Steering control system

Abstract

To provide a steering control device that can stably continue steering control in a redundant configuration even when one piece of vehicle speed information has an error.SOLUTION: The steering control device according to the present invention includes: a plurality of communication lines 41, 42 through which vehicle information that is information on vehicle speeds is transferred; and a plurality of calculation units 51, 53 connected communicably with each other, connected respectively to the plurality of communication lines 41, 42, and configured to calculate transfer ratios based on the vehicle information received through the corresponding communication lines 41, 42. The plurality of calculation units 51, 53 determine whether or not the vehicle speed information respectively received is effective. When it is determined by at least one of the plurality of communication units 51, 53 that the vehicle speed information is not effective, Each calculation control for the transfer ratio is changed from vehicle speed sensitive control by which the transfer ratio is calculated based on the vehicle speed information to specific control by which the transfer ratio is calculated not based on the vehicle speed information.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a steering control device.

Background Art

[0002] Some steering control devices execute vehicle speed-sensitive control that calculates the transmission ratio (gear ratio) between the operating angle of the steering wheel and the steering angle of the steered wheels based on the vehicle speed. In vehicle speed-sensitive control, the transmission ratio increases in the low-speed range and decreases in the high-speed range. For example, Japanese Unexamined Patent Application Publication No. 2020-29194 describes a steering control device in which the transmission ratio is determined based on vehicle speed-sensitive control.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] For example, in a steer-by-wire type system where the operating member and the steering device are not mechanically connected, in order to ensure the redundancy of the system, two arithmetic units (for example, microcomputers) may be mounted on one ECU. In such a redundant configuration, arithmetic processing is independently performed by the two arithmetic units, and even if one arithmetic unit fails, steering control can be continued by the other arithmetic unit. In a redundant configuration, comparison of arithmetic results and the like is performed between the two arithmetic units, and comparison of the calculated transmission ratio and the like is also performed in vehicle speed-sensitive control. In the comparison in vehicle speed-sensitive control, if there is an abnormality in one input information (vehicle speed information), a large difference occurs between the arithmetic results of the two, making it difficult to determine the transmission ratio.

[0005] The objective of the present invention is to provide a steering control device that can stably continue steering control even if one of the vehicle speed information values ​​is abnormal in a redundant configuration. [Means for solving the problem]

[0006] The steering control device of the present invention controls a steering device configured to change the transmission ratio between the operating angle of an operating member and the steering angle of a steering wheel by the operation of a steering motor, and the vehicle speed Represents Vehicle speed information is a piece of information. Each The system comprises a plurality of transmission lines and a plurality of calculation units that are connected to each other in a manner that allows communication and are individually connected to the plurality of communication lines, and each calculates the transfer ratio based on the vehicle speed information received via the corresponding communication line. Each of the plurality of calculation units determines whether the received vehicle speed information is valid or not, and if at least one of the plurality of calculation units determines that the vehicle speed information is not valid, it changes the transfer ratio calculation control from a vehicle speed-sensitive control that calculates the transfer ratio based on the vehicle speed information to a specific control that calculates the transfer ratio without relying on the vehicle speed information. [Effects of the Invention]

[0007] For example, if a failure such as a disconnection occurs in one of multiple communication lines, the vehicle speed information transmitted on that faulty communication line may not be valid. According to the present invention, if invalid vehicle speed information is transmitted on some of the multiple communication lines and this abnormality is detected in at least one calculation unit, the calculation control (calculation method) of the transfer ratio is switched in all calculation units from vehicle speed-sensitive control to specific control. As a result, the transfer ratio is calculated in each of the multiple calculation units independently of the vehicle speed information, thus suppressing instability and complexity of the calculation control of the transfer ratio (e.g., reduced responsiveness of calculation processing). In other words, even if there is an abnormality in the vehicle speed information, the transfer ratio is calculated without using the vehicle speed information, so steering control can continue without control disruption. Thus, according to the present invention, even if one piece of vehicle speed information is abnormal in a redundant configuration, stable steering control can be continued. [Brief explanation of the drawing]

[0008] [Figure 1] This is a diagram showing the configuration of the steering system including the steering control device of this embodiment. [Figure 2] This is a diagram showing the configuration of the steering control device of this embodiment. [Figure 3] This figure shows the relationship between vehicle speed and transmission ratio in the vehicle speed-sensitive control of this embodiment. [Figure 4] This figure shows the relationship between the operating angle and the transmission ratio in the operating angle-sensitive control of this embodiment. [Figure 5] This flowchart shows an example of the control flow in this embodiment. [Figure 6] This is a diagram showing a modified configuration of the steering control device of this embodiment. [Figure 7] This is a diagram showing a modified configuration of the steering control device of this embodiment. [Modes for carrying out the invention]

[0009] Hereinafter, a steering control device 11, which is an embodiment of the present invention, will be described in detail with reference to the figures. In addition to the embodiments described below, the present invention can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art. Furthermore, in this description, a microcomputer is abbreviated as "microcontroller".

[0010] As shown in Figure 1, the steering control device 11 is a device that controls the steering device 10, which is configured to change the transmission ratio between the operating angle of the steering wheel 21, which is an operating member, and the steering angle of the front wheels 9F, which are steering wheels, by the operation of the steering motor 35. The steering system 1 is composed of the steering device 10 and the steering control device 11 that controls it. The steering system 1 is a steer-by-wire type system.

[0011] (Steering system) The steering system 10 comprises mechanically independent operating devices 2 and a steering device 3. The steering device 3 steers a pair of front wheels 9F, which are the steering wheels. Hereafter, the front wheels 9F and the rear wheels 9R may be collectively referred to as wheels 9. The drive wheels are, for example, the rear wheels 9R. Each wheel 9 is also provided with a wheel speed sensor 8 for detecting the wheel speed. The wheel speed sensor 8 is a sensor that detects information related to the vehicle speed.

[0012] The operating device 2 comprises a steering wheel 21, a steering shaft 22, a steering column 23, a reaction force application mechanism 24, and an operating angle sensor 25. The steering wheel 21 is an operating member that is steered by the driver. The steering shaft 22 is a shaft member to which the steering wheel 21 is attached. The steering column 23 is a member that rotatably holds the steering shaft 22 and is supported by an instrument panel reinforcement (not shown).

[0013] The reaction force applying mechanism 24 is a mechanism that applies a reaction force to the steering wheel 21 via the steering shaft 22 with respect to a steering operation (hereinafter also referred to as an "operation reaction force"), using a reaction force motor 26, which is an electric motor supported by the steering column 23, as a power source. The reaction force applying mechanism 24 has a general structure including a speed reducer and the like. A rotation angle sensor 26a is provided in the reaction force motor 26. The operation angle sensor 25 is a sensor that detects the operation angle of the steering wheel 21 as a steering operation amount.

[0014] In addition, in the steering system 1, a torsion bar 27 is incorporated in the steering shaft 22, similar to a general so-called power steering system. The operating device 2 has an operation torque sensor 28 for detecting an operation torque as an operation force applied to the steering wheel 21 by the driver based on the amount of twist of the torsion bar 27.

[0015] Each of the wheels 9 is supported by the vehicle body so as to be steerable via a steering knuckle 39, which is a component of the suspension device. The steering device 3 integrally steers a pair of front wheels 9F by rotating the steering knuckle 39. The steering device 3 has a steering actuator 30 as a main component.

[0016] The steering actuator 30 includes a steering rod 31 (also referred to as a "rack bar"), a housing 32, a rod movement mechanism 33, and a steering motor 35. The steering rod 31 is a member whose both ends are respectively connected to the left and right steering knuckles 39 via link rods 34. The housing 32 is a member that supports the steering rod 31 so as to be movable left and right and is fixedly held by the vehicle body.

[0017] The rod movement mechanism 33 is a mechanism for moving the steering rod 31 left and right, with the steering motor 35, which is an electric motor, as the driving source. The rod movement mechanism 33 mainly consists of a ball screw mechanism composed of a ball groove screwed onto the steering rod 31 and a nut that engages with the ball groove via bearing balls and is rotated by the steering motor 35. Since it has a general structure, a detailed description of the rod movement mechanism 33 is omitted.

[0018] The steering motor 35 is provided with a rotation angle sensor 35a and a current sensor 35b for detecting the current supplied to itself. Further, the steering device 3 has a steering angle sensor 36 for detecting the amount of movement of the steering rod 31 to the left and right from its neutral position in order to detect the steering angle (steering amount) of the front wheel 9F. Thus, the steering device 3 constitutes a steer-by-wire type steering device that is mechanically independent of the operating force of the steering wheel 21 and steers the front wheel 9F by the force of the steering motor 35.

[0019] (Steering control device) As shown in FIG. 2, the steering control device 11 includes a first communication line 41, a second communication line 42, and a steering ECU 5 that controls the steering device 3 in response to a steering request. The first communication line 41 and the second communication line 42 (hereinafter also referred to as "communication lines 41 and 42") are wirings (communication buses) that transmit vehicle speed information, which is information related to the vehicle speed. Specifically, the communication lines 41 and 42 are communication lines that connect the steering ECU 5 and the ECU 7. The ECU 7 is an electronic control unit including one or more processors and one or more memories, etc.

[0020] The ECU 7 corresponds to a vehicle speed calculation unit that calculates the vehicle speed based on the detection value of the wheel speed sensor 8. The ECU 7 is, for example, a brake ECU that controls the braking force and regularly calculates the vehicle speed based on the wheel speed. The detection values of the wheel speed sensors 8 provided on each wheel 9 are respectively input to the ECU 7 via the sensor communication lines 81 and 82.

[0021] In this embodiment, each wheel speed sensor 8 is connected to the microcontroller (corresponding to the "first vehicle speed calculation unit") 71 of the ECU 7 via a sensor communication line 81, and to the microcontroller (corresponding to the "second vehicle speed calculation unit") 72 of the ECU 7 via a sensor communication line 82. Each of the microcontrollers 71 and 72 of the ECU 7 calculates the vehicle speed based on the detected values ​​of the multiple wheel speed sensors 8. In other words, the ECU 7, like the steering ECU 5, is equipped with multiple microcontrollers (calculation units) 71 and 72, and has a redundant configuration in which each microcontroller can perform calculation processing independently. The microcontrollers 71 and 72 each independently calculate the vehicle speed and control the braking force.

[0022] Microcontroller 71 is connected to the first microcontroller 51 of the steering ECU 5 via the first communication line 41. Microcontroller 71 transmits the first vehicle speed information, which is the result of its calculation, to the first microcontroller 51 via the first communication line 41. Microcontroller 72 is connected to the second microcontroller 53 of the steering ECU 5 via the second communication line 42. Microcontroller 72 transmits the second vehicle speed information, which is the result of its calculation, to the second microcontroller 53 via the second communication line 42.

[0023] For example, because each microcontroller performs its own vehicle speed calculation, and due to differences in communication conditions or the state of the communication lines (length, etc.), the first vehicle speed information and the second vehicle speed information may have different values ​​and may be transmitted at different times. Furthermore, even if there is only one microcontroller that calculates vehicle speed within the ECU7, and the same vehicle speed information is output simultaneously from that microcontroller to both communication lines 41 and 42, the state of the communication lines 41 and 42 (for example, whether or not they are disconnected) may cause each microcontroller 51 and 53 to receive vehicle speed information with different values.

[0024] The steering ECU 5 is an electronic control unit equipped with multiple processors and multiple memories. Although the communication lines are not shown in the diagram, the steering ECU 5 is connected to each ECU and each sensor in a communication manner. CAN (car area network or controllable area network) is used for communication within the vehicle. In addition, the vehicle of this embodiment is equipped with an autonomous driving ECU 90 that performs control related to autonomous driving. The vehicle is also equipped with various sensors such as wheel speed sensors 8 and acceleration sensors.

[0025] The steering ECU 5 performs steering control to steer the front wheels 9F in response to a steering request, i.e., the operating angle of the steering wheel 21 during manual driving or a command from the autonomous driving ECU 90 during autonomous driving. The steering ECU 5 obtains the operating angle of the steering wheel 21 based on the rotation angle of the reaction force motor 26 detected by the rotation angle sensor 26a. Based on the operating angle, the steering ECU 5 determines a target front wheel steering angle, which is the target steering angle for the front wheels 9F.

[0026] The steering ECU 5 determines the target rotation angle, which is the target rotation angle of the steering motor 35, based on the target front wheel steering angle. The steering ECU 5 detects the actual rotation angle of the steering motor 35 (hereinafter also referred to as the "actual rotation angle") via the rotation angle sensor 35a and determines the rotation angle deviation, which is the deviation of the actual rotation angle from the target rotation angle. If the torque generated by the steering motor 35 is called the steering torque, the steering ECU 5 determines the steering torque to be generated according to the feedback control law based on the rotation angle deviation. The first microcontroller 51 and the second microcontroller 53 of the steering ECU 5 each perform the above calculations.

[0027] If we call the current supplied to the steering motor 35 the steering current, then the steering torque and the steering current are roughly proportional. According to this relationship, the steering ECU 5 determines the steering current to be supplied to the steering motor 35 based on the determined steering torque, and supplies that steering current to the steering motor 35. The configuration of the steering current supply in the steering ECU 5 will be described later.

[0028] The steering system 1 further includes a reaction force ECU 6 that performs reaction force control to provide the driver with a sense of control over steering operations. The reaction force ECU 6 determines the operating reaction force based on two components: a steering load-dependent component FS and an operating force-dependent reduction component FA. The steering load-dependent component FS is a component relating to the steering force (steering torque of the steering motor 35) required to steer the front wheels 9F, and is determined based on the steering current supplied to the steering motor 35. Although a detailed explanation is omitted, the higher the current value of the steering current, the greater the steering load on the front wheels 9F is perceived to be, and the steering load-dependent component FS is determined to be a large value.

[0029] On the other hand, the operating force-dependent reduction component FA can be considered a component that provides the driver with a sense of operation in a so-called power steering system. In a power steering system, generally, an assist torque corresponding to the operating torque is applied to the steering shaft 22. The reaction force ECU 6 detects the operating torque via the operating torque sensor 28. Based on the operating reaction force, the reaction force ECU 6 determines the reaction force current, which is the current supplied to the reaction force motor 26, and supplies the determined reaction force current to the reaction force motor 26.

[0030] (Detailed configuration of the steering ECU) The steering ECU 5 comprises a circuit board 50, a first microcontroller 51 as a first calculation unit, a first drive circuit 52, a second microcontroller 53 as a second calculation unit, and a second drive circuit 54. The first microcontroller 51 is a microcomputer equipped with one or more processors and one or more memories. The first microcontroller 51 is located on the circuit board 50 and determines the current value of the first steering current supplied to the steering motor 35 via the first drive circuit 52. The first microcontroller 51 controls the first drive circuit 52 (PWM control) so that the first steering current is supplied to the steering motor 35.

[0031] The first drive circuit 52 is a motor drive circuit that drives the steering motor 35 and is configured to include a plurality of switching elements corresponding to the three phases of the steering motor 35. The first drive circuit 52 is located on the circuit board 50 and is communicatively connected to the first microcontroller 51. The first drive circuit 52 supplies power from a battery (not shown) to the steering motor 35 in accordance with the control of the first microcontroller 51.

[0032] The second microcontroller 53, like the first microcontroller 51, is a microcomputer located on the circuit board 50 and includes one or more processors and one or more memories. The second microcontroller 53 determines the current value of the second steering current supplied to the steering motor 35 via the second drive circuit 54. The second microcontroller 53 controls the second drive circuit 54 (PWM control) so that the second steering current is supplied to the steering motor 35. The first microcontroller 51 and the second microcontroller 53 are connected to each other so that they can communicate with one another.

[0033] The second drive circuit 54 is a motor drive circuit that drives the steering motor 35 and is configured to include a plurality of switching elements corresponding to the three phases of the steering motor 35. The second drive circuit 54 is located on the circuit board 50 and is communicatively connected to the second microcontroller 53. The second drive circuit 54 supplies power from a battery (not shown) to the steering motor 35 in accordance with the control of the second microcontroller 53.

[0034] The steering motor 35 is a double-winding electric motor comprising a winding 351 connected to the first drive circuit 52 and a winding 352 connected to the second drive circuit 54. In other words, the steering motor 35 is configured to output a steering torque corresponding to the sum of the steering current (also called the total steering current) supplied by the first steering current supplied from the first drive circuit 52 and the second steering current supplied from the second drive circuit 55. The steering current supplied from the battery via the steering ECU 5 is the sum of the first steering current and the second steering current.

[0035] As described above, the first drive circuit 52 and the second drive circuit 54 (hereinafter also referred to as "drive circuits 52 and 54") correspond individually to microcontrollers 51 and 53, and are configured to supply steering current to the steering motor 35 under the control of the corresponding microcontrollers 51 and 53. Furthermore, the microcontrollers 51 and 53 are connected to each other in a manner that allows them to communicate with one another, and are connected individually to communication lines 41 and 42, and are configured to calculate the transfer ratio based on the vehicle speed information received via the corresponding communication lines 41 and 42. The communication lines 41 and 42 each independently transmit vehicle speed information, which is information related to vehicle speed. In this embodiment, the first communication line 41 connects the first microcontroller 51 and microcontroller 71, and the second communication line 42 connects the second microcontroller 53 and microcontroller 72.

[0036] (Calculation and control of the transfer ratio) The first microcontroller 51 is connected to the first communication line 41 and acquires first vehicle speed information via the first communication line 41. The second microcontroller 53 is connected to the second communication line 42 and acquires second vehicle speed information via the second communication line 42. The first communication line 41 and the second communication line 42 are independent of each other.

[0037] The first microcontroller 51 and the second microcontroller 53 each calculate the transmission ratio (gear ratio) between the operating angle of the steering wheel 21 and the steering angle of the front wheels 9F when calculating the steering current. The transmission ratio is calculated based on the input vehicle speed information. As shown in Figure 3, the relationship between vehicle speed and the transmission ratio is pre-set and stored in the microcontrollers 51 and 53 as the first map. The first map is used in vehicle speed-sensitive control, and the transmission ratio is determined when the vehicle speed is determined. Vehicle speed-sensitive control is a calculation control that calculates the transmission ratio based on vehicle speed information. In vehicle speed-sensitive control, the transmission ratio decreases as the vehicle speed increases.

[0038] Each microcontroller 51 and 53 calculates the transfer ratio based on the input vehicle speed information through vehicle speed-sensitive control. The calculation result information is communicated between the two microcontrollers 51 and 53. For example, if the difference between the first transfer ratio calculated by the first microcontroller 51 and the second transfer ratio calculated by the second microcontroller 53 (hereinafter also referred to as the "transfer ratio calculation difference") is less than a predetermined calculation difference threshold, each microcontroller 51 and 53 sets the first transfer ratio as the common transfer ratio. Each microcontroller 51 and 53 uses a common transfer ratio (in this case, the first transfer ratio). The communication system connected to the first microcontroller 51 is called, for example, the first system, and the communication system connected to the second microcontroller 53 is called, for example, the second system.

[0039] Microcontrollers 51 and 53 each determine whether the received vehicle speed information is valid. If at least one of the microcontrollers 51 or 53 determines that the vehicle speed information is invalid, they each change the transmission ratio calculation control from vehicle speed-sensitive control, which calculates the transmission ratio based on the vehicle speed information, to specific control, which calculates the transmission ratio without relying on the vehicle speed information. The specific control in this embodiment is an operating angle-sensitive control, which calculates the transmission ratio based on the operating angle, as shown in Figure 4. Each microcontroller 51 and 53 has a second map pre-stored that shows the relationship between the operating angle and the transmission ratio. The second map is used in operating angle-sensitive control, and the transmission ratio is determined once the operating angle is determined. In operating angle-sensitive control, the larger the operating angle, the larger the transmission ratio.

[0040] Each microcontroller 51 and 53 determines, for example, that one of the two sets of vehicle speed information is abnormal (i.e., invalid) if the difference between the vehicle speed information received by the first microcontroller 51 and the vehicle speed information received by the second microcontroller 53 (hereinafter also referred to as the "vehicle speed information difference") is greater than or equal to a predetermined vehicle speed difference threshold. For example, if a malfunction such as a break occurs in either of the communication lines 41 or 42, or if one of the microcontrollers 71 or 72 of the ECU 7 malfunctions, the vehicle speed information transmitted on the system where the malfunction has occurred is likely to be an abnormal value. In this case, one set of vehicle speed information is an abnormal value and the other set of vehicle speed information is a normal value, and the vehicle speed information difference becomes large. Therefore, each microcontroller 51 and 53 determines that one of the vehicle speed information is abnormal if the vehicle speed information difference is greater than or equal to the vehicle speed difference threshold. The two sets of vehicle speed information that are the subject of the calculation of the vehicle speed information difference are calculated values ​​based on the detection values ​​detected at the same time by, for example, the wheel speed sensor 8. For example, the two vehicle speed data points being compared are calculated based on the same basis (detected value).

[0041] As an example of information transmission and reception settings, the first microcontroller 51 transmits vehicle speed information to the second microcontroller 53 as soon as it receives it from the first communication line 41, and the second microcontroller 53 transmits vehicle speed information to the first microcontroller 51 as soon as it receives it from the second communication line 42. One of the microcontrollers 51 or 53 that has determined whether the vehicle speed information is valid or invalid transmits the determination result to the other microcontroller 51 or 53 as soon as the determination is complete. Depending on the timing of transmission and reception of vehicle speed information by each microcontroller 51 and 53, the timing of the determinations by each microcontroller 51 and 53 may be simultaneous.

[0042] Furthermore, if each microcontroller 51, 53 can recognize a malfunction in the microcontrollers 71, 72 within the ECU 7 or a malfunction in the communication lines 41, 42 (e.g., a broken wire or traffic congestion) based on the output signal from the ECU 7 that calculates the vehicle speed, it may determine whether the vehicle speed information is valid or invalid based on the output signal from the ECU 7. For example, if each microcontroller 51, 53 is configured to periodically receive signals from the ECU 7 (e.g., the corresponding microcontrollers 71, 72), each microcontroller 51, 53 can recognize that an abnormality has occurred in the microcontroller or communication line by not receiving such signals.

[0043] Regardless of which of the above determination methods is used, if at least one of the microcontrollers 51 and 53 determines that one of the vehicle speed information is invalid, the determination result is shared between both microcontrollers 51 and 53, and the calculation control (calculation method) of the transmission ratio in both microcontrollers 51 and 53 is changed from vehicle speed-sensitive control to operation angle-sensitive control. After the change, each microcontroller 51 and 53 calculates (determines) the transmission ratio based on the detected value of the operation angle sensor 25 and the second map. Similarly, if both microcontrollers 51 and 53 simultaneously determine that "one of the vehicle speed information is invalid," the calculation control of the transmission ratio is changed in both microcontrollers 51 and 53 from vehicle speed-sensitive control to operation angle-sensitive control. In this way, if at least one of the microcontrollers 51 and 53 determines that the vehicle speed information is invalid, the calculation control of the transmission ratio in both microcontrollers 51 and 53 is set to operation angle-sensitive control.

[0044] An example of the control flow performed by each microcontroller 51 and 53 will be explained with reference to Figure 5. Each microcontroller 51 and 53 determines whether the vehicle speed information for its own system is valid (S1). If the vehicle speed information for its own system is valid (S1: Yes), each microcontroller 51 and 53 determines whether the vehicle speed information for the other system is valid (S2). If the vehicle speed information for the other system is valid (S2: Yes), each microcontroller 51 and 53 calculates the transmission ratio using vehicle speed-sensitive control (S3). Note that when each microcontroller 51 and 53 determines the validity of the vehicle speed information based on the difference in vehicle speed information, steps S1 and S2 are executed simultaneously. In other words, in this case, each microcontroller 51 and 53 can be said to determine whether "both vehicle speed information is valid" in one step. Each microcontroller 51 and 53 continues vehicle speed-sensitive control unless it is determined that "the vehicle speed information is invalid".

[0045] If either microcontroller 51 or 53 determines in step S1 or S2 that "vehicle speed information is not valid (invalid)" (S1: No, or S2: No), it changes the transmission ratio calculation control to an operating angle-sensitive control and calculates the transmission ratio using the operating angle-sensitive control (S4). In this way, if vehicle speed information is determined to be invalid in at least one system, the transmission ratio calculation control in both microcontrollers 51 and 53 is changed to an operating angle-sensitive control.

[0046] (Effects of this embodiment) For example, if a failure such as a break occurs in one of the multiple communication lines, the vehicle speed information transmitted on the failed communication line may not be valid. According to this embodiment, if invalid vehicle speed information is transmitted on one of the communication lines 41 and 42, and the abnormality is detected in at least one of the microcontrollers 51 and 53, the transmission ratio calculation control (calculation method) in both microcontrollers 51 and 53 switches from vehicle speed-sensitive control to specific control. As a result, the transmission ratio is calculated in each microcontroller 51 and 53 without relying on the vehicle speed information, thus suppressing instability and complexity of the transmission ratio calculation control due to large differences in vehicle speed information (for example, reduced responsiveness of calculation processing). In other words, even if there is an abnormality in the vehicle speed information, the transmission ratio is calculated without using the vehicle speed information, so steering control can continue without control disruption. Thus, according to this embodiment, even if one piece of vehicle speed information is abnormal in a redundant configuration, stable steering control can be continued.

[0047] Furthermore, in this embodiment, the specific control is set to angle-sensitive control. In angle-sensitive control, the larger the angle of operation, the larger the transmission ratio. However, drivers tend to increase the angle of operation most often when driving at low speeds, and as a result, a transmission ratio similar to that of speed-sensitive control, where the transmission ratio is larger at low speeds, is likely to be set before and after the change in calculation control. When driving at high speeds, drivers tend to operate in a way that reduces the angle of operation, so the transmission ratio becomes smaller in both speed-sensitive control and angle-sensitive control. Thus, by setting the specific control to angle-sensitive control, it is possible to suppress the driver's discomfort after changing the calculation control of the transmission ratio. Note that the specific control may also be a fixed transmission ratio control, where the transmission ratio is set to a fixed value. In this case as well, vehicle speed information is not used in the calculation of the transmission ratio, and steering control continues without control confusion.

[0048] (Other examples of communication line connections) The connection configuration of the communication line connecting the ECU 7 and the steering ECU 5 may be other than that described above. For example, as shown in Figure 6, the steering control device 11 may include a first sub-communication line 43 and a second sub-communication line 44. The first sub-communication line 43 connects the microcontroller 71 and the second microcontroller 53. The second sub-communication line 44 connects the microcontroller 72 and the first microcontroller 51.

[0049] In this configuration, each microcontroller 51 and 53 can directly receive two sets of vehicle speed information from the ECU 7. Therefore, each microcontroller 51 and 53 can calculate the difference in vehicle speed information without waiting for vehicle speed information to be provided from the other microcontroller. The first microcontroller 51 determines whether both sets of vehicle speed information are valid based on the difference between the vehicle speed information received from the first communication line 41 and the vehicle speed information received from the second sub-communication line 44. The second microcontroller 53 determines whether both sets of vehicle speed information are valid based on the difference between the vehicle speed information received from the second communication line 42 and the vehicle speed information received from the first sub-communication line 43.

[0050] In this way, each microcontroller 51 and 53 calculates the difference between two vehicle speed information received from the ECU 7 (vehicle speed information difference) and determines whether the vehicle speed information is valid or not. Even with this configuration, if at least one of the microcontrollers 51 and 53 determines that one of the vehicle speed information is not valid, the calculation control of the transmission ratio of both microcontrollers 51 and 53 is changed to an operating angle-sensitive control.

[0051] (others) The present invention is not limited to the above embodiments. For example, there may be three or more microcontrollers (calculation units) in the steering ECU 5. Even in this case, each of the multiple microcontrollers determines whether the received vehicle speed information is valid, and if at least one of the multiple microcontrollers determines that the vehicle speed information is not valid, each microcontroller is configured to change the calculation control of the transfer ratio from vehicle speed-sensitive control to specific control. For example, as shown in Figure 7, if a redundant configuration is formed with three microcontrollers in the steering ECU 5, the steering ECU 5 may further include a third microcontroller 55 and a third drive circuit 56, and the third microcontroller 55 and ECU 7 may be connected by a third communication line 45. The wheel speed sensor 8 and ECU 7 may be connected by a sensor communication line 83. ECU 7 may include three microcontrollers corresponding to the steering ECU 5.

[0052] Furthermore, the steering control device 11 may include multiple ECUs as multiple processing units. In other words, the processing units are not limited to microcontrollers, but may also be ECUs. In this case as well, the multiple ECUs are connected in a communicative manner. In other words, the redundant configuration may consist of multiple microcontrollers or multiple ECUs. The redundant configuration is a configuration in which two or more processing units (e.g., microcontrollers or ECUs) that perform transfer ratio calculation processing can receive different vehicle speed information from each other at different values ​​and at different timings.

[0053] The vehicle speed information input to microcontrollers 51 and 53 does not have to be information calculated by ECU 7. Represents Any information will suffice. Furthermore, ECU7 is not limited to the brake ECU; it could be any other ECU with a vehicle speed calculation function. Also, there may be only one calculation unit (microcontroller) within ECU7. . The steering device 3 may be a device that steers the rear wheels 9R. The steering device 10 is not limited to a steer-by-wire type, but can be any device with a variable transmission ratio.

[0054] (Structure of this disclosure) The structure of this disclosure includes the following aspects: (Aspect 1) A steering control device for controlling a steering device configured to change the transmission ratio between the operating angle of an operating member and the steering angle of a steering wheel by the operation of a steering motor, comprising: a plurality of communication lines for transmitting vehicle speed information, which is information relating to the vehicle speed; and a plurality of calculation units that are connected to each other in a manner that allows communication and are individually connected to the plurality of communication lines, and each calculates the transmission ratio based on the vehicle speed information received via the corresponding communication line, wherein each of the plurality of calculation units determines whether the received vehicle speed information is valid, and if at least one of the plurality of calculation units determines that the vehicle speed information is not valid, each changes the calculation control of the transmission ratio from a vehicle speed-sensitive control that calculates the transmission ratio based on the vehicle speed information to a specific control that calculates the transmission ratio without relying on the vehicle speed information. (Aspect 2) The steering control device according to embodiment 1, wherein the specific control is an angle-sensitive control that calculates the transfer ratio based on the operating angle. (Aspect 3) A steering control device according to embodiment 1 or 2, comprising a wheel speed sensor for detecting wheel speed and a vehicle speed calculation unit for calculating vehicle speed based on the detected value of the wheel speed sensor, wherein a plurality of communication lines are connected to the vehicle speed calculation unit. (Aspect 4) A steering control device according to any one of embodiments 1 to 3, wherein each of the plurality of calculation units determines whether the vehicle speed information is valid based on the difference between the vehicle speed information transmitted on two of the communication lines, including the communication line connected to itself. (Aspect 5) A steering control device according to any one of embodiments 1 to 4, comprising a plurality of drive circuits that individually correspond to a plurality of calculation units and supply steering current to the steering motor by control of the corresponding calculation unit. (Aspect 6) The steering control device according to embodiment 5, wherein the plurality of communication lines consist of a first communication line and a second communication line, the plurality of calculation units consist of a first calculation unit connected to the first communication line and a second calculation unit connected to the second communication line, and the plurality of drive circuits consist of a first drive circuit connected to the first calculation unit and a second drive circuit connected to the second calculation unit. (Aspect 7) The steering control device according to embodiment 6, wherein the first calculation unit and the second calculation unit each determine that one of the vehicle speed information is invalid if the difference between the vehicle speed information transmitted on the first communication line and the vehicle speed information transmitted on the second communication line is greater than or equal to a predetermined threshold. (Pattern 8) A steering control device according to embodiment 6 or 7, comprising: a wheel speed sensor for detecting wheel speed; a first vehicle speed calculation unit for calculating vehicle speed based on the detected value of the wheel speed sensor; and a second vehicle speed calculation unit for calculating vehicle speed based on the detected value of the wheel speed sensor, wherein the first communication line connects the first vehicle speed calculation unit and the first calculation unit, and the second communication line connects the second vehicle speed calculation unit and the second calculation unit. (Aspect 9) The steering control device according to embodiment 8, wherein the first calculation unit and the second calculation unit each determine that one of the vehicle speed information is invalid if the difference between the vehicle speed information calculated by the first vehicle speed calculation unit and the vehicle speed information calculated by the second vehicle speed calculation unit is greater than or equal to a predetermined threshold. (Aspect 10) A steering control device according to embodiment 8 or 9, comprising a first sub-communication line connecting the first vehicle speed calculation unit and the first calculation unit, and a second sub-communication line connecting the second vehicle speed calculation unit and the second calculation unit. [Explanation of Symbols]

[0055] 1...Steering system, 10...Steering device, 11...Steering control device, 2...Operating device, 3...Steering device, 35...Steering motor, 41...First communication line, 42...Second communication line, 43...First sub-communication line, 44...Second sub-communication line, 5...Steering ECU, 51...First microcontroller (first calculation unit), 52...First drive circuit, 53...Second microcontroller (second calculation unit), 54...Second drive circuit, 7...ECU (vehicle speed calculation unit), 71...Microcontroller (first vehicle speed calculation unit), 72...Microcontroller (second vehicle speed calculation unit), 8...Wheel speed sensor.

Claims

1. A steering control device that controls a steering system configured to change the transmission ratio between the operating angle of an operating member and the steering angle of a steering wheel by the operation of a steering motor, Vehicle speed information, which represents vehicle speed, is transmitted via multiple communication lines, Multiple calculation units are connected to each other in a manner that allows them to communicate with one another, and each unit is connected to a plurality of communication lines, and each unit calculates the transmission ratio based on the vehicle speed information received via the corresponding communication line. Equipped with, Each of the multiple calculation units determines whether the received vehicle speed information is valid, and if at least one of the multiple calculation units determines that the vehicle speed information is not valid, each unit changes the calculation control of the transfer ratio from a vehicle speed-sensitive control that calculates the transfer ratio based on the vehicle speed information to a specific control that calculates the transfer ratio without relying on the vehicle speed information. Steering control device.

2. The aforementioned specific control is an angle-sensitive control that calculates the transfer ratio based on the operating angle. The steering control device according to claim 1.

3. A wheel speed sensor provided on each wheel for detecting the wheel speed, A vehicle speed calculation unit that calculates the vehicle speed based on the detected values ​​of each wheel speed sensor, Equipped with, Multiple communication lines are connected to the vehicle speed calculation unit. The steering control device according to claim 1.

4. Each of the multiple calculation units determines whether the vehicle speed information is valid based on the difference between the vehicle speed information transmitted over two communication lines, including the communication line connected to itself. The steering control device according to claim 1.

5. The system includes multiple drive circuits, each corresponding to a plurality of calculation units, which supply steering current to the steering motor through the control of the corresponding calculation unit. The steering control device according to claim 1.

6. The plurality of communication lines consist of a first communication line and a second communication line. The plurality of calculation units consist of a first calculation unit connected to the first communication line and a second calculation unit connected to the second communication line. The plurality of drive circuits are composed of a first drive circuit connected to the first calculation unit and a second drive circuit connected to the second calculation unit. The steering control device according to claim 5.

7. The first and second calculation units each determine that if the difference between the vehicle speed information transmitted on the first communication line and the vehicle speed information transmitted on the second communication line is greater than or equal to a predetermined threshold, one of the vehicle speed information is invalid. The steering control device according to claim 6.

8. A wheel speed sensor provided on each wheel for detecting the wheel speed, A first vehicle speed calculation unit calculates the vehicle speed based on the detected values ​​of each wheel speed sensor, A second vehicle speed calculation unit calculates the vehicle speed based on the detected values ​​of each of the wheel speed sensors, Equipped with, The first communication line connects the first vehicle speed calculation unit and the first calculation unit. The second communication line connects the second vehicle speed calculation unit and the second calculation unit. The steering control device according to claim 6 or 7.

9. The first and second calculation units each determine that if the difference between the vehicle speed information calculated by the first vehicle speed calculation unit and the vehicle speed information calculated by the second vehicle speed calculation unit is greater than or equal to a predetermined threshold, one of the vehicle speed information is invalid. The steering control device according to claim 8.

10. A first sub-communication line connecting the first vehicle speed calculation unit and the first calculation unit, The system comprises a second vehicle speed calculation unit and a second sub-communication line connecting the second calculation unit, The steering control device according to claim 9.

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