Steering system

Abstract

To provide a steering system that can request gradual restrictions on driving when an abnormal condition is detected. [Solution] The steering system 10 includes a steering wheel 111, an operating device 11 that generates and applies a reaction force to the operation of the steering wheel 111, a steering device 12 that steers the right front wheel 31 and left front wheel 32, which are the steering wheels of the vehicle 1, when the mechanical connection with the operating device 11 is released, and an operating ECU 131, a steering ECU 132, and a response ECU 133 that constitute a controller 13 that performs reaction force control and steering control. When the response ECU 133 detects an abnormal condition related to reaction force control and steering control, it requests a driving restriction on the vehicle 1 in stages based on the vehicle 1's driving continuation status since the detection of the abnormal condition.

Description

Technical Field

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[0001] The present disclosure relates to a steering system.

Background Art

[0002] Conventionally, for example, a steering control device disclosed in Patent Document 1 has been known. When a sign of an abnormality that impairs the smooth operation of the steering device is detected, when the vehicle power is turned off and then turned on again while the sign has been detected at least once, regardless of whether the sign is detected again, the total running time is measured, and a process for processing the sign based on the measured total running time is executed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the conventional steering control device, when a sign of an abnormality that impairs the smooth operation is detected, notification is made based on the total running time after the detection. In this case, notification and running restriction according to the degree of abnormality are not performed, and there is room for further improvement.

[0005] An object of the present disclosure is to provide a steering system that can require stepwise running restriction when an abnormal state is detected.

Means for Solving the Problems

[0006] The steering system of this disclosure includes an operating device having an operating member that generates and applies a reaction force to the operation of the operating member; a steering device that steers the steering wheels of the vehicle when the mechanical connection with the operating device is released; and a controller that performs reaction force control to control the reaction force in the operating device and also performs steering control to control the steering action of the steering wheels by the steering device in response to the operation of the operating member. When the controller detects an abnormal condition related to the reaction force control and steering control, it requests the vehicle to impose driving restrictions in stages based on the vehicle's driving status since the detection of the abnormal condition. [Effects of the Invention]

[0007] According to this disclosure, the steering system can request a phased driving restriction based on the vehicle's driving status when an abnormal condition is detected. This allows for easy and appropriate response to the abnormal condition through a phased driving restriction when an abnormal condition occurs. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram of the vehicle's configuration. [Figure 2] This is a diagram illustrating the controller configuration. [Figure 3] This is a flowchart of the anomaly handling program. [Figure 4] This is a diagram to explain an abnormal condition. [Modes for carrying out the invention]

[0009] Hereinafter, a steering system 10, which is an embodiment of the present disclosure, will be described in detail with reference to the drawings. In addition to the embodiments described below, the present disclosure can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art.

[0010] 1. Configuration of the steering system 10 In this embodiment, the steering system 10 is applied to the vehicle 1 shown in Figure 1. The vehicle 1 comprises a body 2, wheels 3 arranged on the front, rear, left, and right sides respectively, and a suspension unit 4. The wheels 3 consist of a right front wheel 31, a left front wheel 32, a right rear wheel 33, and a left rear wheel 34. In this embodiment, the case in which the right front wheel 31 and the left front wheel 32 are steerable wheels and the right rear wheel 33 and the left rear wheel 34 are non-steerable wheels is illustrated as an example. Furthermore, in the vehicle 1, the drive wheels can be the front wheels, the rear wheels, or all of the wheels. In other words, the vehicle 1 may be a front-wheel drive vehicle, a rear-wheel drive vehicle, or a four-wheel drive vehicle. The suspension unit 4 includes, for example, a coil spring 41 and a shock absorber 42.

[0011] The steering system 10 comprises an operating device 11 operated by the driver and a steering device 12 that steers the right front wheel 31 and the left front wheel 32, which are the steering wheels. Here, the steering system 10 is a steer-by-wire type in which the mechanical connection between the operating device 11 and the steering device 12 is released.

[0012] The operating device 11 mainly comprises a steering wheel 111, a steering shaft 112, a steering column 113, and a reaction force application mechanism 114 as operating members. The steering wheel 111 is operated (steering) by the driver. The steering shaft 112 has the steering wheel 111 attached to its end and is rotatably supported by the steering column 113. The steering column 113 is supported by the instrument panel reinforcement (not shown). The reaction force application mechanism 114 uses a reaction force motor 115 as a driving force source to generate a reaction force Fc (strictly speaking, "reaction force torque," but hereinafter also referred to as "operating reaction force Fc") in response to steering operation and applies it to the steering wheel 111 via the steering shaft 112. The reaction force motor 115 can be exemplified by, for example, a three-phase brushless DC motor.

[0013] Furthermore, the operating device 11 has an operating angle sensor 116 that detects the operating position of the steering wheel 111, in other words, the operating angle δ which represents the amount of operation from the neutral position of the steering wheel 111. Here, if the position that the steering wheel 111 takes when the vehicle 1 is moving straight is defined as the neutral position, then the rotation angle to the left and right from the neutral position, i.e., the amount of operation, is the operating angle δ of the steering wheel 111. In addition, the operating device 11 has an operating torque sensor 117 that detects the operating torque To as the operating force applied to the steering wheel 111 by the driver.

[0014] The steering device 12 rotates the steering knuckle 43, which constitutes the suspension unit 4, thereby integrally steering the right front wheel 31 and the left front wheel 32, which are supported by the vehicle body 2 in a rotatable manner. The steering device 12 has a steering actuator 121 as its main component.

[0015] The steering actuator 121 mainly comprises a steering rod 122, a housing 123, and a rod moving mechanism 124. The steering rod 122 is connected at both ends to the left and right steering knuckles 43 via tie rods 125. The housing 123 is fixed to the vehicle body 2 and supports the steering rod 122 so that it can move in the left and right directions.

[0016] The rod moving mechanism 124 moves the steering rod 122 in the left-right direction, using the steering motor 126 as the driving force source. For example, the rod moving mechanism 124 may mainly consist of a ball screw mechanism comprising a ball groove (not shown) provided on the steering rod 122 and a nut (not shown) that is screwed into the ball groove via bearing balls (not shown) and rotated by the steering motor 126.

[0017] Since the ball screw mechanism is a common structure, a detailed explanation of the specific structure of the rod movement mechanism 124 will be omitted. Furthermore, the structure of the rod movement mechanism 124 is not limited to a ball screw mechanism; other mechanisms can also be used.

[0018] Here, the steering motor 126 can also be exemplified by, for example, a three-phase brushless DC motor, similar to the reaction force motor 115. Incidentally, the reaction force motor 115 and the steering motor 126 each independently have a motor rotation angle sensor (not shown) that detects the motor rotation angle within one rotation for switching the energization phase in the power supply to themselves. Also, the reaction force motor 115 and the steering motor 126 each independently have a current sensor (not shown) for detecting the current actually supplied to themselves.

[0019] Also, the steering device 12 has a steering angle sensor 129 that detects the steering angle θ representing the steering positions of the right front wheel 31 and the left front wheel 32, which are steering wheels. Here, the steering angle sensor 129 detects the steering angle θ of the right front wheel 31 and the left front wheel 32 based on the amount of movement in each of the left and right directions from the neutral position when the position of the steering rod 122 in the straight-ahead state of the vehicle 1 is set as the neutral position.

[0020] The control of the operation device 11, more specifically, the reaction force control, that is, the control of the reaction force motor 115 of the operation device 11, is executed by an operation electronic control unit 131 (hereinafter simply referred to as "operation ECU131") as a reaction force controller constituting the controller 13. The operation ECU131 is an electronic control unit (Electric Control Unit) mainly comprising a microcomputer having a CPU, ROM, RAM, and various interfaces. The operation ECU131 is connected to the communication line L via various interfaces. Incidentally, in FIG. 1, the operation ECU131 is shown as "O-ECU131".

[0021] The control of the steering operation of the steering device 12, more specifically, the steering control, that is, the control of the steering motor 126 of the steering device 12, is executed by the steering electronic control unit 132 (hereinafter simply referred to as "steering ECU 132") as the steering controller constituting the controller 13. The steering ECU 132 is an electronic control unit (Electric Control Unit) mainly composed of a microcomputer having a CPU, ROM, RAM, and various interfaces. The steering ECU 132 is connected to the communication line L via various interfaces. In FIG. 1, the steering ECU 132 is shown as "S-ECU 132".

[0022] Also, as shown in FIG. 2, the operation ECU 131 and the steering ECU 132 are each configured to ensure redundancy. Specifically, the operation ECU 131 has an operation ECU 131A which is the main reaction force control system that executes reaction force control and an operation ECU 131B which is the sub-reaction force control system. Also, the steering ECU 132 has a steering ECU 132A which is the main steering control system that executes steering control and a steering ECU 132B which is the sub-steering control system. The operation ECU 131A and the steering ECU 132A are configured to cooperate with each other through communication via the communication line L. Also, the operation ECU 131B and the steering ECU 132B are configured to cooperate with each other through communication via the communication line L.

[0023] Furthermore, the operation ECU 131A and the operation ECU 131B are configured to grasp the state of the counterpart system through inter-microcomputer communication. And the operation ECU 131B which is the sub-reaction force control system operates according to, for example, the command value supplied from the operation ECU 131A which is the main reaction force control system. Also, the steering ECU 132A and the steering ECU 132B are configured to grasp the state of the counterpart system through inter-microcomputer communication. And the steering ECU 132B which is the sub-steering control system operates according to, for example, the command value supplied from the steering ECU 132A which is the main steering control system.

[0024] Here, the control of the steering system 10 will be explained by illustrating the steering control, which is the control of the steering actuator 121 of the steering device 12, and the reaction force control, which is the control of the reaction force application mechanism 114 of the operating device 11. First, the steering control will be explained. The steering control is the control for steering the right front wheel 31 and the left front wheel 32 in response to a steering request, that is, in accordance with the operating angle δ of the steering wheel 111 in the case of manual driving by the driver. The steering control is performed by the cooperation of the operation ECU 131 (operation ECU 131A and operation ECU 131B) and the steering ECU 132 (steering ECU 132A and steering ECU 132B) that constitute the controller 13.

[0025] In the steering system 10, the motor rotation angle of the reaction motor 115 of the operating device 11 and the operating angle δ of the steering wheel 111 are related in a predetermined gear ratio. For this reason, the operating ECU 131 acquires the operating angle δ based on the motor rotation angle detected via the motor rotation angle sensor. The steering ECU 132 then acquires the operating angle δ information from the operating ECU 131 and determines the target steering angle θd, which is the target steering angle θ of the right front wheel 31 and the left front wheel 32, by multiplying the acquired operating angle δ by the set steering gear ratio Rg according to the following equation (1). θd = Rg × δ …Equation (1)

[0026] In the steering system 10, the steering angle θ of the right front wheel 31 and the left front wheel 32 is controlled using the motor rotation angle. Therefore, the steering ECU 132 determines the target motor rotation angle νd, which is the target of the motor rotation angle ν of the steering motor 126, based on the target steering angle θd determined according to equation (1). The steering ECU 132 then detects the actual motor rotation angle ν of the steering motor 126 via the motor rotation angle sensor and determines the motor rotation angle deviation Δν, which is the deviation of the motor rotation angle ν from the target motor rotation angle νd, according to equation (2) below. Δν = νd - ν …Equation (2)

[0027] Here, in the steering system 10, the steering ECU 132 determines the torque Ts (hereinafter referred to as "steering torque Ts") that the steering motor 126 should generate, according to a feedback control law based on the motor rotation angle deviation Δν. In other words, the steering ECU 132 determines the steering torque Ts according to the following equation (3). Ts=Gp×Δν+Gi×∫Δνdt+Gd×dΔν / dt…Formula (3) However, in equation (3) above, the first term is the proportional term, the second term is the integral term, and the third term is the differential term. Also, in equation (3) above, Gp represents the gain of the proportional term, Gi represents the gain of the integral term, and Gd represents the gain of the differential term.

[0028] In steering control, the steering ECU 132 supplies a steering current to the steering motor 126 corresponding to the steering torque Ts determined according to equation (3). Here, the steering current is approximately proportional to the steering torque Ts. Therefore, the steering ECU 132 determines the steering current to be supplied to the steering motor 126 based on the steering torque Ts determined according to the proportional relationship. Then, the steering ECU 132 operates the steering motor 126 by supplying the steering current to the steering motor 126, for example via an inverter (not shown), and steers the wheels 3, i.e., the right front wheel 31 and the left front wheel 32, until the target steering angle θd is reached.

[0029] Reaction force control is a control that applies an operating reaction force Fc to the steering wheel 111 in order to give the driver a sense of control over steering operations. Reaction force control is performed by the operation ECU 131. Specifically, the operation ECU 131 determines the operating reaction force Fc according to the following equation (4), which uses two components: a steering load-dependent component Fs and an operating force-dependent reduction component Fa. Fc=Fs-Fa…Equation (4)

[0030] Here, the steering load-dependent component Fs in equation (4) is a component relating to the steering force (steering torque Ts of the steering motor 126) required to steer the right front wheel 31 and the left front wheel 32, and is determined based on the steering current supplied to the steering motor 126. While a detailed explanation is omitted, the larger the steering current, the greater the perceived steering load on the right front wheel 31 and the left front wheel 32, and the larger the steering load-dependent component Fs is determined. Information regarding the steering current actually supplied to the steering motor 126 is provided from the steering ECU 132 to the operation ECU 131 via the communication line L.

[0031] Furthermore, the operating force-dependent reduction component Fa in equation (4) is, for example, a component that provides the driver with the operating feel of a conventional power steering system. In conventional power steering systems, an assist torque corresponding to the operating torque To is generally generated, for example, by an electric motor and applied to the steering shaft 112.

[0032] Therefore, the operating force-dependent reduction component Fa is determined according to equation (5) below in order to reproduce the assist torque. The operating ECU 131 then obtains the operating torque To via the operating torque sensor 117. Fa = β × To …Equation (5) However, in equation (5) above, β represents the gain for determining the operating force-dependent reduction component Fa.

[0033] The operation ECU 131 determines the reaction force current Ic, which is the current supplied to the reaction force motor 115, according to the following equation (6), based on the operating reaction force Fc determined according to equation (4). Then, the operation ECU 131 supplies the determined reaction force current Ic to the reaction force motor 115. Ic=α×Fc…Equation (6) However, α in equation (6) above represents a predetermined power determination coefficient.

[0034] Furthermore, in the steering system 10, as will be described later, the controller 13 is equipped with a countermeasure electronic control unit 133 (hereinafter referred to as "countermeasure ECU 133") which acts as a countermeasure controller to deal with abnormal conditions by detecting abnormal conditions in the operation of the steering system 10, more specifically in the reaction force control by the operation ECU 131 (operation ECU 131A and operation ECU 131B) and the steering control by the steering ECU 132 (steering ECU 132A and steering ECU 132B) and requesting driving restrictions. The countermeasure ECU 133 is an electronic control unit (Electric Control Unit) whose main components are a microcomputer having a CPU, ROM, RAM and various interfaces. The countermeasure ECU 133 is connected to the communication line L via various interfaces. In Figure 1, the countermeasure ECU 133 is shown as "H-ECU133".

[0035] 2. Operational description of the ECU 133 that constitutes the controller 13 The corrective ECU 133 executes the abnormality correction program shown in Figure 3 when, for example, the ignition switch (hereinafter sometimes simply referred to as "IG") or the start switch of Vehicle 1 (which is not shown in the illustration) is turned on. Specifically, the corrective ECU 133 starts executing the abnormality correction program in step S10, and in the following step S11, instructs the operation ECU 131 to execute reaction force control and the steering ECU 132 to execute steering control. In other words, the corrective ECU 133 instructs the steering system 10 to start in step S11. In the following explanation, the ignition switch and start switch may be collectively referred to as "ignition switch, etc." or "IG, etc."

[0036] Furthermore, the corrective ECU 133 acquires the cumulative fault time, which represents the accumulated time of the continuous driving state stored in step S17, as described later. Here, the cumulative fault time acquired by the corrective ECU 133 in step S11 represents the time accumulated since the abnormal condition was detected until the ignition switch, etc., was turned off during the previous drive, that is, until the previous trip.

[0037] Next, in step S12, the response ECU 133 determines whether a secondary system failure has occurred, which is a system failure state that is an abnormal state related to reaction force control and steering control. Here, the system failure states will be explained. In this embodiment, as shown in Figure 4, five system operation modes for the operation ECU 131 and steering ECU 132 are given as examples of system failure states. In this embodiment, among the system operation modes, "1. Coordinated operation" is considered a normal state in which no abnormal state has occurred, and any of the abnormal states of "2. Independent operation", "3. Main single-system operation", and "4. Sub-single-system operation" are considered primary system failures, and the abnormal state of "5. Main and sub operation stopped" is considered a secondary system failure. Furthermore, in this embodiment, a secondary system failure is also determined to have occurred if the cumulative failure time obtained in step S11 exceeds a preset reference time.

[0038] Furthermore, "1. Cooperative Operation" is a system operating mode in which the control ECU 131 and steering ECU 132 operate in cooperation while communicating normally via the communication line L, and the microcontroller communication between control ECU 131A and control ECU 131B is normal, as is the microcontroller communication between steering ECU 132A and steering ECU 132B. In addition, "2. Independent Operation" is a system operating mode in which the control ECU 131 and steering ECU 132 operate in cooperation while communicating via the communication line L, but the microcontroller communication between control ECU 131A and control ECU 131B is impossible (communication abnormality), and the microcontroller communication between steering ECU 132A and steering ECU 132B is also impossible (communication abnormality).

[0039] In this case, because the state of the other system is unknown due to a communication error between the main system and the sub-system, that is, the main system and the sub-system operate independently of each other, and therefore the main system and the sub-system operate according to their respective system command values. In this embodiment, "2. Independent Operation" is exemplified as the case where both the microcontroller communication between operation ECU 131A and operation ECU 131B and the microcontroller communication between steering ECU 132A and steering ECU 132B are unable to communicate (communication error). However, it is also possible to define "2. Independent Operation" as the case where at least one of the microcontroller communication between operation ECU 131A and operation ECU 131B and the microcontroller communication between steering ECU 132A and steering ECU 132B is unable to communicate (communication error).

[0040] Furthermore, "3. Main single-system operation" is a system operation mode in which, as shown by the dashed line in Figure 4, the sub-systems, the control ECU 131B and steering ECU 132B, are stopped due to, for example, a fail, and only the main system, the control ECU 131A and steering ECU 132A, operate in coordination while communicating via the communication line L. Furthermore, "4. Sub-system operation" is a system operation mode in which, as shown by the dashed line in Figure 4, the main system, the control ECU 131A and steering ECU 132A, are stopped due to, for example, a fail, and only the sub-systems, the control ECU 131B and steering ECU 132B, operate in coordination while communicating via the communication line L. Furthermore, "5. Main and Sub Operation Stopped" is a system operation mode in which both the control ECU 131 and the steering ECU 132 are in an abnormal state, as shown by the dashed line in Figure 4. In other words, all of the main system, consisting of control ECU 131A and steering ECU 132A, and the sub-system, consisting of control ECU 131B and steering ECU 132B, are in an abnormal state.

[0041] In step S12, the corrective ECU 133 determines "Yes" if there is no system failure condition for the operation ECU 131 and steering ECU 132, i.e., a secondary system failure, i.e., "5. Main / sub system failure," and executes the step process in step S13. On the other hand, if a secondary system failure, i.e., "5. Main / sub system failure," has occurred, the corrective ECU 133 determines "No" and executes the step process in step S18.

[0042] In step S13, the response ECU 133 determines "Yes" if at least one of the following system failure conditions has occurred in the operation ECU 131 and steering ECU 132: a primary system failure, i.e., "2. Independent operation", "3. Main single-system operation", and "4. Sub-single-system operation", and executes the step process in step S14. On the other hand, if the response ECU 133 has not occurred a primary system failure, it determines "No" and executes the step process in step S16.

[0043] In step S14, the response ECU 133 determines and decides the content of the request for gradually changing driving restrictions for vehicle 1 based on the cumulative failure time acquired in step S11. In this embodiment, three functional restriction levels are set as driving restrictions. Specifically, in this embodiment, the driving restrictions for vehicle 1 are determined and decided based on the cumulative failure time so that the upper limit of the vehicle speed when vehicle 1 is running is gradually reduced in three stages, in other words, the driving restrictions are gradually strengthened.

[0044] In other words, in this embodiment, if the cumulative failure time is less than the first predetermined time, the response ECU 133 determines and decides on the request content to be function restriction level 1, which is "a speed at which driving is possible without problems in urban areas" (for example, a vehicle speed limit of 50 km / h). Furthermore, if the cumulative failure time is less than the second predetermined time, which is set to be longer than the first predetermined time, the response ECU 133 determines and decides on the request content to be function restriction level 2, which is "a speed at which driving is possible but impediments are felt" (for example, a vehicle speed limit of 20 km / h). Moreover, if the cumulative failure time is the second predetermined time or longer, the response ECU 133 determines and decides on the request content to be function restriction level 3, which is "a speed at which driving is impedimentous but safety can be ensured" (for example, a vehicle speed limit of 10 km / h). In short, as the cumulative failure time increases, the response ECU 133 determines and decides on the request content so that the upper limit of the vehicle speed, which is the driving restriction, decreases in stages, that is, the driving restriction is gradually strengthened.

[0045] Then, the responsive ECU 133 compares the cumulative failure time with the first predetermined time and the second predetermined time to determine and decide on a function restriction level of 1, 2, or 3 as the requested content, and then executes the step processing of step S15. Here, when the responsive ECU 133 determines and decides on a function restriction level of 1, 2, or 3 as the requested content, it requests a driving restriction by outputting the requested content to a driving controller (not shown) mounted on the vehicle 1 via a communication line L, which controls the driving or braking of the vehicle 1, i.e., the driving of the vehicle 1.

[0046] As a result, when a functional restriction level 1 is requested, the driving controller will drive vehicle 1 to, for example, a maximum vehicle speed of 50 km / h. Furthermore, when a functional restriction level 2 is requested, the driving controller will drive vehicle 1 to, for example, a maximum vehicle speed of 20 km / h. In addition, when a functional restriction level 3 is requested, the driving controller will drive vehicle 1 to, for example, a maximum vehicle speed of 10 km / h.

[0047] In step S15, the corrective ECU 133 adds the time elapsed since the ignition switch, etc., was turned on during the current run (i.e., the cumulative failure time for the current trip) to the cumulative failure time obtained in step S11 (i.e., the cumulative failure time up to the previous trip) to calculate a new cumulative failure time. Once the corrective ECU 133 has calculated the new cumulative failure time, it executes the step process in step S16.

[0048] In step S16, the response ECU 133 determines whether the ignition switch (IG, etc.) is currently turned off by the trip meter. That is, if the IG, etc. is turned off, the response ECU 133 determines "Yes" and executes the step process in step S17. On the other hand, if the IG, etc. is not turned off, in other words, if the IG, etc. remains on, the response ECU 133 determines "No" and executes the step process in step S12 again.

[0049] In step S17, the corrective ECU 133 stores the new cumulative failure time calculated in step S15, that is, the "cumulative failure time until the previous trip" when the corrective program is executed next, in a predetermined memory location. Then, in step S20, the corrective ECU 133 terminates the execution of the corrective program.

[0050] On the other hand, if the response ECU 133 determines in step S12 that a secondary system failure, i.e., "5. Main / sub system failure," has occurred and determines "No," it executes the step process in step S18. In step S18, the response ECU 133 determines the requested driving restriction for vehicle 1 to be function restriction level 3. Here, in a situation where a secondary system failure, i.e., "5. Main / sub system failure," has occurred as an abnormal condition, it is necessary to drive vehicle 1 at a low speed so that it can be safely moved to safety. For this reason, when a secondary system failure occurs, the response ECU 133 requests the driving controller to drive vehicle 1 at function restriction level 3, which restricts driving the most. Then, when the response ECU 133 determines function restriction level 3 as the requested content, it executes the step process in step S19.

[0051] In step S19, the response ECU 133 maximizes the cumulative failure time so that the occurrence of a secondary system failure is reliably determined in step S12, including when the response program is executed in subsequent steps. Specifically, the response ECU 133 maximizes the cumulative failure time so that it exceeds a reference time set to be longer than the second predetermined time. As a result, when the determination process in step S12 is executed next time, the response ECU 133 can determine that a secondary system failure has occurred because the maximized cumulative failure time exceeds the reference time. After maximizing the cumulative failure time in step S19, the response ECU 133 executes the determination process in step S16, stores the maximized cumulative failure time as the new cumulative failure time in a predetermined storage location in the storage process in step S17, and then terminates the execution of the response program in step S20.

[0052] As can be understood from the above description, the steering system 10 of this embodiment includes an operating device 11 which has a steering wheel 111 as an operating member and generates and applies an operating reaction force Fc in response to the operation of the steering wheel 111; a steering device 12 which is released from the mechanical connection with the operating device 11 to steer the right front wheel 31 and the left front wheel 32, which are the steering wheels of the vehicle 1; and an operating ECU 131, a steering ECU 132, and a response ECU 133 which constitute an operating ECU 131, a steering ECU 132, and a response ECU 133 which perform reaction force control to control the operating reaction force Fc in the operating device 11 and perform steering control to control the steering operation of the right front wheel 31 and the left front wheel 32 by the steering device 12 in response to the operation of the steering wheel 111. Furthermore, in the steering system 10, if the response ECU 133 detects an abnormal condition related to reaction force control and steering control, namely "2. Independent operation," "3. Main single-system operation," or "4. Sub-system operation," it requests the vehicle 1 (driving controller) to implement a driving restriction level of 1, 2, or 3 in stages, based on the cumulative failure time, which is the continuous driving state of the vehicle 1 since the detection of the abnormal condition. Additionally, if the response ECU 133 detects "5. Main / sub operation stopped," it requests the most restrictive driving restriction level of the vehicle 1, namely 3.

[0053] According to this, when an abnormal condition is detected, the steering system 10 can sequentially request function restriction levels 1, 2, and 3 based on the cumulative failure time of the vehicle 1, i.e., in stages. This allows for easy and appropriate response to the abnormal condition through progressively changing driving restrictions when an abnormal condition occurs. In other words, the steering system 10 can sequentially determine function restriction levels 1, 2, and 3, which progressively reduce the upper limit of the vehicle speed, as the cumulative failure time increases, thereby progressively strengthening the driving restrictions. As a result, the driver will notice something unusual while driving the vehicle 1 and will be able to understand the abnormal condition that has occurred in the steering system 10. This allows the steering system 10 to prompt the driver to repair the vehicle 1 as soon as possible.

[0054] 3. Variant In the above embodiment, cumulative failure time, i.e., cumulative time, was used as an example of the continuous driving state. Alternatively, or in addition to this, it is also possible to use the cumulative distance, which is the distance traveled by the vehicle 1 since the response ECU 133 detected the abnormal state, as the continuous driving state. In this case, in the step processing of step S14 in the abnormality response program described above, the response ECU 133 can determine and decide on function restriction level 1 as the requested content if the cumulative distance is less than the first predetermined distance, determine and decide on function restriction level 2 as the requested content if the cumulative distance is less than the second predetermined distance which is set to be longer than the first predetermined distance, and determine and decide on function restriction level 3 as the requested content if the cumulative distance is the second predetermined distance or more. Furthermore, in the step processing of step S18 in the abnormality response program described above, the response ECU 133 can maximize the cumulative distance so that it exceeds, for example, a reference distance which is set to be longer than the second predetermined distance. Therefore, the same effects as in the above embodiment can be obtained in the modified example as well. [Explanation of Symbols]

[0055] 1...Vehicle, 2...Vehicle body, 3...Wheels, 4...Suspension unit, 10...Steering system, 11...Operating device, 111...Steering wheel (operating member), 114...Reaction force application mechanism, 12...Steering device, 121...Steering actuator, 13...Controller, 131, 131A, 131B...Operating electronic control unit (reaction force controller), 132, 132A, 132B...Steering electronic control unit (steering controller), 133...Response electronic control unit (response controller)

Claims

1. An operating device having an operating member and generating and applying a reaction force to the operation of the operating member, A steering device that releases the mechanical connection with the aforementioned operating device and steers the steering wheels of the vehicle, The controller includes a controller that performs reaction force control to control the reaction force in the operating device and a controller that performs steering control to control the steering action of the steering wheel by the steering device in response to the operation of the operating member, The aforementioned controller A steering system that, upon detecting an abnormal condition related to the reaction force control and steering control, progressively requests driving restrictions from the vehicle based on the vehicle's driving status since the detection of the abnormal condition.

2. The aforementioned controller The system includes a reaction force controller that performs the reaction force control, a steering controller that performs the steering control in cooperation with the reaction force controller, and a response controller that detects the abnormal condition and takes action to request the driving restriction. The reaction force controller has a main reaction force control system and a sub-reaction force control system that perform the reaction force control. The steering controller has a main steering control system and a sub-steering control system that perform the steering control. The steering system according to claim 1, wherein the countermeasure controller detects the abnormal condition when at least one of the main reaction force control system and the main steering control system, and the sub-reaction force control system and the sub-steering control system stops operating.

3. The aforementioned controller The steering system according to claim 2, which detects the abnormal state when at least one of the following occurs: a communication abnormality between the main reaction force control system and the sub-reaction force control system, or a communication abnormality between the main steering control system and the sub-steering control system.

4. The aforementioned controller The steering system according to claim 1, which requests a driving restriction to gradually reduce the upper limit of the vehicle speed when the vehicle is driving, based on the aforementioned driving continuation state.

5. The aforementioned continuation of driving is The steering system according to any one of claims 1 to 4, wherein the cumulative time the vehicle has traveled since the detection of the abnormal condition, or the cumulative distance the vehicle has traveled since the detection of the abnormal condition.

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