Vehicle control system and steering control device

Abstract

To provide a vehicle control system and a turning control device capable of limiting vehicle speed according to sending / receiving delay between a steering control ECU (steering control device) and a turning control ECU (turning angle control device).SOLUTION: The vehicle control system performs control of a vehicle which is equipped with a reaction device for providing a handlebar with steering reaction force according to a steering angle of the handlebar, and a turning device for driving a turning motor which turns turning wheels according to a steering angle of the handlebar, the system comprising a steering control device (steering control ECU) which controls the reaction device and a turning control device (turning control ECU 70) which controls the turning device. The system performs vehicle speed restraint control of the vehicle according to delay time of data sent / received between the steering control device (steering control ECU) and the turning control device (turning control ECU 70).SELECTED DRAWING: Figure 14

Description

[Technical Field]

[0001] The present invention relates to a vehicle control system and a steering control device. [Background technology]

[0002] There is a steer-by-wire (SBW) system in which a steering mechanism (Force Feedback Actuator: FFA) having a steering wheel operated by a driver and a road wheel actuator (RWA) that steers the steered wheels are mechanically separated. In an SBW system, the steering mechanism and the road wheel actuator are electrically connected via a vehicle control system, and steering operation is transmitted to the road wheel actuator by an electric signal to steer the steered wheels, while the steering mechanism generates a steering reaction force to give the driver an appropriate steering feel. The steering mechanism generates a steering reaction force using a reaction force actuator equipped with a reaction force motor, and the road wheel actuator steers the steered wheels using a steering actuator equipped with a steering motor. The reaction force actuator and the steering wheel are mechanically connected via a column shaft, and the reaction force (torque) generated by the reaction force actuator is transmitted to the driver via the column shaft and the steering wheel (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-185819 Summary of the Invention [Problem to be solved by the invention]

[0004] The vehicle control system is connected to each electronic control unit (ECU), including the engine control module (ECM), the body control module (BCM) that controls the vehicle's electrical equipment such as lights and door locks, and the antilock brake system (ABS), via an in-vehicle communication bus, and sends and receives various data using in-vehicle networks (in-vehicle LANs) such as CAN (Controller Area Network) and FlexRay.

[0005] In SBW systems, where the steering mechanism and the turning mechanism are mechanically separated, the ECU that controls the steering mechanism is connected to the ECU that controls the turning mechanism, and the ECU that controls the steering mechanism and the ECU that controls the turning mechanism communicate with each other to control the steering of the vehicle, but delays can occur in the transmission and reception of various types of data between the two ECUs. For this reason, there is room for improvement in control when transmission and reception delays occur.

[0006] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a vehicle control system and a steering control device that are capable of limiting vehicle speed in accordance with the transmission and reception delay between a steering control ECU and a turning control ECU. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, a vehicle control system according to one embodiment of the present invention is a vehicle control system that controls a vehicle equipped with a reaction force device that applies a steering reaction force to the steering wheel in accordance with the steering angle of the steering wheel, and a steering device that drives a steering motor that steers the steered wheels in accordance with the steering angle of the steering wheel, and is equipped with a steering control device that controls the reaction force device and a steering control device that controls the steering device, and performs vehicle speed suppression control of the vehicle in accordance with the delay time of data transmitted and received between the steering control device and the steering control device.

[0008] According to the above configuration, a vehicle control system can be obtained that can limit the vehicle speed according to the delay in transmission and reception of data transmitted and received between the steering control device and the turning control device.

[0009] As a desirable aspect of the vehicle control system, it is preferable that the steering control device transmits first data to the turning control device, and the turning control device comprises a first delay detection unit that detects a delay time of the first data, and a first vehicle speed limit value generation unit that generates a first vehicle speed limit value according to the delay time of the first data.

[0010] According to the above configuration, the first vehicle speed limit value can be generated according to the delay time of the first data transmitted from the steering control device to the turning control device, thereby enabling the vehicle speed limit to be set according to the delay time of the first data.

[0011] In a preferred embodiment of the vehicle control system, the first vehicle speed limit value monotonically decreases as the delay time of the first data increases.

[0012] According to the above configuration, a first vehicle speed limit value that monotonically decreases as the delay time of the first data increases is obtained.

[0013] In a preferred embodiment of the vehicle control system, the first vehicle speed limit value is reduced at a reduced rate as the delay time of the first data increases.

[0014] According to the above configuration, the first vehicle speed limit value is obtained whose rate of decrease decreases as the delay time of the first data increases.

[0015] In a preferred embodiment of the vehicle control system, the first vehicle speed limit value is approximately inversely proportional to the delay time of the first data.

[0016] According to the above configuration, the first vehicle speed limit value that is approximately inversely proportional to the delay time of the first data is obtained.

[0017] As a desirable aspect of the vehicle control system, it is preferable that the delay time of the first data is limited by a preset maximum delay time value, and the first vehicle speed limit value is limited to a minimum vehicle speed limit value by the maximum delay time value.

[0018] According to the above configuration, even if the delay time of the first data is long, it is possible to continue driving the vehicle.

[0019] As a desirable aspect of the vehicle control system, it is preferable that the first delay detection unit performs a delay detection process on the first data at a predetermined time interval, and detects a delay in the first data based on the presence, consistency, and continuity of the first data acquired during the polling period in which the delay detection process is performed.

[0020] According to the above configuration, it is possible to detect a delay in the first data.

[0021] As a desirable aspect of the vehicle control system, it is preferable that the turning control device transmits second data to the steering control device, and the steering control device includes a delay detection unit that detects a delay time of the second data, and a vehicle speed limit value generation unit that generates a vehicle speed limit value according to the delay time of the second data.

[0022] According to the above configuration, the second vehicle speed limit value can be generated according to the delay time of the second data transmitted from the turning control device to the steering control device, thereby enabling the vehicle speed limit to be set according to the delay time of the second data.

[0023] In a preferred embodiment of the vehicle control system, the second vehicle speed limit value monotonically decreases as the delay time of the second data increases.

[0024] According to the above configuration, the second vehicle speed limit value that monotonically decreases as the delay time of the second data increases is obtained.

[0025] In a preferred embodiment of the vehicle control system, the second vehicle speed limit value is reduced at a reduced rate as the delay time of the second data increases.

[0026] According to the above configuration, the second vehicle speed limit value is obtained whose rate of decrease decreases as the delay time of the second data increases.

[0027] In a preferred embodiment of the vehicle control system, the second vehicle speed limit value is approximately inversely proportional to the delay time of the second data.

[0028] According to the above configuration, the second vehicle speed limit value that is approximately inversely proportional to the delay time of the second data is obtained.

[0029] As a desirable aspect of the vehicle control system, it is preferable that the delay time of the second data is limited by a preset maximum delay time value, and the second vehicle speed limit value is limited to a minimum vehicle speed limit value by the maximum delay time value.

[0030] According to the above configuration, even if the delay time of the second data is long, it is possible to continue driving the vehicle.

[0031] As a desirable aspect of the vehicle control system, it is preferable that the second delay detection unit performs a delay detection process on the second data at a predetermined time interval, and detects a delay in the second data based on the presence, consistency, and continuity of the second data acquired during the polling period in which the delay detection process is performed.

[0032] According to the above configuration, it is possible to detect a delay in the second data.

[0033] As a desirable aspect of the vehicle control system, the steering control device preferably further includes a vehicle speed limit value selection processing unit that selects the smaller of the first vehicle speed limit value and the second vehicle speed limit value.

[0034] According to the above configuration, the vehicle speed can be limited by selecting the smaller of the first vehicle speed limit value and the second vehicle speed limit value.

[0035] As a desirable aspect of the vehicle control system, the steering control device preferably further includes a vehicle speed limit value selection processing section that selects the smaller of the first vehicle speed limit value and the second vehicle speed limit value.

[0036] According to the above configuration, the vehicle speed can be limited by selecting the smaller of the first vehicle speed limit value and the second vehicle speed limit value.

[0037] In order to achieve the above object, a steering control device according to one aspect of the present invention is a steering control device that controls the steering angle of a vehicle based on data transmitted from a steering control device, and performs vehicle speed suppression control of the vehicle according to the delay time of the data transmitted from the steering control device.

[0038] According to the above configuration, a steering control device can be obtained that can limit the vehicle speed in accordance with the transmission delay of data transmitted from the steering control device.

[0039] In a preferred embodiment of the steering control device, it is preferable to include a delay detection unit that detects a delay time of the data, and a vehicle speed limit value generation unit that generates a vehicle speed limit value according to the delay time of the data.

[0040] According to the above configuration, a vehicle speed limit value can be generated according to the delay time of data transmitted from the steering control device to the turning control device, thereby enabling a vehicle speed limit according to the delay in data transmission and reception.

[0041] In a preferred embodiment of the steering control device, the vehicle speed limit value monotonically decreases as the delay time of the data increases.

[0042] According to the above configuration, a vehicle speed limit value that monotonically decreases as the data delay time increases is obtained.

[0043] In a preferred embodiment of the steering control device, the vehicle speed limit value is reduced at a reduced rate as the delay time of the data increases.

[0044] According to the above configuration, a vehicle speed limit value is obtained whose decreasing rate decreases as the data delay time increases.

[0045] In a preferred embodiment of the steering control device, the vehicle speed limit value is approximately inversely proportional to the delay time of the data.

[0046] According to the above configuration, a vehicle speed limit value that is approximately inversely proportional to the data delay time can be obtained.

[0047] In a preferred embodiment of the steering control device, the delay time of the data is limited by a preset maximum delay time value, and the vehicle speed limit value is limited to a minimum vehicle speed limit value by the maximum delay time value.

[0048] According to the above configuration, even if the data delay time is long, the vehicle can continue to be driven.

[0049] As a desirable aspect of the steering control device, it is preferable that the delay detection unit performs delay detection processing on the data at predetermined time intervals, and detects a delay in the data based on the presence or absence, consistency, and continuity of data acquired during the polling period in which the delay detection processing is performed.

[0050] According to the above configuration, it is possible to detect a data delay. [Effects of the Invention]

[0051] According to the present invention, it is possible to provide a vehicle control system and a steering control device that are capable of limiting vehicle speed according to the transmission / reception delay between a steering control ECU (steering control device) and a turning control ECU (turning angle control device). [Brief explanation of the drawings]

[0052] [Figure 1]FIG. 1 is a configuration diagram illustrating an example of an outline of an SBW system according to an embodiment. [Figure 2A] FIG. 2A is a diagram illustrating an example of a schematic configuration of a vehicle control system according to an embodiment. [Figure 2B] FIG. 2B is a schematic diagram showing an example of the hardware configuration of each ECU. [Figure 3] FIG. 3 is a diagram showing an example of a control block configuration related to steering control of a vehicle. [Figure 4] FIG. 4 is a block diagram showing an example of the configuration of the steering torque target value generating unit. [Figure 5A] FIG. 5A is a diagram showing an example of the characteristics of the basic map. [Figure 5B] FIG. 5B is a diagram showing an example of the characteristics of the torque value Tref_basic. [Figure 6A] FIG. 6A is a diagram showing an example of the characteristics of a damper gain map. [Figure 6B] FIG. 6B is a diagram showing an example of the characteristics of the torque value Tref_a+Tref_b. [Figure 7] FIG. 7 is a region diagram for explaining the steering direction in the present disclosure. [Figure 8] FIG. 8 is a block diagram showing an example of the configuration of the steering torque compensation value calculation unit according to the embodiment. [Figure 9] FIG. 9 is a conceptual diagram for explaining a method for calculating the actual road surface reaction torque acting on the steering mechanism. [Figure 10] FIG. 10 is a conceptual diagram showing a configuration for executing a simulation for deriving the transfer function Gfil. [Figure 11] FIG. 11 is a diagram showing an example of the characteristics of the steering torque compensation value map. [Figure 12] FIG. 12 is a diagram conceptually showing an example of the characteristics of the torque value Tref_c after sign conversion. [Figure 13] FIG. 13 is a block diagram showing a modified example of the steering torque compensation value calculation unit according to the embodiment. [Figure 14] FIG. 14 is a block diagram illustrating an example of the configuration of the vehicle speed restriction processing unit according to the first embodiment. [Figure 15] FIG. 15 is a flowchart illustrating an example of a delay detection process according to the first embodiment. [Figure 16A] FIG. 16A is a diagram showing an example of the characteristics of a vehicle speed limit map. [Figure 16B] FIG. 16B is a diagram showing an example of the characteristics of a modified vehicle speed limit map. [Figure 17] FIG. 17 is a block diagram illustrating an example of the configuration of a vehicle speed restriction processing unit according to the second embodiment. [Figure 18] FIG. 18 is a flowchart illustrating an example of a delay detection process according to the second embodiment. [Figure 19] FIG. 19 is a block diagram illustrating an example of the configuration of a vehicle speed restriction processing unit according to the third embodiment. [Figure 20] FIG. 20 is a block diagram showing an example of the configuration of a vehicle speed restriction processing unit according to a first modified example of the third embodiment. [Figure 21] FIG. 21 is a block diagram showing an example of the configuration of a vehicle speed restriction processing unit according to a second modification of the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0053] Hereinafter, modes for carrying out the invention (hereinafter referred to as embodiments) will be described in detail with reference to the drawings. Note that the present invention is not limited to the following embodiments. Furthermore, the components in the following embodiments include those that can be easily imagined by a person skilled in the art, those that are substantially the same, and those that are within the so-called equivalent range. Furthermore, the components disclosed in the following embodiments can be combined as appropriate.

[0054] 1 is a block diagram showing an example of an outline of a SBW system according to an embodiment, which includes a reaction force device 30 constituting a steering mechanism having a steering wheel operated by a driver, a steering device 40 constituting a steering mechanism for steering steered wheels, and a vehicle control system 50.

[0055] The SBW system does not have an intermediate shaft that is mechanically connected to the column shaft (steering shaft, handle shaft) 2, which is found in general electric power steering devices, and instead transmits the driver's operation of the steering wheel 1 as an electrical signal, specifically the steering angle θh output from the reaction force device 30, as an electrical signal.

[0056] The reaction force device 30 includes a reaction force motor 31 and a speed reduction mechanism 32 that reduces the rotational speed of the reaction force motor 31. The reaction force device 30 transmits the vehicle's motion state, which is transmitted from the steered wheels 5L, 5R, to the driver as a steering reaction force. The reaction force motor 31 applies the steering reaction force to the steering wheel 1 via the speed reduction mechanism 32.

[0057] The reaction force device 30 further includes a steering angle sensor 33 and a torque sensor 34. The steering angle sensor 33 detects the steering angle θh of the steering wheel 1. The torque sensor 34 detects the steering torque Th of the steering wheel 1. Hereinafter, the steering angle θh detected by the steering angle sensor 33 will also be referred to as the "actual steering angle θh_act," and the steering torque Th detected by the torque sensor 34 will also be referred to as the "actual steering torque Th_act."

[0058] In the present disclosure, a stopper (rotation limiting mechanism) 35 that physically sets a steering end point, which is the limit of possible steering, is provided on the column shaft 2. That is, the magnitude (absolute value) of the steering angle θh is limited by the stopper 35.

[0059] The steering device 40 includes a steering motor 41, a speed reduction mechanism 42 that reduces the rotational speed of the steering motor 41, and a pinion rack mechanism 44 that converts the rotational motion of the steering motor 41 into linear motion. The steering device 40 drives the steering motor 41 in accordance with the steering angle θh, and the resulting drive force is applied to the pinion rack mechanism 44 via the speed reduction mechanism 42, and the drive force is passed through the tie rods 3a and 3b to steer the steerable wheels 5L and 5R. An angle sensor 43 is disposed near the pinion rack mechanism 44 and detects the steering angle θt of the steerable wheels 5L and 5R. Instead of the steering angle θt of the steerable wheels 5L and 5R, for example, the motor angle of the steering motor 41 or the position of the rack may be detected and the detected value may be used. Hereinafter, the steering angle θt detected by the angle sensor 43 will also be referred to as the "actual steering angle θt_act."

[0060] In order to cooperatively control the reaction force device 30 and the steering device 40, the vehicle control system 50 generates a voltage control command value Vref1 for driving and controlling the reaction force motor 31 and a voltage control command value Vref2 for driving and controlling the steering motor 41 based on information such as the steering angle θh and the steering angle θt output from both devices, as well as the vehicle speed Vs detected by the vehicle speed sensor 10.

[0061] The vehicle control system 50 is supplied with power from the battery 12 and receives an ignition key signal via the ignition key 11 .

[0062] 2A is a diagram illustrating an example of a schematic configuration of a vehicle control system according to an embodiment. The vehicle control system 50 includes, as electronic control units (ECUs) related to vehicle control, a steering control ECU (steering control device) 60, a turning control ECU (turning control device) 70, and a brake control ECU 80. The brake control ECU 80 is exemplified by an antilock brake system (ABS). In addition to the above ECUs, the vehicle control system 50 may also include other ECUs, such as an engine control module (ECM), a body control module (BCM), a meter controller (MET), and an advanced driver assistance system (ADAS).

[0063] The ECUs transmit and receive various types of data using an in-vehicle network (in-vehicle LAN) such as a Controller Area Network (CAN) or FlexRay. The ECUs are connected to each other via an in-vehicle communication bus 20 (first communication path 20) that transmits and receives various types of information required to control the vehicle. In addition to the vehicle speed sensor 10, various sensors such as a front camera module (FCM) and ultrasonic sensors such as a clearance sonar or a back sonar may be connected to the in-vehicle communication bus 20.

[0064] In the present disclosure, various data required for steering control of the vehicle are transmitted and received between the steering control ECU 60 and the turning control ECU 70 using a private CAN that is independent of the in-vehicle communication bus 20. The steering control ECU 60 and the turning control ECU 70 are connected via the in-vehicle communication bus 21 (second communication path 21).

[0065] Fig. 2B is a schematic diagram showing an example of the hardware configuration of each ECU. Specifically, each ECU is mainly composed of a CPU (including an MCU, an MPU, etc.). Cooperative control of reaction force device 30 and steering device 40 is performed by a program executed within the CPUs of steering control ECU 60 and steering control ECU 70. Each ECU may include, for example, a RAM (random access memory), a ROM (read only memory), etc., as shown in Fig. 2B, in order to store data, programs, etc.

[0066] Fig. 3 is a diagram showing an example of a control block configuration related to vehicle steering control. In Fig. 3, reaction force device 30 includes reaction force motor 31 and the above-mentioned configuration, as well as a PWM (pulse width modulation) control unit 37, an inverter 38, and a motor current detector 39. Furthermore, turning device 40 includes steering motor 41 and the above-mentioned configuration, as well as a PWM control unit 47, an inverter 48, and a motor current detector 49. Steering control ECU 60 and turning control ECU 70 cooperate to control reaction force device 30 and turning device 40.

[0067] It should be noted that some or all of the components of vehicle control system 50 may be realized by hardware. Specifically, steering control ECU 60 may include PWM control unit 37, inverter 38, and motor current detector 39. Furthermore, turning control ECU 70 may include PWM control unit 47, inverter 48, and motor current detector 49.

[0068] 3, steering control ECU 60 includes, as control blocks, a steering torque target value generation section 200, a steering torque control section 400, and a current control section 500. Furthermore, turning control ECU 70 includes a turning angle target value generation section 600, a turning angle control section 700, and a current control section 800.

[0069] The steering control ECU 60 performs control such that the actual steering torque Th_act detected by the torque sensor 34 follows the steering torque target value Th_ref, which is the target value of the steering torque of the reaction force device 30.

[0070] The steering torque target value generating section 200 generates a steering torque target value Th_ref.

[0071] The steering torque control unit 400 generates a motor current command value Ih_ref, which is a control target value of the current to be supplied to the reaction force motor 31. The steering torque control unit 400 calculates the motor current command value Ih_ref so that the deviation Th_err between the steering torque target value Th_ref and the actual steering torque Th_act approaches zero.

[0072] The current control unit 500 controls the current of the reaction force motor 31. The current control unit 500 calculates a voltage control command value Vh_ref such that the deviation Ih_err between the motor current command value Ih_ref output from the steering torque control unit 400 and the actual current value (motor current value) Ih_act of the reaction force motor 31 detected by the motor current detector 39 approaches zero.

[0073] In the reaction force device 30, the reaction force motor 31 is controlled and driven via a PWM control unit 37 and an inverter 38 based on the voltage control command value Vh_ref.

[0074] The steering control ECU 70 performs control such that the actual steering angle θt_act detected by the angle sensor 43 follows the target steering angle value θt_ref.

[0075] The steering angle target value generating section 600 generates the steering angle target value θt_ref based on the steering angle θh transmitted from the steering control ECU 60 via the in-vehicle communication bus 21 (second communication path 21).

[0076] Steering angle control unit 700 generates motor current command value It_ref, which is a control target value for the current supplied to steering motor 41. Steering angle control unit 700 calculates motor current command value It_ref such that deviation θt_err between steering angle target value θt_ref and actual steering angle θt_act approaches zero.

[0077] Current control unit 800 controls the current of steering motor 41. Current control unit 800 calculates a voltage control command value Vt_ref such that deviation It_err between motor current command value It_ref output from steering angle control unit 700 and actual current value (motor current value) It_act of steering motor 41 detected by motor current detector 49 approaches zero.

[0078] In the steering device 40, the steering motor 41 is controlled and driven via a PWM control unit 47 and an inverter 48 based on the voltage control command value Vt_ref.

[0079] In this embodiment, steering torque target value generation section 200, steering torque control section 400 and current control section 500 are not limited by the configuration of each control block as long as they are configured to realize the respective controls in steering control ECU 60. Furthermore, turning angle target value generation section 600, turning angle control section 700 and current control section 800 are not limited by the configuration of each control block as long as they are configured to realize the respective controls in steering control ECU 70.

[0080] 4 is a block diagram showing an example of the configuration of the steering torque target value generating unit 200. As shown in FIG. 4, the steering torque target value generating unit 200 includes, as main components, a basic map unit 210, a damper torque generating unit 220, and a steering torque compensation value generating unit 230.

[0081] The sign extraction unit 280 shown in Fig. 4 extracts the sign of the steering angle θh. Specifically, for example, the value of the steering angle θh is divided by the absolute value of the steering angle θh. As a result, the sign extraction unit 280 outputs "1" when the sign of the steering angle θh is "+", and outputs "-1" when the sign of the steering angle θh is "-". Specifically, the sign extraction unit 280 generates, for example, a sign function Sgn(θh) of the steering angle θh.

[0082] Fig. 5A is a diagram showing an example of the characteristics of the basic map. The steering angle |θh| and vehicle speed Vs that have been subjected to absolute value processing in the absolute value calculation unit 260 are input to the basic map unit 210. The basic map unit 210 generates a torque value Tref_basic using the vehicle speed Vs as a parameter, using the basic map shown in Fig. 5A. The torque value Tref_basic is used to generate a basic steering reaction force according to the steering angle |θh| and the vehicle speed Vs.

[0083] The torque value Tref_basic has an angle-sensitive characteristic that increases or decreases according to the steering angle |θh|. More specifically, as shown in FIG. 5A, the torque value Tref_basic increases as the steering angle |θh| increases. Furthermore, the torque value Tref_basic has a vehicle-speed-sensitive characteristic that increases or decreases according to the vehicle speed Vs. More specifically, as shown in FIG. 5A, the torque value Tref_basic increases as the vehicle speed Vs increases. In other words, the reaction force obtained by the torque value Tref_basic derived from the basic map shown in FIG. 5A increases as the amount of operation of the steering wheel 1 by the driver (steering angle θh) increases, and also increases as the vehicle speed (vehicle speed Vs) increases. Note that although the basic map shown in FIG. 5A has a vehicle-speed-sensitive characteristic, the present invention is not limited to this.

[0084] Fig. 5B is a diagram showing an example of the characteristics of the torque value Tref_a. The torque value Tref_a shown in Fig. 5B is obtained by multiplying the torque value Tref_basic output from the basic map unit 210 by the sign function Sgn(θh) output from the sign extraction unit 280 in a multiplier 293. Note that a configuration may be adopted that does not include the sign extraction unit 280, and instead obtains the torque value Tref_a using a basic map corresponding to the positive or negative steering angle θh, as shown in Fig. 5B.

[0085] The damper torque generation unit 220 includes a damper gain map unit 221 and a multiplication unit 222. Fig. 6A is a diagram showing an example of the characteristics of the damper gain map. The vehicle speed Vs is input to the damper gain map unit 221. The damper gain map unit 221 generates the damper gain DG using the damper gain map shown in Fig. 6A.

[0086] 6A, the damper gain DG has a vehicle speed-sensitive characteristic that increases or decreases according to the vehicle speed Vs. The damper torque generation unit 220 multiplies the angular velocity of the steering wheel 1 (hereinafter also referred to as "steering angular velocity ωh") calculated by differentiating the steering angle θh (differentiation unit 270) by the damper gain DG output from the damper gain map unit 221 (multiplication unit 222), and outputs the result as a torque value Tref_b.

[0087] The torque value Tref_b output from the damper torque generation unit 220 is added to the torque value Tref_a output from the basic map unit 210 (addition unit 291). This makes it possible to compensate for the steering reaction force in proportion to the steering angular velocity ωh.

[0088] Fig. 6B is a diagram showing an example of the characteristics of the torque value Tref_a+Tref_b. The torque value Tref_a+Tref_b is obtained by adding the torque value Tref_a to the torque value Tref_b output from the damper torque generation unit 220. In Fig. 6B, the solid line indicates the torque value Tref_a+Tref_b when the steering angular velocity ωh is a positive value (ωh>0), and the dashed line indicates the torque value Tref_a+Tref_b when the steering angular velocity ωh is a negative value (ωh<0). Also in Fig. 6B, the dashed line indicates the torque value Tref_a.

[0089] 7 is a region diagram for explaining the steering direction in the present disclosure, in which the horizontal axis represents the steering angle θh and the vertical axis represents the steering angular velocity ωh.

[0090] Area A ((θh, ωh) = (+, +)) shown in FIG. 7 indicates that the steering wheel 1 is turned to the right (θh > 0) and is being turned further to the right (ωh > 0). Area B ((θh, ωh) = (+, -)) shown in FIG. 7 indicates that the steering wheel 1 is turned to the right (θh > 0) and is being turned back to the left (ωh < 0). Area C ((θh, ωh) = (-, -)) shown in FIG. 7 indicates that the steering wheel 1 is turned to the left (θh < 0) and is being turned further to the left (ωh < 0). Area D ((θh, ωh) = (-, +)) shown in FIG. 7 indicates that the steering wheel 1 is turned to the left (θh < 0) and is being turned back to the right (ωh > 0). Also, in Figure 7, on the steering angle θh axis (ωh=0), it is shown that the steering wheel 1 is neither being turned further nor turned back ((θh, ωh)=(θh,0)), and on the steering angular velocity ωh axis (θh=0), it is shown that the steering wheel 1 is in the center position ((θh, ωh)=(0, ωh)).

[0091] The torque value Tref_b output from the damper torque generation unit 220 is a positive value in regions A and D where the steering angular velocity ωh>0, and a negative value in regions B and C where the steering angular velocity ωh<0. As a result, when the steering angular velocity ωh>0, that is, in region A where the steering wheel 1 is turned to the right (θh>0) and further turned to the right, or in region D where the steering wheel 1 is turned to the left (θh<0) and turned back to the right, the torque value Tref_b is a value obtained by adding |Tref_b| to Tref_a, as shown by the solid line in Fig. 6B. On the other hand, when the steering angular velocity ωh<0, that is, in region B where the steering wheel 1 is turned to the right (θh>0) and turned back to the left, or in region C where the steering wheel 1 is turned to the left (θh<0) and further turned to the left, the torque value Tref_b is a value obtained by subtracting |Tref_b| from Tref_a, as shown by the dashed line in Fig. 6B.

[0092] 6B, the torque value Tref_a+Tref_b increases with increasing steering angle θ as the steering angle θh increases and approaches the steering end point limited by the stopper (rotation limiting mechanism) 35. In other words, the torque value Tref_a+Tref_b has a characteristic that the rate of change gradually decreases as the steering angle θh increases.

[0093] As described above, the SBW system does not have an intermediate shaft mechanically coupled to the column shaft 2. In other words, the steering mechanism and the turning mechanism are mechanically separated. For this reason, it is necessary to transmit to the reaction device 30 the steering reaction force when the vehicle is oversteered or understeered, for example, when traveling on a low-μ road where the frictional resistance of the road surface is significantly reduced due to an icy road surface or hydroplaning during rainy weather.

[0094] In the present disclosure, as shown in Figures 3 and 4, there is provided a steering torque compensation value generation unit 230 that estimates road surface reaction torque according to motor current command value It_ref generated by steering angle control unit 700, and torque value Tref_c generated by steering torque compensation value generation unit 230 is added to torque value Tref_a+Tref_b. This makes it possible to apply a steering reaction force according to the estimated value of road surface reaction torque to steering wheel 1. Below, a detailed description is given of the configuration and operation that can apply a steering reaction force according to the estimated value of road surface reaction torque to steering wheel 1.

[0095] Fig. 8 is a block diagram showing an example of the configuration of a steering torque compensation value calculation unit according to the embodiment. In the example configuration shown in Fig. 8, a steering torque compensation value calculation unit 240 includes, as main components, a road surface reaction force torque estimator 241 and a steering torque compensation value map unit 242.

[0096] First, a method for estimating the road surface reaction torque estimated value Tsat_est in the road surface reaction torque estimating section 241 will be described.

[0097] The road surface reaction force torque estimating section 241 receives as input the motor current command value It_ref transmitted from the steering control ECU 70 via the in-vehicle communication bus 21 (second communication path 21). Also, a transfer function Gfil shown in the following equation (1) is set in the road surface reaction force torque estimating section 241. The transfer function Gfil is stored in the ROM of the steering control ECU 60, for example.

[0098] Gfil=N(s) / D(s)=(Ds+E) / (As 2 +Bs+C)···(1)

[0099] In the above equation (1), the linear function N(s) = Ds + E and the quadratic function D(s) = As 2 A, B, C, D, and E in +Bs+C are coefficients set by the simulation shown below.

[0100] In the present disclosure, the transfer function Gfil is assumed to be a transfer function with a first order numerator and a second order denominator, but the order of the numerator and denominator can be changed as appropriate depending on the allowable error between the actual road surface reaction torque Tsat_act and the road surface reaction torque estimate value Tsat_est, the load on the ECU, etc.

[0101] For example, if the order of the numerator and denominator is increased, the relationship between the motor current command value It_ref and the actual road surface reaction torque Tsat_act determined by an experiment described below can be made to match well with the transfer characteristics of the transfer function Gfil, making it possible to estimate a road surface reaction torque estimated value Tsat_est that is close to the actual measured value.

[0102] On the other hand, if the order of the numerator and denominator is reduced, the load on the ECU can be reduced.

[0103] Assume that the relationship shown in the following equation (2) holds between the road surface reaction torque Tsat and the motor current command value It_ref. The road surface reaction torque Tsat shown in the following equation (2) is defined as the road surface reaction torque estimated value Tsat_est in this disclosure.

[0104] In other words, the transfer function Gfil calculates the road surface reaction torque estimated value Tsat_est from the motor current command value It_ref by simulating the relationship between the motor current command value It_ref and the actual road surface reaction torque Tsat_act obtained through experiments.

[0105] Tsat=Gfil×It_ref=Tsat_est···(2)

[0106] On the other hand, the actual road surface reaction torque Tsat_act acting on the steering mechanism can be calculated from the axial force applied to the tie rod. Fig. 9 is a conceptual diagram for explaining a method for calculating the actual road surface reaction torque acting on the steering mechanism.

[0107] The actual road surface reaction torque Tsat_act can be calculated by the following equation (3) using the axial forces FL and FR applied to the tie rods 3a and 3b and the length L of the arms 6a and 6b determined for each vehicle type.

[0108] Tsat_act = FL × L - FR × L (3)

[0109] In the present disclosure, the actual road surface reaction torque Tsat_act is calculated using the above formula (3) that uses the axial forces FL and FR measured in advance through experiments using an actual vehicle. The axial forces FL and FR can be measured, for example, by attaching force sensors to the tie rods 3 a and 3 b.

[0110] FIG. 10 is a conceptual diagram showing a configuration for executing a simulation for deriving the transfer function Gfil.

[0111] The motor current command value It_ref and axial forces FL and FR are input to the processing device shown in Fig. 10. The processing device derives a transfer function Gfil such that the road surface reaction torque estimated value Tsat_est shown in the above equation (2) approximates the actual road surface reaction torque Tsat_act calculated by the above equation (3). An example of the processing device shown in Fig. 10 is one that includes a frequency characteristic analysis device (servo analyzer).

[0112] Specifically, the processing device performs curve fitting using a sweep method to derive the coefficients A, B, C, D, and E of the transfer function Gfil shown in the above equation (1). An example of the curve fitting method is the least squares approximation method. The curve fitting method is not limited to the least squares approximation method.

[0113] Road surface reaction torque estimating section 241 performs filtering on motor current command value It_ref generated by steering angle control section 700 using transfer function Gfil derived as described above, and calculates road surface reaction torque estimated value Tsat_est shown in equation (2) above. This makes it possible to obtain road surface reaction torque estimated value Tsat_est that corresponds to the behavior of actual road surface reaction torque Tsat_act when the vehicle is actually traveling.

[0114] Returning to FIG. 8 , the sign extraction unit 244 extracts the sign of the road reaction force torque estimated value Tsat_est. Specifically, for example, the value of the road reaction force torque estimated value Tsat_est is divided by the absolute value of the road reaction force torque estimated value Tsat_est. As a result, the sign extraction unit 244 outputs "1" when the sign of the road reaction force torque estimated value Tsat_est is "+", and outputs "-1" when the sign of the road reaction force torque estimated value Tsat_est is "-". Specifically, the sign extraction unit 244 generates, for example, a sign function Sgn(Tsat_est) of the road reaction force torque estimated value Tsat_est.

[0115] Fig. 11 is a diagram showing an example of the characteristics of a steering torque compensation value map. The road surface reaction torque estimated value |Tsat_est| and vehicle speed Vs that have been subjected to absolute value processing in absolute value calculation section 243 are input to steering torque compensation value map section 242. Steering torque compensation value map section 242 generates a torque value Tref_c0 using the steering torque compensation value map shown in Fig. 11 with vehicle speed Vs as a parameter.

[0116] As shown in FIG. 11, the torque value Tref_c0 has a torque-sensitive characteristic that increases or decreases according to the road surface reaction torque estimated value |Tsat_est|.

[0117] More specifically, the torque value Tref_c0 increases as the road surface reaction torque estimated value |Tsat_est| increases, and the rate of increase decreases as the road surface reaction torque estimated value |Tsat_est| increases.

[0118] Furthermore, the torque value Tref_c0 has a vehicle speed-sensitive characteristic that increases and decreases according to the vehicle speed Vs. More specifically, the torque value Tref_c0 increases as the vehicle speed Vs increases, as shown in Fig. 11 .

[0119] That is, the reaction force obtained by the torque value Tref_c0 derived from the steering torque compensation value map shown in Fig. 11 increases as the road surface reaction torque estimated value |Tsat_est| increases and as the vehicle speed (vehicle speed Vs) increases. Note that although the steering torque compensation value map shown in Fig. 11 has a vehicle speed sensitive characteristic, the present invention is not limited to this.

[0120] The steering torque compensation value calculation unit 240 multiplies the torque value Tref_c0, which is the output value of the steering torque compensation value map unit 242, by a sign function Sgn(Tsat_est) of the road surface reaction torque estimated value Tsat_est in a multiplication unit 245, and outputs the sign-converted torque value Tref_c. Fig. 12 is a diagram conceptually showing an example of the characteristics of the torque value Tref_c after sign conversion.

[0121] The steering torque compensation value calculation unit 240 may also be configured as shown in Fig. 13. Fig. 13 is a block diagram showing a modified example of the steering torque compensation value calculation unit according to the embodiment.

[0122] The steering torque compensation value map section 242a in the modified example of the steering torque compensation value calculation section shown in FIG. 13 may have a steering torque compensation value map with the characteristics shown in FIG. 12 instead of the steering torque compensation value map with the characteristics shown in FIG. 11.

[0123] The torque value Tref_c output from the steering torque compensation value generation unit 230 is added to the torque value Tref_a and the torque value Tref_b in the addition units 291 and 292 shown in Fig. 4. As a result, the steering torque target value generation unit 200 outputs the steering torque target value Th_ref.

[0124] As described above, the road reaction torque estimator 241 calculates the road reaction torque estimated value Tsat_est using the transfer function Gfil derived by simulating an actual vehicle, thereby obtaining the road reaction torque estimated value Tsat_est according to the behavior of the actual road reaction torque Tsat_act when the vehicle is actually traveling, and applying a steering reaction force according to the road reaction torque estimated value Tsat_est. This makes it possible to obtain a steering feel that reflects the road surface conditions.

[0125] The transfer function used when calculating the road surface reaction torque estimated value Tsat_est in the road surface reaction torque estimator 241 is not limited to the above-described (1). Specifically, the present disclosure is not limited by the orders of the functions N(s) and D(s), for example.

[0126] Furthermore, the characteristics of the steering torque compensation value map are not limited to the aspects shown in Fig. 11 or 12. Furthermore, for example, instead of the aspects of the maps shown in Fig. 11 or 12, the characteristics may be defined by a predetermined transfer function.

[0127] Furthermore, a phase compensation unit that performs phase lag compensation and tracking compensation for the torque value Tref_c output from the steering torque compensation value calculation unit 240 may be provided downstream of the steering torque compensation value calculation unit 240.

[0128] In the above-described configuration, steering angle θh and motor current command value It_ref are transmitted and received between steering control ECU 60 and turning control ECU 70 via in-vehicle communication bus 21 (second communication path 21) shown in Fig. 2A. Specifically, turning angle target value generation section 600 generates turning angle target value θt_ref based on steering angle θh transmitted from steering control ECU 60 via in-vehicle communication bus 21 (second communication path 21). Furthermore, road surface reaction force torque estimator 241 receives as input motor current command value It_ref transmitted from turning control ECU 70 via in-vehicle communication bus 21 (second communication path 21). That is, in the present disclosure, as data necessary for performing steering control of the vehicle, the steering angle θh is transmitted from the steering control ECU 60 to the turning control ECU 70 via the in-vehicle communication bus 21 (second communication path 21), and the turning angle target value θt_ref is transmitted from the turning control ECU 70 to the steering control ECU 60 via the in-vehicle communication bus 21 (second communication path 21).

[0129] In the vehicle control system 50 of this type, a delay in data transfer may occur in the in-vehicle communication bus 21 (second communication path 21). In the present disclosure, "a delay occurs" refers to a delay that exceeds the amount of delay (time) due to a processing delay, a communication delay, or the like in each ECU when data transfer is performed normally.

[0130] Specifically, if there is a delay in transmission of data including information about steering angle θh that is transmitted from steering control ECU 60 to steering control ECU 70 via in-vehicle communication bus 21 (second communication path 21), a delay occurs in steering angle target value θt_ref that is generated based on steering angle θh in steering angle target value generation section 600, and the control of steering angle θt is delayed relative to the original steering angle θh that is not subject to delay. If this delay time of steering angle θh becomes long, the delay in control of steering angle θt becomes significant, and there is room for improvement.

[0131] Furthermore, a delay occurs in motor current command value It_ref calculated based on steering angle target value θt_ref in steering angle control unit 700, and a delay occurs in steering torque target value Th_ref generated based on motor current command value It_ref in steering torque target value generation unit 200. More specifically, torque value Tref_c generated by steering torque compensation value generation unit 230 based on delayed motor current command value It_ref is added to torque value Tref_basic generated by basic map unit 210 based on non-delayed vehicle speed Vs and steering angle θh, thereby generating steering torque target value Th_ref (see FIG. 4).

[0132] In the present disclosure, when a delay occurs in data transfer between the steering control ECU 60 and the turning control ECU 70, control is performed to suppress the vehicle speed. This allows the vehicle to continue driving without falling into a situation where it becomes impossible to control the vehicle's attitude. Below, a description is given of the configuration and operation that realizes vehicle speed limiting processing in accordance with the delay in data transfer between the steering control ECU 60 and the turning control ECU 70.

[0133] (Embodiment 1) 14 is a block diagram showing an example of the configuration of a vehicle speed restriction processing unit according to embodiment 1. In this embodiment, an example in which a vehicle speed restriction processing unit 71 is provided in a steering control ECU 70 will be described.

[0134] The vehicle speed limit processing unit 71 includes a delay detection unit 711 and a vehicle speed limit value generation unit 712 .

[0135] The vehicle speed restriction processing unit 71 receives the first data Data1 output from the steering control ECU 60 via the in-vehicle communication bus 21 (second communication path 21). The first data Data1 includes, for example, information on the steering angle θh. The information included in the first data Data1 is not limited to the steering angle θh.

[0136] The delay detection unit 711 detects the delay time Dt_dly1 of the first data Data1 output from the steering control ECU 60. Fig. 15 is a flowchart showing an example of the delay detection process according to the first embodiment.

[0137] The delay detection unit 711 performs the delay detection process shown in Fig. 15 at predetermined time intervals. Specifically, the delay detection unit 711 performs polling (cyclic processing) at intervals of, for example, 10 [ms]. During this polling period (for example, 10 [ms]), a plurality of first data Data1 output from the steering control ECU 60 is acquired.

[0138] In the delay detection process according to the first embodiment described below, the maximum data delay time value Dt_dly_max, which is the maximum value of the delay time Dt_dly1 of the first data Data1, the minimum data delay time value Dt_dly_min, which is the minimum value of the delay time Dt_dly1 of the first data Data1, and the maximum delay counter value DC_max, which is the maximum value of the delay counter DC, are pre-stored, for example, in the ROM of the steering control ECU 70.

[0139] The delay detection unit 711 acquires the first data Data1 output from the steering control ECU 60 (step S101), and performs processing to determine whether the first data Data1 output from the steering control ECU 60 exists (step S102).

[0140] Specifically, the delay detection unit 711 detects, for example, a predetermined flag included in the first data Data 1. If the predetermined flag cannot be detected, the delay detection unit 711 determines that the first data Data 1 does not exist (step S102; No).

[0141] If it is determined in step S102 that the first data Data1 exists (step S102; Yes), the delay detection unit 711 then performs a consistency determination process for the first data Data1 (step S103).

[0142] Specifically, the delay detection unit 711 executes, for example, CRC (Cyclic Redundancy Check) to perform an error detection process on the first data Data1. The integrity determination process of the first data Data1 in step S103 is not limited to CRC, and may be implemented using other error detection methods such as parity check or checksum.

[0143] If no error is detected in step S103 (step S103; Yes), then subsequently, the delay detection unit 711 performs a continuity determination process on the first data Data1 (step S104).

[0144] Specifically, the delay detection unit 711 checks, for example, the counter value indicating the acquisition order of the steering angle θh, and if it detects missing, duplicate, or discontinuous (error in data order) of the first data Data1, it determines that there is an abnormality in the continuity of the first data Data1 (step S104; No).

[0145] If it is determined in step S102 that the first data Data1 does not exist (step S102; No), if an error is detected based on the CRC execution result in step S103 (step S103; No), or if it is determined in step S104 that there is an abnormality in the continuity of the first data Data1 (step S104; No), the delay detection unit 711 increments the delay counter DC (DC = DC + 1) (step S105), and determines whether the delay counter DC is less than the maximum delay counter value DC_max (DC < DC_max) (step S106).

[0146] If the delay counter DC is less than the maximum delay counter value DC_max (step S106; Yes), the delay detection unit 711 multiplies the delay counter DC by a preset minimum data delay time Dt_dly_min to calculate the delay time Dt_dly1 (= Dt_dly_min × DC) of the first data Data1 (step S107).

[0147] When the delay counter DC becomes equal to or greater than the delay counter maximum value DC_max (DC≧DC_max) (step S106; No), the delay detection unit 711 sets the delay time Dt_dly1 of the first data Data1 to the preset data delay time maximum value Dt_dly_max (Dt_dly1=Dt_dly_max) (step S108).

[0148] If there is no abnormality in the continuity of the first data Data1 in step S104 (step S104; Yes), the delay detection unit 711 resets the delay counter DC (DC=0) (step S109).

[0149] FIG. 16A is a diagram showing an example of the characteristics of a vehicle speed limit map. A delay time Dt_dly1 of the first data Data1 detected by the delay detection unit 711 is input to the vehicle speed limit value generation unit 712. The vehicle speed limit value generation unit 712 uses the vehicle speed limit map shown in FIG. 16A to generate a vehicle speed limit value Vs_lim1 corresponding to the delay time Dt_dly1 of the first data Data1 detected by the delay detection unit 711. In this embodiment, the vehicle speed limit map is stored in advance in, for example, the ROM of the steering control ECU 70. In FIG. 16A, the maximum data delay time Dt_dly_max shown at point A is set to, for example, several thousand ms, and the minimum vehicle speed limit value Vs_lim_min at this time is set to, for example, 5 km / h to 20 km / h. Furthermore, the data delay time at point B shown in FIG. 16A is, for example, several tens of ms, and the vehicle speed limit value at this time is set to, for example, 120 km / h or more.

[0150] As shown in Fig. 16A, the vehicle speed limit value Vs_lim1 has a delay-time-sensitive characteristic that increases or decreases according to the delay time Dt_dly1 of the first data Data1. In the example shown in Fig. 16A, the vertical axis represents the delay time Dt_dly, and the delay time Dt_dly1 increases as the value increases upward on the graph. Also, in the example shown in Fig. 16A, the horizontal axis represents the vehicle speed limit value Vs_lim, and the vehicle speed limit value Vs_lim1 increases as the value increases rightward on the graph.

[0151] More specifically, the vehicle speed limit Vs_lim1 monotonically decreases as the delay time Dt_dly1 of the first data Data1 increases, and the rate of decrease decreases as the delay time Dt_dly1 of the first data Data1 increases. That is, the vehicle speed limit Vs_lim1 has a characteristic that is approximately inversely proportional to the delay time Dt_dly1 of the first data Data1. This allows the vehicle speed limit Vs_lim1 to be significantly reduced as the delay changes from a slight to a moderate delay, thereby achieving safe driving.

[0152] Furthermore, the vehicle speed limit value Vs_lim1 is limited to the minimum vehicle speed limit value Vs_lim_min by the preset maximum data delay time Dt_dly_max, which allows the vehicle to continue driving even if the delay time Dt_dly1 of the first data Data1 is long.

[0153] At vehicle speeds higher than the vehicle speed limit value Vs_lim shown in Fig. 16A, vehicle attitude control may become unstable. For this reason, in the vehicle speed limit map shown in Fig. 16A, a vehicle speed that can maintain stable vehicle behavior relative to the data delay time is set as the vehicle speed limit value Vs_lim in advance. The vehicle speed limit value relative to the data delay time is not limited to the map shown in Fig. 16A, and may be, for example, one in which the characteristics are defined by a predetermined transfer function, or one in which a vehicle speed limit value is set according to the data delay time.

[0154] 16B is a diagram showing an example of the characteristics of a modified vehicle speed limit map. The vehicle speed limit map may be configured such that a vehicle speed that can maintain stable vehicle behavior relative to the data delay time is set as the vehicle speed limit value Vs_lim in advance. For example, as shown in FIG. 16B, the vehicle speed limit value Vs_lim1 may have a characteristic that decreases linearly with respect to the delay time Dt_dly1 of the first data Data1.

[0155] Vehicle speed limit processing unit 71 outputs vehicle speed limit value Vs_lim1 generated by vehicle speed limit value generation unit 712 to brake control ECU 80. In other words, steering control ECU 70 transmits vehicle speed limit value Vs_lim1 to brake control ECU 80 via, for example, in-vehicle communication bus 20 (first communication path 20).

[0156] The brake control ECU 80 performs brake control so that the vehicle speed Vs is limited to the vehicle speed limit value Vs_lim1 transmitted from the steering control ECU 70. Specifically, the brake control ECU 80 compares the vehicle speed Vs detected by the vehicle speed sensor 10 with the vehicle speed limit value Vs_lim1 transmitted from the steering control ECU 70, and when the vehicle speed Vs is equal to or greater than the vehicle speed limit value Vs_lim1, performs brake control so that the vehicle speed Vs is limited to the vehicle speed limit value Vs_lim1. This allows the vehicle to continue driving without falling into a situation where it becomes impossible to control the attitude of the vehicle.

[0157] (Embodiment 2) 17 is a block diagram showing an example of the configuration of a vehicle speed restriction processing unit according to embodiment 2. In this embodiment, an example in which a vehicle speed restriction processing unit 61 is provided in a steering control ECU 60 will be described.

[0158] The vehicle speed limit processing unit 61 includes a delay detection unit 611 and a vehicle speed limit value generation unit 612 .

[0159] Vehicle speed restriction processing unit 61 receives second data Data2 output from steering control ECU 70 via in-vehicle communication bus 21 (second communication path 21). Second data Data2 includes, for example, information on motor current command value It_ref. Information included in first data Data1 is not limited to motor current command value It_ref.

[0160] The delay detection unit 611 detects the delay time Dt_dly2 of the second data Data2 output from the steering control ECU 70. Fig. 18 is a flowchart showing an example of a delay detection process according to the second embodiment.

[0161] Delay detection unit 611 performs the delay detection process shown in Fig. 18 at predetermined time intervals. Specifically, delay detection unit 611 performs polling (cyclic processing) at intervals of, for example, 10 [ms]. During this polling period (for example, 10 [ms]), a plurality of pieces of second data Data2 output from steering control ECU 70 are acquired.

[0162] In the delay detection process according to the second embodiment described below, a maximum data delay time value Dt_dly_max, which is the maximum value of the delay time Dt_dly2 of the second data Data2, a minimum data delay time value Dt_dly_min, which is the minimum value of the delay time Dt_dly2 of the second data Data2, and a maximum delay counter value DC_max, which is the maximum value of the delay counter DC, are stored in advance in, for example, the ROM of the steering control ECU 60. The maximum data delay time value Dt_dly_max, the minimum data delay time value Dt_dly_min, and the maximum delay counter value DC_max may be the same as or different from the maximum data delay time value Dt_dly_max, the minimum data delay time value Dt_dly_min, and the maximum delay counter value DC_max described in the first embodiment, respectively.

[0163] Delay detection unit 611 acquires second data Data2 output from turning control ECU 70 (step S201), and performs processing to determine whether second data Data2 output from turning control ECU 70 exists (step S202).

[0164] Specifically, the delay detection unit 611 detects, for example, a predetermined flag included in the second data Data 2. If the predetermined flag cannot be detected, the delay detection unit 611 determines that the second data Data 2 does not exist (step S202; No).

[0165] If it is determined in step S202 that the second data Data2 exists (step S202; Yes), the delay detection unit 611 then performs a consistency determination process for the second data Data2 (step S203).

[0166] Specifically, the delay detection unit 611 executes, for example, CRC (Cyclic Redundancy Check) to perform an error detection process on the second data Data2. The consistency determination process of the second data Data2 in step S203 is not limited to CRC, and for example, other error detection methods such as parity check or checksum may be used.

[0167] If no error is detected in step S203 (step S203; Yes), subsequently, the delay detection unit 611 performs a continuity determination process on the second data Data2 (step S204).

[0168] Specifically, the delay detection unit 611 checks, for example, the counter value indicating the acquisition order of the motor current command value It_ref, and if it detects missing, duplicate, or discontinuous (error in data order) of the second data Data2, it determines that there is an abnormality in the continuity of the second data Data2 (step S204; No).

[0169] If it is determined in step S202 that the second data Data2 does not exist (step S202; No), if an error is detected based on the CRC execution result in step S203 (step S203; No), or if it is determined in step S204 that there is an abnormality in the continuity of the second data Data2 (step S204; No), the delay detection unit 611 increments the delay counter DC (DC = DC + 1) (step S205), and determines whether the delay counter DC is less than the maximum delay counter value DC_max (DC < DC_max) (step S206).

[0170] If the delay counter DC is less than the maximum delay counter value DC_max (step S206; Yes), the delay detection unit 611 multiplies the delay counter DC by a preset minimum data delay time Dt_dly_min to calculate the delay time Dt_dly2 of the second data Data2 (= Dt_dly_min × DC) (step S207).

[0171] When the delay counter DC becomes equal to or greater than the delay counter maximum value DC_max (DC≧DC_max) (step S206; No), the delay detection unit 611 sets the delay time Dt_dly2 of the second data Data2 to the preset data delay time maximum value Dt_dly_max (Dt_dly2=Dt_dly_max) (step S208).

[0172] If there is no abnormality in the continuity of the second data Data2 in step S204 (step S204; Yes), the delay detection unit 611 resets the delay counter DC (DC=0) (step S209).

[0173] The delay time Dt_dly2 of the second data Data2 detected by the delay detection unit 611 is input to the vehicle speed limit value generation unit 612. The vehicle speed limit map applied to the vehicle speed limit value generation unit 612 is the same as the vehicle speed limit map (see FIGS. 16A and 16B) described in the first embodiment. The vehicle speed limit value generation unit 712 uses the vehicle speed limit map (see FIGS. 16A and 16B) to generate a vehicle speed limit value Vs_lim2 that corresponds to the delay time Dt_dly2 of the second data Data2 detected by the delay detection unit 611. In the present embodiment, the vehicle speed limit map is stored in advance in, for example, a ROM of the steering control ECU 60.

[0174] Similar to the vehicle speed limit value Vs_lim1 described in the first embodiment, the vehicle speed limit value Vs_lim2 has a delay time sensitive characteristic that increases or decreases according to the delay time Dt_dly2 of the second data Data2.

[0175] More specifically, the vehicle speed limit value Vs_lim2 monotonically decreases as the delay time Dt_dly2 of the second data Data2 increases, and the rate of decrease decreases as the delay time Dt_dly2 of the second data Data2 increases. In other words, the vehicle speed limit value Vs_lim2 has a characteristic that is approximately inversely proportional to the delay time Dt_dly2 of the second data Data2. As a result, the vehicle speed limit value is significantly reduced as the delay changes from a slight to a moderate delay, thereby achieving safe driving.

[0176] Furthermore, the vehicle speed limit value Vs_lim2 is limited to the minimum vehicle speed limit value Vs_lim_min by the preset maximum data delay time Dt_dly_max, which allows the vehicle to continue driving even if the delay time Dt_dly2 of the second data Data2 is long.

[0177] The vehicle speed limit map is set in advance to a vehicle speed that can maintain stable vehicle behavior with respect to the data delay time. The vehicle speed limit value with respect to the data delay time is not limited to the form of a map, but may be a form in which the characteristics are defined by a predetermined transfer function, or a form in which a vehicle speed limit value is set according to the data delay time.

[0178] The vehicle speed limit processing unit 61 outputs the vehicle speed limit value Vs_lim2 generated by the vehicle speed limit value generating unit 612 to the brake control ECU 80. In other words, the steering control ECU 60 transmits the vehicle speed limit value Vs_lim2 to the brake control ECU 80 via, for example, the in-vehicle communication bus 20 (first communication path 20).

[0179] The brake control ECU 80 performs brake control so that the vehicle speed Vs is limited to the vehicle speed limit value Vs_lim2 transmitted from the steering control ECU 60. Specifically, the brake control ECU 80 compares the vehicle speed Vs detected by the vehicle speed sensor 10 with the vehicle speed limit value Vs_lim2 transmitted from the steering control ECU 60, and when the vehicle speed Vs is equal to or greater than the vehicle speed limit value Vs_lim2, performs brake control so that the vehicle speed Vs is limited to the vehicle speed limit value Vs_lim2. This allows the vehicle to continue driving without falling into a situation where it becomes impossible to control the vehicle's attitude.

[0180] (Embodiment 3) FIG. 19 is a block diagram illustrating an example of the configuration of a vehicle speed restriction processing unit according to the third embodiment.

[0181] The vehicle speed limit processing unit 61a according to Embodiment 3 includes a first delay detection unit 711, a first vehicle speed limit value generation unit 712, a second delay detection unit 611, a second vehicle speed limit value generation unit 612, and a vehicle speed limit value selection processing unit 613.

[0182] In the example shown in FIG. 19, the first delay detection unit 711 and the first vehicle speed limit value generation unit 712 are provided in the steering control ECU 70, and in the steering control ECU 60a, in addition to the second delay detection unit 611 and the second vehicle speed limit value generation unit 612, a vehicle speed limit value selection processing unit 613 is provided. The first delay detection unit 711 and the first vehicle speed limit value generation unit 712 respectively correspond to the delay detection unit 711 and the vehicle speed limit value generation unit 712 described in Embodiment 1, and the second delay detection unit 611 and the second vehicle speed limit value generation unit 612 respectively correspond to the delay detection unit 611 and the vehicle speed limit value generation unit 612 described in Embodiment 2.

[0183] The vehicle speed limit value selection processing unit 613 compares the first vehicle speed limit value Vs_lim1 output from the first vehicle speed limit value generation unit 712 with the second vehicle speed limit value Vs_lim2 output from the second vehicle speed limit value generation unit 612. When Vs_lim1 < Vs_lim2, it transmits the first vehicle speed limit value Vs_lim1 to the brake control ECU 80 as the vehicle speed limit value Vs_lim. When Vs_lim1 > Vs_lim2, it transmits the second vehicle speed limit value Vs_lim2 to the brake control ECU 80 as the vehicle speed limit value Vs_lim. In the example shown in FIG. 19, the steering control ECU 70 transmits the first vehicle speed limit value Vs_lim1 to the steering control ECU 60a via, for example, the in-vehicle communication bus 20 (the first communication path 20).

[0184] The brake control ECU 80 performs brake control so that the vehicle speed Vs is limited to the vehicle speed limit value Vs_lim transmitted from the steering control ECU 60a. Specifically, the brake control ECU 80 compares the vehicle speed Vs detected by the vehicle speed sensor 10 with the vehicle speed limit value Vs_lim transmitted from the steering control ECU 60a, and when the vehicle speed Vs is equal to or greater than the vehicle speed limit value Vs_lim, performs brake control so that the vehicle speed Vs is limited to the vehicle speed limit value Vs_lim. This allows the vehicle to continue driving without falling into a situation where it becomes impossible to control the vehicle's attitude.

[0185] FIG. 20 is a block diagram showing an example of the configuration of a vehicle speed restriction processing unit according to a first modified example of the third embodiment.

[0186] The vehicle speed limit processing unit 71a according to the first variant of the third embodiment includes a first delay detection unit 711, a first vehicle speed limit value generation unit 712, a vehicle speed limit value selection processing unit 713, a second delay detection unit 611, and a second vehicle speed limit value generation unit 612.

[0187] 20, steering control ECU 70a is provided with a vehicle speed limit value selection processing unit 713 in addition to a first delay detection unit 711 and a first vehicle speed limit value generation unit 712, and steering control ECU 60 is provided with a second delay detection unit 611 and a second vehicle speed limit value generation unit 612. The first delay detection unit 711 and the first vehicle speed limit value generation unit 712 correspond to the delay detection unit 711 and the vehicle speed limit value generation unit 712 described in the first embodiment, respectively, and the second delay detection unit 611 and the second vehicle speed limit value generation unit 612 correspond to the delay detection unit 611 and the vehicle speed limit value generation unit 612 described in the second embodiment, respectively.

[0188] The vehicle speed limit value selection processing unit 713 compares the first vehicle speed limit value Vs_lim1 output from the first vehicle speed limit value generation unit 712 with the second vehicle speed limit value Vs_lim2 output from the second vehicle speed limit value generation unit 612. When Vs_lim1 < Vs_lim2, the first vehicle speed limit value Vs_lim1 is transmitted to the brake control ECU 80 as the vehicle speed limit value Vs_lim. When Vs_lim1 > Vs_lim2, the second vehicle speed limit value Vs_lim2 is transmitted to the brake control ECU 80 as the vehicle speed limit value Vs_lim. In the example shown in FIG. 20, the steering control ECU 60 transmits the second vehicle speed limit value Vs_lim2 to the steering control ECU 70a via, for example, the in-vehicle communication bus 20 (the first communication path 20).

[0189] In the brake control ECU 80, brake control is performed so that the vehicle speed Vs is limited to the vehicle speed limit value Vs_lim transmitted from the steering control ECU 70a. Specifically, the brake control ECU 80 compares the vehicle speed Vs detected by the vehicle speed sensor 10 with the vehicle speed limit value Vs_lim transmitted from the steering control ECU 70a, and when the vehicle speed Vs is equal to or higher than the vehicle speed limit value Vs_lim, performs brake control so that the vehicle speed Vs is limited to the vehicle speed limit value Vs_lim. Thereby, the operation can be continued without falling into a situation where the attitude control of the vehicle becomes impossible.

[0190] FIG. 21 is a block diagram showing a configuration example of a vehicle speed limit processing unit according to a second modification of Embodiment 3.

[0191] The vehicle speed limit processing unit 81 according to the second modification of Embodiment 3 includes a first delay detection unit 711, a first vehicle speed limit value generation unit 712, a second delay detection unit 611, a second vehicle speed limit value generation unit 612, and a vehicle speed limit value selection processing unit 813.

[0192] In the example shown in FIG. 21, a first delay detection unit 711 and a first vehicle speed limit value generation unit 712 are provided in the steering control ECU 70, and a second delay detection unit 611 and a second vehicle speed limit value generation unit 612 are provided in the steering control ECU 60. The vehicle speed limit value selection processing unit 813 is provided in the brake control ECU 80a. The first delay detection unit 711 and the first vehicle speed limit value generation unit 712 respectively correspond to the delay detection unit 711 and the vehicle speed limit value generation unit 712 described in Embodiment 1, and the second delay detection unit 611 and the second vehicle speed limit value generation unit 612 respectively correspond to the delay detection unit 611 and the vehicle speed limit value generation unit 612 described in Embodiment 2.

[0193] The vehicle speed limit value selection processing unit 813 compares the first vehicle speed limit value Vs_lim1 output from the steering control ECU 70 with the second vehicle speed limit value Vs_lim2 output from the steering control ECU 60. When Vs_lim1 < Vs_lim2, the first vehicle speed limit value Vs_lim1 is set as the vehicle speed limit value Vs_lim. When Vs_lim1 > Vs_lim2, the second vehicle speed limit value Vs_lim2 is set as the vehicle speed limit value Vs_lim. In the example shown in FIG. 21, the steering control ECU 70 transmits the first vehicle speed limit value Vs_lim1 to the brake control ECU 80a via, for example, the in-vehicle communication bus 20 (the first communication path 20), and the steering control ECU 60 transmits the second vehicle speed limit value Vs_lim2 to the brake control ECU 80a via, for example, the in-vehicle communication bus 20 (the first communication path 20).

[0194] The brake control ECU 80a performs brake control so that the vehicle speed Vs is limited to the vehicle speed limit value Vs_lim output from the vehicle speed limit value selection processing unit 813. Specifically, the brake control ECU 80a compares the vehicle speed Vs detected by the vehicle speed sensor 10 with the vehicle speed limit value Vs_lim output from the vehicle speed limit value selection processing unit 813, and when the vehicle speed Vs is greater than or equal to the vehicle speed limit value Vs_lim, performs brake control so that the vehicle speed Vs is limited to the vehicle speed limit value Vs_lim. Thereby, the driving can be continued without falling into a situation where the attitude control of the vehicle becomes impossible.

[0195] In the above-described embodiment, the first data Data1 is transmitted from the steering control ECU (steering control device) 60 via the in-vehicle communication bus 21, but the first data Data1 may be transmitted remotely to a vehicle's driving system. An example of such a configuration is an autopilot system that realizes unmanned driving of a vehicle. The autopilot system receives data transmitted from a control device provided outside the vehicle via a network such as satellite communication or 5G (fifth generation mobile communication system), and performs automatic driving control of the vehicle.

[0196] When the present disclosure is applied to such an autopilot system, steering control ECU (steering control device) 70 receives first data Data1 (including information equivalent to steering angle θh) transmitted via satellite communication or 5G communication (second communication path 21) from a control device (steering control device) provided outside the vehicle, and controls steering device 40. Even in this case, by providing steering control ECU 70 with the above-mentioned vehicle speed restriction processing unit 71, it becomes possible to perform vehicle speed suppression control in accordance with the data delay time.

[0197] In the above-described embodiment, when the delay counter DC is equal to or greater than the maximum delay counter value DC_max (DC≧DC_max), the vehicle speed limit value is limited to the minimum value Vs_lim_min, allowing the vehicle to continue operating even if the delay time Dt_dly1 (Dt_dly2) of the first data Data1 (second data Data2) is long. However, it is also possible to determine that an abnormality has occurred and take measures such as stopping the remote operation mode or stopping the vehicle.

[0198] Furthermore, the drawings used in the above-described embodiments are conceptual diagrams for qualitatively explaining the present disclosure, and are not intended to be limiting. Furthermore, while the above-described embodiment is an example of a preferred embodiment of the present disclosure, the present disclosure is not limited thereto, and various modifications can be made without departing from the spirit and scope of the present disclosure. [Explanation of symbols]

[0199] 1 handle 2 column axis 3a, 3b tie rod 5L,5R steered wheels 6a,6b Arms 10 Vehicle speed sensor 11 Ignition key 12 Battery 20 In-vehicle communication bus (first communication path) 21 In-vehicle communication bus (second communication path) 30 Reaction Device 31 Reaction motor 32 Reduction mechanism 33 Steering angle sensor 34 Torque sensor 35 Stopper (rotation limiting mechanism) 40 Steering gear 41 Steering motor 42 Reduction mechanism 43 Angle Sensor 44 Pinion rack mechanism 50 Vehicle Control System 60, 60a Steering control ECU (steering control device) 61, 61a Vehicle speed limit processing unit 70, 70a ECU for steering control (steering control device) 71, 71a Vehicle speed limit processing unit 80,80a Brake control ECU 81 Vehicle speed limit processing unit 200 Steering torque target value generation unit 210 Basic Map Section 220 Damper torque generating unit 221 Damper gain map section 222 Multiplication section 230 Steering torque compensation value generation unit 240 Steering torque compensation value calculation unit 241 Road reaction torque estimation unit 242, 242a Steering torque compensation value map section 243 Absolute value calculation unit 244 Code extraction part 245 Multiplication Unit 260 Absolute value calculation unit 270 Differential part 280 Code extraction part 291,292 Addition section 293 Multiplication section 400 Steering torque control unit 500 Current control section 600 steering angle target value generation unit 611 delay detection unit (second delay detection unit) 612 vehicle speed limit value generation unit (second vehicle speed limit value generation unit) 613 Vehicle speed limit value selection processing unit 700 Steering angle control unit 711 Delay detection unit (first delay detection unit) 712 Vehicle speed limit value generation unit (first vehicle speed limit value generation unit) 713 Vehicle speed limit value selection processing unit 800 Current control section 813 Vehicle speed limit value selection processing unit

Claims

1. A vehicle control system for controlling a vehicle including a reaction force device that applies a steering reaction force to a steering wheel in accordance with a steering angle of the steering wheel, and a steering device that drives a steering motor that steers steered wheels in accordance with the steering angle of the steering wheel, a steering control device for controlling the reaction force device; a steering control device that controls the steering device; Equipped with performing a vehicle speed suppression control of the vehicle in accordance with a delay time of data transmitted and received between the steering control device and the turning control device; the steering control device transmits first data to the turning control device, The steering control device includes: a first delay detection unit that detects a delay time of the first data; a first vehicle speed limit value generating unit that generates a first vehicle speed limit value according to a delay time of the first data; Equipped with the first vehicle speed limit value monotonically decreases as the delay time of the first data increases; Vehicle control system.

2. A vehicle control system for controlling a vehicle including a reaction force device that applies a steering reaction force to a steering wheel in accordance with a steering angle of the steering wheel, and a steering device that drives a steering motor that steers steered wheels in accordance with the steering angle of the steering wheel, a steering control device for controlling the reaction force device; a steering control device that controls the steering device; Equipped with performing a vehicle speed suppression control of the vehicle in accordance with a delay time of data transmitted and received between the steering control device and the turning control device; the steering control device transmits first data to the turning control device, The steering control device includes: a first delay detection unit that detects a delay time of the first data; a first vehicle speed limit value generating unit that generates a first vehicle speed limit value according to a delay time of the first data; Equipped with a decrease rate of the first vehicle speed limit value decreases as the delay time of the first data increases; Vehicle control system.

3. A vehicle control system for controlling a vehicle including a reaction force device that applies a steering reaction force to a steering wheel in accordance with a steering angle of the steering wheel, and a steering device that drives a steering motor that steers steered wheels in accordance with the steering angle of the steering wheel, a steering control device for controlling the reaction force device; a steering control device that controls the steering device; Equipped with performing a vehicle speed suppression control of the vehicle in accordance with a delay time of data transmitted and received between the steering control device and the turning control device; the steering control device transmits first data to the turning control device, The steering control device includes: a first delay detection unit that detects a delay time of the first data; a first vehicle speed limit value generating unit that generates a first vehicle speed limit value according to a delay time of the first data; Equipped with the first vehicle speed limit value is inversely proportional to the delay time of the first data; Vehicle control system.

4. The delay time of the first data is limited by a preset maximum delay time value; The first vehicle speed limit value is limited to a minimum vehicle speed limit value by the maximum delay time value. The vehicle control system according to any one of claims 1 to 3.

5. the first delay detection unit performs a delay detection process on the first data at predetermined time intervals; detecting a delay in the first data based on the presence, consistency, and continuity of the first data acquired during a polling period in which the delay detection process is performed; A vehicle control system according to any one of claims 1 to 4.

6. the turning control device transmits second data to the steering control device, The steering control device includes: a second delay detection unit that detects a delay time of the second data; a second vehicle speed limit value generating unit that generates a second vehicle speed limit value according to the delay time of the second data; Equipped with the second vehicle speed limit value monotonically decreases as the delay time of the second data increases. A vehicle control system according to any one of claims 1 to 5.

7. the turning control device transmits second data to the steering control device, The steering control device includes: a second delay detection unit that detects a delay time of the second data; a second vehicle speed limit value generating unit that generates a second vehicle speed limit value according to the delay time of the second data; Equipped with The second vehicle speed limit value decreases in a decreasing rate as the delay time of the second data increases. A vehicle control system according to any one of claims 1 to 5.

8. the turning control device transmits second data to the steering control device, The steering control device includes: a second delay detection unit that detects a delay time of the second data; a second vehicle speed limit value generating unit that generates a second vehicle speed limit value according to the delay time of the second data; Equipped with The second vehicle speed limit value is inversely proportional to the delay time of the second data. A vehicle control system according to any one of claims 1 to 5.

9. The delay time of the second data is limited by a preset maximum delay time value; The second vehicle speed limit value is limited to a minimum vehicle speed limit value by the maximum delay time value.

9. A vehicle control system according to any one of claims 6 to 8.

10. the second delay detection unit performs a delay detection process on the second data at predetermined time intervals; detecting a delay in the second data based on the presence, consistency, and continuity of the second data acquired during a polling period in which the delay detection process is performed; 10. A vehicle control system according to any one of claims 6 to 9.

11. The steering control device includes: a vehicle speed limit value selection processing unit that selects the smaller of the first vehicle speed limit value and the second vehicle speed limit value; A vehicle control system according to any one of claims 6 to 10.

12. The steering control device includes: a vehicle speed limit value selection processing unit that selects the smaller of the first vehicle speed limit value and the second vehicle speed limit value; A vehicle control system according to any one of claims 6 to 10.

13. A steering control device that controls a steering angle of a vehicle based on data transmitted from a steering control device, performing a vehicle speed suppression control of the vehicle in accordance with a delay time of the data transmitted from the steering control device; a delay detection unit that detects a delay time of the data; a vehicle speed limit value generation unit that generates a vehicle speed limit value according to the delay time of the data; Equipped with the vehicle speed limit value monotonically decreases as the delay time of the data increases; Steering control device.

14. A steering control device that controls a steering angle of a vehicle based on data transmitted from a steering control device, performing a vehicle speed suppression control of the vehicle in accordance with a delay time of the data transmitted from the steering control device; a delay detection unit that detects a delay time of the data; a vehicle speed limit value generation unit that generates a vehicle speed limit value according to the delay time of the data; Equipped with The vehicle speed limit value decreases in a decreasing rate as the delay time of the data increases. Steering control device.

15. A steering control device that controls a steering angle of a vehicle based on data transmitted from a steering control device, performing a vehicle speed suppression control of the vehicle in accordance with a delay time of the data transmitted from the steering control device; a delay detection unit that detects a delay time of the data; a vehicle speed limit value generation unit that generates a vehicle speed limit value according to the delay time of the data; Equipped with The vehicle speed limit value is inversely proportional to the delay time of the data. Steering control device.

16. The delay time of the data is limited by a preset maximum delay time value, The vehicle speed limit value is limited to a minimum vehicle speed limit value by the maximum delay time value.

16. A steering control device according to any one of claims 13 to 15.

17. the delay detection unit performs a delay detection process on the data at predetermined time intervals; Detecting a delay in the data based on the presence, consistency, and continuity of data acquired during a polling period in which the delay detection process is performed.

17. A steering control device according to any one of claims 13 to 16.

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