Steering control device and vehicle

Abstract

A steering control device according to one embodiment of the present disclosure comprises: an acquisition unit capable of acquiring a steering angular velocity obtained by monitoring; and a control unit capable of controlling steering on the basis of the steering angular velocity. In a case where the steering angular velocity exceeds a first threshold value, the control unit is capable of outputting, to an EPS, a control signal for causing the EPS to output a torque that makes a steering angular acceleration smaller than a second threshold value, when the steering angular acceleration, which is a change in the steering angular velocity, exceeds the second threshold value, or when a sign of the steering angular acceleration is different from a sign of the steering angular velocity.

Description

Steering control device and vehicle

[0001] The present disclosure relates to a steering control device mounted on a vehicle, and a vehicle equipped with such a steering control device.

[0002] 2. Description of the Related Art Conventionally, techniques have been proposed for automatic driving control, such as preventing vehicle sway.

[0003] Japanese Patent Application Laid-Open No. 2020-01539

[0004] A steering control device according to a first aspect of the present disclosure includes an acquisition unit capable of acquiring a steering angular velocity obtained by monitoring, and a control unit capable of controlling steering based on the steering angular velocity. When the steering angular velocity exceeds a first threshold, and steering angular acceleration, which is a change in the steering angular velocity, exceeds a second threshold, or when the sign of the steering angular acceleration differs from the sign of the steering angular velocity, the control unit is capable of outputting a control signal to an electric power steering (EPS) to cause the EPS to output a torque that reduces the steering angular acceleration below the second threshold.

[0005] A steering control device according to a second aspect of the present disclosure includes an acquisition unit capable of acquiring the steering torque obtained by monitoring, and a control unit capable of controlling steering based on the steering torque. When the steering torque exceeds a predetermined threshold and the steering torque decreases, the control unit is capable of outputting a control signal to the EPS to cause the EPS to output a torque that suppresses the decrease in the steering torque.

[0006] A vehicle according to a third aspect of the present disclosure includes a steering control device, a steering speed monitoring device, and an EPS. The steering control device has an acquisition unit capable of acquiring the steering angular velocity obtained by monitoring, and a control unit capable of controlling steering based on the steering angular velocity. When the steering angular velocity exceeds a first threshold, the control unit is capable of outputting a control signal to the EPS to cause the EPS to output a torque that reduces the steering angular acceleration below the second threshold when the steering angular acceleration, which is a change in the steering angular velocity, exceeds a second threshold or when the sign of the steering angular acceleration differs from that of the steering angular velocity.

[0007] A vehicle according to a fourth aspect of the present disclosure includes a steering control device, a steering torque monitoring device, and an EPS. The steering control device has an acquisition unit capable of acquiring the steering torque obtained by monitoring, and a control unit capable of controlling steering based on the steering torque. When the steering torque exceeds a predetermined threshold and the steering torque decreases, the control unit is capable of outputting a control signal to the EPS to cause the EPS to output a torque that suppresses the decrease in steering torque.

[0008] The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate one embodiment and, together with the description, serve to explain the principles of the disclosure.

[0009] FIG. 1 is a diagram illustrating an example of functional blocks of a vehicle according to a first embodiment of the present disclosure. FIG. 2(A) is a diagram illustrating an example of a change in steering angle over time in the vehicle of FIG. 1. FIG. 2(B) is a diagram illustrating an example of a change in steering angular velocity over time in the vehicle of FIG. 1. FIG. 2(C) is a diagram illustrating an example of a change in steering angular acceleration over time in the vehicle of FIG. 1. FIG. 3 is a diagram for explaining an example of a steering control procedure in the vehicle of FIG. 1. FIG. 4 is a diagram for explaining a modified example of the steering control procedure in the vehicle of FIG. 1. FIG. 5 is a diagram illustrating an example of functional blocks of a vehicle according to a second embodiment of the present disclosure. FIG. 6(A) is a diagram illustrating an example of a change in steering angle over time in the vehicle of FIG. 5. FIG. 6(B) is a diagram illustrating an example of a change in steering torque over time in the vehicle of FIG. 5. FIG. 7 is a diagram for explaining an example of a steering control procedure in the vehicle of FIG. 5.

[0010] <1. Background> Beginner drivers who have just started driving may accidentally let the steering wheel slip from their hands while steering at intersections or curves, or may unintentionally turn the steering wheel too much. Lane-keeping control, which controls vehicle sway, has difficulty responding to such sudden steering operations.

[0011] In lane keeping control, when a slight steering operation is performed that causes the vehicle to turn in a direction different from the traveling direction of the road, a torque is output from the EPS (Electric Power Steering) to return the traveling direction of the vehicle to the traveling direction of the road. However, on road structures such as intersections where it is difficult to fix the traveling direction, lane keeping control cannot be enabled. Furthermore, on multi-lane roads where lane changes are possible, sudden steering operations automatically disable the lane keeping control. If the lane keeping control were effective even in response to sudden steering operations, the lane keeping control would not be able to return the traveling direction of the vehicle to the traveling direction of the road when a sudden steering operation is performed, resulting in unstable vehicle behavior.

[0012] It is desirable to provide a steering control device and a vehicle that can respond to sudden steering operations without destabilizing the behavior of the vehicle.

[0013] Some exemplary embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. Note that the following description illustrates one specific example of the present disclosure and should not be construed as limiting the present disclosure. For example, each element, including numerical values, shapes, materials, parts, the position of each part, and the connection method of each part, is merely an example and should not be construed as limiting the present disclosure. Furthermore, in the following exemplary embodiments, components not described in independent claims based on the highest concept of the present disclosure are optional and may be provided as needed. The drawings are schematic and are not intended to be drawn to scale. Throughout this specification and the drawings, components having substantially the same function and configuration are designated by the same reference numerals, and redundant description will be omitted. Furthermore, components not directly related to one embodiment of the present disclosure are not shown in the drawings.

[0014] The present disclosure will be described in the following order: 1. First embodiment (FIGS. 1 to 3): An example of performing steering control by comparing steering angular acceleration with a threshold value 2. Modification of the first embodiment (FIG. 4): An example of performing steering control by comparing the sign of steering angular acceleration with the sign of steering angular velocity 3. Second embodiment (FIGS. 5 to 7): An example of performing steering control when steering torque decreases

[0015] 1 illustrates an example of functional blocks of a vehicle 1 according to a first embodiment of the present disclosure. As shown in FIG. 1, the vehicle 1 includes, for example, a sensor unit 10, a communication unit 20, a control unit 30, a storage unit 40, a notification unit 50, a motor 60, a brake 70, and an ESP motor 80.

[0016] The sensor unit 10 is configured to include various sensors mounted on the vehicle 1. The sensor unit 10 is configured to include, for example, a vehicle speed sensor, an acceleration sensor, an angular velocity sensor, a steering angular velocity sensor, and a steering torque sensor. The sensor unit 10 may also include sensors other than those described above.

[0017] The vehicle speed sensor is capable of detecting the speed (vehicle speed) of the vehicle 1. The vehicle speed sensor is capable of outputting time series data (vehicle speed data) about the detected vehicle speed to the control unit 30. The acceleration sensor is capable of detecting acceleration applied to the vehicle 1. The acceleration sensor is capable of outputting time series data (acceleration data) about the detected acceleration in three directions to the control unit 30. The angular velocity sensor is capable of detecting the angular velocity of the vehicle 1. The angular velocity sensor is capable of outputting time series data (angular velocity data) about the detected three angular velocities (yaw angular velocity, roll angular velocity, and pitch angular velocity) to the control unit 30.

[0018] The steering angular velocity sensor is capable of detecting the rotation speed of the steering angle (steering wheel angle) of the steering wheel of the vehicle 1. The steering angular velocity sensor is capable of outputting time series data (steering angular velocity dδ / dt) of the detected steering angular velocity to the control unit 30. The steering torque sensor is capable of detecting the steering torque generated by the driver's steering wheel operation. The steering torque sensor is capable of outputting time series data (steering torque TR) of the detected steering torque to the control unit 30.

[0019] The sensor unit 10 further includes a stereo camera mounted on the vehicle 1 and a driving environment detection unit. The stereo camera is an autonomous sensor that senses the real space around the vehicle 1. The stereo cameras are, for example, arranged at symmetrical positions on either side of the central part in the width direction of the vehicle 1, and are capable of capturing stereo images of the area in front of the vehicle 1 from different viewpoints. The stereo cameras are capable of outputting image data Da (a pair of stereo image data) obtained by capturing images to the control unit 30.

[0020] The stereo camera is capable of generating distance image data Db calculated from the amount of displacement between corresponding objects based on image data Da (a pair of stereo image data) obtained by capturing images. The driving environment detection unit is capable of, for example, calculating lane markings that divide the road around the vehicle 1 based on the distance image data Db. The driving environment detection unit is also capable of calculating the road curvature of the markings that divide the left and right sides of the road (driving lane) on which the vehicle 1 is traveling, and the width between the left and right markings (vehicle width). The driving environment detection unit is also capable of performing predetermined pattern matching on the distance image data Db to detect lanes and three-dimensional objects such as structures present around the vehicle 1.

[0021] Here, the detection of a three-dimensional object by the driving environment detection unit includes, for example, detecting the type of the three-dimensional object, the distance to the three-dimensional object, the speed of the three-dimensional object, and the relative speed between the three-dimensional object and the vehicle (host vehicle). Examples of three-dimensional objects to be detected include traffic lights, intersections, road signs, stop lines, other vehicles, pedestrians, bicycles, and buildings. Examples of buildings include detached houses, apartment complexes (condominiums), commercial facilities, factories, and signs. The driving environment detection unit is capable of outputting driving environment information around the vehicle 1, including the thus acquired information on the three-dimensional object, to the control unit 30.

[0022] The communication unit 20 can acquire data to supplement data that cannot be obtained from the image data Da and the distance image data Db, for example, through vehicle-to-vehicle communication, road-to-vehicle communication, and satellite communication. The communication unit 20 can output the acquired data to the control unit 30.

[0023] The communication unit 20 can acquire data (e.g., vehicle position and vehicle speed) obtained by other vehicles through, for example, vehicle-to-vehicle communication. The communication unit 20 can receive positioning signals transmitted from multiple positioning satellites through, for example, satellite communication.

[0024] The communication unit 20 is capable of acquiring road map data of the surroundings of the vehicle 1, for example, through road-to-vehicle communication. The road map data is made up of, for example, highly accurate road map information (dynamic map) and has static information and quasi-static information that mainly constitute road information, and quasi-dynamic information and dynamic information that mainly constitute traffic information.

[0025] The static information that makes up road information is composed of information that requires updates within one month, such as roads, structures on roads, structures around roads, lane information, road surface information, and permanent regulation information. "Roads" include, for example, road locations and shapes, intersections, and road attributes (e.g., national roads, prefectural roads, city roads, private roads, priority roads, non-priority roads, general roads, and expressways). "Structures on roads" include, for example, traffic signs, traffic lights, convex mirrors, pedestrian bridges, bus stops, and garbage collection stations. "Structures around roads" include, for example, various buildings and parks.

[0026] The quasi-static information that constitutes the road information is made up of information that needs to be updated every hour, such as traffic regulation information due to road construction or events, wide-area weather information, and congestion forecasts.

[0027] The semi-dynamic information that constitutes traffic information is composed of information that requires updating within one minute, such as the actual traffic congestion situation at the time of observation, driving restrictions, temporary driving obstructions such as fallen objects and obstacles, actual accident conditions, and narrow-area weather information.

[0028] The dynamic information that constitutes the traffic information is composed of information that needs to be updated every second, such as information sent and exchanged between mobile bodies, information on currently displayed traffic signals, information on pedestrians and bicycles at intersections, information on vehicles traveling on roads, etc. Such road map information is maintained and updated periodically until the next information is received from each vehicle, and the updated road map information is transmitted to each vehicle as appropriate via the communication unit 20.

[0029] The storage unit 40 is configured, for example, by a non-volatile memory, such as an EEPROM (Electrically Erasable Programmable Read-Only Memory), a flash memory, or a resistance change memory. As shown in FIG. 1 , the storage unit 40 stores a road map DB 41 and thresholds 42. The thresholds 42 store, for example, a threshold th1 for steering angular velocity and a threshold th2 for steering angular acceleration. The threshold th1 corresponds to a specific example of a "first threshold" in the present disclosure. The threshold th2 corresponds to a specific example of a "second threshold" in the present disclosure.

[0030] The threshold value th1 is a value that can be considered to indicate that the driver of the vehicle 1 has started to turn the steering wheel intentionally to change the direction of travel of the vehicle 1 when the vehicle 1 enters, for example, an intersection or a curve. The threshold value th1 is a value that is greater than the range of steering angular velocity that can be considered to indicate swaying of the vehicle 1 when the vehicle 1 is traveling straight. The threshold value th2 is a value that can be considered to indicate that the driver of the vehicle 1 has performed an unintentional sudden steering operation while the vehicle 1 is changing the direction of travel of the vehicle 1 at, for example, an intersection or a curve. The threshold value th2 is a value that is greater than the range of steering angular acceleration that can be considered to indicate swaying of the vehicle 1 when the vehicle 1 is traveling straight.

[0031] The control unit 30 is capable of controlling the entire vehicle 1. The control unit 30 is, for example, a so-called ECU (Electronic Control Unit) and is configured to include, for example, one or more processors and one or more memories. The control unit 30 may be configured to include, for example, a CPU (Central Processing Unit). In this case, the control unit 30 is capable of controlling the entire vehicle 1 by, for example, executing a program stored in a storage unit.

[0032] The control unit 30 includes, for example, a locator unit. The locator unit is capable of acquiring the position coordinates of the vehicle 1 based on the positioning signal received through the communication unit 20. The locator unit is capable of estimating the vehicle's position on a road map by map-matching the acquired position coordinates with route map information. Based on the acquired position coordinates of the vehicle 1, the locator unit acquires map information of a predetermined range including the vehicle 1 from map information stored in a road map DB (database) 41 (described later).

[0033] In an environment where it is not possible to receive valid positioning signals from positioning satellites due to reduced sensitivity, such as when driving inside a tunnel, the locator unit can switch to autonomous navigation, which estimates the vehicle's position based on the vehicle speed, angular velocity, and longitudinal acceleration detected by sensor unit 10, and estimate the vehicle's position on a road map.

[0034] As described above, the locator unit estimates the position of vehicle 1 (vehicle position) on a road map based on the positioning signal received through communication unit 20 or information detected by sensor unit 10, and is then able to determine the road type, etc. of the road on which vehicle 1 is traveling based on the estimated vehicle position on the road map.

[0035] The locator unit is capable of updating the road map information stored in the road map DB 41 to the latest version using road map information acquired through external communication (roadside-to-vehicle communication and vehicle-to-vehicle communication) via the communication unit 20. This information update is performed not only for static information but also for quasi-static information, quasi-dynamic information, and dynamic information. As a result, the road map information includes road information and traffic information acquired through communication with the outside of the vehicle, and information on moving bodies such as vehicles traveling on roads is updated in approximately real time.

[0036] The locator unit verifies road map information based on the traveling environment information recognized as described above, and updates the road map information stored in the road map DB 41 to the latest version. This information update is performed not only on static information, but also on semi-static information, semi-dynamic information, and dynamic information. As a result, information on moving objects such as vehicles traveling on roads recognized as described above is updated in real time.

[0037] The control unit 30 further includes a driving control unit 35, for example, as shown in FIG. 1. The driving control unit 35 is capable of performing driving control using various data and various control signals acquired by a data acquisition unit 32 (described later). The driving control unit 35 is capable of controlling the driving of the vehicle 1 (for example, the torque of the prime mover 60, the braking force of the brakes, and the operation of the steering wheel). The driving control unit 35 includes an accelerator control unit 36, a brake control unit 37, and a steering control unit 38, for example, as shown in FIG. 1. The steering control unit 38 corresponds to a specific example of a "control unit" in the present disclosure.

[0038] Accelerator control unit 36 ​​is capable of controlling the torque of prime mover 60 based on a required torque corresponding to the amount of accelerator pedal depression by the driver of vehicle 1. Accelerator control unit 36 ​​is further capable of controlling the torque of prime mover 60 based on a target torque obtained by adding a correction torque generated by automatic control to the required torque. Prime mover 60 is configured to drive the steered wheels of vehicle 1, and is capable of driving the steered wheels of vehicle 1 in accordance with the required torque or target torque input from accelerator control unit 36.

[0039] The brake control unit 37 is capable of controlling the torque (braking force) of the brake 70 based on a required torque corresponding to the amount of brake pedal depression by the driver of the vehicle 1. The brake control unit 37 is further capable of controlling the torque (braking force) of the brake 70 based on a target torque obtained by adding a correction torque generated by automatic control to the required torque. The brake 70 is configured to brake the steered wheels of the vehicle 1, and is capable of braking the steered wheels of the vehicle 1 in accordance with the required torque or target torque input from the brake control unit 37.

[0040] The steering control unit 38 is capable of deriving a steering assist torque that assists the steering torque generated by the driver's steering wheel operation and setting an EPS torque corresponding to the derived steering assist torque. The steering control unit 38 is capable of outputting a control signal to the EPS motor 80 so that the output torque of the EPS motor 80 becomes the set EPS torque. The EPS motor 80 generates an output torque based on the control signal input from the steering control unit 38 and is capable of controlling the steering of the steering wheel.

[0041] The control unit 30 further includes a steering determination unit 31, for example, as shown in Fig. 1. The steering determination unit 31 corresponds to a specific example of a "control unit" in the present disclosure. The steering determination unit 31 includes a data acquisition unit 32, an erroneous steering determination unit 33, and a notification control unit 35, for example, as shown in Fig. 1. The data acquisition unit 32 corresponds to a specific example of an "acquisition unit" in the present disclosure.

[0042] The data acquisition unit 32 is capable of periodically acquiring data on the situation or state of the vehicle 1 by monitoring. Specifically, the data acquisition unit 32 is capable of periodically acquiring various data obtained from the sensor unit 10, various data obtained from the outside via the communication unit 20, and various control signals for various devices of the vehicle 1 by monitoring. The data acquisition unit 32 is further capable of acquiring new data, for example, based on the various acquired data and various control signals. For example, the data acquisition unit 32 is capable of calculating the steering angular acceleration dδ / dt based on the steering angular velocity dδ / dt obtained from the steering angular velocity sensor. ２ It is now possible to obtain the following.

[0043] The erroneous steering determination unit 33 receives data related to the steering of the vehicle 1 (specifically, the steering angular velocity dδ / dt and the steering angular acceleration dδ / dt ２ ) based on the steering data, the erroneous steering determination unit 33 can determine whether the driver of the vehicle 1 has erroneously steered the vehicle 1. The erroneous steering determination unit 33 can further cooperate with the steering control unit 38 to control the steering of the vehicle 1 based on the data related to the steering of the vehicle 1.

[0044] When the steering angular velocity dδ / dt exceeds the threshold value th1, the erroneous steering determination unit 33 determines the steering angular acceleration dδ / dt, which is a change in the steering angular velocity dδ / dt. ２ When exceeds the threshold value th2, the steering angular acceleration dδ / dt ２ The steering control unit 38 generates a steering intervention command to cause the EPS motor 80 to output a torque that makes the steering angular acceleration dδ / dt smaller than the threshold value th2, and outputs the steering intervention command to the steering control unit 38. When the steering intervention command is input from the erroneous steering determination unit 33, the steering control unit 38 calculates the steering angular acceleration dδ / dt based on the input steering intervention command. ２ It is possible to output a control signal to the EPS motor 80 to output a torque that makes the torque smaller than the threshold value th2.

[0045] The erroneous steering determination unit 33 is capable of generating the steering intervention command in accordance with a control signal generated by the steering control unit 38 based on the steering intervention command so that the torque output from the EPS motor 80 is within a range of torque that prevents the vehicle 1 from deviating from the route (driving path). The erroneous steering determination unit 33 is capable of deriving the magnitude of the torque output from the EPS motor 80 based on, for example, road map information 41 in the storage unit 40 and data such as lane markings obtained from distance image data Db, etc. The erroneous steering determination unit 33 is capable of outputting a notification signal to the notification control unit 34 to notify that steering intervention has been made to the EPS motor 80.

[0046] When the notification signal is input from the erroneous steering determination unit 33, the notification control unit 34 can generate, for example, an audio signal of a voice message notifying that steering intervention has occurred, and output the voice signal to the notification unit 50. The notification unit 50 is configured to include, for example, a microphone, and can output the voice message based on the audio signal input from the notification control unit 34.

[0047] 2A shows an example of the change over time of the steering angle δ in the vehicle 1. FIG. 2B shows an example of the change over time of the steering angular velocity dδ / dt in the vehicle 1. FIG. 2C shows an example of the change over time of the steering angular acceleration dδ / dt in the vehicle 1. ２2A shows an example of a time change of the steering wheel 1a. In FIG. 2A, the dashed line represents an OFF control curve La1 obtained when the above-mentioned steering intervention control is not performed, and the solid line represents an ON control curve Lb1 obtained when the above-mentioned steering intervention control is performed. In FIG. 2B, the dashed line represents an OFF control curve La2 obtained when the above-mentioned steering intervention control is not performed, and the solid line represents an ON control curve Lb2 obtained when the above-mentioned steering intervention control is performed. In FIG. 2C, the dashed line represents an OFF control curve La3 obtained when the above-mentioned steering intervention control is not performed, and the solid line represents an ON control curve Lb3 obtained when the above-mentioned steering intervention control is performed. FIGS. 2A to 2C illustrate data obtained when the driver of vehicle 1 accidentally lets the steering wheel slip from his / her hands while turning vehicle 1 right at an intersection.

[0048] The dashed line in Figure 2(A) shows that when the driver of vehicle 1 accidentally lets the steering wheel slip from his / her hands, the steering angle δ suddenly decreases, and then he / she quickly regains grip on the steering wheel and operates the steering wheel, causing the steering angle δ to suddenly increase. The dashed line in Figure 2(B) shows that when the driver of vehicle 1 accidentally lets the steering wheel slip from his / her hands, the steering angular velocity dδ / dt suddenly decreases to a negative value, and then he / she quickly regains grip on the steering wheel and operates the steering wheel, causing the steering angular velocity dδ / dt to suddenly increase. The dashed line in Figure 2(C) shows that when the driver of vehicle 1 accidentally lets the steering wheel slip from his / her hands, the steering angular acceleration dδ / dt ２ becomes a negative value, and then, when the driver quickly grips the steering wheel again and operates the steering wheel, the steering angular velocity dδ / dt becomes a positive value.

[0049] In the initial stage of the solid lines in Figures 2(A) and 2(B), the driver of vehicle 1 starts to turn vehicle 1 right at an intersection, causing the steering angle δ to increase linearly and the steering angular velocity dδ / dt to exceed the threshold value th1. From the initial stage to the middle stage of the solid lines in Figures 2(B) and 2(C), the driver of vehicle 1 accidentally lets the steering wheel slip from his hands, causing the steering angular velocity dδ / dt to suddenly decrease to a negative value, and further, the steering angular acceleration dδ / dt ２ At this time, the above-described steering intervention control is initiated, and as shown in the area α surrounded by the dashed line in the solid line in FIG. 2B, a torque that suppresses a sudden decrease in the steering angular velocity dδ / dt is output from the EPS motor 80, and at least the steering angular acceleration dδ / dt ２ The above-described steering intervention control is continued until the steering angular velocity dδ / dt becomes smaller than the threshold value th2 or until the change in the steering angular velocity dδ / dt becomes zero. The driver of the vehicle 1 quickly grips the steering wheel again and operates the steering wheel while the above-described steering intervention control is being performed. As described above, the above-described steering intervention control does not perform control to forcibly return the vehicle 1 to the original driving line, but merely performs control to suppress a sudden decrease in the steering angular velocity dδ / dt. Therefore, the above-described steering intervention control does not destabilize the behavior of the vehicle 1.

[0050] [Operation] Next, steering control of the vehicle 1 will be described with reference to Fig. 3. Fig. 3 illustrates an example of a steering control procedure in the vehicle 1.

[0051] First, the control unit 30 calculates the steering angular velocity dδ / dt and the steering angular acceleration dδ / dt ２ (Step S101). The control unit 30 determines whether the steering angular velocity dδ / dt exceeds the threshold value th1 (Step S102). As a result, if the steering angular velocity dδ / dt does not exceed the threshold value th1 (Step S102; N), the control unit 30 does not perform steering intervention. On the other hand, if the steering angular velocity dδ / dt exceeds the threshold value th1 (Step S102; Y), the control unit 30 obtains the steering angular acceleration dδ / dt ２It is determined whether the steering angular acceleration dδ / dt exceeds the threshold value th2 (step S103). ２ If does not exceed the threshold value th2 (step S103; N), the control unit 30 does not intervene in the steering.

[0052] On the other hand, the steering angular acceleration dδ / dt ２ exceeds the threshold value th2 (step S103; Y), the control unit 30 calculates the steering angular acceleration dδ / dt ２ The EPS motor 80 outputs a control signal to the EPS motor 80 to cause the EPS motor 80 to output a torque that reduces the steering angular acceleration dδ / dt ２ The control unit 30 generates an output torque that reduces the steering torque of the EPS motor 80 to less than the threshold value th2, thereby controlling the steering of the steering wheel. At this time, the control unit 30 generates an audio signal of a voice message notifying the driver of the vehicle 1 that steering intervention has been made to the EPS motor 80, and outputs the voice signal to the notification unit 50. As a result, the notification unit 50 notifies the driver of the vehicle 1 of the steering intervention to the EPS motor 80 as an audio message (step S105). In this manner, the steering control of the vehicle 1 is performed.

[0053] [Effects] Next, the effects of the vehicle 1 according to this embodiment will be described.

[0054] In this embodiment, when the steering angular velocity dδ / dt exceeds the threshold value th1, the steering angular acceleration dδ / dt ２ When exceeds the threshold value th2, the steering angular acceleration dδ / dt ２ is output to the EPS motor 80. A control signal is output to the EPS motor 80 to cause the EPS motor 80 to output a torque that reduces the steering angular velocity dδ / dt to be less than the threshold value th2. This performs steering torque control that suppresses a sudden decrease in the steering angular velocity dδ / dt, making it possible to respond to sudden steering operations without destabilizing the behavior of the vehicle 1.

[0055] In this embodiment, the control signal is a control signal that causes the EPS motor 80 to output a torque within a range that prevents the vehicle 1 from deviating from the route (traveling path) based on road map information 41, etc., to the EPS motor 80. This allows steering torque control to be performed within a range that prevents the vehicle 1 from deviating from the route (traveling path), making it possible to respond to sudden steering operations without destabilizing the behavior of the vehicle 1.

[0056] In the present embodiment, a signal informing that steering control for outputting the control signal to the EPS motor 80 has been intervened in the EPS motor 80 is output to the notification unit 50. This makes it possible to notify the driver of the vehicle 1, for example, by a voice message via the notification unit 50 that steering intervention has been made in the EPS motor 80. As a result, the driver of the vehicle 1 can continue driving after understanding that the discomfort felt at the steering wheel is due to steering intervention in the EPS motor 80.

[0057] 3. Modification of the First Embodiment In the first embodiment, the erroneous steering determination unit 33 may be configured to determine erroneous steering by the driver of the vehicle 1 without using the threshold value th2. Specifically, when the steering angular velocity dδ / dt exceeds the threshold value th1, the erroneous steering determination unit 33 determines the erroneous steering by the driver of the vehicle 1 without using the threshold value th2. ２ When the sign of the steering angular velocity dδ / dt is different from the sign of the steering angular acceleration dδ / dt ２ It may be possible to generate a steering intervention command to cause the EPS motor 80 to output a torque that reduces the threshold th1 to be less than the threshold th2, and output the command to the steering control unit 38.

[0058] 4 illustrates a modified example of the steering control procedure for the vehicle 1. The control unit 30 first calculates the steering angular velocity dδ / dt and the steering angular acceleration dδ / dt ２(Step S201). The control unit 30 determines whether the steering angular velocity dδ / dt exceeds the threshold value th1 (Step S202). As a result, if the steering angular velocity dδ / dt does not exceed the threshold value th1 (Step S202; N), the control unit 30 does not perform steering intervention. On the other hand, if the steering angular velocity dδ / dt exceeds the threshold value th1 (Step S202; Y), the control unit 30 obtains the steering angular acceleration dδ / dt ２ It is determined whether the sign of dδ / dt coincides with the sign of the steering angular velocity dδ / dt (step S203). ２ If the sign of dδ / dt matches the sign of the steering angular velocity dδ / dt (step S203; Y), the control unit 30 does not intervene in the steering.

[0059] On the other hand, the steering angular acceleration dδ / dt ２ If the sign of dδ / dt does not match the sign of the steering angular velocity dδ / dt (step S203; N), the control unit 30 calculates the steering angular acceleration dδ / dt ２ The EPS motor 80 outputs a control signal to the EPS motor 80 to cause the EPS motor 80 to output a torque that reduces the steering angular acceleration dδ / dt ２ The control unit 30 generates an output torque that reduces the steering torque of the EPS motor 80 to less than the threshold value th2, thereby controlling the steering of the steering wheel. At this time, the control unit 30 generates an audio signal of a voice message notifying the driver of the vehicle 1 that steering intervention has been made to the EPS motor 80, and outputs the voice signal to the notification unit 50. As a result, the notification unit 50 notifies the driver of the vehicle 1 of the steering intervention to the EPS motor 80 as an audio message (step S205). In this manner, the steering control of the vehicle 1 is performed.

[0060] In this modification, when the steering angular velocity dδ / dt exceeds the threshold value th1, the steering angular acceleration dδ / dt ２ When the sign of does not match the sign of the steering angular velocity dδ / dt, the steering angular acceleration dδ / dt ２is output to the EPS motor 80. A control signal is output to the EPS motor 80 to cause the EPS motor 80 to output a torque that reduces the steering angular velocity dδ / dt to be less than the threshold value th2. This performs steering torque control that suppresses a sudden decrease in the steering angular velocity dδ / dt, making it possible to respond to sudden steering operations without destabilizing the behavior of the vehicle 1.

[0061] 4. Second embodiment [Configuration] Next, a vehicle 2 according to a second embodiment of the present disclosure will be described. In the following, components common to the first embodiment will be assigned the same reference numerals. Furthermore, descriptions of components common to the first embodiment will be omitted as appropriate.

[0062] FIG. 5 shows an example of functional blocks of the vehicle 2. For example, as shown in FIG. 5, the vehicle 2 includes a sensor unit 10, a communication unit 20, a control unit 30, a memory unit 40, a notification unit 50, a motor 60, a brake 70, and an ESP motor 80. For example, as shown in FIG. 5, the control unit 30 includes a steering determination unit 31 and a driving control unit 35. For example, as shown in FIG. 5, the steering determination unit 31 includes a data acquisition unit 32, an erroneous steering determination unit 39, and a notification control unit 35. For example, as shown in FIG. 5, the driving control unit 35 includes an accelerator control unit 36, a brake control unit 37, and a steering control unit 38. For example, as shown in FIG. 5, the memory unit 40 stores a road map DB 41 and a threshold value 43. In other words, vehicle 2 corresponds to vehicle 1 of the first embodiment described above, except that it has an erroneous steering judgment unit 39 instead of erroneous steering judgment unit 33, and has threshold value 43 stored in memory unit 40 instead of threshold value 42.

[0063] The threshold value th3 corresponds to a specific example of a "third threshold value" in the present disclosure. The threshold value th3 is a threshold value for steering torque. The threshold value th3 is a value at which it can be determined that the driver of the vehicle 2 has intentionally started to turn the steering wheel to change the direction of travel of the vehicle 2 when the vehicle 2 enters, for example, an intersection or a curve. The threshold value th3 is a value greater than the range of steering torque that can be generated when the vehicle 2 is traveling straight and is considered to be swaying of the vehicle 2.

[0064] The erroneous steering determination unit 39 is capable of determining erroneous steering by the driver of the vehicle 2 based on data related to the steering of the vehicle 2 (specifically, the steering torque TR). The erroneous steering determination unit 39 is further capable of controlling the steering of the vehicle 2 in cooperation with the steering control unit 38 based on the data related to the steering of the vehicle 2.

[0065] When the steering torque TR exceeds the threshold value th3 and the steering torque TR decreases, the erroneous steering determination unit 39 is capable of generating a steering intervention command to cause the EPS motor 80 to output a torque that suppresses the decrease in the steering torque TR, and outputting the generated steering intervention command to the steering control unit 38. When the steering intervention command is input from the erroneous steering determination unit 33, the steering control unit 38 is capable of outputting a control signal to the EPS motor 80 to output a torque that suppresses the decrease in the steering torque TR, based on the input steering intervention command.

[0066] The erroneous steering determination unit 39 is capable of generating the steering intervention command so that the torque output from the EPS motor 80 in response to a control signal generated by the steering control unit 38 based on the steering intervention command is within a range of torque that prevents the vehicle 2 from deviating from the route (driving path). The erroneous steering determination unit 39 is capable of deriving the magnitude of the torque output from the EPS motor 80 based on, for example, road map information 41 in the storage unit 40 and data such as lane markings obtained from the distance image data Db, etc. The erroneous steering determination unit 39 is capable of outputting a notification signal to the notification control unit 34 to notify that steering intervention has been made to the EPS motor 80.

[0067] When the notification signal is input from the erroneous steering determination unit 39, the notification control unit 34 can generate, for example, an audio signal of a voice message notifying that steering intervention has occurred, and output the voice signal to the notification unit 50. The notification unit 50 is configured to include, for example, a microphone, and can output the voice message based on the audio signal input from the notification control unit 34.

[0068] FIG. 6(A) shows an example of the change over time in the steering angle δ of the vehicle 2. FIG. 6(B) shows an example of the change over time in the steering torque TR of the vehicle 2. In FIG. 6(A), the dashed line is the OFF control curve La1 obtained when the above-mentioned steering intervention control is not being performed, and the solid line is the ON control curve Lb1 obtained when the above-mentioned steering intervention control is being performed. In FIG. 6(B), the dashed line is the OFF control curve La4 obtained when the above-mentioned steering intervention control is not being performed, and the solid line is the ON control curve Lb4 obtained when the above-mentioned steering intervention control is being performed. FIGS. 6(A) and 6(B) show examples of data obtained when the driver of the vehicle 2 accidentally lets the steering wheel slip from his / her hands while turning the vehicle 2 right at an intersection.

[0069] The dashed line in Figure 6(A) shows how the steering angle δ suddenly decreases when the driver of vehicle 2 accidentally lets the steering wheel slip from his hands, and then the driver quickly regains grip on the steering wheel and operates the steering wheel, causing the steering angle δ to suddenly increase. The dashed line in Figure 6(B) shows how the steering torque TR suddenly decreases to 0 (zero) when the driver of vehicle 2 accidentally lets the steering wheel slip from his hands, and then the driver quickly regains grip on the steering wheel and operates the steering wheel, causing the steering torque TR to suddenly increase.

[0070] In the initial period indicated by the solid lines in Figures 6A and 6B, the driver of vehicle 2 begins to turn vehicle 2 right at an intersection, causing the steering angle δ to increase linearly and the steering torque TR to reach a constant value exceeding threshold value th3. From the initial period to the middle period indicated by the solid lines in Figure 6B, the driver of vehicle 2 accidentally slips the steering wheel, causing the steering torque TR to suddenly decrease. At this time, the above-described steering intervention control is initiated, and as shown in the area β enclosed by the dashed line in Figure 6B, a torque that suppresses the sudden decrease in steering torque TR is output from EPS motor 80. The above-described steering intervention control continues until the change (decrease) in steering torque TR reaches zero. While the above-described steering intervention control is being performed, the driver of vehicle 2 quickly regains grip on the steering wheel and operates the steering wheel. In this way, the above-described steering intervention control does not perform control to forcibly return the vehicle 2 to the original driving line, but merely performs control to suppress a sudden decrease in the steering torque TR. Therefore, the above-described steering intervention control does not destabilize the behavior of the vehicle 1.

[0071] [Operation] Next, steering control of the vehicle 2 will be described with reference to Fig. 7. Fig. 7 illustrates an example of a steering control procedure in the vehicle 2.

[0072] The control unit 30 first acquires the steering torque TR (step S301). The control unit 30 determines whether the steering torque TR exceeds the threshold value th3 (step S302). As a result, if the steering torque TR does not exceed the threshold value th3 (step S302; N), the control unit 30 does not perform steering intervention. On the other hand, if the steering torque TR exceeds the threshold value th3 (step S302; Y), the control unit 30 determines whether the steering torque TR has decreased (step S303). As a result, if the steering torque TR has not decreased (step S303; N), the control unit 30 does not perform steering intervention.

[0073] On the other hand, if the steering torque TR is decreasing (step S303; Y), the control unit 30 outputs a control signal to the EPS motor 80 to cause the EPS motor 80 to output a torque that suppresses the decrease in the steering torque TR (step S304). As a result, the EPS motor 80 generates an output torque that suppresses the decrease in the steering torque TR based on the control signal, and controls the steering of the steering wheel. At this time, the control unit 30 generates an audio signal of an audio message notifying the EPS motor 80 that steering intervention has been made, and outputs the audio signal to the notification unit 50. As a result, the notification unit 50 notifies the driver of the vehicle 2 of the steering intervention in the EPS motor 80 as an audio message (step S305). In this manner, the steering control of the vehicle 2 is performed.

[0074] [Effects] Next, the effects of the vehicle 2 according to this embodiment will be described.

[0075] In this embodiment, when the steering torque TR exceeds the threshold value th3 and the steering torque TR decreases, a control signal for causing the EPS motor 80 to output a torque that suppresses the decrease in the steering torque TR is output to the EPS motor 80. This performs steering torque control that suppresses a sudden decrease in the steering torque TR, making it possible to respond to a sudden steering operation without destabilizing the behavior of the vehicle 2.

[0076] In this embodiment, the control signal is a control signal that causes the EPS motor 80 to output a torque within a range that prevents the vehicle 2 from deviating from the route (travel path) based on road map information 41, etc., to the EPS motor 80. This allows steering torque control to be performed within a range that prevents the vehicle 2 from deviating from the route (travel path), making it possible to respond to sudden steering operations without destabilizing the behavior of the vehicle 2.

[0077] In the present embodiment, a signal informing that steering control for outputting the control signal to the EPS motor 80 has been intervened in the EPS motor 80 is output to the notification unit 50. This makes it possible to notify the driver of the vehicle 2, for example, by a voice message via the notification unit 50 that steering intervention has been made in the EPS motor 80. As a result, the driver of the vehicle 2 can continue driving after understanding that the discomfort felt at the steering wheel is due to steering intervention in the EPS motor 80.

[0078] Although the present disclosure has been described above using embodiments, the present disclosure is not limited to these embodiments and various modifications are possible. The effects described in this specification are merely examples, and the effects of the present disclosure are not limited to the effects described in this specification. Therefore, other effects may be obtained with respect to the present disclosure.

[0079] Furthermore, the present disclosure may take the following aspects. (1) A steering control device comprising: an acquisition unit capable of acquiring a steering angular velocity obtained by monitoring; and a control unit capable of controlling steering based on the steering angular velocity, wherein, when the steering angular velocity exceeds a first threshold, the control unit is capable of outputting a control signal to the EPS to cause the EPS to output a torque that reduces the steering angular acceleration to less than the second threshold when steering angular acceleration, which is a change in the steering angular velocity, exceeds a second threshold or when the sign of the steering angular acceleration differs from the sign of the steering angular velocity. (2) A steering control device comprising: an acquisition unit capable of acquiring a steering torque obtained by monitoring; and a control unit capable of controlling steering based on the steering torque, wherein, when the steering torque exceeds a predetermined threshold and the steering torque decreases, the control unit is capable of outputting a control signal to the EPS to cause the EPS to output a torque that suppresses the decrease in steering torque. (3) The steering control device according to (1) or (2), wherein the control unit is capable of outputting, to the EPS, a control signal that causes the EPS to output torque within a range that prevents the vehicle from deviating from the route based on map information. (4) The steering control device according to any one of (1) to (3), wherein the control unit is capable of outputting a signal that notifies the EPS that steering control that outputs the control signal to the EPS has been intervened. (5) A vehicle comprising: a steering control device; a steering speed monitoring device; and an EPS, wherein the steering control device has an acquisition unit capable of acquiring the steering speed from the steering speed monitoring device; and a control unit capable of controlling steering based on the steering speed, and when the steering speed exceeds a first threshold, and a steering angular velocity, which is a change in the steering speed, exceeds a second threshold, or when the sign of the steering angular velocity differs from the sign of the steering angular velocity, the control unit is capable of outputting a control signal to the EPS to cause the EPS to output a torque that makes the steering angular velocity smaller than the second threshold.(6) A vehicle comprising a steering control device, a steering torque monitoring device, and an EPS, wherein the steering control device comprises: an acquisition unit capable of acquiring steering torque from the steering torque monitoring device; and a control unit capable of controlling steering based on the steering torque, wherein the control unit is capable of outputting a control signal to the EPS to cause the EPS to output a torque that suppresses the decrease in steering torque when the steering torque exceeds a predetermined threshold and the steering torque decreases. (7) The vehicle described in (5) or (6), wherein the control unit is capable of outputting, as the control signal, a control signal to the EPS to cause the EPS to output a torque within a range that does not cause the vehicle to deviate from the route, based on map information. (8) The vehicle described in any one of (5) to (7), wherein the control unit is capable of outputting a signal notifying that the EPS has intervened in steering control to output the control signal to the EPS.

[0080] The control unit 30 shown in FIGS. 1 and 5 may be implemented by circuitry including at least one semiconductor integrated circuit, such as at least one processor (e.g., a central processing unit (CPU)), at least one application-specific integrated circuit (ASIC), and / or at least one field-programmable gate array (FPGA). The at least one processor may be configured to perform all or a portion of the various functions of the control unit 30 shown in FIGS. 1 and 5 by reading instructions from at least one non-transitory, tangible computer-readable medium. Such medium may take various forms, including, but not limited to, various magnetic media such as hard disks, various optical media such as CDs or DVDs, and various semiconductor memories (i.e., semiconductor circuits) such as volatile or non-volatile memories. Volatile memory may include DRAM and SRAM. Non-volatile memory may include ROM and NVRAM. An ASIC is an integrated circuit (IC) specialized to perform all or a portion of the various functions of the control unit 30 shown in FIGS. 1 and 5. An FPGA is an integrated circuit that is designed to be configurable after manufacture so as to perform all or part of the various functions of the control unit 30 shown in FIGS.

Claims

1. A steering control device comprising: an acquisition unit capable of acquiring a steering angular velocity obtained by monitoring; and a control unit capable of controlling steering based on the steering angular velocity, wherein when the steering angular velocity exceeds a first threshold, the control unit is capable of outputting a control signal to the EPS (Electric Power Steering) to cause the EPS to output a torque that reduces the steering angular acceleration below the second threshold when the steering angular velocity exceeds a first threshold and steering angular acceleration, which is a change in the steering angular velocity, exceeds a second threshold, or when the sign of the steering angular acceleration differs from the sign of the steering angular velocity.

2. A steering control device comprising: an acquisition unit capable of acquiring steering torque obtained by monitoring; and a control unit capable of controlling steering based on the steering torque, wherein the control unit is capable of outputting a control signal to the EPS (Electric Power Steering) to cause the EPS to output a torque that suppresses the decrease in steering torque when the steering torque decreases in a case where the steering torque exceeds a predetermined threshold value.

3. A steering control device as claimed in claim 1 or claim 2, wherein the control unit is capable of outputting to the EPS, as the control signal, a control signal that causes the EPS to output torque within a range that will prevent the vehicle from deviating from the route, based on map information.

4. A steering control device as claimed in claim 1 or claim 2, wherein the control unit is capable of outputting a signal to notify that the EPS has intervened in steering control to output the control signal to the EPS.

5. A vehicle comprising: a steering control device; a steering speed monitoring device; and an EPS (Electric Power Steering), wherein the steering control device has an acquisition unit capable of acquiring the steering speed from the steering speed monitoring device; and a control unit capable of controlling steering based on the steering speed, and when the steering speed exceeds a first threshold, and the steering angular velocity, which is a change in the steering speed, exceeds a second threshold, or when the sign of the steering angular velocity differs from the sign of the steering angular velocity, the control unit is capable of outputting a control signal to the EPS to cause the EPS to output a torque that makes the steering angular velocity smaller than the second threshold.

6. A vehicle comprising: a steering control device; a steering torque monitoring device; and an EPS (Electric Power Steering), wherein the steering control device comprises: an acquisition unit capable of acquiring steering torque from the steering torque monitoring device; and a control unit capable of controlling steering based on the steering torque, and wherein the control unit is capable of outputting a control signal to the EPS to cause the EPS to output a torque that suppresses the decrease in steering torque when the steering torque exceeds a predetermined threshold and the steering torque decreases.

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