Control device for steering mechanism

Abstract

The present invention relates to a control device (30) for a steering mechanism (2), in which the steering mechanism (2) includes a motor (20) having a plurality of coils (24). The plurality of coils (24) include a first coil (24a) and a second coil (24b). The control device (30) includes a first control system and a second control system configured to calculate a command value for a torque to be applied to the steering mechanism (2) for the motor (20). The first control system and the second control system are each configured to control the power supply to the plurality of coils (24) of the motor (20) based on the command value. The first control system includes a first microcomputer (32a) having a first characteristic, and the second control system includes a second microcomputer (32b) having a second characteristic different from the first characteristic.

Description

Technical Field

[0001] The invention relates to a control device for a steering mechanism. Background Art

[0002] The following steering device is known: the steering device assists the driver in steering operation by applying the driving force of the motor to the steering mechanism of the vehicle. Such a steering device includes an electronic control unit (ECU) that controls the operation of the motor. For example, Japanese Unexamined Patent Application Publication No. 2011-195089 (JP 2011-195089 A) describes a device in which the ECU is formed with a plurality of control systems, each of which includes a motor, a microcomputer that controls the drive of the motor, and a drive circuit that controls the power supply to the plurality of coils of the motor. In this case, each microcomputer of the control system independently controls the power supply to the plurality of coils by controlling each drive circuit corresponding to the control system. Summary of the invention

[0003] In the case where power is supplied to the coil in the same manner in the control system, the control load is applied in the same manner to each component of the control system, such as a microcomputer and a drive circuit corresponding to the control system. For example, if each component of the control system has the same configuration, an abnormality may occur in each component of the control system due to the same factor. In this case, the abnormality may occur simultaneously in each component of the control system.

[0004] The present invention suppresses the simultaneous occurrence of abnormalities in the respective constituent elements of the control system.

[0005] One aspect of the present invention provides a control device for a steering mechanism. The steering mechanism includes a motor having a plurality of coils, the plurality of coils including a first coil and a second coil. The control device includes a first control system and a second control system configured to calculate a command value of a torque to be applied to the steering mechanism by the motor. The first control system is configured to control the power supply to the first coil based on a first command value, wherein the first command value is a command value of the torque to be generated by the first coil. The second control system is configured to control the power supply to the second coil based on a second command value, wherein the second command value is a command value of the torque to be generated by the second coil. The first control system includes a first microcomputer having a first characteristic, and the second control system includes a second microcomputer having a second characteristic different from the first characteristic.

[0006] By the above configuration, the first control system is formed using the first microcomputer having the first characteristic, and the second control system is formed using the second microcomputer having the second characteristic different from the first characteristic. Since the constituent elements of the control system have different characteristics, even if the constituent elements of the control system have, for example, the same configuration, it is possible to suppress the simultaneous occurrence of abnormalities in the constituent elements of the respective control systems.

[0007] In the control device, the first microcomputer can be manufactured using a first raw material, and the second microcomputer can be manufactured using a second raw material different from the first raw material. With the above configuration, the first control system is formed using a first constituent element manufactured from the first raw material, and the second control system is formed using a second constituent element manufactured from the second raw material different from the first raw material. Since the constituent elements of the control system are manufactured from different raw materials, even if the constituent elements of the control system have, for example, the same configuration, simultaneous occurrence of abnormalities in the constituent elements of the respective control systems can be suppressed.

[0008] In the control device, the first microcomputer may be manufactured in a first factory, and the second microcomputer may be manufactured in a second factory different from the first factory. With the above configuration, the first control system is formed using the first microcomputer manufactured in the first factory, and the second control system is formed using the second microcomputer manufactured in the second factory different from the first factory. Since the constituent elements of the control system are manufactured in different factories, even if the constituent elements of the control system have, for example, the same configuration, the simultaneous occurrence of abnormalities in the constituent elements of the respective control systems can be suppressed.

[0009] In the control device, the first microcomputer may be manufactured by a first manufacturing device, and the second microcomputer may be manufactured by a second manufacturing device different from the first manufacturing device.

[0010] By the above configuration, the first control system is formed using the first microcomputer manufactured by the first manufacturing device, and the second control system is formed using the second microcomputer manufactured by the second manufacturing device different from the first manufacturing device. Since the constituent elements of the control system are manufactured by different manufacturing devices, even if the constituent elements of the control system have, for example, the same configuration, it is possible to suppress the simultaneous occurrence of abnormalities in the constituent elements of the respective control systems.

[0011] With the steering control device according to the present invention, it is possible to suppress the simultaneous occurrence of abnormalities in the constituent elements of the respective control systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals represent like elements, and in which:

[0013] Figure 1 is a diagram illustrating a schematic configuration of a steering device according to an embodiment incorporating a steering control device;

[0014] Figure 2 is a block diagram illustrating a schematic configuration of a steering control device;

[0015] Figure 3 is a block diagram illustrating a schematic configuration of a first microcomputer and a second microcomputer;

[0016] Figure 4 is a block diagram illustrating a schematic configuration of a first assist torque calculation unit;

[0017] Figure 5 is a graph indicating the relationship between the basic command value and the steering torque;

[0018] Figure 6 is a graph illustrating the relationship between the assist amount for control system A and the assist amount for control system B; and

[0019] Figure 7 is a flow chart illustrating the steps of a manufacturing process for a steering control device. DETAILED DESCRIPTION

[0020] An embodiment of applying the steering control device to an electric power steering system (referred to as "EPS") will be described below. Figure 1 As shown in the figure, EPS 1 includes: a steering mechanism 2, which steers a steering wheel 15 based on the driver's operation of a steering wheel 10; an auxiliary mechanism 3, which assists the driver in steering operations; and an electronic control unit (ECU) 30, which serves as a steering control device for controlling the auxiliary mechanism 3.

[0021] The steering mechanism 2 includes a steering wheel 10 operated by a driver and a steering shaft 11 that rotates together with the steering wheel 10. The steering shaft 11 has a column shaft 11a connected to the steering wheel 10, an intermediate shaft 11b coupled to the lower end of the column shaft 11a, and a pinion shaft 11c coupled to the lower end of the intermediate shaft 11b. The lower end of the pinion shaft 11c is coupled to the rack shaft 12 via a rack-pinion mechanism 13. The rotational motion of the steering shaft 11 is converted into a rotation of the rack shaft 12 in the axial direction ( Figure 1 The reciprocating linear motion of the rack shaft 12 is transmitted to the left and right steering wheels 15 via tie rods 14 connected to the ends of the rack shaft 12 to change the steering angle of the steering wheel 15 and thus change the forward direction of the vehicle.

[0022] The assist mechanism 3 includes a motor 20 having a rotating shaft 21, and a reduction mechanism 22. The motor 20 applies torque to the steering shaft 11. The rotating shaft 21 of the motor 20 is connected to the column shaft 11a via the reduction mechanism 22. The reduction mechanism 22 reduces the rotation speed of the motor 20 and transmits the rotational force to the column shaft 11a at a reduced speed. That is, the torque of the motor 20 is applied to the steering shaft 11 to assist the driver in steering operations.

[0023] The ECU 30 controls the motor 20 based on the detection results performed by various sensors provided in the vehicle. Examples of the various sensors include torque sensors 40a and 40b, a rotation angle sensor 41, and a vehicle speed sensor 42 used as torque detection means. The torque sensors 40a and 40b are provided at the column shaft 11a. The rotation angle sensor 41 is provided at the motor 20. The torque sensors 40a, 40b detect the steering torque τ1 and the steering torque τ2 to be applied to the steering shaft 11 in association with the steering operation performed by the driver. The rotation angle sensor 41 detects the rotation angle θ of the rotating shaft 21 of the motor 20. The vehicle speed sensor 42 detects the vehicle speed V which is the running speed of the vehicle. The ECU 30 sets the target torque of the motor 20 to be applied to the steering mechanism 2 based on the output values ​​from the sensors, and controls the current to be supplied to the motor 20 so that the actual torque of the motor 20 becomes the target torque.

[0024] Next, we will refer to Figure 2 The function of the motor 20 is described in detail. The motor 20 includes a stator (not shown) and a rotor 23. A plurality of permanent magnets are provided in the rotor 23. The stator includes a plurality of coils 24 wound around a stator core (not shown). The coil 24 includes a first coil 24a and a second coil 24b. The first coil 24a and the second coil 24b each include coils of a U phase, a V phase, and a W phase connected by a star connection.

[0025] Next, we will refer to Figure 2 The functions of the ECU 30 are described. The ECU 30 has a control system A serving as a first control system for controlling the supply of electric power to the first coil 24a and a control system B serving as a second control system for controlling the supply of electric power to the second coil 24b.

[0026] The control system A of ECU 30 is composed of a first microcomputer 32a, a first current sensor 33a and a first drive circuit 34a. The control system B of ECU 30 is composed of a second microcomputer 32b, a second current sensor 33b and a second drive circuit 34b. The first microcomputer 32a and the second microcomputer 32b have the same configuration. The first current sensor 33a and the second current sensor 33b have the same configuration. The first drive circuit 34a and the second drive circuit 34b have the same configuration. The term "same configuration" used in the present embodiment refers to having the same function and performance under the same design concept. In the following description, only one of those configurations having the same configuration will be described, and other configurations will not be described in detail.

[0027] The first drive circuit 34a is supplied with power from a direct current (DC) power supply 81, such as a battery installed on the vehicle. The first drive circuit 34a and the DC power supply 81 (particularly, the positive terminal of the DC power supply 81) are connected to each other through a first power supply line 82. The first power supply line 82 is provided with a power switch 83 for the vehicle, such as an ignition switch. The power switch 83 is turned on and off by the driver operating a switch provided on the vehicle. When the power switch 83 is turned on, the power from the DC power supply 81 is supplied to the first drive circuit 34a via the first power supply line 82.

[0028] The second drive circuit 34b is supplied with power from the DC power supply 81. A connection point P is provided in the first power supply line 82 between the power switch 83 and the ECU 30. The connection point P and the second drive circuit 34b are connected to each other through the second power supply line 84. When the power switch 83 is turned on, power from the DC power supply 81 is supplied to the second drive circuit 34b via the second power supply line 84.

[0029] The first microcomputer 32a, the rotation angle sensor 41, the first current sensor 33a, the second microcomputer 32b, and the second current sensor 33b are supplied with power from the DC power supply 81 via a power supply line (not shown). Figure 1 and Figure 2 As illustrated in FIG. 1 , a plurality of connectors 90 are provided between the torque sensors 40 a and 40 b and the ECU 30, between the rotation angle sensor 41 and the ECU 30, between the vehicle speed sensor 42 and the ECU 30, and between the connection point P and the ECU 30. The connector 90 has a function of electrically connecting the torque sensors 40 a and 40 b, the rotation angle sensor 41, the vehicle speed sensor 42, and the connection point P to the ECU 30.

[0030] The first drive circuit 34a is a drive circuit for three phases (U phase, V phase, and W phase). The first drive circuit 34a converts the DC power supplied from the DC power supply 81 into three-phase alternating current (AC) power by turning on and off the switching elements constituting the first drive circuit 34a based on the control signal Sm1 generated by the first microcomputer 32a at the time of control operation. The first drive circuit 34a supplies the three-phase AC power to the first coil 24a.

[0031] The first microcomputer 32a generates a control signal Sm1 (power width modulation (PWM) signal) in each control cycle based on the steering torque τ1 detected by the torque sensor 40a, the rotation angle θ (first rotation angle θ1) detected by the rotation angle sensor 41, the vehicle speed V detected by the vehicle speed sensor 42, and the current value I1 detected by the first current sensor 33a. The first current sensor 33a detects the current of each phase (U phase, V phase, and W phase) of the power supply path between the first drive circuit 34a and the first coil 24a.

[0032] The second microcomputer 32b generates a control signal Sm2 (PWM signal) based on the steering torque τ2 detected by the torque sensor 40b, the rotation angle θ (second rotation angle θ2) detected by the rotation angle sensor 41, the vehicle speed V detected by the vehicle speed sensor 42, and the current value I2 detected by the second current sensor 33b when controlling the operation. The first rotation angle θ1 maintained by the first microcomputer 32a and the second rotation angle θ2 maintained by the second microcomputer 32b are detected by the same rotation angle sensor 41 and therefore generally have the same value. The second current sensor 33b detects the current of each phase flowing through the power supply path between the second drive circuit 34b and the second coil 24b.

[0033] The second drive circuit 34b converts the DC power supplied from the DC power source 81 into three-phase AC power by turning on and off the switching elements constituting the second drive circuit 34b based on the control signal Sm2 generated by the second microcomputer 32b at the time of the control operation. The second drive circuit 34b supplies the three-phase AC power to the second coil 24b.

[0034] In this way, the first microcomputer 32a and the second microcomputer 32b control the power supply to the first coil 24a of the control system A and the second coil 24b of the control system B by controlling the first drive circuit 34a and the second drive circuit 34b.

[0035] Next, we will refer to Figure 3The functions of the first microcomputer 32a and the second microcomputer 32b are described in detail. The first microcomputer 32a includes a first assist torque calculation unit 50 and a first current feedback control unit 51. The second microcomputer 32b includes a second assist torque calculation unit 60 and a second current feedback control unit 61.

[0036] The first assist torque calculation unit 50 calculates a first command value T1a* and a second command value T2a* based on the steering torque τ1 detected by the torque sensor 40a and the vehicle speed V detected by the vehicle speed sensor 42. The first command value T1a* is a command value regarding the torque to be generated by the first coil 24a of the control system A. The second command value T2a* is a command value regarding the torque to be generated by the second coil 24b of the control system B. The first assist torque calculation unit 50 outputs the first command value T1a* to the first current feedback control unit 51, and outputs the second command value T2a* to the second microcomputer 32b, that is, the second current feedback control unit 61 through inter-microcomputer communication.

[0037] The second assist torque calculation unit 60 calculates a first command value T1b* and a second command value T2b* based on the steering torque τ2 detected by the torque sensor 40b and the vehicle speed V detected by the vehicle speed sensor 42. The first command value T1b* is a command value regarding the torque to be generated by the first coil 24a of the control system A. The second command value T2b* is a command value regarding the torque to be generated by the second coil 24b of the control system B. The second assist torque calculation unit 60 outputs the first command value T1b* to the first microcomputer 32a, that is, the first current feedback control unit 51, and outputs the second command value T2b* to the second current feedback control unit 61 through inter-microcomputer communication.

[0038] The control of setting the first command values ​​T1a* and T1b* and the second command values ​​T2a* and T2b* to different values ​​is called "unbalanced control". The control of setting the first command values ​​T1a* and T1b* and the second command values ​​T2a* and T2b* to equal values ​​is called "parallel control". In the present embodiment, the first assist torque calculation unit 50 and the second assist torque calculation unit 60 always perform parallel control.

[0039] The first current feedback control unit 51 acquires not only the first command value T1a* and the first command value T1b*, but also the first rotation angle θ1 and the current value I1. The first current feedback control unit 51 uses one of the first command value T1a* and the first command value T1b* to perform calculation of the control signal Sm1. In the case where the torque sensor 40a is normal, the first current feedback control unit 51 uses the first command value T1a* calculated by the first assist torque calculation unit 50 to perform calculation of the control signal Sm1. Conversely, in the case where it is determined that the torque sensor 40a is abnormal through fail-safe processing or the like, the first current feedback control unit 51 uses the first command value T1b* calculated by the second assist torque calculation unit 60 to calculate the control signal Sm1.

[0040] In the case where the torque sensor 40b is normal, the second current feedback control unit 61 uses the second command value T2a* calculated by the first assist torque calculation unit 50 to perform calculation of the control signal Sm2. Conversely, in the case where the torque sensor 40b is determined to be abnormal by fail-safe processing or the like, the second current feedback control unit 61 uses the second command value T2b* calculated by the second assist torque calculation unit 60 to perform calculation of the control signal Sm2. In the case where the torque sensor 40a is normal, the first microcomputer 32a functions as a so-called master device, and the second microcomputer 32b functions as a so-called slave device. Meanwhile, in the case where the torque sensor 40a is abnormal and the torque sensor 40b is normal, the first microcomputer 32a functions as a slave device, and the second microcomputer 32b functions as a master device.

[0041] The first current feedback control unit 51 acquires not only the first command value T1a* and the first command value T1b*, but also the first rotation angle θ1 and the current value I1. The first current feedback control unit 51 performs calculation of the control signal Sm1 using one of the first command value T1a* and the first command value T1b*. The first current feedback control unit 51 calculates the control signal Sm1 based on the first command value T1a* (or the first command value T1b*), the first rotation angle θ1, and the current value I1. Specifically, the first current feedback control unit 51 calculates the control signal Sm1 by performing current feedback control based on the deviation between the current command value corresponding to the first command value T1a* (or the first command value T1b*) and the current value I1, so that the current value I1 follows the current command value.

[0042] The second current feedback control unit 61 acquires not only the second command value T2a* and the second command value T2b*, but also the second rotation angle θ2 and the current value I2. The second current feedback control unit 61 uses one of the second command value T2a* and the second command value T2b* to perform calculation of the control signal Sm2. The second current feedback control unit 61 calculates the control signal Sm2 based on the second command value T2a* (or the second command value T2b*), the second rotation angle θ2, and the current value I2. More specifically, the second current feedback control unit 61 calculates the control signal Sm2 by performing current feedback control based on the deviation between the current command value corresponding to the second command value T2a* (or the second command value T2b*) and the current value I2, so that the current value I2 follows the current command value.

[0043] Next, we will refer to Figure 4 The function of the first assist torque calculation unit 50 is described in detail. The first assist torque calculation unit 50 includes a first assist control unit 52 and an equal distribution unit 53. The second assist torque calculation unit 60 also has constituent elements similar to those of the first assist torque calculation unit 50.

[0044] The first assist control unit 52 calculates a basic command value Ta* based on the steering torque τ1 and the vehicle speed V. The basic command value Ta* is the sum of the first command value T1a* and the second command value T2a*. Figure 5 As indicated in , the first auxiliary control unit 52 calculates the basic command value Ta*, which has a larger absolute value when the absolute value of the input steering torque τ1 is larger or the vehicle speed V is lower. The ratio (|ΔTa* / Δτ1|) of the change in the absolute value of the basic command value Ta* to the change in the absolute value of the steering torque τ1 |Δτ1| becomes larger as the absolute value of the steering torque τ1 increases. Whether the steering torque Δτ1 is positive or negative is determined based on whether the steering wheel 10 is turned to the right or to the left. The basic command value Ta* calculated by the first auxiliary control unit 52 also has a positive sign or a negative sign depending on whether the sign of the steering torque τ1 is positive or negative.

[0045] The equal distribution unit 53 multiplies the input basic command value Ta* by "1 / 2". That is, the equal distribution unit 53 calculates the equal command value Tae* ("Ta* / 2") obtained by equally dividing the basic command value Ta*. The equal command value Tae* calculated by the equal distribution unit 53 is output as the first command value T1a* and the second command value T2a* as they are. In short, the first command value T1a* and the second command value T2a* calculated by the equal distribution unit 53 are set to equal values.

[0046] The equal command value Tae* becomes larger as the absolute values ​​of the steering torque τ1 and the steering torque τ2 become larger. When the vehicle speed V is the same, the relationship between the equal command value Tae* and the absolute values ​​of the steering torque τ1 and the steering torque τ2 is the same as that having the following relationship: Figure 5 The relationship represented by the curve of half the slope of the relationship between the basic command value Ta* and the absolute values ​​of the steering torque τ1 and the steering torque τ2 shown in is the same as that represented by the curve of half the slope of the relationship between the basic command value Ta* and the absolute values ​​of the steering torque τ1 and the steering torque τ2 shown in . Therefore, the slope of the equalized command value Tae* relative to the steering torque τ1 and the steering torque τ2 becomes larger as the absolute values ​​of the steering torque τ1 and the steering torque τ2 become larger.

[0047] exist Figure 6 , the second command values ​​T2a* and T2b* are plotted on the horizontal axis, and the first command values ​​T1a* and T1b* are plotted on the vertical axis. Figure 6 The relationship is shown in the case where the first command values ​​T1a* and T1b* are the same as the second current command values ​​T2a* and T2b*.

[0048] In the present embodiment, the first microcomputer 32a as a constituent element of the control system A and the second microcomputer 32b as a constituent element of the control system B are manufactured to have different characteristics despite having the same computing performance related to the computing processing function, such as computing processing speed. The term "characteristic" used in the present embodiment refers to durability such as life and failure rate related to the composition ratio of the material, the content of internal particles (particulate foreign matter, impurities or contaminants), the manufacturing plant, the manufacturing device as a facility of the manufacturing plant, the temperature-voltage performance as a test result of the temperature-voltage test, the environmental load performance as a test result of the environmental load test, etc.

[0049] Specifically, the first microcomputer 32a, which is a constituent element of the control system A, and the second microcomputer 32b, which is a constituent element of the control system B, are manufactured from different raw materials (ingots). More specifically, the first microcomputer 32a and the second microcomputer 32b are manufactured in different factories, so that the first ingot used to manufacture the first microcomputer 32a and the second ingot used to manufacture the second microcomputer 32b are different from each other. The fact that the first microcomputer 32a and the second microcomputer 32b are manufactured in different factories can be expressed in another way, that is, the first microcomputer 32a and the second microcomputer 32b are manufactured on different production lines.

[0050] The first microcomputer 32a and the second microcomputer 32b are manufactured in different factories, so that the first manufacturing device for manufacturing the first microcomputer 32a and the second manufacturing device for manufacturing the second microcomputer 32b are different from each other. For example, the first manufacturing device of the facility of the first factory Fa used in the pre-processing step of the first factory Fa is different from the second manufacturing device of the facility of the second factory Fb used in the pre-processing step of the second factory Fb. The manufacturing device used in the pre-processing step may be various manufacturing devices, such as a manufacturing device for forming a wafer from an ingot, a manufacturing device for polishing the surface of a wafer, a manufacturing device for forming a film on the surface of a wafer, and a manufacturing device for etching. The first manufacturing device of the facility of the first factory Fa used in the post-processing step of the first factory Fa is different from the second manufacturing device of the facility of the second factory Fb used in the post-processing step of the second factory Fb. The manufacturing device used in the post-processing step may be: a manufacturing device for mounting electronic components on a wafer that has undergone a pre-processing step, a manufacturing device for soldering already mounted electronic components, a manufacturing device for molding resin around mounted electronic components, and a testing device and a measuring device for performing a temperature-voltage test and an environmental load test. In this way, the first microcomputer 32a and the second microcomputer 32b are manufactured in the first factory Fa and the second factory Fb, respectively, and the first factory Fa and the second factory Fb are different from each other, so that the first manufacturing device for manufacturing the first microcomputer 32a and the second manufacturing device for manufacturing the second microcomputer 32b can be different from each other. The first microcomputer 32a is an example of the first constituent element defined, and the second microcomputer 32b is an example of the second constituent element.

[0051] In the case where the power supply to the first coil 24a or the second coil 24b cannot be continued due to an abnormality in one of the first microcomputer 32a of the control system A and the second microcomputer 32b of the control system B, the control system that can continue the power supply to the first coil 24a or the second coil 24b can generate the torque of the motor 20. In this case, the control system that can continue the power supply to the first coil 24a or the second coil 24b can generate a torque of, for example, up to half of the maximum torque of the motor 20, and can continue to assist based on the torque.

[0052] Will refer to Figure 7The manufacturing steps of ECU 30 are described. A design step (step S10) is performed in the first factory Fa, in which the functions and performances of the first microcomputer 32a are set and the circuits implementing the functions and performances are designed. After step S10 is completed, a pre-processing step (step S11) is performed, in which a wafer formed by the first ingot is processed. In the pre-processing step, it includes forming a wafer, polishing the surface of the wafer, forming an insulating film or a conductive film on the surface of the wafer, and etching. After step S11 is completed, a post-processing step (S12) is performed, in which electronic components are mounted on the wafer that has undergone the pre-processing step to assemble an integrated circuit (IC), that is, the first microcomputer 32a. In the post-processing step, electronic components are mounted on the wafer that has undergone the pre-processing step, the mounted electronic components are soldered, resin is molded around the mounted electronic components, the IC is subjected to temperature-voltage test and environmental load test, and the reliability of the manufactured IC is checked.

[0053] These steps S10 to S12 are performed in the first factory Fa, and the first microcomputer 32a is manufactured in the first factory Fa. A design step (step S20) is performed in the second factory Fb, in which the functions and performances of the second microcomputer 32b are set and a circuit for implementing the functions and performances is designed. After the completion of step S20, a pre-processing step (step S21) is performed, in which a wafer formed from the second ingot is processed. After the completion of step S21, a post-processing step (step S22) is performed, in which electronic components are mounted on the wafer that has been subjected to the pre-processing step to assemble an IC.

[0054] These steps S20 to S22 are performed in a second factory Fb different from the first factory Fa, and the second microcomputer 32b is manufactured in the second factory Fb. An acquisition step (step S30) is performed in the third factory Fc, in which the first microcomputer 32a manufactured in the first factory Fa and the second microcomputer 32b manufactured in the second factory Fb are acquired. Next, ECU 30 is manufactured using the first microcomputer 32a manufactured in the first factory Fa and acquired in the acquisition step and the second microcomputer 32b manufactured in the second factory Fb and acquired in the acquisition step (step S31). The acquisition step in step S30 and the manufacturing step for ECU 30 in step S31 are performed in a third factory Fc different from the first factory Fa and the second factory Fb. The third factory Fc is managed so that: control system A can be formed by installing the first microcomputer 32a acquired in the acquisition step, and control system B can be formed by installing the second microcomputer 32b acquired in the acquisition step. In the third factory Fc, in the manufacturing step, the first microcomputer 32a manufactured by the first manufacturing apparatus in the first factory Fa using the first ingot is installed in the control system A, and the second microcomputer 32b manufactured by the second manufacturing apparatus in the second factory Fb using the second ingot is installed in the control system B. Therefore, the ECU 30 is manufactured in the manufacturing step so that the first microcomputer 32a of the control system A and the second microcomputer 32b of the control system B have different characteristics.

[0055] Functions and effects of the present embodiment will be described. In the case where the first microcomputer 32a of the control system A and the second microcomputer 32b of the control system B are used under the same control load, when the ingot for the first microcomputer 32a of the control system A and the ingot for the second microcomputer 32b of the control system B are identical to each other, abnormalities may occur in the constituent elements of each control system due to the same factor. In this case, abnormalities may occur simultaneously in the same components of each control system.

[0056] For example, in the case where the first microcomputer 32a of the control system A and the second microcomputer 32b of the control system B are manufactured using the same ingot, the characteristics related to the material composition ratio of the two microcomputers are sometimes the same as each other considering that the composition ratio of the materials is the same. Therefore, if the two microcomputers are used under the same control load, it is considered that the two microcomputers deteriorate at approximately the same deterioration rate over time, and it is therefore assumed that abnormalities occur simultaneously in the two microcomputers.

[0057] In the present embodiment, different ingots are used for the first microcomputer 32a and the second microcomputer 32b, and the control system A and the control system B are controlled in parallel with the same control load. In this case, the material composition ratio of the microcomputers constituting the respective control systems depends on the ingots used for molding. Therefore, the characteristics of the first microcomputer 32a and the second microcomputer 32b can be different from each other. Therefore, even if the first microcomputer 32a and the second microcomputer 32b have the same computing performance, it is possible to suppress the occurrence of abnormalities in the first microcomputer 32a and the second microcomputer 32b at the same time.

[0058] The first microcomputer 32a manufactured in the first factory Fa is used to control the system A, and the second microcomputer 32b manufactured in the second factory Fb is used to control the system B. The content of particles in each microcomputer depends on the manufacturing environment, such as a production line. Therefore, the characteristics of the first microcomputer 32a and the second microcomputer 32b can be different from each other. Therefore, even if the microcomputers of the respective control systems have the same computing performance, it is possible to suppress the occurrence of abnormalities in the first microcomputer 32a and the second microcomputer 32b at the same time.

[0059] The first microcomputer 32a manufactured by the first manufacturing device is used for the control system A, and the second microcomputer 32b manufactured by the second manufacturing device is used for the control system B. The temperature-voltage performance and environmental load performance of each microcomputer, etc., depend on the manufacturing device, such as the test device and the measuring device for measuring and testing these performances. Therefore, the characteristics of the first microcomputer 32a and the second microcomputer 32b can be different from each other. Therefore, even if the microcomputers of the respective control systems have the same computing performance, it is possible to suppress the occurrence of abnormalities in the first microcomputer 32a and the second microcomputer 32b at the same time.

[0060] By combining the first microcomputer 32a and the second microcomputer 32b which are constituent elements of the ECU 30 and are manufactured from different ingots in the acquisition step, the ECU 30 can be manufactured in the manufacturing step such that the characteristics of the first microcomputer 32a and the second microcomputer 32b are different from each other.

[0061] By combining the first microcomputer 32a and the second microcomputer 32b which are constituent elements of the ECU 30 and manufactured in different factories in the acquisition step, the ECU 30 can be manufactured in the manufacturing step such that the characteristics of the first microcomputer 32a and the second microcomputer 32b are different from each other.

[0062] By combining the first microcomputer 32a and the second microcomputer 32b, which are constituent elements of the ECU 30 and are manufactured by different manufacturing devices, such as a testing device and a measuring device, in the acquisition step, the ECU 30 can be manufactured in the manufacturing step so that the characteristics of the first microcomputer 32a and the second microcomputer 32b are different from each other.

[0063] The present embodiment may be modified as follows. The following other embodiments may be combined with each other as long as they are not technically contradictory to each other. Although two control systems, namely control system A and control system B, are provided in the present embodiment, three or more control systems may also be provided. For example, the motor 20 may have three coils when three or more control systems are provided. In this case, the microcomputers of the respective control systems may perform parallel control on the power supply so that the coils share the generation of the maximum torque of the motor 20.

[0064] When the difference between the first command value T1a* and the first command value T1b* is smaller than a predetermined value, the first current feedback control unit 51 may calculate the control signal Sm1 using the average value of the first command value T1a* and the first command value T1b*. This also applies to the second current feedback control unit 61.

[0065] The present embodiment may be applied to an electromechanical motor device in which the motor 20 and the ECU 30 are constructed integrally with each other. The rotation angle sensor 41 may include an MR sensor, a Hall sensor, or a resolver.

[0066] The first rotation angle θ1 held by the first microcomputer 32a and the second rotation angle θ2 held by the second microcomputer 32b are detected by the same rotation angle sensor 41. However, the present invention is not limited thereto. For example, the first rotation angle θ1 to be held by the first microcomputer 32a may be detected by the first rotation angle sensor, and the second rotation angle θ2 to be grasped by the second microcomputer 32b may be detected by a second rotation angle sensor different from the first rotation angle sensor.

[0067] In the present embodiment, the first assist torque calculation unit 50 and the second assist torque calculation unit 60 always perform parallel control. However, the present invention is not limited thereto. For example, the first assist torque calculation unit 50 and the second assist torque calculation unit 60 may always perform unbalanced control in which the first command value T1a* and T1b* and the second command value T2a* and T2b* are set to different values. Alternatively, the first assist torque calculation unit 50 and the second assist torque calculation unit 60 may perform unbalanced control when the steering torque τ1 and the steering torque τ2 are equal to or less than a threshold value, and perform parallel control when the steering torque τ1 and the steering torque τ2 exceed a threshold value.

[0068] Although the first auxiliary control unit 52 calculates the basic command value Ta* based on the steering torque τ1 and the vehicle speed V, the first auxiliary control unit 52 may calculate the basic command value Ta* based only on the steering torque τ1. In the present embodiment, an external ECU may also be separately provided, which calculates a command value that serves as a basis for a command value regarding a torque that the motor 20 should generate and outputs (provides) the command value to the ECU 30.

[0069] In the present embodiment, the first microcomputer 32a and the second microcomputer 32b are manufactured in different factories so that different ingots are used to manufacture the first microcomputer 32a and the second microcomputer 32b. However, the present invention is not limited thereto. For example, the first microcomputer 32a and the second microcomputer 32b may be manufactured on different production lines in the same factory. In this case, since the manufacturing lines are different from each other, the first manufacturing device for manufacturing the first microcomputer 32a and the second manufacturing device for manufacturing the second microcomputer 32b may be different from each other. Alternatively, for example, the first microcomputer 32a and the second microcomputer 32b may be manufactured in the same factory on the same production line using the first ingot and the second ingot, respectively, which are different from each other, wherein the first ingot is used to manufacture the first microcomputer 32a and the second ingot is used to manufacture the second microcomputer 32b. In this case as well, the ECU 30 may be manufactured by using different ingots, in different factories or by different manufacturing devices in the manufacturing step to manufacture the first microcomputer 32a and the second microcomputer 32b.

[0070] In the present embodiment, the first microcomputer 32a and the second microcomputer 32b are manufactured in a first factory Fa and a second factory Fb, respectively, which are different from each other. However, the present invention is not limited to this. For example, the components constituting the first microcomputer 32a and the components constituting the second microcomputer 32b may be manufactured in different factories. In this case, in the factory where the ECU 30 is to be manufactured, the ECU 30 may be manufactured after the first microcomputer 32a and the second microcomputer 32b are assembled from these components. Alternatively, the first drive circuit 34a and the second drive circuit 34b may be manufactured in different factories. Alternatively, the first current sensor 33a and the second current sensor 33b may be manufactured in different factories. In the case where the control system A and the control system B are provided with an oscillator, the oscillator of the control system A and the oscillator of the control system B may be manufactured in different factories.

[0071] The first microcomputer 32a is manufactured in the first factory Fa, the second microcomputer 32b is manufactured in the second factory Fb, and the ECU 30 is manufactured in the third factory Fc. However, the present invention is not limited to this. The first microcomputer 32a and the ECU 30 may be manufactured in the same factory, while the second microcomputer 32b may be manufactured in a different factory. Alternatively, the second microcomputer 32b and the ECU 30 may be manufactured in the same factory, while the first microcomputer 32a may be manufactured in a different factory. Alternatively, the first microcomputer 32a, the second microcomputer 32b and the ECU 30 may be manufactured in the same factory. In this case, as described above, it is only necessary to manufacture the first microcomputer 32a and the second microcomputer 32b on different production lines as described above.

[0072] The first factory Fa, the second factory Fb, and the third factory Fc may belong to different manufacturing companies, or may belong to the same manufacturing company. In the case where all factories belong to the same manufacturing company, since the first factory Fa and the second factory Fb are different factories, although the first factory Fa and the second factory Fb belong to the same manufacturing company, the first microcomputer 32a and the second microcomputer 32b can still be manufactured using different ingots or by different manufacturing devices. In addition, the first factory Fa and the second factory Fb may belong to the same manufacturing company, while the third factory Fc may belong to a different manufacturing company. Alternatively, the first factory Fa and the third factory Fc may belong to the same manufacturing company, while the second factory Fb may belong to a different manufacturing company. Alternatively, the second factory Fb and the third factory Fc may belong to the same manufacturing company, while the first factory Fa may belong to a different manufacturing company.

[0073] In the present embodiment, the first assist torque calculation unit 50 may calculate only the first command value T1a*, and the second assist torque calculation unit 60 may calculate only the second command value T2b*. That is, the first microcomputer 32a and the second microcomputer 32b may control the power supply to the first coil 24a and the second coil 24b independently of each other.

[0074] In the present embodiment, the connector 90 of the control system A and the connector 90 of the control system B may be manufactured in different factories. Alternatively, the connector 90 of the control system A and the connector 90 of the control system B may be manufactured on different production lines in the same factory. Alternatively, the connector 90 of the control system A and the connector 90 of the control system B may be manufactured by different manufacturing companies. In this way, the connector 90 may be manufactured using different ingots, in different factories, or by different manufacturing devices.

[0075] In the present embodiment, the steering device is implemented as an EPS 1 that applies an auxiliary force to the steering shaft 11 through a motor 20. However, the present invention is not limited to this. For example, the steering device may be implemented as an EPS 1 that applies an auxiliary force to the rack shaft 12 through a motor 20 having a rotating shaft 21 arranged parallel to the rack shaft 12. Alternatively, the steering device may be implemented as a wire-controlled steering device. That is, the steering device may be any device that applies power to the steering mechanism 2 through the motor 20.

Claims

1. A control device (30) for a steering mechanism (2), The steering mechanism (2) includes a motor (20) having a plurality of coils (24), wherein the plurality of coils (24) include a first coil (24a) and a second coil (24b). The control device (30) is characterized by comprising a first control system and a second control system configured to calculate a command value of a torque to be applied by the motor (20) to the steering mechanism (2), the first control system and the second control system each being configured to control the supply of power to the plurality of coils (24) of the motor (20) based on the command value, The first control system is configured to control the power supply to the first coil (24a) based on a first command value, wherein: The first command value is the command value of the torque to be generated by the first coil (24a), The second control system is configured to control the power supply to the second coil (24b) based on a second command value, wherein the second command value is the command value of the torque to be generated by the second coil (24b), and The first control system includes a first microcomputer (32a) having a first characteristic, and the second control system includes a second microcomputer (32b) having a second characteristic different from the first characteristic, and since the first microcomputer and the second microcomputer have different characteristics, it is possible to suppress the simultaneous occurrence of abnormalities in the constituent elements of the respective control systems, The first assist torque calculation unit of the first microcomputer calculates the first command value and the second command value based on the steering torque detected by the torque sensor and the vehicle speed detected by the vehicle speed sensor; The second assist torque calculation unit of the second microcomputer calculates the first command value and the second command value based on the steering torque detected by another torque sensor and the vehicle speed detected by the vehicle speed sensor, The first microcomputer and the second microcomputer perform parallel control, which is control of setting the first command value and the second command value to equal values.

2. The control device (30) for a steering mechanism (2) according to claim 1, wherein: The first microcomputer (32a) is manufactured using a first raw material, and the second microcomputer (32b) is manufactured using a second raw material different from the first raw material.

3. The control device (30) for a steering mechanism (2) according to claim 1, wherein: The first microcomputer (32a) is manufactured in a first factory (Fa), and the second microcomputer (32b) is manufactured in a second factory (Fb) different from the first factory (Fa).

4. The control device (30) for a steering mechanism (2) according to claim 1, wherein: The first microcomputer (32a) is manufactured by a first manufacturing device, and the second microcomputer (32b) is manufactured by a second manufacturing device different from the first manufacturing device.

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