Driving assistance system, driving assistance device, driving assistance method, and driving assistance program

Abstract

This driving assistance system has a processor to assist in driving a host vehicle equipped with an external sensor that senses the inside of an external field of view, the processor being configured to execute: acquiring, as a reference speed (Vb), the travel speed of the host vehicle when an emergency condition (Ec) requiring an emergency operation is satisfied in the host vehicle; adjusting, in a stepwise manner, the angular resolution (θr) of the external sensor during the emergency operation to a performance-up side in accordance with a decrease in the reference speed (Vb); and controlling the travel speed of the host vehicle during the emergency operation to at least a required lower speed limit (Vmin) correlated for each stepwise angular resolution (θr).

Description

Driving support system, driving support device, driving support method, driving support program Cross-reference to related applications

[0001] This application is based on Japanese Patent Application No. 2024-207623 filed in Japan on November 28, 2024, and the content of the base application is incorporated herein by reference in its entirety.

[0002] The present disclosure relates to a driving support technology for supporting the driving of a vehicle equipped with an external sensor that senses within an external field of view.

[0003] The driving support technology disclosed in Patent Document 1 outputs a correct probability value that represents the plausibility of the recognition result for each of the peripheral monitoring sensors that serve as a plurality of external sensors in a vehicle, and adjusts the weighting for integrating the recognition results for each of these peripheral monitoring sensors based on the correct probability value. Further, the driving support technology disclosed in Patent Document 1 performs safe emergency stop control as an emergency operation on the vehicle when the weight of the peripheral monitoring sensor determined to be abnormal or the risk level corresponding to the weight is equal to or higher than a threshold value.

[0004] Japanese Patent No. 7466396

[0005] In the driving support technology as disclosed in Patent Document 1, the angular resolution of a normal peripheral monitoring sensor is usually a fixed value according to the sensor specifications. However, depending on the traveling speed of the vehicle before the emergency stop control, an appropriate angular resolution that can be sensed properly may not be ensured for the peripheral monitoring sensor, and there was a concern that it would interfere with the emergency stop control.

[0006] An object of the present disclosure is to provide a driving support system that ensures safety in an emergency operation of a vehicle. Another object of the present disclosure is to provide a driving support device that ensures safety in an emergency operation of a vehicle. Still another object of the present disclosure is to provide a driving support method that ensures safety in an emergency operation of a vehicle. Yet another object of the present disclosure is to provide a driving support program that ensures safety in an emergency operation of a vehicle.

[0007] Hereinafter, the technical means of the present disclosure for solving the problems will be described.

[0008] A first aspect of this disclosure is a driver assistance system having a processor for assisting the driving of a host vehicle equipped with an external sensor that senses within the external field of view, wherein the processor is configured to perform the following actions when an emergency condition requiring emergency operation is met in the host vehicle: to acquire the driving speed of the host vehicle as a reference speed; to adjust the angular resolution of the external sensor during the emergency operation in stages toward performance improvement in accordance with the decrease in the reference speed; and to control the driving speed of the host vehicle during the emergency operation to be above the required lower limit speed correlated for each stage of angular resolution.

[0009] A second aspect of this disclosure is a driving assistance device configured to be mounted on a host vehicle, having a processor for assisting the driving of a host vehicle equipped with an external sensor that senses within the external field of view, wherein the processor is configured to perform the following actions when an emergency condition requiring emergency operation is met in the host vehicle: to acquire the driving speed of the host vehicle as a reference speed; to adjust the angular resolution of the external sensor during the emergency operation in stages toward performance improvement in accordance with the decrease in the reference speed; and to control the driving speed of the host vehicle during the emergency operation to be above the required lower limit speed correlated for each stage of angular resolution.

[0010] A third aspect of this disclosure is a driving assistance method executed by a processor to assist the driving of a host vehicle equipped with an external sensor that senses within the external field of view, the method comprising: acquiring the driving speed of the host vehicle as a reference speed when an emergency condition requiring emergency operation is met in the host vehicle; adjusting the angular resolution of the external sensor during the emergency operation in stages to improve performance in accordance with the decrease in the reference speed; and controlling the driving speed of the host vehicle during the emergency operation to be above the required lower limit speed for correlation according to the staged angular resolution.

[0011] A fourth aspect of this disclosure is a driving assistance program stored in a storage medium to assist in the driving of a host vehicle equipped with an external sensor that senses within the external field of view, and which includes instructions for a processor to perform said assistance, the program including instructions for the following actions when an emergency condition requiring emergency operation is met in the host vehicle: to acquire the driving speed of the host vehicle as a reference speed; to adjust the angular resolution of the external sensor during the emergency operation in stages toward performance improvement in accordance with the decrease in the reference speed; and to control the driving speed of the host vehicle during the emergency operation to be above the required minimum speed correlated for each stage of angular resolution.

[0012] According to these first to fourth embodiments, when an emergency condition requiring emergency operation is met in a host vehicle equipped with external sensors, the host vehicle's speed is acquired as the reference speed. Therefore, the angular resolution of the external sensors during the emergency operation is adjusted in stages to improve performance in accordance with the decrease in the reference speed. As a result, the required lower speed, which correlates with each progressively improved angular resolution, can be reduced as much as possible from the reference speed in accordance with the performance improvement. Therefore, during an emergency operation in which the driving speed is controlled to be above the required lower speed for each angular resolution, it is possible to expand the dynamic range of the driving speed control and ensure the safety of the host vehicle.

[0013] This is a block diagram showing the overall configuration of the first embodiment. This is a top view showing the driving environment of the host vehicle to which the first embodiment is applied. This is a block diagram showing the functional configuration of the driver assistance system according to the first embodiment. This is a flowchart showing the driver assistance flow according to the first embodiment. This is a top view for explaining the driver assistance flow according to the first embodiment. This is a graph for explaining the driver assistance flow according to the first embodiment. This is a graph for explaining the driver assistance flow according to the first embodiment. This is a top view for explaining the driver assistance flow according to the first embodiment. This is a graph for explaining the driver assistance flow according to the first embodiment. This is a top view for explaining the driver assistance flow according to the first embodiment. This is a top view for explaining the driver assistance flow according to the first embodiment. This is a block diagram showing the overall configuration of the second embodiment. This is a top view for explaining the driver assistance flow according to the second embodiment. This is a graph for explaining the driver assistance flow according to the second embodiment. This is a block diagram showing the overall configuration of the third embodiment. This is a top view for explaining the driver assistance flow according to the third embodiment. This is a graph for explaining the driver assistance flow according to the third embodiment.

[0014] Hereinafter, several embodiments of this disclosure will be described with reference to the drawings. In each embodiment, the same reference numerals will be used for corresponding components, and redundant explanations may be omitted. Furthermore, if only a part of the configuration is described in each embodiment, the configuration of other embodiments described earlier may be applied to the other parts of that configuration. Moreover, not only the combinations of configurations explicitly stated in the description of each embodiment, but also the configurations of multiple embodiments can be partially combined even if not explicitly stated, as long as there are no particular problems with the combination.

[0015] (First Embodiment)

[0016] The first embodiment of the driver assistance system 1 shown in Figure 1 assists in the driving of the host vehicle 2. The host vehicle 2 can be considered the ego-vehicle from a perspective centered on that vehicle. The host vehicle 2 is a mobile body, such as an automobile, that can travel on the road 3 as shown in Figure 2, with an occupant on board. Therefore, the directions in the following description are defined with respect to the host vehicle 2 on the horizontal plane. Although Figure 2 shows an example of application to a host vehicle 2 traveling on a road 3 in a country that uses left-hand traffic, it can of course also be applied to a host vehicle 2 traveling on a road 3 in a country that uses right-hand traffic.

[0017] In the host vehicle 2, an automated driving mode is provided, which is categorized into levels according to the degree of manual intervention by the occupant in dynamic driving tasks. The automated driving mode may be implemented by autonomous driving control, such as conditional driving automation, highly automated driving, or fully automated driving, in which the system performs all dynamic driving tasks (DDTs) during operation. The automated driving mode may also be implemented by advanced driver assistance control, such as driver assistance or partial driving automation, in which the occupant performs some or all of the dynamic driving tasks. The automated driving mode may be implemented by either one of these autonomous driving controls or advanced driver assistance controls, in combination, or by switching between them.

[0018] As shown in Figures 1-3, the host vehicle 2 is equipped with multiple external sensors 20 that sense within their individual external field of view Av and output sensor signals. Specifically, the external sensors 20 mounted in the front area of ​​the host vehicle 2 are assumed to be a front sensor 20f whose external field of view Av is set in front of the vehicle's direction of travel. The external sensors 20 mounted in the rear area of ​​the host vehicle 2 are assumed to be a rear sensor 20r whose external field of view Av is set behind the vehicle's direction of travel. The external sensors 20 mounted in the left area of ​​the host vehicle 2 are assumed to be a left front sensor 20lf whose external field of view Av is set diagonally to the left and forward of the vehicle's direction of travel, and a left rear sensor 20lr whose external field of view Av is set diagonally to the left and rear of the vehicle's direction of travel. The external environment sensor 20 mounted on the right side of the host vehicle 2 is assumed to include a right-front sensor 20rf whose external environment field of view Av is set to the right-front diagonally relative to the direction of travel of the vehicle, and a right-rear sensor 20rr whose external environment field of view Av is set to the right-rear diagonally relative to the direction of travel of the vehicle.

[0019] Each of these external sensors 20 consists of at least one type from among, for example, radar sensors, camera sensors, and optical scanning sensors such as LiDAR (light detection and ranging / laser imaging detection and ranging), depending on the mounting area on the host vehicle 2. In particular, each external sensor 20 in the first embodiment is configured to include at least a millimeter-wave transmitting and receiving type radar sensor Rs. Furthermore, in the first embodiment, in a host vehicle 2 traveling on a road 3 in a country that uses left-hand traffic, the sensors 20lf and 20lr in the left area may be given superior sensor performance, such as angular resolution, compared to the sensors 20rf and 20rr in the right area. Alternatively, in the first embodiment, in a host vehicle 2 traveling on a road 3 in a country that uses right-hand traffic, the sensors 20rf and 20rr in the right area may be given superior sensor performance, such as angular resolution, compared to the sensors 20lf and 20lr in the left area. Furthermore, it is perfectly acceptable for the sensors 20lf and 20lr in the left area and the sensors 20rf and 20rrr in the right area to be given substantially the same level of sensor performance.

[0020] As shown in Figure 1, the driver assistance system 1 is configured to include at least one dedicated computer. The driver assistance system 1 is connected to each external sensor 20 via at least one of the following: a LAN (local area network) line, a wire harness, and an internal bus. If there are multiple dedicated computers constituting the driver assistance system 1, the connections between those dedicated computers are similar. Figure 1 shows a representative example where the entire driver assistance system 1 is configured to be mounted on the host vehicle 2, as an example of implementation in the form of a driver assistance device such as a processing circuit or semiconductor chip. However, the driver assistance system 1 may also be constructed across the host vehicle 2, for example, to an external center that can communicate with the vehicle.

[0021] The dedicated computer constituting the driver assistance system 1 may be a driving control ECU (electronic control unit) that controls the driving of the host vehicle 2. The dedicated computer constituting the driver assistance system 1 may be a navigation ECU that navigates the driving route of the host vehicle 2. The dedicated computer constituting the driver assistance system 1 may be a locator ECU that estimates the self-state quantities of the host vehicle 2. The dedicated computer constituting the driver assistance system 1 may be an actuator ECU that controls the driving actuators of the host vehicle 2. The dedicated computer constituting the driver assistance system 1 may be an HCU (HMI (human machine interface) control unit) that controls the presentation of information in the host vehicle 2. The dedicated computer constituting the driver assistance system 1 may be a communication ECU that controls the communication system of the host vehicle 2. The dedicated computer constituting the driver assistance system 1 may be a computer other than the host vehicle 2 that constructs an external center or mobile terminal that can communicate via the communication system of the host vehicle 2.

[0022] The dedicated computer constituting the driver assistance system 1 has at least one memory 10 and one processor 12. The memory 10 is at least one type of non-transitory tangible storage medium, such as a semiconductor memory, magnetic medium, and optical medium, which non-temporarily stores programs and data that can be read by the computer. Here, storage may be accumulation in which data is retained even when the host vehicle 2 is turned off, or temporary storage in which data is erased when the host vehicle 2 is turned off. The processor 12 includes at least one type as a core, such as a CPU (central processing unit), GPU (graphics processing unit), RISC (reduced instruction set computer)-CPU, DFP (data flow processor), and GSP (graph streaming processor).

[0023] In the driver assistance system 1, the processor 12 executes multiple instructions included in the driver assistance program stored in the memory 10 to assist in the driving of the host vehicle 2. This allows the driver assistance system 1 to construct multiple functional blocks to assist in the driving of the host vehicle 2. The functional blocks constructed in the driver assistance system 1 include a monitoring block 100, an adjustment block 110, and a control block 120, as shown in Figure 3.

[0024] Through the combined action of these blocks 100, 110, and 120, the driver assistance method by which the driver assistance system 1 assists the driving of the host vehicle 2 is executed according to the driver assistance flow shown in Figure 4. This driver assistance flow is executed repeatedly while the host vehicle 2 is in motion. In this driver assistance flow, each "S" represents a step executed by multiple instructions included in the driver assistance program.

[0025] In S10, the monitoring block 100 monitors whether an emergency condition Ec requiring emergency operation has been met in the host vehicle 2. Specifically, an emergency operation is defined as an automated driving operation that transitions the host vehicle 2 to a minimum risk condition (MRC), such as a minimum risk maneuver (MRM) or DDT fallback. In particular, in the first embodiment, for a host vehicle 2 traveling on a road 3 in a country that uses left-hand traffic, two types of emergency maneuvers are envisioned: an emergency maneuver that causes the vehicle to move to the shoulder 30 secured on the left edge of the road 3 and then stop, as shown by the dashed arrow in Figure 5, and an emergency stop operation that causes the vehicle to stop near its current position by immediately decelerating. Alternatively, in the first embodiment, for a host vehicle 2 traveling on a road 3 in a country that uses right-hand traffic, an emergency evacuation operation is envisioned in which the vehicle moves to the shoulder 30 secured on the right edge of the road 3 and then stops, and an emergency stop operation is envisioned in which the vehicle immediately slows down and stops near its current position.

[0026] Such an emergency condition Ec requiring emergency operation is defined as an operating condition that arises, for example, from a malfunction, functional failure, or anticipated behavior of the host vehicle 2 that poses a potential risk. Therefore, the emergency condition Ec is an operating condition that is established when an abnormality or failure occurs in at least one type of physical element or functional block in the host vehicle 2. In particular, the emergency condition Ec in the first embodiment is established when an abnormality or failure occurs in at least one external sensor 20. In this case, the abnormality and failure of each external sensor 20 may be diagnosed based on, for example, a sensor signal.

[0027] As shown in Figure 4, if the emergency condition Ec is met in S10 and a positive judgment is made, the driving support flow proceeds to S20. In S20, the monitoring block 100 determines whether at least one of the external sensors 20 required to sense for the emergency evacuation operation of the host vehicle 2 is in a normal state. At this time, for the host vehicle 2 traveling on a road 3 in a country that uses left-hand traffic, the external sensors 20lf and 20lr in the left area on the shoulder 30 side are assumed to be the external sensors 20 required to sense for the emergency evacuation operation, as shown in Figure 5. Alternatively, for the host vehicle 2 traveling on a road 3 in a country that uses right-hand traffic, the external sensors 20rf and 20rr in the right area on the shoulder 30 side are assumed to be the external sensors 20 required to sense for the emergency evacuation operation. Furthermore, as external sensors 20 required for sensing in emergency evacuation operations, regardless of whether it is left-hand traffic or right-hand traffic, at least one of the sensors 20f, 20r in the front and rear areas may be assumed along with the sensors 20lf, 20lr or sensors 20rf, 20rr on the shoulder 30 side. In the following, the external sensors 20 required for sensing in emergency evacuation operations will be specifically referred to as emergency request sensors 200 (see lf, 20lr in Figure 5).

[0028] In S20, if at least one of the emergency request sensors 200 is determined to be in a normal state and a positive judgment is made, the driving support flow proceeds to S30 as shown in Figure 4. In S30, the monitoring block 100 acquires the current driving speed of the host vehicle 2 traveling on the road 3 as the reference speed Vb. In this first embodiment, it is preferable that relative speed information of stationary objects, recognized by the FFT (fast fourier transform) analysis processing of the received wave relative to the transmitted wave in the radar sensor Rs included in the emergency request sensor 200, is extracted from the sensor signal. This makes it possible to acquire the reference speed Vb based on the extracted relative speed information. However, instead of or in addition to relying on such relative speed information, the reference speed Vb may be directly acquired by the speed sensor of the host vehicle 2.

[0029] As shown in Figure 4, in S40 following S30, the adjustment block 110 dynamically adjusts the angular resolution θr realized by at least one external sensor 20 in software during emergency operation in response to the fulfillment of emergency condition Ec. At this time, as shown in Figure 6, the angular resolution θr is adjusted in stages toward performance improvement in accordance with the decrease in the reference velocity Vb acquired in S30. Here, angular resolution θr is defined as the minimum angle around the vertical axis in the external field of view Av that allows sensing positions to be separated and identified. Therefore, performance improvement of angular resolution θr means that the angular value representing the angular resolution θr becomes smaller.

[0030] Among the external sensors 20 whose angular resolution θr is subject to adjustment, an emergency request sensor 200 is selected that is required to sense during an emergency evacuation operation, which is an emergency operation in response to the fulfillment of an emergency condition Ec. In particular, in the first embodiment, the radar sensor Rs that constitutes the emergency request sensor 200 is included as a target for adjustment of the angular resolution θr. As shown in Figure 5, the radar sensor Rs as such an emergency request sensor 200 is at least a sensor 20lf, 20lr (in the case of left-hand traffic in Figure 5) or a sensor 20rf, 20rr (in the case of right-hand traffic) with an external field of view Av set on the side where the host vehicle 2 evacuates to the shoulder 30 during the emergency evacuation operation. On the other hand, in the host vehicle 2 of the first embodiment, the radar sensor Rs that constitute the external sensors 20 other than the emergency request sensor 200 are excluded from the adjustment of the angular resolution θr, and it is preferable that the angular value of the angular resolution θr be maintained from before the emergency evacuation operation. However, radar sensors Rs that constitute the external sensors 20 other than the emergency request sensor 200 may also be added as targets for adjustment of the angular resolution θr.

[0031] The adjustment principle of the first embodiment will be explained regarding the stepwise adjustment of the angular resolution θr performed on such a radar sensor Rs. In the following explanation, the adjustment principle will be explained using the example of stopping the host vehicle 2 on the shoulder 30 via an emergency lane change operation from the host lane 31 before the emergency evacuation operation to the adjacent lane 32 adjacent to the evacuation side due to the emergency evacuation operation, as shown in Figure 5.

[0032] As shown in Figure 7, the target resolution θt, which is the target of the angular resolution θr during an emergency evacuation operation, is set so that the performance gradually improves as the reference speed Vb of the host vehicle 2 decreases, with the angular value gradually decreasing as the reference speed Vb decreases. In this case, the target resolution θt should be set to the minimum angular resolution θr required in accordance with the reference speed Vb during the emergency evacuation operation. Therefore, the target resolution θt that correlates with the reference speed Vb, especially in the case of an emergency lane change operation among emergency evacuation operations, is expressed according to the following equations 1 and 2.

[0033] Here, Dr in equations 1 and 2 represents the required deceleration distance Dr in the longitudinal direction of the host lane 31 so that the following vehicle 4, which is traveling behind the host vehicle 2 in the host lane 31, can decelerate to match the reference speed Vb, as shown in Figure 8. Ar in equation 2 represents the magnitude of deceleration (i.e., the absolute value of acceleration) Ar that is imparted to the following vehicle 4 by decelerating to match the host vehicle 2, as shown in Figure 8. Vr in equation 2 represents the travel speed Vr of the following vehicle 4, as shown in Figure 8. This magnitude of deceleration Ar and travel speed Vr are obtained based on the relative speed information of the following vehicle 4, which is recognized, for example, by FFT analysis processing in the radar sensor Rs of the emergency request sensor 200, and extracted from the sensor signal, and based on this relative speed information and the reference speed Vb.

[0034] Furthermore, as shown in Figure 8, Dt in equation 1 represents the deviation distance Dt, which is the distance that an adjacent vehicle 5 traveling in the adjacent lane 32 behind the host vehicle 2 is deviated from the host vehicle 2 in the lateral direction of the host lane 31 and the adjacent lane 32. This deviation distance Dt is obtained based on distance information, which is extracted from the sensor signal by, for example, FFT analysis processing in the radar sensor Rs of the emergency request sensor 200.

[0035] The angular resolution θr of the radar sensor Rs is set to multiple levels in stages by correcting the target resolution θt, as shown in Figure 9. Specifically, in the example in Figure 9, when the target resolution θt is less than or equal to the first threshold θt1 according to the reference speed Vb, the angular resolution θr is forced to the first angle value θr1 by correcting the target resolution θt to a fixed first angle value θr1 that is smaller than the first threshold θt1. In this case, the first angle value θr1 should be set to correspond to the lower limit of the reference speed Vb that is the minimum required when initiating an emergency operation. Also in the example in Figure 9, when the target resolution θt is greater than the first threshold θt1 and less than or equal to the second threshold θt2 according to the reference speed Vb, the angular resolution θr is forced to the second angle value θr2 by correcting the target resolution θt to a fixed second angle value θr2 that is equal to the first threshold θt1. Furthermore, in the example shown in Figure 9, when the second threshold θt2 is exceeded according to the reference velocity Vb, the target resolution θt is corrected to a fixed third angular value θr3 that is equal to the second threshold θt2, thereby forcing the angular resolution θr to be set to the third angular value θr3.

[0036] In radar sensors Rs, setting the level of angular resolution θr is achieved by differentiating the angle measurement processing method of the received wave relative to the transmitted wave in software. Specifically, in the example in Figure 9, the DML (determined maximum likelihood) method is applied to correct the target resolution θt when it is below the first threshold θt1 and set the angular resolution θr to the first angular value θr1. Also in the example in Figure 9, the MUSIC (multiple signal classification) method is applied to correct the target resolution θt when it exceeds the first threshold θt1 and is below the second threshold θt2 and set the angular resolution θr to the second angular value θr2. Furthermore, in the example in Figure 9, the FFT analysis method is applied to correct the target resolution θt when it exceeds the second threshold θt2 and set the angular resolution θr to the third angular value θr3. It should be noted that each threshold θt1 and θt2 is set considering the characteristics of each of these angle measurement processing methods.

[0037] The correlations shown in Figures 7 and 9 above can be combined to form the correlation between the reference velocity Vb and the angular resolution θr shown in Figure 6. Therefore, in S40, according to the combined correlation in Figure 6, the angular resolution θr is variably adjusted so that performance improves in stages to multiple angular values ​​that become progressively smaller as the reference velocity Vb decreases. Specifically, in the example of Figure 6, at a reference velocity Vb of Vb1 or less, which corresponds to a first threshold θt1 or less, the angular resolution θr is adjusted to the smallest first angular value θr1, which shows the greatest performance improvement. Also in the example of Figure 6, at a reference velocity Vb exceeding Vb1, which corresponds to exceeding the first threshold θt1, and below the second threshold θt2, the angular resolution θr is adjusted to the second angular value θr2, which shows an intermediate performance improvement. Furthermore, in the example of Figure 6, at a reference velocity Vb exceeding Vb2, which corresponds to exceeding the second threshold θt2, the angular resolution θr is adjusted to the largest third angular value θr3, where the performance improvement is limited.

[0038] In the stepwise adjustment of the angular resolution θr described above, the processing resources in the processor 12 and memory 10 increase in the order of FFT analysis, MUSIC, and DML, which are applied as angle measurement processing methods to set the angular resolution θr as described above. In other words, the higher the reference speed Vb corresponding to each applied angle measurement processing method, the lower the computational cost required to adjust the angular resolution θr.

[0039] As shown in Figure 4, in S50 following S40, the control block 120 controls the driving speed of the host vehicle 2 during an emergency operation to be at or above the required lower limit speed Vmin. At this time, based on the sensor signals of at least the emergency request sensor 200 among the external sensors 20, the driving environment of the host vehicle 2 is recognized, and automatic driving control of the host vehicle 2, including driving speed control at or above the required lower limit speed Vmin, is performed. In order to ensure the environmental recognition performance during such driving speed control, the required lower limit speed Vmin is set according to the correlation relationship shown in Figure 10 with respect to the angular resolution θr adjusted in S40, which assumes an emergency evacuation operation as an emergency operation. In particular, in the case of an emergency lane change operation among emergency evacuation operations, the driving speed of the host vehicle 2 is controlled to be at or above the speed value of the required lower limit speed Vmin correlated with the angular resolution θr according to the following equation 3. However, in the emergency evacuation operation, from the lane 32 to which the vehicle has transitioned due to the emergency lane change operation, to the shoulder 30, the vehicle speed control should be performed so as to gradually decelerate to a speed value below the required lower limit speed Vmin before stopping at the shoulder 30.

[0040] In the driving control performed in S50, the driving state of the preceding vehicle 6, which is traveling in front of the host vehicle 2 in the host lane 31, may be taken into consideration, as shown in Figure 11. Therefore, during the emergency evacuation operation, the driving speed of the host vehicle 2 may be controlled to be below a speed value of the upper limit speed limit set based on, for example, the driving speed Vf of the preceding vehicle 6 and the distance Df between the host vehicle 2 and the preceding vehicle 6 in the longitudinal direction of the host lane 31.

[0041] Also, assuming that all of the emergency request sensors 200 are in an abnormal or faulty state in the aforementioned S20 and a negative determination is made, the operation support flow proceeds to S60. In S60, the control block 120 immediately decelerates the host vehicle 2 by means of automatic driving control that gives an emergency stop operation under an emergency condition Ec with a higher degree of emergency than the emergency evacuation operation, and causes it to make an emergency stop near the current position. Upon completion of the execution of S60, the current execution of the operation support flow ends. Incidentally, prior to the start of the emergency evacuation operation by S50, if the inter-vehicle distance Df to the preceding traveling vehicle 6 as shown in FIG. 11 has been shortened to outside the allowable range, instead of the emergency evacuation operation by S50, the emergency stop operation by S60 may be carried out.

[0042] Also, assuming that the emergency condition Ec is not satisfied in the aforementioned S10 and a negative determination is made, the operation support flow proceeds to S70. In S70, the control block 120 causes the host vehicle 2 to travel normally by means of automatic driving control that gives a nominal operation during normal times. Upon completion of the execution of S70, the current execution of the operation support flow ends.

[0043] (Operational Effects) The operational effects of the first embodiment described above will be described below.

[0044] According to the first embodiment, when an emergency condition Ec that requires an emergency operation is satisfied in the host vehicle 2 equipped with the external sensor 20, the traveling speed of the host vehicle 2 is acquired as the reference speed Vb. Therefore, the angular resolution θr of the external sensor 20 during the emergency operation is adjusted step by step toward the performance improvement side in accordance with the decrease in the reference speed Vb. According to this, as the traveling speed of the host vehicle 2 during the emergency operation, the required lower limit speed Vmin that correlates with each angular resolution θr with stepwise performance improvement can be reduced as much as possible from the reference speed Vb in accordance with the performance improvement. Therefore, during an emergency operation in which the traveling speed is controlled to be not less than the required lower limit speed Vmin for each angular resolution θr, it is possible to expand the dynamic range of the traveling speed control and ensure the safety of the host vehicle 2.

[0045] According to the first embodiment, an external sensor 20 that sets an external field of view Av on the evacuation side where the host vehicle 2 evacuates by an emergency operation is assumed as an emergency request sensor 200 that is required to sense an emergency operation. Therefore, the angular resolution θr of the emergency request sensor 200 is gradually adjusted to the performance improvement side in response to a decrease in the reference speed Vb. According to this, by correlating the necessary lower limit speed Vmin for each angular resolution θr of the emergency request sensor 200, which is particularly important in an emergency evacuation operation among emergency operations, the traveling speed can be controlled within a dynamic range of the necessary lower limit speed Vmin or higher. Therefore, it becomes possible to complete an emergency evacuation operation with ensured safety in the host vehicle 2.

[0046] The emergency evacuation operation according to the first embodiment is performed so as to stop the host vehicle 2 on the road shoulder 30 via an adjacent lane 32 adjacent to the evacuation side from the host lane 31 before the operation. According to this, an appropriate necessary lower limit speed Vmin is ensured for each stepwise angular resolution θr of the emergency request sensor 200 whose external field of view Av during the emergency evacuation operation is on the evacuation side to the road shoulder 30, and the traveling speed can be controlled within a dynamic range of the necessary lower limit speed Vmin or higher. Therefore, it becomes possible to complete an emergency operation with ensured safety until stopping at the road shoulder 30 in the host vehicle 2.

[0047] According to the first embodiment, as the angular resolution θr of the emergency request sensor 200 is adjusted, the angular resolution θr of the external sensor 20 other than the emergency request sensor 200 is maintained from before the establishment of the emergency condition Ec. According to this, it is possible to preferentially allocate the processing resources in the processor 12 and the memory 10 to the variable adjustment of the angular resolution θr for the emergency request sensor 200, and enhance the reliability for ensuring safety in the emergency evacuation operation.

[0048] According to the first embodiment, the angular resolution θr of the radar sensor Rs constituting the external sensor 20 is adjusted in stages to improve performance in accordance with the decrease in the reference speed Vb. As a result, in the host vehicle 2 during emergency operation, the required lower speed Vmin, which correlates with each stage of the angular resolution θr of the radar sensor Rs, can be reduced in accordance with the performance improvement of the corresponding angular resolution θr. Therefore, during emergency operation at a required lower speed Vmin or higher based on the angular resolution θr of the radar sensor Rs, it is possible to expand the dynamic range of the driving speed control and ensure the safety of the host vehicle 2.

[0049] (Second Embodiment) The second embodiment is a modification of the first embodiment. As shown in Figure 12, each external sensor 20 in the second embodiment is configured to include at least a global shutter type camera sensor Cs. Therefore, in S30 of the driving support flow according to the second embodiment, it is preferable that the reference speed Vb is directly acquired by the speed sensor of the host vehicle 2.

[0050] Furthermore, in S40 of the driving assistance flow according to the second embodiment, the camera sensors Cs constituting the emergency request sensor 200 are included as targets for adjustment of the angular resolution θr. As shown in Figure 13, these camera sensors Cs as emergency request sensors 200 are at least sensors 20lf, 20lr (in the case of left-hand traffic in Figure 13) or sensors 20rf, 20rr (in the case of right-hand traffic), with the external field of view Av set on the side where the host vehicle 2 takes refuge on the shoulder 30 due to the emergency refuge operation. On the other hand, camera sensors Cs constituting external sensors 20 other than the emergency request sensor 200 in the host vehicle 2 of the second embodiment are excluded from the adjustment of the angular resolution θr, and it is preferable that the angular value of the angular resolution θr be maintained from before the emergency refuge operation. However, camera sensors Cs constituting external sensors 20 other than the emergency request sensor 200 may of course be added to the targets for adjustment of the angular resolution θr.

[0051] Furthermore, the angular resolution θr of the camera sensor Cs to be adjusted in the second embodiment is set to multiple stepped levels by correcting the target resolution θt according to the adjustment principle similar to that of the first embodiment. However, as an adjustment principle unique to the second embodiment, which differs from that of the first embodiment, the level setting of the angular resolution θr is achieved in the camera sensor Cs by making the resolution of the camera image (i.e., the number of pixels as image data) different in software, as shown in Figure 14. This adjustment principle unique to the second embodiment relies on the fact that the angular pitch between vertical lines in the image data, which determines the resolution in the horizontal line direction in the camera image, is equivalent to the angular resolution θr.

[0052] In the example shown in Figure 14, the highest first resolution R1 is applied to the camera image in order to correct the target resolution θt when it is less than or equal to the first threshold θt1 and set the angular resolution θr to the first angular value θr1 (same as in Figure 9 of the first embodiment). Also in the example shown in Figure 14, the intermediate second resolution R2 is applied to the camera image in order to correct the target resolution θt when it exceeds the first threshold θt1 and is less than or equal to the second threshold θt2 and set the angular resolution θr to the second angular value θr2 (same as in Figure 9 of the first embodiment). Furthermore, in the example shown in Figure 14, the lowest third resolution R3 is applied to the camera image in order to correct the target resolution θt when it exceeds the second threshold θt2 and set the angular resolution θr to the third angular value θr3 (same as in Figure 9 of the first embodiment).

[0053] In S40 of this second embodiment, as the reference speed Vb decreases, variable adjustment is achieved to improve the performance of the angular resolution θr by decreasing the angular value in steps in multiple stages, similar to the first embodiment. However, in this stepwise adjustment of the angular resolution θr, the processing resources in the processor 12 and memory 10 increase in accordance with the resolution given to the camera image. In other words, the higher the reference speed Vb corresponding to each resolution of the camera image, the lower the computational cost required to adjust the angular resolution θr. The second embodiment may be implemented in combination with the first embodiment.

[0054] According to the second embodiment described above, the angular resolution θr of the camera sensor Cs constituting the external sensor 20 is adjusted in stages to improve performance in accordance with the decrease in the reference speed Vb. As a result, in the host vehicle 2 during emergency operation, the required lower speed Vmin, which correlates with each stage of angular resolution θr of the camera sensor Cs, can be reduced in accordance with the performance improvement of the corresponding angular resolution θr. Therefore, during emergency operation at a required lower speed Vmin or higher based on the angular resolution θr of the camera sensor Cs, it is possible to expand the dynamic range of the driving speed control and ensure the safety of the host vehicle 2.

[0055] (Third Embodiment) The third embodiment is a modification of the first embodiment. As shown in Figure 15, each external sensor 20 in the third embodiment is configured to include at least an optical scanning sensor Ls which is a LiDAR. Therefore, in S30 of the driving support flow according to the third embodiment, the reference speed Vb is preferably obtained directly by the speed sensor of the host vehicle 2, as in the case of the second embodiment described above.

[0056] Furthermore, in S40 of the driving support flow according to the third embodiment, the optical scanning sensors Ls constituting the emergency request sensor 200 are included as targets for adjustment of the angular resolution θr. As shown in Figure 16, these optical scanning sensors Ls as emergency request sensors 200 are at least sensors 20lf, 20lr (in the case of left-hand traffic in Figure 16) or sensors 20rf, 20rr (in the case of right-hand traffic), with the external field of view Av set on the side where the host vehicle 2 takes refuge on the shoulder 30 due to the emergency refuge operation. On the other hand, in the host vehicle 2 of the third embodiment, optical scanning sensors Ls constituting the external sensors 20 other than the emergency request sensor 200 are excluded from the adjustment of the angular resolution θr, and it is preferable that the angular value of the angular resolution θr be maintained from before the emergency refuge operation. However, optical scanning sensors Ls constituting the external sensors 20 other than the emergency request sensor 200 may of course be added to the targets for adjustment of the angular resolution θr.

[0057] Furthermore, in the third embodiment, the angular resolution θr of the optical scanning sensor Ls to be adjusted is set to multiple stepped levels by correcting the target resolution θt according to the adjustment principle similar to that of the first embodiment. However, as an adjustment principle specific to the third embodiment, which differs from the first embodiment, the level setting of the angular resolution θr is achieved in the optical scanning sensor Ls by varying the scanning angle pitch, as shown in Figure 17, in the software, which determines the angular resolution θr in the horizontal scanning direction. Thus, for the optical scanning sensor Ls, the angular difference of the beam irradiation direction for each vertical scanning line is variably controlled in the software, and this angular difference becomes equivalent to the scanning angle pitch and the angular resolution θr.

[0058] In the example shown in Figure 17, the minimum first angular pitch P1 is applied as the scanning angular pitch in order to correct the target resolution θt when it is less than or equal to the first threshold θt1 and set the angular resolution θr to the first angular value θr1 (same as in Figure 9 of the first embodiment). Also in the example shown in Figure 17, the intermediate second angular pitch P2 is applied as the scanning angular pitch in order to correct the target resolution θt when it exceeds the first threshold θt1 and is less than or equal to the second threshold θt2 and set the angular resolution θr to the second angular value θr2 (same as in Figure 9 of the first embodiment). Furthermore, in the example shown in Figure 17, the maximum third angular pitch P3 is applied as the scanning angular pitch in order to correct the target resolution θt when it exceeds the second threshold θt2 and set the angular resolution θr to the third angular value θr3 (same as in Figure 9 of the first embodiment).

[0059] In S40 of this third embodiment, as the reference speed Vb decreases, variable adjustment is achieved to improve the performance of the angular resolution θr by decreasing the angular value in steps in multiple stages, similar to the first embodiment. However, in this stepwise adjustment of the angular resolution θr, the processing resources in the processor 12 and memory 10 increase in accordance with the increase in the number of vertical scanning lines due to the reduction in the scanning angle pitch. In other words, the higher the reference speed Vb corresponding to each scanning angle pitch, the lower the computational cost required to adjust the angular resolution θr. The third embodiment may be implemented in combination with at least one of the first and second embodiments.

[0060] According to the third embodiment described above, the angular resolution θr of the optical scanning sensor Ls constituting the external sensor 20 is adjusted in stages to improve performance in accordance with the decrease in the reference speed Vb. As a result, in the host vehicle 2 during emergency operation, the required lower speed Vmin, which correlates with each stage of the angular resolution θr of the optical scanning sensor Ls, can be reduced in accordance with the performance improvement of the corresponding angular resolution θr. Therefore, during emergency operation at a required lower speed Vmin or higher based on the angular resolution θr of the optical scanning sensor Ls, it is possible to expand the dynamic range of the driving speed control and ensure the safety of the host vehicle 2.

[0061] (Other Embodiments) Although several embodiments have been described above, this disclosure is not to be construed as being limited to those embodiments, and can be applied to various embodiments and combinations without departing from the spirit of this disclosure.

[0062] In the modified example, the dedicated computer constituting the driver assistance system 1 may have at least one of the digital circuit and the analog circuit as a processor. Here, the digital circuit is at least one of the following, for example, ASIC (application specific integrated circuit), FPGA (field programmable gate array), SOC (system on a chip), PGA (programmable gate array), and CPLD (complex programmable logic device). Furthermore, such a digital circuit may have a memory that stores a program.

[0063] In addition to the configurations described so far, the host vehicle 2 to which the driving assistance system 1 is applied in the above-described embodiments and modifications may be, for example, an autonomous robot capable of transporting cargo or collecting information by autonomous driving or remote driving.

[0064] (Addendum) This specification discloses several technical ideas and several combinations thereof, as listed below. The symbols in parentheses in this addendum indicate the correspondence with the specific means described in the embodiments described in detail earlier, and do not limit the technical scope of this disclosure.

[0065] (Technical Concept 1) A driving assistance system having a processor (12) to assist in the driving of a host vehicle (2) equipped with an external sensor (20) that senses within the external field of view (Av), wherein the processor is configured to perform the following actions when an emergency condition (Ec) requiring emergency operation is met in the host vehicle: to acquire the driving speed of the host vehicle as a reference speed (Vb); to adjust the angular resolution (θr) of the external sensor during the emergency operation in stages toward performance improvement in accordance with the decrease in the reference speed; and to control the driving speed of the host vehicle during the emergency operation to be above the required lower limit speed (Vmin) correlated for each of the stages of angular resolution.

[0066] (Technical Concept 2) The driver assistance system according to Technical Concept 1, wherein the adjustment of the angular resolution is performed by setting the external field of view of the external sensor on the retreat side from which the host vehicle retreats due to the emergency operation as an emergency request sensor (200) whose sensing is required for the emergency operation, and adjusting the angular resolution of the said emergency request sensor in stages toward the performance improvement side in accordance with the decrease in the reference speed.

[0067] (Technical Concept 3) The driver assistance system according to Technical Concept 2, wherein the adjustment of the angular resolution is performed by adjusting the angular resolution of the emergency request sensor in stages toward the performance improvement side in accordance with the decrease in the reference speed during the emergency operation in which the host vehicle is stopped on the shoulder (30) from the host lane (31) before the emergency operation, via the adjacent lane (32) adjacent to the evacuation side.

[0068] (Technical Concept 4) The driving support system according to technical concept 2 or 3, wherein the adjustment of the angular resolution is performed in conjunction with adjusting the angular resolution of the emergency request sensor, and the angular resolution of the external sensors other than the emergency request sensor is maintained from before the emergency operation.

[0069] (Technical Idea 5) The driver assistance system according to any one of Technical Ideas 1 to 4, wherein the adjustment of the angular resolution is performed by adjusting the angular resolution of the radar sensor (Rs) constituting the external sensor in steps according to the decrease in the reference speed.

[0070] (Technical Concept 6) The driver assistance system according to any one of Technical Concepts 1 to 5, wherein the adjustment of the angular resolution is to adjust the angular resolution of the camera sensor (Cs) constituting the external sensor in stages to improve performance in accordance with the decrease in the reference speed.

[0071] (Technical Concept 7) The driving support system according to any one of Technical Concepts 1 to 6, wherein the adjustment of the angular resolution is to adjust the angular resolution of the optical scanning sensor (Ls) constituting the external sensor in stages to improve performance in accordance with the decrease in the reference speed.

[0072] Furthermore, the technical concepts 1 to 7 described above may be understood as technical concepts for the apparatus, method, and program, respectively.

Claims

A driver assistance system having a processor (12) to support the driving of a host vehicle (2) equipped with an external sensor (20) that senses within the external field of view (Av), The aforementioned processor, When an emergency condition (Ec) requiring emergency operation is met in the host vehicle, the driving speed of the host vehicle is acquired as the reference speed (Vb), The angular resolution (θr) of the external sensor during the emergency operation is adjusted in stages to improve performance in accordance with the decrease in the reference speed, A driver assistance system configured to control the travel speed of the host vehicle during the emergency operation to be above a minimum required speed (Vmin) correlated for each of the stepwise angular resolutions. 　 The adjustment of the angular resolution is as follows: The driving assistance system according to claim 1, further comprising setting the external field of view of the external sensor on the retreat side from which the host vehicle retreats due to the emergency operation as an emergency request sensor (200) whose sensing is required for the emergency operation, and adjusting the angular resolution of the emergency request sensor to gradually improve performance in accordance with the decrease in the reference speed. 　 The adjustment of the angular resolution is as follows: The driving assistance system according to claim 2, which includes, during the emergency operation in which the host vehicle is stopped on the shoulder (30) via the adjacent lane (32) adjacent to the evacuation side from the host lane (31) before the emergency operation, the angular resolution of the emergency request sensor is adjusted in stages to improve performance in accordance with the decrease in the reference speed. 　 The adjustment of the angular resolution is as follows: The driving assistance system according to claim 2, further comprising adjusting the angular resolution of the emergency request sensor, while maintaining the angular resolution of the external sensors other than the emergency request sensor from before the emergency operation. 　 The adjustment of the angular resolution is as follows: The driving assistance system according to claim 1, further comprising adjusting the angular resolution of the radar sensor (Rs) constituting the external sensor in steps according to the decrease in the reference speed. 　 The adjustment of the angular resolution is as follows: The driving assistance system according to claim 1, further comprising adjusting the angular resolution of the camera sensor (Cs) constituting the external sensor in stages to improve performance in accordance with the decrease in the reference speed. 　 The adjustment of the angular resolution is as follows: The driving support system according to claim 1, further comprising adjusting the angular resolution of the optical scanning sensor (Ls) constituting the external sensor in stages to improve performance in accordance with the decrease in the reference speed. 　 A driver assistance device having a processor (12) to support the driving of a host vehicle (2) equipped with an external sensor (20) that senses within the external field of view (Av), and configured to be mountable on the host vehicle, The aforementioned processor, When an emergency condition (Ec) requiring emergency operation is met in the host vehicle, the driving speed of the host vehicle is acquired as the reference speed (Vb), The angular resolution (θr) of the external sensor during the emergency operation is adjusted in stages to improve performance in accordance with the decrease in the reference speed, A driving assistance device configured to control the travel speed of the host vehicle during the emergency operation to be above a minimum required speed (Vmin) correlated for each of the stepwise angular resolutions. 　 A driving assistance method performed by a processor (12) to assist the driving of a host vehicle (2) equipped with an external sensor (20) that senses within the external field of view (Av), When an emergency condition (Ec) requiring emergency operation is met in the host vehicle, the driving speed of the host vehicle is acquired as the reference speed (Vb), The angular resolution (θr) of the external sensor during the emergency operation is adjusted in stages to improve performance in accordance with the decrease in the reference speed, A driving assistance method comprising controlling the driving speed of the host vehicle during the emergency operation to be above a minimum required speed (Vmin) correlated according to the stepwise angular resolution. 　 A driving assistance program, which is stored in a storage medium (10) to assist in the driving of a host vehicle (2) equipped with an external sensor (20) that senses within the external field of view (Av), and which includes instructions for causing a processor (12) to perform said assistance, When an emergency condition (Ec) requiring emergency operation is met in the host vehicle, the driving speed of the host vehicle is acquired as the reference speed (Vb), The angular resolution (θr) of the external sensor during the emergency operation is adjusted in stages to improve performance in accordance with the decrease in the reference speed, A driving assistance program including the command to control the driving speed of the host vehicle during the emergency operation to be above a minimum required speed (Vmin) correlated for each of the stepwise angular resolutions.

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