a virtually formed three-dimensional coordinate system. The collision determination device 200 also calculates a target solid, which is a solid that indicates the transition of the target's existence area on the target's estimated path, based on the target position and the target's relative speed with respect to the host vehicle output from the target detection device 110, in the three-dimensional coordinate system. The collision determination device 200 then determines whether or not the host vehicle will collide with the target based on the presence or absence of an intersection between the host vehicle solid and the target solid. In the following description, the target position and the target's relative speed with respect to the host vehicle output from the target detection device 110 will also be referred to as "target information."

[0017] When the collision determination device 200 determines that a target will collide with the host vehicle and executes a braking operation, it activates the collision suppression device 300 to execute collision suppression control for the host vehicle. For example, the collision determination device 200 executes collision suppression control by generating and outputting a deceleration signal to the braking device 310 and an activation signal to the seat belt actuator 320.

[0018] The collision determination device 200 is configured as a computer including a CPU 220, a ROM 260, and a RAM 270. In this embodiment, the collision determination device 200 further includes a path estimation device 210. The path estimation device 210 uses the yaw rate detected by the yaw rate sensor 120 and the host vehicle speed detected by the wheel speed sensor 130 to calculate an estimated path of the host vehicle.

[0019] In this embodiment, the route estimation device 210 is configured as a computer including a CPU 211, a ROM 214, and a RAM 150. The CPU 211 functions as an acquisition unit 212 and a vehicle route estimation unit 213 by loading a program stored in advance in the ROM 214 into the RAM 215 and executing the program.

[0020] The acquisition unit 212 acquires the yaw rate and vehicle speed of the host vehicle. In this embodiment, the acquisition unit 212 calculates the yaw rate of the host vehicle using the yaw rate signal output from the yaw rate sensor 120, and calculates the vehicle speed using the wheel speed signal output from the wheel speed sensor 130. In the following description, the yaw rate calculated using the yaw rate signal output from the yaw rate sensor 120 is also referred to as the "uncorrected yaw rate."

[0021] Furthermore, if the host vehicle is configured as a four-wheel steering vehicle, the acquisition unit 212 also acquires rear-wheel steering information in addition to the above. A "four-wheel steering vehicle" refers to a vehicle that is capable of controlling the steering of not only the front wheels but also the rear wheels. "Rear-wheel steering information" refers to information related to the steering angle of the rear wheels of the host vehicle. In this embodiment, the acquisition unit 212 acquires, as the rear-wheel steering information, a control signal that instructs a rear-wheel steering device (not shown) equipped in the host vehicle to set the rear-wheel steering angle. The history of the rear-wheel steering angle indicated by the acquired control signal is stored in ROM 214. Note that if the host vehicle VM is equipped with a rear-wheel steering angle sensor that calculates the rear-wheel steering angle, the acquisition unit 212 may acquire a detection signal from the rear-wheel steering angle sensor as the rear-wheel steering information.

[0022] The host vehicle path estimation unit 213 calculates a host vehicle estimated path PA1 indicating an estimated path of the host vehicle VM using the acquired yaw rate and host vehicle speed of the host vehicle. In this embodiment, the host vehicle path estimation unit 213 calculates an estimated curve radius of the host vehicle using the yaw rate and host vehicle speed of the host vehicle. Then, the host vehicle path estimation unit 213 calculates the path that the host vehicle will take if it travels along the calculated estimated curve radius as the host vehicle estimated path PA1. The host vehicle path estimation unit 213 outputs the calculated host vehicle estimated path PA1 to the CPU 220.

[0023] The route estimation by the host vehicle path estimation unit 213 of this embodiment will be described in more detail. In this embodiment, the host vehicle path estimation unit 213 performs route estimation using different methods when the host vehicle VM is configured as a two-wheel steering vehicle and when the host vehicle VM is configured as a four-wheel steering vehicle. The uncorrected yaw rate described above includes a yaw rate of a revolution component resulting from the turning motion of the host vehicle and a yaw rate of a rotation component resulting from the yaw rotation motion of the host vehicle. When the host vehicle VM is configured as a two-wheel steering vehicle, only the front wheels are steered, so the yaw rotation motion occurs in response to the turning motion, and it can be assumed that the uncorrected yaw rate is equal to the yaw rate of the revolution component. Therefore, the host vehicle path estimation unit 213 can accurately calculate the estimated curve radius of the host vehicle using the uncorrected yaw rate, and can accurately calculate the host vehicle's estimated path PA1, which is calculated based on the estimated curve radius.

[0024] In contrast, if the host vehicle is configured as a four-wheel steering vehicle, not only steering control of the front wheels but also steering control of the rear wheels is performed, resulting in a yaw rotational motion independent of the turning motion, and the influence of the yaw rate, which is the rotation component, becomes more pronounced. Therefore, if the estimated curve radius of the host vehicle is calculated using the uncorrected yaw rate, an error will occur in the estimated curve radius of the host vehicle VM, and an error will occur in the host vehicle's estimated path PA1 calculated based on the estimated curve radius. Therefore, if the host vehicle VM is configured as a four-wheel steering vehicle, the host vehicle path estimation unit 213 of this embodiment calculates a corrected yaw rate and uses the calculated corrected yaw rate to calculate the estimated curve radius of the host vehicle VM. The "corrected yaw rate" refers to a yaw rate obtained by correcting the uncorrected yaw rate based on the time rate of change of the rear wheel steering angle. The host vehicle path estimation unit 213 determines the time rate of change of the rear wheel steering angle using the history of the rear wheel steering angle acquired as rear wheel steering information. In this embodiment, the vehicle path estimation unit 213 performs the correction by subtracting the time rate of change of the rear wheel steering angle from the uncorrected yaw rate. By subtracting the uncorrected yaw rate using the time rate of change of the rear wheel steering angle, i.e., the yaw rate of the rotation component caused by the steering control of the rear wheels, the yaw rate of the rotation component caused by the steering control of the rear wheels can be excluded from the corrected yaw rate. By calculating the estimated curve's radius of the vehicle using the corrected yaw rate calculated in this way, errors in the estimated curve's radius can be reduced, and errors in the vehicle's estimated path PA1 calculated based on the estimated curve's radius can also be reduced.

[0025] The CPU 220 implements the above collision determination by loading a program stored in advance in the ROM 260 into the RAM 270 and executing the program. In this embodiment, the CPU 220 functions as a host vehicle transition calculation unit 230, a target transition calculation unit 240, and a collision determination unit 250. The host vehicle transition calculation unit 230 is implemented by a host vehicle area calculation unit 231 and a host vehicle information calculation unit 232. The target transition calculation unit 240 is implemented by a target path estimation unit 241, a target area calculation unit 242, and a target information calculation unit 243.

[0026] As will be described below, the host vehicle transition calculation unit 230 calculates a host vehicle solid, which is a solid that indicates the transition of the host vehicle's existence area on the host vehicle's estimated route, in a virtually formed three-dimensional coordinate system. Also, the target transition calculation unit 240, as will be described below, calculates a target solid, which is a solid that indicates the transition of the target's existence area on the target's estimated route, which is calculated from the target position output from the target detection device 110 and the target's relative speed with respect to the host vehicle, in a three-dimensional coordinate system.

[0027] The vehicle area calculation unit 231 calculates a vehicle existence area EA1 indicating an area where the vehicle exists at regular time intervals on the vehicle's estimated route PA1 calculated by the route estimation device 210 on the XY plane of a two-dimensional coordinate system defined by the distance Y in the vehicle's travel direction from the current time T0 and the distance X in the vehicle's width direction. In this embodiment, the vehicle area calculation unit 231 calculates the vehicle existence area EA1 at each position on the vehicle's estimated route PA1 during the period from the current time T0 (hereinafter also referred to as "current T0") to the estimation end time TN.

[0028] The upper part of FIG. 2 shows a host vehicle existence area EA1 calculated for the host vehicle VM at the current time T0, i.e., when the elapsed time T is 0. In this embodiment, the host vehicle existence area EA1 is defined as a rectangular area that includes the entire periphery of the host vehicle VM when the host vehicle VM is viewed from above. The host vehicle area calculation unit 231 defines the rectangular area that forms the host vehicle existence area EA1 in accordance with vehicle specifications that indicate the size of the host vehicle. For example, the host vehicle existence area EA1 at the current time T0 is defined so that the intersection (0,0) of the X axis and the Y axis is the reference position P0 of the host vehicle VM. Furthermore, the reference position P0 of the host vehicle VM is set to be the center in the vehicle width direction in front of the host vehicle.

[0029] The lower part of Fig. 2 shows a comparison of the host vehicle existence area EA1 at the current time T0 shown in the upper part of Fig. 2 with the host vehicle existence area EA1 at the future time T1 from the current time T0. Note that, in the lower diagram, for ease of explanation, the host vehicle existence area EA1 at the current time T0 and the host vehicle existence area EA1 at the future time T2 from the current time T0 (T2>T1) are shown by dashed lines.

[0030] The host vehicle existence area EA1 located in the future by the elapsed time T1 from the current time T0 indicates the host vehicle existence area after the elapsed time T1 from the host vehicle position at the current time T0 when the host vehicle VM moves along the host vehicle estimated route PA1. For example, the host vehicle area calculation unit 231 calculates, based on the host vehicle estimated route PA1 calculated at the host vehicle position at the current time T0 and the host vehicle speed, a passing position on the host vehicle estimated route PA1 after the elapsed time Tn (n is a value between 0 and N) from the reference position P0 of the host vehicle VM at the current time T0. Then, a rectangular area with each passing position as the reference position Pn is calculated as the host vehicle existence area EA1 located in the future by the elapsed time Tn from the current time T0. In this embodiment, the orientation of the host vehicle existence area EA1 at each elapsed time Tn is determined to be the orientation of a tangent to the host vehicle estimated route PA1 at each reference position Pn.

[0031] The host vehicle information calculation unit 232 calculates a host vehicle solid D1 indicating the transition of the host vehicle existence area EA1 by interpolating multiple host vehicle existence areas EA1 in a three-dimensional coordinate system defined by a distance Y in the host vehicle's traveling direction, a distance X in the vehicle width direction, and an elapsed time T from the current time T0. In the three-dimensional coordinate system shown in Fig. 4, the point (0,0,0) indicates the host vehicle's reference position P0 at the current time T0. The host vehicle solid D1 indicates the movement transition of the host vehicle existence area EA1 over the elapsed time T in the three-dimensional coordinate system. In Fig. 4, the host vehicle solid D1 is calculated for a predicted time width from the current time T0 to the estimated end time TN.

[0032] In this embodiment, the host vehicle information calculation unit 232 converts the calculated host vehicle existence areas EA1 into information in a three-dimensional coordinate system. Then, in the three-dimensional coordinate system, the host vehicle solid D1 is calculated by linearly interpolating the four corners between adjacent host vehicle existence areas EA1 in the direction of the T axis that defines the elapsed time.

[0033] In the target transition calculation unit 240, the target path estimation unit 241 calculates an estimated target path PA2 indicating an estimated path of the target from target information detected by the target detection device 110. For example, the target path estimation unit 241 calculates a movement trajectory of the target from changes in the target position detected by the target detection device 110, and sets this movement trajectory as the estimated target path PA2. Note that the estimated target path PA2 corresponds to the "movement path of the target."

[0034] The target area calculation unit 242 calculates a target existence area EA2 that indicates an area where a target exists at a fixed time interval on the target estimated path PA2 on the XY plane of a two-dimensional coordinate system defined based on the current vehicle position. The target existence area EA2 indicates an area where a target exists at a fixed time interval when the target moves along the target estimated path PA2.

[0035] The upper part of Fig. 3 shows a target existence area EA2 calculated for the target TG at the current time T0. The target existence area EA2 on the XY plane at the current time T0 indicates the existence area of ​​the target TG detected by the target detection device 110 at the current host vehicle position. In this embodiment, another vehicle is shown as an example of the target TG. The target area calculation unit 242 sets the target existence area EA2 as a rectangular area that includes the entire periphery of the target when the target TG is viewed from above. For example, the rectangular area that forms the target existence area EA2 is set according to the size of the target calculated by the target detection device 110.

[0036] The lower part of Fig. 3 shows a comparison of the target existence area EA2 at the current time T0 and the target existence area EA2 that is the future by the elapsed time T1 from the current time T0 with the target existence area EA2 at the current time T0 shown in the upper part of Fig. 3. For example, the target area calculation unit 242 calculates, on the estimated target path PA2, the passing position of the target TG after the elapsed time Tn from the reference position B0 of the target TG at the current time T0, according to the estimated target path PA2 and the relative speed of the target with respect to the host vehicle. Then, a rectangular area with each passing position as the reference position Bn is calculated as the target existence area EA2 that is the future by the elapsed time Tn from the current time T0.

[0037] The target information calculation unit 243 calculates a target solid D2, which is a solid that indicates the transition of the target existence area EA2, by interpolating multiple target existence areas EA2 in a three-dimensional coordinate system defined based on the current vehicle position at T0. The target solid D2 shown in FIG. 4 indicates the movement transition of the target existence area EA2 over elapsed time T in the three-dimensional coordinate system. In this embodiment, the target information calculation unit 243 converts the calculated multiple target existence areas EA2 into information in the three-dimensional coordinate system. Then, in the three-dimensional coordinate system, the target solid D2 is calculated by linearly interpolating the four corners between adjacent target existence areas EA2 in the direction of the T axis that defines the elapsed time.

[0038] The collision determination unit 250 determines whether or not the host vehicle will collide with the target based on whether or not the host vehicle solid D1 and the target solid D2 intersect. In this embodiment, the collision determination unit 250 calculates a first determination area DA1 indicating a host vehicle existence area EA1 at a set elapsed time T using the host vehicle solid D1. The collision determination unit 250 also calculates a second determination area DA2 indicating a target existence area EA2 at the same elapsed time T as the first determination area DA1 using the target solid D2. Then, if an overlapping area CPA exists between the calculated first determination area DA1 and second determination area DA2 at the same elapsed time T, the collision determination unit 250 determines that the host vehicle solid D1 and the target solid D2 intersect.

[0039] When the host vehicle solid D1 and the target solid D2 intersect, there is an overlapping area CPA between the first determination area DA1 and the second determination area DA2 on the XY plane at the same elapsed time Ta, as shown in Fig. 5. Therefore, the collision determination unit 250 determines that the host vehicle and the target will collide when there is an overlapping area CPA between the first determination area DA1 and the second determination area DA2 at the same elapsed time T.

[0040] On the other hand, when the host vehicle solid D1 and the target solid D2 do not intersect, there is no overlapping area CPA between the first determination area DA1 and the second determination area DA2 on the XY plane at any elapsed time T. Therefore, the collision determination unit 250 determines that there will be no collision between the host vehicle and the target when there is no overlapping area CPA between the first determination area DA1 and the second determination area DA2 at the same elapsed time T.

[0041] In this embodiment, the collision determination unit 250 calculates the first determination region DA1 and the second determination region DA2 at the same elapsed time T at predetermined elapsed time intervals ΔT between the current time T0 and the estimated end time TN. Then, the presence or absence of an overlapping region CPA is determined using the calculated first determination region DA1 and second determination region DA2 at the same elapsed time T.

[0042] A-2. Collision detection processing: The collision determination device 200 performs the collision determination process shown in Figures 6 and 7 to realize the above collision determination. After the collision determination device 200 is instructed to execute the process, the collision determination process is repeatedly performed until an instruction to end the process is given.

[0043] In step S102, the acquisition unit 212 acquires the yaw rate from the yaw rate sensor 120 and the host vehicle speed from the wheel speed sensor .

[0044] In step S104, the vehicle path estimation unit 213 determines whether the vehicle is a four-wheel steering vehicle. The vehicle path estimation unit 213 makes this determination, for example, according to a preset type of the vehicle. Note that if it is determined in advance that the route estimation device 210 will be installed in a four-wheel steering vehicle, the vehicle path estimation unit 213 may not execute step S104, but may execute step S106 (described later) following step S102.

[0045] If it is determined that the vehicle to be determined is a four-wheel steering vehicle (step S104: Yes), in step S106, the vehicle path estimation unit 213 acquires the time change rate of the rear wheel steering angle. In step S108, the vehicle path estimation unit 213 calculates a corrected yaw rate.

[0046] In step S110, the host vehicle path estimation unit 213 calculates the host vehicle estimated path PA1 using the corrected yaw rate and the host vehicle speed. More specifically, the host vehicle path estimation unit 213 calculates the estimated curve radius of the host vehicle VM using the corrected yaw rate and the host vehicle speed, and calculates the host vehicle estimated path PA1 based on the calculated estimated curve radius.

[0047] In step S104, if it is determined that the vehicle to be determined is not a four-wheel steering vehicle (step S104: No), the above-mentioned steps S106 and S108 are not executed, and the above-mentioned step S110 is executed. In other words, if the vehicle to be determined is not a four-wheel steering vehicle, the host vehicle path estimation unit 213 calculates the host vehicle estimated path PA1 using the uncorrected yaw rate and the host vehicle speed.

[0048] In step S112, the target path estimation unit 241 acquires target information from the target detection device 110. In step S114, the target path estimation unit 241 calculates an estimated target path PA2 using the target information. Note that steps S112 and S114 are not limited to being performed after steps S102 to S110 described above, and may be performed in parallel with steps S102 to S110.

[0049] 7, the host vehicle information calculation unit 232 calculates a host vehicle solid D1 that indicates the transition of the host vehicle existence area EA1 on the host vehicle estimated path PA1 from the current time T0 until a certain time has elapsed in a three-dimensional coordinate system defined based on the current position of the host vehicle (see FIGS. 2 and 4). Also, in this step, the target information calculation unit 243 calculates a target solid D2 that indicates the transition of the target existence area EA2 on the target estimated path PA2 in the three-dimensional coordinate system (see FIGS. 3 and 4). Note that, as a specific procedure for calculating the host vehicle solid D1 and the target solid D2, for example, the procedure described in the above-mentioned Prior Art Document 2 (JP 2020-8288 A) may be used.

[0050] In step S118, the collision determination unit 250 determines whether the host vehicle solid D1 and the target object solid D2 intersect in the three-dimensional coordinate system. Specifically, as described with reference to Fig. 5, if there is an area CPA where the first determination area DA1 and the second determination area DA2 overlap at the same elapsed time T, the collision determination unit 250 determines that the host vehicle solid D1 and the target object solid D2 intersect. If it is determined that the host vehicle solid D1 and the target object solid D2 do not intersect (step S118: No), the above-described step S102 is executed again.

[0051] If it is determined that the host vehicle solid D1 and the target object solid D2 intersect (step S118: Yes), in step S120, the collision determination unit 250 calculates the time to collision. The "time to collision" means the time until the host vehicle and the target object collide at the current host vehicle position. The collision determination unit 250 calculates the time to collision, for example, by dividing the straight-line distance from the current host vehicle position to the target object by the relative speed of the target object with respect to the host vehicle.

[0052] In step S122, the collision determination unit 250 determines whether the calculated time to collision is equal to or less than a predetermined threshold. If it is determined that the time to collision is not equal to or less than the threshold (step S122: No), in other words, if the time to collision is longer than the threshold, braking control is not executed and the above-mentioned step S102 is executed again. The determination result that the host vehicle and the target will collide is merely an estimation result based on the current host vehicle position, and if the time to collision is longer than the threshold, there is a possibility that the collision will be avoided by moving the host vehicle in the future. For this reason, if the time to collision is longer than the threshold, the braking control described below is not executed and the process returns to step S102, thereby preventing the smooth running of the host vehicle VM from being hindered.

[0053] If it is determined that the time to collision is equal to or less than the threshold value (step S122: Yes), braking control is executed by the collision suppression device 300 in step S124. At this time, a warning may be issued by a warning device (not shown) together with the braking control. Thereafter, the above-mentioned step S102 is executed again. The collision determination device 200 repeatedly executes the above-mentioned collision determination, and ends the collision determination process when an instruction to end the process is received.

[0054] According to the path estimation device 210 of the embodiment described above, when the host vehicle is a four-wheel steering vehicle, the host vehicle estimated path PA1 is estimated using a corrected yaw rate, so that the influence of the yaw rate of the rotation component of the host vehicle VM at the uncorrected yaw rate can be suppressed, and a decrease in the estimation accuracy of the host vehicle estimated path PA1 can be suppressed.

[0055] Furthermore, since a control signal indicating the rear wheel steering angle is acquired as rear wheel steering information, the vehicle to be judged does not need to be equipped with a rear wheel steering angle sensor for acquiring the rear wheel steering angle, and route estimation can be achieved even for vehicles that do not have a rear wheel steering angle sensor.

[0056] Furthermore, the collision determination device 200 equipped with the path estimation device 210 of this embodiment performs collision determination based on the host vehicle estimated path PA1 calculated using a corrected yaw rate. Therefore, in a four-wheel steering vehicle, compared to form 1 in which collision determination is performed based on an estimated path calculated using an uncorrected yaw rate, the error between the host vehicle estimated path PA1 and the actual driving path of the host vehicle VM can be reduced, and collision determination can be performed appropriately.

[0057] B. Other Embodiments: (B1) In the above embodiment, the acquisition unit 212 acquires, as the uncorrected yaw rate, a yaw rate calculated using a yaw rate signal output from the yaw rate sensor 120, but the present disclosure is not limited to this. For example, the acquisition unit 212 may acquire a yaw rate calculated using a steering angle signal output from a front wheel steering angle sensor, or a yaw rate calculated using a lateral acceleration signal output from a lateral acceleration sensor. Even with this configuration, the same effects as those of the above embodiment can be achieved.

[0058] (B2) In the above embodiment, the vehicle path estimation unit 213 calculates a corrected yaw rate and calculates the vehicle's estimated path PA1 using the corrected yaw rate, but the present disclosure is not limited to this. For example, the vehicle path estimation unit 213 may calculate a corrected curve radius by adding a correction value determined according to the time rate of change of the rear wheel steering angle to the estimated curve radius calculated using the uncorrected yaw rate, and then calculate the vehicle's estimated path PA1 using the corrected curve radius. Even in this embodiment, the vehicle's estimated path PA1 is calculated using the time rate of change of the rear wheel steering angle, so the influence of the yaw rate of the vehicle's rotation component on the uncorrected yaw rate can be suppressed, and a decrease in the estimation accuracy of the vehicle's estimated path PA1 can be suppressed.

[0059] (B3) In the above embodiment, the path estimation device 210 is provided as a device separate from the CPU 220 in the collision determination device 200, but the present disclosure is not limited to this. The acquisition unit 212 and the host vehicle path estimation unit 213, which are functional units realized by the path estimation device 210, may be realized in the CPU 220. Even in this embodiment, the same effects as those of the above embodiment are achieved. Furthermore, the path estimation device 210 does not have to be provided in the collision determination device 200, and may be provided independently of the collision determination device 200.

[0060] (B4) In the above embodiment, the path estimation device 210 is installed in the collision determination device 200 and performs path prediction for collision determination, but the present disclosure is not limited to this. The path estimation device 210 may perform various path predictions for vehicle control, not limited to path prediction for collision determination. For example, the host vehicle path estimation unit 213 may be provided in a position estimation device that estimates the current position of a vehicle configured as a four-wheel steering vehicle, and may perform path estimation to estimate the amount of movement from a certain point in the past using a yaw rate history. Even in this configuration, by using a corrected yaw rate, it is possible to suppress a decrease in the accuracy of estimating the amount of movement from a certain point in the past, compared to a configuration in which an uncorrected yaw rate is used in a four-wheel steering vehicle.

[0061] (B5) In the above embodiment, the path estimation device 210 is provided in the collision determination device 200 mounted on a vehicle and performs path estimation for the vehicle on which it is mounted, but the present disclosure is not limited to this. The path estimation device 210 is not limited to the vehicle on which it is mounted, and may be mounted in a control system that comprehensively controls multiple vehicles and performs path estimation for each of the multiple vehicles. This configuration also achieves the same effects as the above embodiment.

[0062] (B6) In the above embodiment, the target detection device 110 is a device configured with the millimeter-wave radar sensor 111 and the radar ECU 112. However, the present invention is not limited to this and may be a device including an image sensor that detects the position of a target using a captured image or a laser sensor that detects the position of a target using laser light. Furthermore, when the host vehicle is capable of performing vehicle-to-vehicle communication with another vehicle traveling around the host vehicle, the host vehicle may acquire the position of a target detected by a target detection device provided in the other vehicle through vehicle-to-vehicle communication. Furthermore, a device that combines these various devices may be used.

[0063] (B7) In the above embodiment, a vehicle is used as an example of a target, but this is not limited to this, and the target may be any object that has the potential to collide with the vehicle, such as a vehicle, bicycle, motorcycle, pedestrian, animal, or structure.

[0064] (B8) In the above embodiment, the target existence area EA2 of the target is set as a rectangular area that includes the entire periphery of the target when viewed from above, but this is not limited to this and may be any polygon that is set to include the entire periphery of the target.

[0065] (B9) In the above embodiment, the collision determination unit 250 determines whether or not a collision has occurred based on whether or not the host vehicle solid D1 and the target solid D2, which have an extension in a three-dimensional coordinate system, intersect. However, the present disclosure is not limited to this. The collision determination may be performed based on whether or not the linear host vehicle estimated path PA1 and the linear target object estimated path PA2 of the target intersect in a two-dimensional coordinate system. The collision determination can also be performed in this manner.

[0066] The route estimation apparatus 210 and the method described herein may be implemented by a special-purpose computer configured with a processor and memory programmed to perform one or more functions embodied in a computer program. Alternatively, the route estimation apparatus 210 and the method described herein may be implemented by a special-purpose computer configured with a processor configured with one or more dedicated hardware logic circuits. Alternatively, the route estimation apparatus 210 and the method described herein may be implemented by one or more special-purpose computers configured with a processor and memory programmed to perform one or more functions in combination with a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory tangible storage medium.

[0067] The present disclosure is not limited to the above-described embodiments and can be realized in various configurations without departing from the spirit thereof. For example, the technical features in each embodiment corresponding to the technical features in the form described in the Summary of the Invention section can be appropriately replaced or combined to solve some or all of the above-described problems or achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted. (Form 1) A path estimation device (210) that estimates a travel path (PA1) of a vehicle (VM) configured as a four-wheel steering vehicle, an acquisition unit (212) that acquires rear wheel steering information, which is information regarding the steering angle of the rear wheels of the vehicle; a vehicle path estimation unit (213) that estimates the driving path using a time change rate of the steering angle of the rear wheels identified using the rear wheel steering information; Equipped with Route estimation device. (Form 2) The route estimation device according to aspect 1, The vehicle path estimation unit Calculating a corrected yaw rate by correcting the yaw rate determined using the detection value by a sensor (120) provided on the vehicle with a time rate of change of the steering angle of the rear wheels; Estimating the travel path using the corrected yaw rate; To execute Route estimation device. (Form 3) The route estimation device according to aspect 1 or aspect 2, the acquisition unit acquires, as the rear wheel steering information, a control signal instructing the steering angle. Route estimation device. (Form 4) A collision determination device (200) that determines whether or not a collision occurs between a target (TG) located around the vehicle detected by a target detection device (110) and the vehicle, A route estimation device according to any one of aspects 1 to 3; a vehicle information calculation unit that calculates a vehicle solid (D1) that is a solid showing a transition of a vehicle existence area (EA1) at predetermined time intervals on the estimated travel route in a three-dimensional coordinate system defined by a distance from a current position along a traveling direction of the vehicle, a distance along a vehicle width direction of the vehicle, and an elapsed time from the present; a target path estimation unit (241) that estimates a movement path (PA2) of the target in the three-dimensional coordinate system based on the position of the target detected by the target detection device; a collision determination unit (250) that determines whether or not the target has collided with the vehicle according to whether or not the calculated vehicle solid intersects with the calculated movement path of the target; Equipped with Collision determination device. [Explanation of symbols]

[0068] 210...route estimation device, 212...acquisition unit, 213...own vehicle route estimation unit, PA1...own vehicle estimated route, VM...own vehicle

Claims

1. A route estimation device (210) that estimates a travel route (PA1) of a vehicle (VM) configured as a four-wheel steering vehicle, an acquisition unit (212) that acquires rear wheel steering information, which is information regarding the steering angle of rear wheels of the vehicle; a vehicle path estimation unit (213) that estimates the driving path by using a time rate of change of the steering angle of the rear wheels identified by using the rear wheel steering information; Equipped with Route estimation device.

2. 2. The route estimation device according to claim 1, The vehicle path estimation unit Calculating a corrected yaw rate by correcting the yaw rate determined using the detection value by a sensor (120) provided on the vehicle with the time rate of change of the steering angle of the rear wheels; Estimating the travel path using the corrected yaw rate; To execute Route estimation device.

3. 2. The route estimation device according to claim 1, the acquisition unit acquires, as the rear wheel steering information, a control signal instructing the steering angle. Route estimation device.

4. A collision determination device (200) that determines whether or not a collision occurs between a target (TG) located around the vehicle detected by a target detection device (110) and the vehicle, A route estimation device according to any one of claims 1 to 3; a vehicle information calculation unit that calculates a vehicle solid (D1) that is a solid showing a transition of a vehicle existence area (EA1) at each predetermined time interval on the estimated travel route in a three-dimensional coordinate system defined by a distance from a current position along a traveling direction of the vehicle, a distance along a vehicle width direction of the vehicle, and an elapsed time from the present; a target path estimation unit (241) that estimates a movement path (PA2) of the target in the three-dimensional coordinate system based on the position of the target detected by the target detection device; a collision determination unit (250) that determines whether or not the target has collided with the vehicle according to whether or not the calculated vehicle solid intersects with the calculated movement path of the target; Equipped with Collision determination device.

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