JP3595980B2 - Variable steering angle ratio steering device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention uses an electronic device having a plurality of CPUs as a control device and controls a ratio of a steering angle of a steered wheel to a preferable steering angle of a steering wheel (hereinafter referred to as a “steering angle ratio”) in accordance with a driving operation situation of a vehicle by a driver. ) Is automatically and automatically controlled.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as a vehicular steering device that assists a driver in driving, a vehicular steering device that automatically sets a steering angle ratio according to a surrounding environment of a vehicle is known.
[0003]
For example, the present applicant discloses a variable steering angle ratio steering apparatus for a vehicle in Japanese Patent Application Laid-Open No. H11-78944. The variable steering angle ratio steering device for a vehicle includes a variable steering angle ratio device capable of changing the amount of rotation of a steered wheel with respect to a steering wheel, and a control device for controlling the variable steering angle ratio device. Further, the variable steering angle ratio steering device includes an electric motor for varying the steering angle ratio.
[0004]
Then, the steering angle ratio is automatically set according to the vehicle speed and the like. For example, when the vehicle runs lightly on a mountain road with continuous curves, the steering angle ratio is increased. Conversely, when traveling on a highway or the like at a substantially constant speed, the steering angle ratio is set to be small, and a steering angle ratio suitable for each case is set.
[0005]
[Problems to be solved by the invention]
In such a variable steering angle ratio steering device, it is necessary to consider safety and the like when a failure occurs in the control device . For this reason, the control device includes a main CPU that is normally used, a sub CPU that mutually detects a failure between the main CPU, and a backup CPU that is used when a failure occurs in the main CPU or the sub CPU. It is conceivable to use an electronic device having the following.
[0006]
However, when such an electronic device is used as a control device, the processing amount of the sub CPU and the backup CPU is very small as compared with the main CPU. As described above, designing and manufacturing CPUs each having a small processing amount separately may be wasteful. As a result, the cost of the electronic device itself increases.
[0007]
In addition, a main CPU, a sub CPU, and a backup CPU are provided on a board of the electronic device , and a voltage of a current supplied to each CPU is specified. At this time, for example, if the backup CPU is installed at the position where the sub CPU is installed and the sub CPU is installed at the position where the backup CPU is installed, an appropriate voltage is not applied to the sub CPU and the backup CPU. Therefore, there is a problem that the sub CPU and the backup CPU do not function properly.
[0008]
Therefore, an object of the present invention is to improve the efficiency of designing and manufacturing a CPU and not to mistake the installation position when installing a CPU.
[0012]
[Means for Solving the Problems]
The invention according to claim 1 provides a steering system from a steering wheel to a steered wheel with a variable steering angle ratio device capable of changing a steering angle ratio of the steered wheel with respect to the steering wheel, and controls the variable steering angle ratio device. In the variable steering angle ratio steering device provided with a control device that performs a normal steering, the control device includes a main CPU that is normally used, a sub CPU that monitors failures between the main CPU and the main CPU, the main CPU and the main CPU. A backup CPU to be used when at least one of the sub CPUs has failed. Both the program corresponding to the sub CPU and the program corresponding to the backup CPU are provided as the sub CPU and the backup CPU. The sub CPU and the backup CPU are determined while being written. A CPU provided with a discrimination port is used. The CPU is mounted on a board, a discrimination voltage is applied from the board via the discrimination port, and based on the discrimination voltage, the CPU A variable steering angle ratio steering device for determining which of a CPU and a backup CPU is used.
[0013]
In the invention according to claim 1 , since the sub CPU and the backup CPU have programs for the sub CPU and the backup CPU, respectively, it is possible to save the trouble of designing and manufacturing the sub CPU and the backup CPU separately. In addition, since the sub CPU and the backup CPU have a smaller processing amount than the main CPU, the number of unnecessary programs not used in each CPU can be reduced. Further, a voltage of, for example, 0 V is applied to the sub CPU via the determination port, and a voltage of 5 V is applied to the backup CPU via the determination port. Therefore, there is no mistake when attaching the sub CPU and the backup CPU.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
First, the overall configuration of the variable steering angle ratio steering device will be described.
FIG. 1 is an overall configuration diagram of a variable steering angle ratio steering device according to the present invention. A variable steering angle ratio steering device 1 according to the present invention includes a variable steering angle ratio device 10 provided in a steering system S from a steering wheel 2 as a steering wheel to steered wheels W, W, and a variable steering angle ratio based on a vehicle speed. A control device 40 for controlling the device 10 is provided.
[0015]
In the steering system S, a steering shaft 3 provided integrally with a steering wheel 2 is connected to an input shaft of a variable steering angle ratio device 10 via a connecting shaft 4 having universal joints 4A and 4B. The variable steering angle ratio device 10 is capable of continuously changing the ratio β / α of the rotation angle β of the output shaft to the rotation angle α of the input shaft. The output shaft of the variable steering angle ratio device 10 is provided with a pinion 5. By meshing the pinion 5 with the rack teeth of the rack shaft 6, the rotation of the output shaft is linearly moved (L ), And the linear motion of the rack shaft 6 is converted into the steering motion (T) of the steered wheels W, W via the tie rods 7, 7 and the knuckle arm.
[0016]
On the side of the rack shaft 6, an electric motor (hereinafter, referred to as "EPS motor") 8 for an electric power steering device (hereinafter, referred to as "EPS") for generating an auxiliary steering torque is coaxial with the rack shaft 6. It is arranged in. Then, the rotation of the EPS motor 8 is converted into thrust via a ball screw mechanism 9 provided coaxially with the rack shaft 6, and this thrust acts on the rack ball screw shaft 9A.
[0017]
Next, the structure of a specific example of the variable steering angle ratio device 10 according to the present embodiment will be described with reference to FIGS.
As shown in FIG. 2, the input shaft 11 is rotatably supported via a ball bearing 15 at an eccentric position of a support member 14 rotatably supported by an upper casing 13 a via a ball bearing 12. . At the end of the input shaft 11 protruding into the lower casing 13b, a coupling 16 for transmitting a rotational force to the output shaft 17 is integrally formed. The input shaft 11 is connected to the connection shaft 4 (see FIG. 1), and is configured to rotate through the connection shaft 4 when the driver steers the steering wheel 2.
[0018]
The output shaft 17 is rotatably supported by the lower casing 13b via a pair of ball bearings 18a, 18b. A pinion 5 meshed with the rack teeth 6a of the rack shaft 6 is integrally formed below the output shaft 17. An end of the output shaft 17 protrudes into the lower casing 13b, and an intermediate shaft 19 protrudes from the end of the output shaft 17 at a position eccentric from the center of the output shaft 17. The intermediate shaft 19 and the coupling 16 formed integrally with the input shaft 11 are connected to each other via a slider 21 having a flat needle bearing 20 interposed therebetween and a tapered roller bearing 22. Further, a seal member 35 having a flexible tubular portion is provided between the input shaft 11 and the upper casing 13a. The seal member 35 maintains airtightness in the variable steering angle ratio device 10.
[0019]
As shown in FIG. 3, a groove 23 having a trapezoidal cross section is formed on the lower surface of the coupling 16 so that the lower part is expanded and opened. A slider 21 having a pair of flat needle bearings 20 interposed therein is engaged with the groove 23 so as to slide on mutually opposing inclined surfaces of the groove 23. An intermediate shaft 19 is engaged with the center of the lower surface of the slider 21 via a tapered roller bearing 22 so as to be relatively rotatable.
[0020]
As shown in FIG. 2, an adjusting screw 24 that is in contact with an outer race of a ball bearing 18 b that supports a lower end of the output shaft 17 is screwed to the lower casing 13 b. By properly tightening the adjusting screw 24, the pinion 5 is pressed in the axial direction, and an appropriate preload is applied between the input shaft 11 and the output shaft 17 via the coupling 16. In this way, it is possible to improve the coupling rigidity by removing the play of the coupling 16.
[0021]
As shown in FIG. 4, a fan-shaped partial worm wheel 25 is provided on a part of the outer peripheral portion of the support member 14. A worm 28 driven by a motor 27 which is an electric motor is engaged with the partial worm wheel 25 via a worm reduction mechanism 26. The rotational driving force of the motor 27 allows the support member 14 to rotate the upper casing 13a over a predetermined angular range.
[0022]
The worm 28 is supported by the upper casing 13a via a backlash removing member 29 using an eccentric cam. The hexagonal wrench is engaged with the hexagonal hole 30 formed at the end of the backlash removing member 29, and the hexagonal wrench is rotated with respect to the upper casing 13a, so that the axis of the wrench is moved. The engagement with the partial worm wheel 25 is changed. The worm 28 and the worm reduction mechanism 26 are connected via an Oldham coupling 31 in order to allow the axis of the worm 28 to move.
[0023]
Further, a displacement sensor 33, which is a steering angle ratio sensor of the present invention, including a differential transformer and the like engaged with a pin 32 protruding from the upper surface of the support member 14, is attached to the upper casing 13a. This displacement sensor 33 detects the amount of displacement of the support member 14. The displacement sensor 33 controls the detected rotation amount of the support member 14, that is, an eccentricity signal (corresponding to the "steering angle ratio signal" of the present invention) 33a of the input shaft 11 supported by the support member 14. 40. In the present embodiment, in the variable steering angle ratio steering device 1, the steering angle ratio characteristic changes according to the amount of eccentricity, and the steering angle ratio continuously changes according to the steering angle of the steering wheel based on the steering angle ratio characteristic. To the optimal value for That is, in the present embodiment, the steering angle ratio changes according to the amount of eccentricity. Therefore, in the present embodiment, the actual eccentric amount corresponding to the actual steering angle ratio is detected by the displacement sensor 33 instead of directly detecting the steering angle ratio.
[0024]
The control device 40 includes a target eccentric amount (corresponding to the target steering angle ratio) determined based on the vehicle speed signal Va from the vehicle speed sensor VS, an actual eccentric amount (corresponding to the actual steering angle ratio) 33a detected by the displacement sensor 33, and The rotational drive of the motor 27 is controlled by feedback control so as to match (see FIG. 7). The control device 40 will be described later in detail.
[0025]
The vehicle speed sensor VS is provided in a speedometer (not shown) and detects the speed of the vehicle. Then, the vehicle speed sensor VS transmits to the control device 40 a vehicle speed signal Va of an analog electric signal corresponding to the detected vehicle speed. The vehicle speed sensor VS may be a dedicated sensor of the variable steering angle ratio steering device 1 or a sensor shared with another system.
[0026]
Next, the operation principle of the variable steering angle ratio device will be described.
FIG. 5 is an explanatory diagram showing the operation principle of the variable steering angle ratio device, and FIG. 6 is an input / output angle characteristic diagram showing the steering angle ratio characteristics of the variable steering angle ratio device.
[0027]
As shown in FIG. 5, the rotation center of the input shaft 11 is A, the rotation center of the output shaft 17 is B, and the action point of the intermediate shaft 19 is C. Further, the dimension between BC is b, the amount of eccentricity between the input shaft 11 and the output shaft 17 (dimension between AB) is a, the rotation angle of the input shaft 11 (steering wheel steering angle) is α, and the rotation angle of the output shaft 17 is α. (Pinion rotation angle) is β. At this time, b · sin β = (b · cos β−a) tan α
Because
α = tan ⁻¹ (b · sin β / (b · cos β-a))
Is represented by
[0028]
When the driver rotates the input shaft 11 by operating the steering wheel 2, the intermediate shaft 19 cranks around the axis of the output shaft 17 due to the engagement of the coupling 16 of the input shaft 11 with the slider 21. . For example, as shown in FIG. 5, when the rotation angle α1 of the input shaft 11 is 90 degrees, the rotation angle β1 of the output shaft 17 becomes as shown in FIG.
[0029]
Here, when the support member 14 is rotated, the axis of the input shaft 11 changes within the range indicated by reference numerals A0 to A2 in FIGS. 3 and 4 due to the eccentric cam action of the support member 14. When the amount of eccentricity a between the input and output shafts is appropriately determined by changing the axis of the input shaft 11 and the axes of the input shaft 11 and the output shaft 17 are eccentric to each other, the input shaft 11 and the output shaft 17 The rotation angles do not match. In addition, the angle change of the output shaft 17 when the input shaft 11 is rotated by equal angles gradually increases (see the solid lines a1 and a2 in FIG. 6).
[0030]
When the eccentricity a of the axis between the input shaft 11 and the output shaft 17 is continuously changed in the range of a2 to a0 (a2>a1> a0 = 0), the output shaft with respect to the rotation angle of the input shaft 11 is changed. 17, the ratio β / α of the rotation angle, that is, the practical steering angle ratio can be continuously changed. Now, if the amount of eccentricity a between the input and output axes is increased, the rate of change of the output angle β with respect to the input angle α gradually increases, and if the amount of eccentricity a between the input and output axes is set to 0, the dashed line (a0) in FIG. ), The input angle α and the output angle β are equal.
[0031]
If this change in the steering angle ratio is controlled to be, for example, the a0 side in a low-speed running range and the a2 side in a high-speed running range, the rack stroke with respect to the steering angle α of the steering wheel in the low-speed running range is smaller than that of the conventional steering device. , The sensitivity can be further increased (quick). Further, in the high-speed running range, the rack stroke with respect to the steering angle α of the steering wheel is set smaller than that of the conventional steering device, so that a more insensitive (dull) characteristic can be realized. Therefore, the relationship between the practical steering wheel angle and the traveling speed can be made flat characteristics.
[0032]
Subsequently, the control device 40 will be described with reference to FIG.
As shown in FIG. 7, the control device 40 includes a main CPU 41 that is used at normal times, and a sub CPU 42 that mutually detects a failure between the main CPU 41 and the main CPU 41 or the sub CPU 42. It has a backup CPU 43 to be used when it is done. The main CPU 41, the sub CPU 42, and the backup CPU 43 are connected to a switching circuit 44, respectively.
[0033]
The switching circuit 44 is connected to the motor driving circuit 45 and has a switching switch (not shown). The switching circuit 44 is provided with either a motor driving signal 41a output from the main CPU 41 or a motor driving signal 43a output from the backup CPU 43. Is output to the motor drive circuit 45. The motor drive circuit 45 is configured by a bridge circuit composed of four FET switching elements, is connected to a battery power supply (not shown), and supplies a current to the motor 27 based on a signal from the switching circuit 44 to supply a current to the motor 27. 27.
[0034]
The main CPU 41 and the sub CPU 42 are connected to an EPS motor drive circuit 47 via a gate drive circuit 46 for driving the EPS motor 8. The EPS motor drive circuit 47 is configured by a bridge circuit including four FET switching elements, is connected to a battery (not shown), and supplies a current to the EPS motor 8 based on an EPS drive signal 41b from the main CPU 41. Then, the EPS motor 8 is driven. Further, between the EPS motor drive circuit 47 and the EPS motor 8, a motor current detecting means 71 for detecting a current supplied to the EPS motor 8 is provided. The current of the EPS motor 8 detected by the motor current detecting means 71 is output to the main CPU 41 and used for feedback control.
[0035]
Further, the control device 40 is provided with an actual steering angle ratio input circuit 48. The actual steering angle ratio input circuit 48 outputs the actual eccentricity of the input shaft 11 (FIG. 2) detected by the displacement sensor 33 to the main CPU 41, the sub CPU 42, and the backup CPU 43. On the other hand, the control device 40 includes a steering torque input circuit 49 and a vehicle speed input circuit 50. The steering torque input circuit 49 outputs a steering torque signal Ta from the steering torque sensor TS to the main CPU 41 and the sub CPU 42. The vehicle speed input circuit 50 outputs a vehicle speed signal Va from the vehicle speed sensor VS to the main CPU 41, the sub CPU 42, and the backup CPU 43, respectively.
[0036]
As shown in FIG. 8, the main CPU 41 controls the variable steering angle ratio device 10 to control the target eccentricity amount determination unit 51, the deviation calculation unit 52, the PID control unit 53, the PWM signal generation unit 54, and the gate drive. A circuit 55 is provided. In addition, a target current setting unit 56, a deviation calculation unit 57, a PID control unit 58, and a PWM signal generation unit 59 are provided for performing EPS control. Further, a sub CPU mutual monitoring unit 60 for mutually detecting a failure with the sub CPU 42 and a backup CPU failure detecting unit 61 for detecting a failure of the backup CPU 43 are provided.
[0037]
First, the control of the variable steering angle ratio device 10 will be described. The target eccentricity determining unit 51 includes storage means such as a ROM, and corresponds to the correspondence between the vehicle speed signal Va set in advance based on experimental values or design values and the target eccentricity. Data (conversion table) to be stored. Then, the target eccentricity determining unit 51 reads out the corresponding target eccentricity using the vehicle speed signal Va as an address, and outputs the target eccentricity signal 51a to the deviation calculating unit 52. Here, the target eccentric amount is associated with the vehicle speed signal Va at a low speed where the road surface reaction force is large, and a large value at a high speed in order to secure stability during traveling. Corresponding. The vehicle speed signal Va input to the target eccentricity determination unit 51 is obtained by converting the vehicle speed signal Va input from the vehicle speed sensor VS via an FV converter (not shown) from an analog signal to a digital signal.
[0038]
The deviation calculator 52 calculates the deviation between the target eccentricity signal 51a and the eccentricity signal 33a indicating the actual eccentricity detected by the displacement sensor 33 (corresponding to the actual steering angle ratio), and outputs a deviation signal 52a. The eccentricity signal 33a is output to the deviation calculator 52 via the actual steering angle ratio input circuit 48. The PID control unit 53 performs processing such as proportionality, integration, and differentiation on the deviation signal 52a, and generates a drive control signal 53a indicating the direction and the current value of the current supplied to the motor 27 to reduce the deviation to zero. And output.
[0039]
The PWM signal generation section 54 outputs a PWM (pulse width modulation) signal 54a for performing the PWM operation of the motor 27 to the gate drive circuit 55 based on the drive control signal 53a. The gate drive circuit 55 outputs to the switching circuit 44 a motor drive signal 55a for driving the gate of each FET of the motor drive circuit 45 based on the PWM signal 54a to switch and drive each FET.
[0040]
Next, the steps of the EPS control will be described. The target current setting unit 56 includes storage means such as a ROM, and stores data (corresponding to the steering torque signal Ta set in advance based on an experimental value or a design value) and the target eccentric amount. Conversion table). Then, the target current setting unit 56 reads the corresponding target current value using the steering torque signal Ta as an address, and outputs the target current signal 56a to the deviation calculation unit 57.
[0041]
The deviation calculation unit 57 obtains a deviation between the target current signal 56a and the current signal 71a supplied to the EPS motor 8 by the motor current detection unit 71, and outputs the deviation signal 57a to the PID control unit 58. The PID control unit 58 performs a process such as proportionality, integration, and differentiation on the deviation signal 57a, and generates a drive control signal 58a indicating the direction and the current value of the current supplied to the EPS motor 8 in order to reduce the deviation to zero. It is generated and output to the PWM signal generator 59.
[0042]
The PWM signal generation unit 59 outputs a PWM (pulse width modulation) signal 59a for performing the PWM operation of the EPS motor 8 to the gate drive circuit 46 based on the drive control signal 58a. The gate drive circuit 46 outputs to the EPS motor drive circuit 47 a motor drive signal 46a for driving the gate of each FET of the EPS motor drive circuit 47 based on the PWM signal 59a to switch the FETs.
[0043]
In addition, in the main CPU 41, the sub CPU mutual monitoring unit 60 mutually detects a failure with the sub CPU 42. The backup CPU failure detection unit 61 detects a failure of the backup CPU 43. As described above, the main CPU 41 performs an extremely large number of processes.
[0044]
Further, CPUs having the same structure are used as the sub CPU 42 and the backup CPU 43, and each have a sub program control unit 65, a backup program control unit 66, and a determination port 67. The “program corresponding to the sub CPU” of the present invention is written in the subprogram control unit 65, and the “program corresponding to the backup CPU” of the present invention is written in the backup program control unit 66. .
[0045]
The sub-program control unit 65 in the sub-CPU 42 exchanges the failure detection signal 42a with the sub-CPU mutual monitoring unit 60 in the main CPU 41 to mutually detect failures. Then, when a failure is detected in the main CPU 41, a failure signal 42 b is output to the switching circuit 44. Upon receiving the failure signal 42b, the switching circuit 44 stops outputting the motor drive signal 41a output to the motor drive circuit 45. Instead, it outputs a motor drive signal 43 a of the backup CPU 43 to the motor drive circuit 45. In the sub CPU 42, the backup program control unit 66 does not perform any operation.
[0046]
On the other hand, when at least one of the main CPU 41 and the sub CPU 42 fails, the backup program control unit 66 in the backup CPU 43 generates an electric motor drive signal 43 a for driving the motor 27 and outputs the generated signal to the switching circuit 44. I have. Normally, that is, when the main CPU 41 and the sub CPU 42 are functioning normally, the motor drive signal 43 a generated by the backup CPU 43 is not output to the motor drive circuit 45. When a failure occurs in at least one of the main CPU 41 and the sub CPU 42, the switching circuit 44 is switched, and the motor drive signal 43a from the backup CPU 43 is output to the motor drive circuit 45 instead of the motor drive signal 41a from the main CPU 41. Is done. The backup CPU 43 is used when a failure occurs in the main CPU 41. When at least one of the main CPU 41 and the sub CPU 42 fails, the control of the variable steering angle ratio device 10 by the main CPU 41 becomes impossible. . Therefore, the backup program control unit 66 in the backup CPU 43 generates the motor drive signal 43a for shifting the variable steering angle ratio device 10 to the dull side (the maximum eccentric amount side) from the viewpoint of fail-safe, and the switching circuit 44 Output to In generating the motor drive signal 43a, feedback control is performed using the eccentricity amount signal 33a output from the actual steering angle ratio input circuit 48. In the backup CPU 43, the sub-program control unit 65 does not perform any operation.
[0047]
Thus, the processing amounts of the sub CPU 42 and the backup CPU 43 are small. Therefore, even if these are manufactured as CPUs having the same structure, and a program not used for processing is written in each of them, it is not a great waste.
[0048]
Further, a discrimination voltage is applied to the discrimination ports 67, 67 of the sub CPU 42 and the backup CPU 43 from a board (not shown). The determination voltage given from the board determines which of the sub CPU 42 and the backup CPU 43 is used. Now, a voltage of 0V is applied to the determination port 67 of the sub CPU 42, in other words, the grounding is performed, and a voltage of 5V is applied to the determination port 67 of the backup CPU 43. That is, when the CPU is installed on the board, a voltage of 0 V is automatically applied to the determination port 67 of the CPU installed at the position where the sub CPU 42 is to be installed. On the other hand, a voltage of 5 V is automatically applied to the determination port 67 of the CPU installed at the position where the backup CPU 43 is to be installed.
[0049]
The determination processing procedure in each of these CPUs will be described with reference to the flowchart shown in FIG. 9. The CPU is installed at a predetermined position and the processing is started (S1). When the process is started, a determination voltage applied to the determination port 67 is detected (S2). As a result, if the discrimination voltage is 0 V, it is used as the sub CPU 42, and the subprogram is executed (S3). On the other hand, if the discrimination voltage is 5 V, it is used as the backup CPU 43, and the backup program is executed (S4). After the subprogram is started or the backup program is executed, it is determined whether or not the control or the like has been completed (S5). As a result, if the control or the like has not been completed, the flow returns to step S2 to detect the determination voltage applied to the determination port 67. On the other hand, if the control or the like has been completed, the determination processing ends (S6).
In this way, the sub CPU 42 and the backup CPU 43 are automatically determined only by installing the same CPU at each position, so that the sub CPU 42 and the backup CPU 43 are not mistaken. Further, since the same CPU is manufactured, it is possible to prevent the sub CPU 42 and the backup CPU 43 from being erroneously manufactured at the time of manufacturing, and to prevent a program from being written wrongly.
[0050]
The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment . For example, in the above-described embodiment, the CPUs used for the sub CPU and the backup CPU have the same structure. However, the CPUs may not have the same structure as long as they have both the sub program control unit and the backup program control unit. Furthermore, if there is a common routine between the subprogram and the backup program, this can be written in one program and shared by both. Even when a program having many such common routines is written, it is effective to use a CPU having the same structure. On the other hand, the sub CPU and the backup CPU may have another program control unit other than the sub program control unit and the backup program control unit.
[0051]
【The invention's effect】
As described above, according to the first aspect of the present invention, in a variable steering angle ratio steering device having a main CPU, a sub CPU, and a backup CPU, it is necessary to design and manufacture the sub CPU and the backup CPU separately. Disappears. Also, there is no mistake in attaching the sub CPU and the backup CPU.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of a variable steering angle ratio steering device according to the present embodiment.
FIG. 2 is a front sectional view of the variable steering angle ratio device according to the embodiment.
FIG. 3 is an exploded perspective view of a shaft portion of the variable steering angle ratio device according to the present embodiment.
FIG. 4 is a sectional view taken along line AA of FIG. 2;
FIG. 5 is an explanatory diagram illustrating an operation principle of the variable steering angle ratio steering device according to the present embodiment.
FIG. 6 is an input / output angle characteristic diagram showing a steering angle ratio characteristic of the variable steering angle ratio steering device according to the present embodiment.
FIG. 7 is a block diagram of a control device of the variable steering angle ratio steering device according to the present embodiment.
FIG. 8 is a block diagram of the periphery of a main CPU of the variable steering angle ratio steering device according to the present embodiment.
FIG. 9 is a flowchart illustrating a determination processing procedure in a sub CPU and a backup CPU;
[Explanation of symbols]
1 Variable steering angle ratio steering device 2 Steering wheel (handle)
10 Variable steering angle ratio device 40 Control device 41 Main CPU
42 Sub CPU (first CPU)
43 Backup CPU (second CPU)
65 Subprogram control unit (first program)
66 Backup program control unit (second program)
67 Discrimination port W Steering wheel

Claims (1)

A variable steering system in which a variable steering angle ratio device capable of changing the ratio of the steering angle of the steered wheel to the steering wheel is provided in a steering system from the steering wheel to the steered wheels, and a control device that controls the variable steering angle ratio device is provided. In the steering angle ratio steering device,
The control device includes a main CPU that is normally used, a sub CPU that monitors failures between the main CPU and a backup CPU that is used when at least one of the main CPU and the sub CPU fails. And a CPU.
As the sub CPU and the backup CPU, both a program corresponding to the sub CPU and a program corresponding to the backup CPU are written, and a determination port for determining the sub CPU and the backup CPU is provided. CPU is used,
The CPU is mounted on a board, and a discrimination voltage is given from the board through the discrimination port, and based on the discrimination voltage, it is determined whether the CPU is used as the sub CPU or the backup CPU. A variable steering angle ratio steering device, characterized in that:

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