Vehicle control device and vehicle control system
The vehicle control system addresses the lack of evacuation guidance in steer-by-wire abnormalities by outputting lateral controllable limits and controlling differential braking/driving forces to safely guide the vehicle, enhancing driver and automatic evacuation capabilities.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- ASTEMO LTD
- Filing Date
- 2025-07-10
- Publication Date
- 2026-06-18
Smart Images
Figure JP2025024851_18062026_PF_FP_ABST
Abstract
Description
Vehicle control device and vehicle control system 【0001】 The present invention relates to a vehicle control device and a vehicle control system. 【0002】 The vehicle control device of Patent Document 1 is provided in a vehicle having a steer-by-wire system and in which the scrub radius of the steered wheels is set negative. And when the control unit included in the vehicle control device acquires an abnormal signal of the steering function in the steer-by-wire system, when the driving force is a positive physical quantity and the braking force is a negative physical quantity, the total value of the driving force and the braking force applied to the steered wheels on the outer side of the turn is made smaller than the total value of the driving force and the braking force applied to the steered wheels on the inner side of the turn, and a drive / brake command is output. 【0003】 International Publication No. 2024 / 128063 【0004】 By the way, when an abnormality occurs in the steering function in the steer-by-wire system and the vehicle is turned by controlling the drive / brake forces applied to the left and right wheels by the vehicle control device, since the turning performance by such drive / brake force control is not known to the outside, appropriate evacuation instructions or automatic evacuation to the driver based on the turning performance cannot be performed. 【0005】 Therefore, an object of the present invention is to provide a vehicle control device and a vehicle control system that can enable appropriate evacuation instructions or automatic evacuation to the driver when an abnormality occurs in the steering function in the steer-by-wire system. 【0006】 Therefore, the vehicle control device and the vehicle control system according to the present invention, in one aspect, when an abnormal signal of the steering function in the steer-by-wire system is acquired, output information regarding the controllable limit in the lateral direction of the vehicle, which is obtained based on the specifications of the vehicle and the speed of the vehicle. 【0007】 According to the present invention, when an abnormality occurs in the steering function in the steer-by-wire system, appropriate evacuation instructions or automatic evacuation to the driver can be enabled. 【0008】This is an overall configuration diagram showing the vehicle control system. This is a block diagram showing the control systems of various actuators. This is a diagram showing the correlation between scrub radius and maximum lateral acceleration. This is a diagram showing the switching between locked and free states according to vehicle speed. This is a functional block diagram showing the control of braking and driving forces and the output of lateral control limit information. This is a diagram showing the time course of vehicle speed and lateral control limit information. This is a diagram showing two-dimensional range information. This is a flowchart showing the output processing of information regarding the lateral controllable limit. This is a block diagram showing one aspect of the automatic driving control output. This is a block diagram showing another aspect of the automatic driving control output. 【0009】 Hereinafter, embodiments of the vehicle control device and vehicle control system according to the present invention will be described with reference to the drawings. Figure 1 is an overall configuration diagram showing a vehicle control system 100 mounted on a vehicle 10. Figure 2 is a block diagram showing the control systems of various actuators in the vehicle control system 100. 【0010】 The vehicle 10 on which the vehicle control system 100 is installed is a four-wheeled automobile having a pair of left and right front wheels 11, 12 and a pair of left and right rear wheels 13, 14, and is equipped with a steer-by-wire system 40 as a steering device. The vehicle control system 100 has a function to turn the vehicle 10 in a specified direction by controlling the difference in braking and driving force between the left and right wheels when an abnormality occurs in the steering function of the steer-by-wire system 40. 【0011】 The vehicle control system 100 will be described in detail below with reference to Figures 1 and 2. The vehicle 10 is equipped with a drive unit 70. The drive unit 70 includes a motor 71 that applies driving force to the front wheels 11 and 12, and a motor 72 that applies driving force to the rear wheels 13 and 14, as drive force actuators. 【0012】The drive force control unit 31 acquires signals such as the amount of operation of the accelerator pedal 73 output by the accelerator pedal sensor 74. Based on the amount of operation of the accelerator pedal 73, the drive force control unit 31 determines a target drive force and outputs control signals corresponding to the target drive force to the motors 71 and 72, thereby controlling the drive force applied to the front wheels 11 and 12 and the rear wheels 13 and 14. 【0013】 The steer-by-wire system 40 is a steering device in which the steering wheel 51, which serves as the steering input mechanism, and the front wheels 11 and 12, which are the steering wheels, are mechanically separated, and the steering angle of the front wheels 11 and 12 is electronically controlled based on the electrical signal of the amount of operation of the steering wheel 51. The steer-by-wire system 40 includes a reaction force actuator 41 that simulates applying an operating reaction force torque to the steering wheel 51, a wheel actuator 42 that applies steering force to the front wheels 11 and 12, and a steering control unit 32 that controls the reaction force actuator 41 and the wheel actuator 42. 【0014】 Furthermore, the steering wheel 51 is equipped with an operating angle sensor 52 that detects the operating angle θ of the steering wheel 51. The steering control unit 32 acquires the signal of the operating angle θ of the steering wheel 51 detected by the operating angle sensor 52 (in other words, the steering angle instruction signal), the signals of the rotational speeds WS1-WS4 of each wheel 11-14 detected by the wheel speed sensor 53, or the vehicle speed signal which is the vehicle speed signal based on the rotational speeds WS1-WS4, and calculates the target steering angle and target reaction torque based on these. 【0015】 The steering control unit 32 then controls the wheel actuators 42 so that the steering angle (in other words, the tire angle) of the front wheels 11 and 12, which are the steering wheels, becomes the target steering angle. The steering control unit 32 also controls the reaction force actuator 41 so that the target reaction force torque is applied to the steering wheel 51. 【0016】Furthermore, the steer-by-wire system 40 includes a steer lock switching mechanism 90 having a steer lock actuator 91. The steer lock switching mechanism 90 is a mechanism that selectively stops the steering movement of the front wheels 11 and 12, which are the steering wheels, and fixes the steering angle of the front wheels 11 and 12 to a constant value. 【0017】 In other words, the locked state of the steering lock switching mechanism 90 is a state in which the steering movement of the front wheels 11 and 12 is stopped and the steering angle is fixed. On the other hand, the free state of the steering lock switching mechanism 90 is a normal state in which the steering movement of the front wheels 11 and 12 is permitted and the steering angle can be changed. 【0018】 The steering lock switching mechanism 90 is a mechanism that, for example, mechanically stops the rotation of the pinion shaft or the axial movement of the rack bar in a rack and pinion mechanism by mechanical engagement or abutment of a locking member, or by electromagnetic force. Furthermore, by controlling the wheel actuator 42 to generate a steering force that resists changes in the steering angle of the front wheels 11 and 12, it can be used as a steering lock actuator 91. 【0019】 The vehicle 10 is also equipped with a braking device 60 that applies braking force to each wheel 11-14. The braking device 60 includes a brake control unit 33, a brake pedal sensor 62 that detects the amount of operation of the brake pedal 61, and brake actuators 15, 16, 17, and 18 provided on each wheel 11, 12, 13, and 14. 【0020】 The brake control unit 33 controls the braking force applied by the brake actuators 15, 16, 17, and 18 to each wheel 11, 12, 13, and 14 based on the output of the brake pedal sensor 62 and other factors. The braking device 60 is configured to allow individual adjustment of the braking force applied to each wheel 11, 12, 13, and 14. 【0021】The vehicle 10 is also equipped with a car navigation system 81 and an automatic driving control unit 82 (automatic driving control device). The car navigation system 81 has a GPS (Global Positioning System) receiver, a map database, and a liquid crystal display device, and has the function of displaying the current location of the vehicle 10 and the route to the destination on the screen of the liquid crystal display device. In this embodiment, as will be described later, the car navigation system 81 is used as a notification device that notifies the driver of lateral control limit information (in other words, the limit of turning performance) when an abnormality occurs in the steering function of the steer-by-wire system 40. 【0022】 The automated driving control unit 82 uses the GPS receiver and map database that make up the car navigation system 81, as well as on-board cameras and radar, to perform external environment recognition and action planning for the vehicle 10. Then, based on the results of external environment recognition and action planning, the automated driving control unit 82 generates a target trajectory for the vehicle 10 and outputs steering angle commands and braking force commands to the steer-by-wire system 40, drive unit 70, and braking unit 60 to drive the vehicle 10 along the target trajectory, thereby executing automated driving of the vehicle 10. The target trajectory includes information on the target driving route and information on the target vehicle speed. 【0023】 Furthermore, the vehicle control system 100 includes an integrated control unit 34. The integrated control unit 34 is provided as a higher-level control unit for lower-level control units, including the drive force control unit 31, steering control unit 32, brake control unit 33, car navigation system 81, and automatic driving control unit 82. 【0024】The drive force control unit 31, steering control unit 32, brake control unit 33, car navigation system 81, autonomous driving control unit 82, and integrated control unit 34 are connected to an in-vehicle network and configured to communicate with each other. In this embodiment, each control unit connected to the in-vehicle network is equipped with a computer as its control unit. 【0025】 The integrated control unit 34 receives a signal from the steering control unit 32 indicating the result of diagnosing the steering function of the steer-by-wire system 40, that is, a signal indicating whether the steering function is normal or abnormal. When the integrated control unit 34 receives an abnormal signal regarding the steering function of the steer-by-wire system 40, it sets the vehicle 10 to move to limp home mode. 【0026】 An abnormality in the steering function refers to a state in which the steering wheels, the front wheels 11 and 12, are unable to be steered, and the steering angle of the front wheels 11 and 12 cannot be controlled to the target steering angle corresponding to the operating angle θ of the steering wheel 51. Abnormalities in the steering function can occur due to a malfunction of the wheel actuator 42, a malfunction of the drive circuit of the wheel actuator 42, or a malfunction of various sensors. 【0027】 Limp Home mode is a fail-safe mode that drives the vehicle 10 to a safe location such as the shoulder of the road and stops it. In this limp home mode, the integrated control unit 34 decelerates the vehicle 10 according to a predetermined deceleration schedule and controls the direction of travel of the vehicle 10 in accordance with steering instructions such as the operating angle θ of the steering wheel 51. Here, because there is an abnormality in the steering function of the steer-by-wire system 40, the integrated control unit 34 changes the direction of travel of the vehicle 10 by controlling the difference in braking and driving force between the left and right wheels instead of steering by the steer-by-wire system 40. 【0028】In limp home mode, the predetermined deceleration schedule is set in advance to, for example, to reduce the vehicle speed at a constant deceleration rate after a certain period of time has elapsed. In addition, steering instructions in limp home mode are based on the operating angle θ of the steering wheel 51, and in automatic driving based on an escape route, steering angle commands are used to drive the vehicle 10 along the escape route. 【0029】 Furthermore, the integrated control unit 34 has a function to switch the locked state and the free state of the steering lock switching mechanism 90 according to the vehicle speed in order to maximize the lateral acceleration that can be generated by the difference in braking and driving force between the front wheels 11 and 12 in limp-home mode. The following describes in detail the control of switching between the locked state and the free state of the steering lock switching mechanism 90 in limp-home mode. 【0030】 Figure 3 shows the correlation between the scrub radius of the front wheels 11 and 12 and the maximum lateral acceleration obtained by braking force difference control between the front wheels 11 and 12. Figure 4 shows the correlation between the vehicle speed and the maximum lateral acceleration obtained by braking force control when the steering lock switching mechanism 90 is locked and when the steering lock switching mechanism 90 is free. 【0031】 As shown in Figure 3, in the free state of the steering lock switching mechanism 90, if the scrub radius of the front wheels 11 and 12 is negative, applying braking force to the outer front wheel during a turn will cause the front wheels 11 and 12 to steer in the turning direction, generating lateral acceleration. Conversely, in the free state of the steering lock switching mechanism 90, if the scrub radius of the front wheels 11 and 12 is positive, applying braking force to the inner front wheel during a turn will cause the front wheels 11 and 12 to steer in the turning direction, generating lateral acceleration. In other words, controlling the difference in braking and driving forces between the front wheels 11 and 12 in the free state is steering control that changes the steering angle of the front wheels 11 and 12. 【0032】On the other hand, when the steering lock switching mechanism 90 is locked, the scrub radius of the front wheels 11 and 12 does not affect the vehicle, and by applying braking force to the front wheel on the inside of the turn, a yaw moment in the turning direction can be generated in the vehicle 10. In other words, controlling the difference in braking and driving forces between the front wheels 11 and 12 in the locked state becomes yaw moment control, which generates a yaw moment in the vehicle 10. 【0033】 Here, the maximum lateral acceleration obtained with braking force control in the locked state is not affected by the scrub radius of the front wheels 11 and 12, as shown in Figure 3, because no steering occurs in the locked state, but it increases as the vehicle speed increases, as shown in Figure 4. On the other hand, the maximum lateral acceleration obtained with braking force control in the free state changes according to the scrub radius of the front wheels 11 and 12, as shown in Figure 3, because steering is performed on the front wheels 11 and 12, but it is not affected by the vehicle speed, as shown in Figure 4. 【0034】 As shown in Figure 4, the maximum lateral acceleration obtained with braking force control in the locked state and the maximum lateral acceleration obtained with braking force control in the free state are the same when the vehicle speed is a predetermined vehicle speed VTH. Therefore, in the vehicle speed range lower than the predetermined vehicle speed VTH, a higher maximum lateral acceleration can be obtained by performing braking force control in the free state than by performing braking force control in the locked state. Conversely, in the vehicle speed range higher than the predetermined vehicle speed VTH, a higher maximum lateral acceleration can be obtained by performing braking force control in the locked state than by performing braking force control in the free state. 【0035】 Therefore, in limp home mode, the integrated control unit 34 switches the steering lock switching mechanism 90 between a locked state and a free state depending on whether the vehicle speed is higher or lower than a predetermined vehicle speed VTH, which is a threshold, thereby maximizing the lateral acceleration that can be generated by the difference in braking and driving forces between the front wheels 11 and 12, i.e., the turning performance. In other words, if the vehicle speed is less than or equal to the predetermined vehicle speed VTH, the integrated control unit 34 controls the steering lock switching mechanism 90 to the free state, and if the vehicle speed is higher than the predetermined vehicle speed VTH, it controls the steering lock switching mechanism 90 to the locked state. 【0036】 Furthermore, when the integrated control unit 34 controls the steering lock switching mechanism 90 to a free state, it commands the brake control unit 33 to apply a control pattern for the braking and driving force difference so that if the scrub radius of the front wheels 11 and 12 is negative, it applies braking force to the outside of the turn, and if the scrub radius of the front wheels 11 and 12 is positive, it applies braking force to the inside of the turn. If it is possible to individually control the driving force applied to each wheel, such as by equipping each wheel 11-14 with an in-wheel motor as a driving force actuator, the vehicle 10 can be turned by controlling the driving force difference between the left and right wheels along with the braking force difference between the left and right wheels. 【0037】 Incidentally, in limp home mode, if the turning performance due to the difference in braking and driving force between the left and right wheels is unknown, it becomes impossible to give appropriate evasive instructions to the driver or to automatically evacuate based on the turning performance. Therefore, the integrated control unit 34 has a function to output information regarding the lateral controllable limit of the vehicle 10 (hereinafter abbreviated as lateral control limit information), which is determined based on the specifications of the vehicle 10 and the speed of the vehicle 10, when it acquires an abnormal signal of the steering function in the steer-by-wire system 40. 【0038】 The integrated control unit 34 outputs lateral control limit information to, for example, the car navigation system 81. The car navigation system 81 then notifies the driver of the lateral control limit information by displaying it on the screen of the liquid crystal display device, thereby providing the driver with appropriate evasive instructions based on the turning performance. As a result, the driver recognizes the lateral control limit and can appropriately operate the steering wheel 51 (in other words, give steering instructions) to move the vehicle 10 out of the way, enabling the vehicle 10 to move to a safe position stably. 【0039】Furthermore, in limp home mode, the automatic driving control unit 82 can generate an evacuation path, which is a driving path for moving the vehicle 10 to a safe position, and perform automatic evacuation by automatically driving the vehicle 10 along this evacuation path. When such automatic evacuation is performed, the integrated control unit 34 outputs lateral control limit information to the automatic driving control unit 82 so that the automatic evacuation is performed taking the lateral control limit information into consideration. 【0040】 In automatic retraction, the automatic driving control unit 82, for example, generates a retraction path considering lateral control limit information, or imposes restrictions on vehicle behavior command values such as lateral acceleration and yaw moment considering lateral control limit information. The automatic driving control unit 82 also achieves automatic retraction by outputting a steering angle command that replaces the steering angle command based on the operating angle θ of the steering wheel 51, or by directly outputting braking and driving commands to the braking and driving actuators, including the brake actuators 15-18 and motors 71 and 72. 【0041】 Figure 5 is a functional block diagram showing the control of braking and driving forces and the output processing of lateral control limit information in limp-home mode of the vehicle control system 100. In Figure 5, the integrated control unit 34 is a vehicle control device that outputs braking and driving force commands and lateral control limit information in limp-home mode. 【0042】 However, the steering control unit 32 and the brake control unit 33 can be vehicle control devices that perform braking and driving force control and output processing of lateral control limit information in limp-home mode. Furthermore, a first vehicle control device that controls braking and driving force and a second vehicle control device that performs output processing of lateral control limit information can be provided separately. 【0043】The steer-by-wire system 40 (steering control unit 32) outputs a command signal for the target steering angle, a vehicle speed signal, an abnormality signal of the steering function of the steer-by-wire system 40, etc. to the integrated control unit 34. The integrated control unit 34 includes functional units such as a failure-time command calculation unit 34A, a failure-time lateral control performance calculation unit 34B, and a two-dimensional range calculation unit 34C. 【0044】 The failure-time command calculation unit 34A calculates a control driving force command for turning the vehicle 10 in a direction corresponding to a command such as a steering angle command in the limp home mode in which an abnormality occurs in the steering function of the steer-by-wire system 40, and outputs the calculated control driving force command to the control driving actuator 95 including the brake actuators 15, 16, 17, 18 and the motors 71, 72. Here, the control driving force command output by the failure-time command calculation unit 34A includes a command for decelerating the vehicle 10 along a predetermined deceleration schedule, and a command for controlling the control driving force difference between the left and right wheels in order to change the traveling direction of the vehicle 10 according to the operation of the steering wheel 51 or the steering angle command in automatic driving. Further, although not shown in FIG. 5, the failure-time command calculation unit 34A outputs a command for setting the steering lock switching mechanism 90 to the locked state or the free state according to the vehicle speed in the limp home mode. 【0045】 The failure-time lateral control performance calculation unit 34B acquires a vehicle speed signal and an abnormality signal of the steering function of the steer-by-wire system 40 from the steering control unit 32. Here, the failure-time lateral control performance calculation unit 34B obtains lateral control limit information in the limp home mode in which an abnormality occurs in the steering function of the steer-by-wire system 40 and the vehicle 10 is turned by controlling the control driving force difference between the left and right wheels, based on the specifications and vehicle speed of the vehicle 10. Then, the failure-time lateral control performance calculation unit 34B outputs the calculated lateral control limit information to the car navigation system 81 and the automatic driving control unit 82. 【0046】Note that the vehicle control system 100 may not include the automatic driving control unit 82 and may not have an automatic driving function. In that case, the lateral control performance calculation unit 34B during failure outputs information on the lateral control limit to the car navigation system 81. Also, when the vehicle control system 100 includes the automatic driving control unit 82 and automatic evacuation by the automatic driving control unit 82 is executed, the lateral control performance calculation unit 34B during failure can output the information on the lateral control limit only to the automatic driving control unit 82. 【0047】 Here, the lateral control performance calculation unit 34B during failure calculates, as information on the controllable limit in the lateral direction of the vehicle 10, for example, limit values such as lateral acceleration, yaw rate, and turning radius that can be realized by controlling the drive force difference between the left and right wheels. The lateral control performance calculation unit 34B during failure calculates the limit values such as lateral acceleration from the specifications of the vehicle 10, such as the scrub radius of the front wheels 11 and 12, vehicle weight, vehicle length, tread, and trail, in the free state of the steer lock switching mechanism 90. 【0048】 Also, the lateral control performance calculation unit 34B during failure calculates the limit values such as lateral acceleration from the specifications of the vehicle 10, vehicle speed, and drive force applied to each wheel in the locked state of the steer lock switching mechanism 90. Also, in the limp home mode, control is performed to stop the vehicle 10 according to a predetermined deceleration schedule. Therefore, the lateral control performance calculation unit 34B during failure can estimate the future time course of the vehicle speed, that is, the vehicle speed at each time, from the deceleration schedule. 【0049】The loss-of-control lateral control performance calculation unit 34B can estimate the future time progression of lateral acceleration, yaw rate, turning radius, etc., by referring to information on the future time progression of vehicle speed, and can output the time progression information of these future limit values as lateral control limit information for the vehicle 10. In addition, the loss-of-control lateral control performance calculation unit 34B can output information on the lateral control limit of the vehicle 10, along with limit value information such as lateral acceleration, etc., including the time progression information of vehicle speed until the vehicle 10 comes to a stop due to deceleration control according to the deceleration schedule, the remaining time until the vehicle 10 comes to a stop due to deceleration control according to the deceleration schedule, the reachable distance of the vehicle 10 when decelerating according to the deceleration schedule, and the lateral control limit time of the vehicle 10 (in other words, the timing when lateral control capability is lost) estimated from future time progression information such as lateral acceleration, yaw rate, turning radius. 【0050】 The car navigation system 81, having acquired information regarding the lateral control limit from the lateral control performance calculation unit 34B in the event of failure, notifies the driver of the acquired information regarding the lateral control limit by displaying it on the screen of the liquid crystal display device. In limp home mode, when the direction of travel of the vehicle 10 is changed in response to the driver's operation of the steering wheel 51, providing the driver with information regarding the lateral control limit allows the driver to operate the steering wheel 51 to move the vehicle 10 out of the way while recognizing the limit to which the direction of travel of the vehicle 10 can be arbitrarily changed. Therefore, in limp home mode caused by an abnormality in the steering function of the steer-by-wire system 40, the driver can appropriately operate the steering wheel 51 to stop the vehicle 10 in a safe position. 【0051】Furthermore, the lateral control performance calculation unit 34B in case of loss can output information on the time progression of limit values such as lateral acceleration, yaw rate, and turning radius as information on physical quantities at each time point, that is, as numerical data such as lateral acceleration, yaw rate, and turning radius at each time point. When time progression information is provided in this way as information on physical quantities at each time point, the automatic driving control unit 82 in particular can use the information on physical quantities as reference data in automatic evasive control to perform appropriate evasive control. For example, the automatic driving control unit 82 can impose restrictions on vehicle behavior command values such as lateral acceleration and yaw moment based on the lateral control limit information provided as physical quantities. 【0052】 The two-dimensional range calculation unit 34C maps the maximum movable range in two dimensions based on future time-dependent information such as lateral acceleration, yaw rate, and turning radius, and outputs it to the automatic driving control unit 82 as two-dimensional range information. Here, the automatic driving control unit 82 can, for example, refer to the two-dimensional range information obtained from the two-dimensional range calculation unit 34C during automatic evacuation to generate feasible evacuation routes. 【0053】 Figure 6 is a diagram illustrating the time-elapsed information of vehicle speed according to the deceleration schedule, and the time-elapsed information of limit values such as lateral acceleration and yaw rate, calculated by the lateral control performance calculation unit 34B during loss of control. Note that the time-elapsed information of limit values such as yaw rate corresponds to the time-elapsed information of the controllable limit in the lateral direction. In other words, as the vehicle 10 is decelerated according to the deceleration schedule, the vehicle speed decreases at a constant deceleration rate, and in this deceleration state, the maximum lateral acceleration and maximum yaw rate that can be generated by the difference in braking and driving forces between the left and right wheels gradually decrease with deceleration. 【0054】Here, the integrated control unit 34 can determine the point at which the lateral controllable limit (limit values such as lateral acceleration and yaw rate) falls below a set value, or the point at which the vehicle speed falls below a set speed, as the loss timing when lateral control capability (in other words, turning capability) is lost. The integrated control unit 34 can then provide the car navigation system 81 and the autonomous driving control unit 82 with the time from the present moment to the loss timing as the lateral controllable limit time of the vehicle 10. 【0055】 Figure 7 shows one aspect of the two-dimensional range information calculated by the two-dimensional range calculation unit 34C, which represents information regarding the controllable limit in the lateral direction. The two-dimensional range information in Figure 7 is represented by coordinates where the horizontal axis is the lateral direction (left-right direction) of the vehicle 10 and the vertical axis is the forward direction (direction of travel) of the vehicle 10, and it shows the future change in the vehicle position when it is turned to its maximum extent from the current point (origin). 【0056】 In other words, the two-dimensional range information in Figure 7 shows the future change in the turning radius of the vehicle 10 when the maximum lateral acceleration is generated by the difference in braking and driving forces between the left and right wheels. Since the position of the vehicle 10 changes moment by moment according to the turning and vehicle speed, plotting the position of the vehicle 10 at each time point will show the path taken when the vehicle is turned to its maximum extent, as shown in Figure 7. 【0057】 The automatic driving control unit 82, having acquired the two-dimensional range information, generates an automatic escape route by adding restrictions based on the limit of the movable range represented by the two-dimensional range information. This allows for the generation of a feasible escape route even in limp-home mode, where the direction of travel of the vehicle 10 is changed by the difference in braking and driving force between the left and right wheels. In other words, the shaded area in Figure 7 is an unreachable area that the vehicle 10 cannot reach even when performing the maximum possible turn. Therefore, the automatic driving control unit 82 generates an escape route that does not pass through this unreachable area, or in other words, does not use the unreachable area as a stopping position. This allows for the generation of an escape route that is feasible by turning due to the difference in braking and driving force between the left and right wheels. 【0058】Figure 8 is a flowchart showing the procedure for outputting information regarding the lateral controllable limit in limp home mode. In step S101, the integrated control unit 34 determines whether or not an abnormality has occurred in the steering function of the steer-by-wire system 40, based on the results of the self-diagnosis of the steer-by-wire system 40. 【0059】 Then, if an abnormality occurs in the steering function of the steer-by-wire system 40, the integrated control unit 34 proceeds to step S102 and controls the difference in braking and driving force between the left and right wheels in order to turn the vehicle 10 according to the steering angle command, etc. Also, in step S102, the integrated control unit 34 calculates information regarding the lateral controllable limit of the vehicle 10. 【0060】 Information regarding the lateral controllable limit includes, as mentioned above, instantaneous or elapsed values such as lateral acceleration, yaw rate, and turning radius, as well as two-dimensional range information based on elapsed time (information on the limit of movement range). In addition, information regarding the lateral controllable limit can include elapsed vehicle speed, the timing of loss of lateral control capability, the lateral controllable limit time, and the reachable distance. 【0061】 Next, in step S103, the integrated control unit 34 outputs information regarding the lateral controllable limits of the vehicle 10, calculated in step S102, to the car navigation system 81 (notification device) and / or the automatic driving control unit 82 (automatic driving control device). In step S104, the integrated control unit 34 determines whether the lateral control capability (in other words, turning capability), which is the ability to change the direction of travel of the vehicle 10 by the difference in braking and driving force between the left and right wheels, has been lost due to the decrease in vehicle speed. 【0062】Here, the integrated control unit 34 repeats the processes of steps S102 and S103 as long as lateral control capability is not lost, that is, as long as the vehicle 10 can be moved while turning. Then, after lateral control capability is lost, when the vehicle 10 stops in step S105, the integrated control unit 34 terminates the limp home mode process. 【0063】 In step S103, the car navigation system 81 obtains information regarding the lateral controllable limits of the vehicle 10 from the integrated control unit 34. The system then notifies the driver of the obtained information regarding the lateral controllable limits or notification information obtained based on such information, either by displaying it on a liquid crystal display or by voice guidance. The car navigation system 81 can also notify the driver of the time remaining until the lateral control capability is lost due to the difference in braking and driving force between the left and right wheels (the remaining time during which turning is possible), the location on the route guidance where the lateral control capability is lost, and the range in which it is recommended to pull over on the route guidance. 【0064】 This allows the driver to recognize the timing of loss of lateral control capability and the range within which escape is possible, and then operate the steering wheel 51 to move the vehicle 10 out of the way. The notification device for informing the driver of the lateral control limits of the vehicle 10 is not limited to the car navigation system 81. In other words, the integrated control unit 34 can use a notification device, such as a liquid crystal display, independently of the car navigation system 81, to notify the driver of the lateral control limits. 【0065】Furthermore, in the process described in step S103, the automatic driving control unit 82 obtains information regarding the lateral controllable limits of the vehicle 10 from the integrated control unit 34. Based on the obtained information regarding the lateral controllable limits, the automatic driving control unit 82 can move the vehicle 10 to a safe position according to the feasible turning capability. Here, in calculating the escape route, the automatic driving control unit 82 can limit the reach of the vehicle 10 based on two-dimensional range information. 【0066】 Furthermore, when the automatic driving control unit 82 acquires physical quantities such as lateral acceleration and yaw rate as information regarding the lateral controllable limits, it can use the acquired physical quantities as limit values to restrict command values such as lateral acceleration during automatic driving (automatic evacuation). As a result, the automatic driving control unit 82 can automatically evacuate the vehicle 10 to a safe position within the limits imposed by the limp home mode. 【0067】 Figure 9 is a control block diagram showing one mode of control output of the automatic driving control unit 82 when the automatic driving control unit 82 acquires information regarding the lateral controllable limits of the vehicle 10 from the integrated control control unit 34. In the control configuration shown in Figure 9, the automatic driving control unit 82 outputs an automatic driving steering angle command to the loss command calculation unit 34A, which is the result of calculating an escape route and limiting vehicle behavior commands based on the information regarding the lateral controllable limits acquired from the loss lateral control performance calculation unit 34B and the two-dimensional range calculation unit 34C. The loss command calculation unit 34A then calculates a braking force control command (in other words, a braking force difference command between the left and right wheels) based on the automatic driving steering angle command output by the automatic driving control unit 82 in limp home mode when an abnormality occurs in the steering function of the steer-by-wire system 40, and outputs the calculated braking force control command to the braking actuator 95. 【0068】Figure 10 is a control block diagram showing another mode of control output of the automatic driving control unit 82 when the automatic driving control unit 82 acquires information regarding the lateral controllable limits of the vehicle 10 from the integrated control control unit 34. In the control configuration shown in Figure 10, the automatic driving control unit 82, based on the information regarding the lateral controllable limits acquired from the loss-of-situation lateral control performance calculation unit 34B and the two-dimensional range calculation unit 34C, calculates an escape route and restricts vehicle behavior commands, and then directly outputs a braking force control command (in other words, a braking force difference command between the left and right wheels) to the braking actuator 95 to realize driving along the escape route or vehicle behavior commands. 【0069】 The technical ideas described in the above embodiments can be used in appropriate combinations, provided that no contradictions arise. Furthermore, although the content of the present invention has been specifically described with reference to preferred embodiments, it will be obvious to those skilled in the art that various modifications can be taken based on the basic technical ideas and teachings of the present invention. 【0070】 For example, the steering input mechanism is not limited to the steering wheel 51, but may be a dial-type or stick-type steering input mechanism. Also, the vehicle control system 100 may not have a steering lock switching mechanism 90, and may be a system in which switching between locked and free states is not performed. 【0071】 Furthermore, in manual driving where the direction of travel of the vehicle 10 is changed in response to the driver's operation of the steering wheel 51, the automatic driving control unit 82 can display the escape route or escape position generated on the car navigation system 81, and the driver can be recommended to steer along the escape route or steer towards the escape position. In addition, the timing of loss of lateral control capability can be notified to the driver by changes in the color or flashing interval of a warning lamp, in which case the warning lamp acts as a notification device. 【0072】Furthermore, the information regarding the lateral controllable limit output to the car navigation system 81 preferably includes future time-elapsed information, but it may also only include the timing of loss when lateral control capability is lost. In addition, the time-elapsed information regarding the lateral controllable limit can be two-dimensional information, physical quantities at each time point, or a combination of two-dimensional information and physical quantities at each time point. 【0073】 10...Vehicle, 11, 12...Front wheels (steering wheels), 34...Integrated control unit (vehicle control device), 40...Steer-by-wire system, 51...Steering wheel, 81...Car navigation system (notification device), 82...Automated driving control unit (automated driving control device), 100...Vehicle control system
Claims
1. A vehicle control device provided in a vehicle equipped with a steer-by-wire system that steers the steering wheels of the vehicle, which are mechanically disconnected from the steering input mechanism, wherein the control unit of the vehicle control device, when it acquires an abnormal signal of the steering function in the steer-by-wire system, outputs information relating to the lateral controllable limit of the vehicle, which is determined based on the vehicle's specifications and the vehicle's speed.
2. A vehicle control device according to claim 1, wherein the information relating to the lateral controllable limit is time-elapsed information relating to the lateral controllable limit, and the control unit outputs the time-elapsed information to an automatic driving control device that generates the vehicle's travel path.
3. A vehicle control device according to claim 2, wherein the control unit outputs the time elapsed information as two-dimensional range information.
4. A vehicle control device according to claim 3, wherein the control unit outputs time-elapsed information of the vehicle's speed in addition to the two-dimensional range information.
5. A vehicle control device according to claim 2, wherein the control unit outputs the time elapsed information as a physical quantity at each time point.
6. A vehicle control device according to claim 5, wherein the physical quantity at each time includes at least one of the turning radius of the vehicle, the limit of lateral controllable time of the vehicle, and the reachable distance of the vehicle.
7. A vehicle control device according to claim 1, wherein the control unit outputs information relating to the lateral controllable limit to a notification device mounted on the vehicle.
8. A vehicle control system comprising a vehicle control device and an automatic driving control device mounted on a vehicle having a steer-by-wire system that steers the steering wheels of the vehicle, which are mechanically disconnected from a steering input mechanism, wherein the vehicle control device, upon acquiring an abnormal signal of the steering function in the steer-by-wire system, obtains two-dimensional range information, which is time-elapsed information relating to the lateral controllable limit of the vehicle, based on the vehicle's specifications and the vehicle's speed, outputs the two-dimensional range information and the time-elapsed information of the vehicle's speed to the automatic driving control device, and the automatic driving control device determines the vehicle's travel path by referring to the two-dimensional range information and the time-elapsed information of the vehicle's speed.