control unit

Abstract

To provide a control unit capable of efficiently utilizing a plurality of control devices included in the control unit.SOLUTION: A control unit 10 includes a plurality of control devices that control driving of an electric motor. The plurality of control devices have a general function used for actuating the electric motor in both a normal time in which the plurality of control devices are normal and an abnormal time in which any of the plurality of control devices is abnormal, and separately have a normal time function that is used in the normal time but is not necessary in the abnormal time.SELECTED DRAWING: Figure 3

Description

Technical Field

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

Background Art

[0002] Conventionally, a control system for driving an electric motor using a plurality of control devices has been proposed. For example, the control system of the electric motor described in Patent Document 1 controls the driving of an electric motor having two sets of windings by a main control device and a sub-control device. In the main control device, a d-q axis current command generation unit and a phase speed generation unit calculate a q-axis current command, a d-axis current command, and a phase speed based on a torque command input from a higher-level control device. The q-axis current command, the d-axis current command, and the phase speed are transmitted from the main control device to the sub-control device. Further, the power converters each possessed by the main control device and the sub-control device drive the electric motor with electric power converted into three-phase alternating current using a value obtained by converting a voltage error in a two-phase / three-phase conversion unit into two-phase / three-phase conversion.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to prevent the electric motor from not being driven at all when an abnormality occurs in the control device, it is desired to provide a plurality of control devices. Since the control device is an expensive product and a valuable product that is difficult to procure, it is desired to utilize it efficiently. The present invention has been made in view of such points, and an object thereof is to provide a control unit or the like that can efficiently utilize a plurality of provided control devices.

Means for Solving the Problems

[0005] The present invention, completed with this objective in mind, is a control unit comprising a plurality of control devices for controlling the drive of an electric motor, wherein the plurality of control devices have general functions used to operate the electric motor in both normal conditions when the plurality of control devices are functioning correctly and in abnormal conditions when any of the control devices among the plurality of control devices are malfunctioning, and also have distributed normal-condition functions that are used in normal conditions but not necessary in abnormal conditions. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a control unit or the like that can efficiently utilize multiple control devices. [Brief explanation of the drawing]

[0007] [Figure 1] This figure shows an example of a schematic configuration of the steering system according to the first embodiment. [Figure 2] This figure shows an example of a schematic configuration of a control unit according to the first embodiment. [Figure 3] This figure shows an example of the schematic configuration of the first setting unit and the second setting unit. [Figure 4] This is a diagram illustrating the operation of the steering system. [Figure 5] This is an example of a block diagram of the first control device and the second control device according to the comparative example. [Figure 6] This figure shows an example of a schematic configuration of a control unit according to the second embodiment. [Figure 7] This is a diagram illustrating the operation of the steering device according to the second embodiment. [Figure 8] This figure shows an example of a schematic configuration of a control unit according to the third embodiment. [Figure 9] This is a diagram illustrating the operation of the steering device according to the third embodiment. [Figure 10] This figure shows an example of a schematic configuration of a control unit according to the fourth embodiment. [Modes for carrying out the invention]

[0008] Embodiments of the present invention will be described in detail below with reference to the attached drawings. <First Embodiment> Figure 1 is a diagram showing an example of a schematic configuration of the steering system 1 according to the first embodiment. Figure 2 shows an example of a schematic configuration of the control unit 10 according to the first embodiment. The steering system 1 includes a vehicle control device 5 installed in a vehicle 100 such as an automobile, which controls the operation of the vehicle 100, and a steering device 6 that changes the direction of travel of the vehicle 100 by rolling the front wheels 101 of the vehicle 100. The steering device 6 is an electric power steering device. Figure 1 is a view of the vehicle from the front. Although Figure 1 illustrates a pinion assist type device, a rack assist type device or a column assist type device may also be used.

[0009] Vehicle 100 is equipped with an automated driving system that enables automated driving without requiring driver intervention (e.g., acceleration, deceleration, steering), and a driver assistance system that assists in driving vehicle 100 toward objects ahead. Hereinafter, the automated driving system and the driver assistance system may be collectively referred to as the "autonomous driving system." Examples of functions of the automated driving system include a collision avoidance function to prevent vehicle 100 from colliding with objects ahead, a skid suppression function to prevent vehicle 100 from skidding, and a parking assist function to assist in the rolling of the front wheels 101 when parking vehicle 100 in a parking lot, etc. Other examples of functions of the automated driving system include a lane keeping assist function that controls the rolling angle of the front wheels 101 so that vehicle 100 maintains its lane, and a lane change assist function that controls the rolling angle of the front wheels 101 so that vehicle 100 changes lanes.

[0010] The automated driving system includes, for example, an automated steering system that automatically steers the vehicle 100 without requiring driver steering input, an automated braking system that applies braking force to the vehicle 100 without requiring driver deceleration input, and an automated drive system that drives the vehicle 100 without requiring driver acceleration input. The steering system 1 functions as an automated steering system. In addition, automated driving and driver assistance are sometimes collectively referred to as "autonomous driving." When the vehicle 100 is performing automated driving, the steering device 6 performs automated steering.

[0011] (Vehicle control device 5) The vehicle control device 5 has an arithmetic logic circuit consisting of a CPU (not shown), ROM (not shown), RAM (not shown), etc. The vehicle control device 5 is connected to an external information detection unit (not shown) that detects external information of the vehicle 100. The external information detection unit constitutes an object position measuring device that measures the positions of objects around the vehicle 100. Examples of the external information detection unit include a digital camera and radar such as a laser radar, infrared radar, or millimeter-wave radar. Alternatively, the external information detection unit may be an ultrasonic sensor, an infrared sensor, etc.

[0012] The vehicle control device 5 grasps the surrounding conditions of the vehicle 100 based on information acquired from the external information detection unit, etc., and determines command values ​​for realizing automated driving or driver assistance, such as the vehicle's speed. The vehicle control device 5 then transmits the command values ​​for realizing automated driving or driver assistance to the control unit 10 of the steering device 6 (described later), the control device for the automatic braking system, the control device for the automatic drive system, etc. As a result, the vehicle control device 5 realizes automated driving control or driver assistance control.

[0013] (Steering gear 6) The steering system 6 includes a steering wheel 102 operated by the driver to change the direction of travel of the vehicle 100, and a steering shaft 103 integrally provided with the steering wheel 102. The steering device 6 includes a tie rod 104 connected to the left and right front wheels 101, and a rack shaft 105 connected to the tie rod 104. Further, the steering device 6 includes a pinion 106a that constitutes a rack and pinion mechanism together with rack teeth 105a formed on the rack shaft 105. A pinion shaft 106 having the pinion 106a is connected to a connecting shaft 108 via a torsion bar 107. The connecting shaft 108 is connected to the steering shaft 103 via a universal joint or the like and rotates in conjunction with the rotation of the steering wheel 102.

[0014] The steering device 6 has a torque sensor 109 that detects a steering torque T applied to the steering wheel 102 based on the amount of twist of the torsion bar 107. Further, the steering device 6 has an electric motor 110 supported by a steering gear box (not shown) that houses the torque sensor 109, and a reduction mechanism 120 that reduces the driving force of the electric motor 110 and transmits it to the pinion shaft 106.

[0015] The electric motor 110 is a dual three-phase motor having a first winding set 111 and a second winding set 112, which are two sets of three-phase windings with doubled windings. The maximum output when only the first winding set 111 is energized is the same as the maximum output when only the second winding set 112 is energized.

[0016] The steering device 6 includes a control unit 10 that controls the operation of the electric motor 110. An output signal from the above-described torque sensor 109 is input to the control unit 10. Further, vehicle speed Vc and the like, which are the moving speed of the vehicle 100, are input to the control unit 10 via a network (hereinafter sometimes referred to as "CAN") that conducts communication for flowing signals for controlling various devices mounted on the vehicle 100.

[0017] (Control unit 10) The control unit 10 includes a first control device 20 that controls the current flowing through the first winding set 111, and a second control device 50 that controls the current flowing through the second winding set 112. The first control device 20 and the second control device 50 are each capable of communicating with the vehicle control device 5 via CAN.

[0018] (First control device 20) The first control device 20 includes a first control unit 21 that determines the current value to be supplied to the first winding assembly 111, and a first drive unit 22 that supplies the determined current value to the first winding assembly 111. The first control unit 21 has an arithmetic logic circuit consisting of a CPU (not shown), ROM (not shown), RAM (not shown), etc. The ROM stores the basic program (operating system) and various settings that are executed by the CPU. The CPU uses the RAM as a work area and executes the application program read from the ROM.

[0019] The first control unit 21 has a first setting unit 30 that sets the target current It1 to be supplied to the first winding assembly 111. The first setting unit 30 will be described in detail later. Furthermore, the first control unit 21 has a first feedback unit (hereinafter sometimes referred to as "FB") 40 that performs feedback control so that the deviation between the target current It1 set by the first setting unit 30 and the current actually flowing through the first winding assembly 111 becomes zero.

[0020] The first drive unit 22 includes a first inverter circuit 221 that supplies a power supply voltage from a battery (not shown) provided in the automobile to the first winding assembly 111, and a first generation unit 222 that generates a PWM signal to control the drive of the first inverter circuit 221 based on a drive command signal from the first control unit 21, and outputs the generated PWM signal.

[0021] (Second control device 50) The second control device 50 includes a second control unit 51 that determines the current value to be supplied to the second winding assembly 112, and a second drive unit 52 that supplies the determined current value to the second winding assembly 112. The second control unit 51 has an arithmetic logic circuit consisting of a CPU (not shown), ROM (not shown), RAM (not shown), etc. The ROM stores the basic program (operating system) and various settings that are executed by the CPU. The CPU uses the RAM as a work area and executes the application program read from the ROM.

[0022] The second control unit 51 and the first control unit 21 can communicate with each other via the network 45. The network 45 is not particularly limited as long as it is a communication network used for data communication between control units, and can be wired or wireless, or a combination of both. In the case of wireless, for example, Bluetooth® can be used.

[0023] The second control unit 51 has a second setting unit 60 that sets the target current It2 to be supplied to the second winding assembly 112. The second setting unit 60 will be described in detail later. Furthermore, the second control unit 51 includes a second FB unit 70 that performs feedback control so that the deviation between the target current It2 set by the second setting unit 60 and the current actually flowing through the second winding assembly 112 becomes zero.

[0024] The second drive unit 52 includes a second inverter circuit 521 that supplies a power supply voltage from a battery (not shown) to the second winding assembly 112, and a second generation unit 522 that generates a PWM signal to control the drive of the second inverter circuit 521 based on a drive command signal from the second control unit 51, and outputs the generated PWM signal.

[0025] {Regarding the first setting unit 30 and the second setting unit 60} Figure 3 shows an example of the schematic configuration of the first setting unit 30 and the second setting unit 60. The first setting unit 30 of the first control unit 21 and the second setting unit 60 of the second control unit 51 will be described below.

[0026] (First setting section 30) The first setting unit 30 has a first EPS unit 31 that sets a target current Ie1 using the steering torque T detected by the torque sensor 109. The first EPS unit 31 sets a target current Ie1 for the electric motor 110 to generate torque to assist the driver in steering the steering wheel 102. The first EPS unit 31 can be exemplified by setting the target current Ie1 by having the CPU read and execute programs and various settings for functions that assist the driver's steering, which are stored in the ROM.

[0027] The first EPS unit 31 sets the target current Ie1 using the steering torque T and the vehicle speed Vc. For example, the first EPS unit 31 sets the target current Ie1 to a positive value when the steering torque T is positive, and to a negative value when the steering torque T is negative. Furthermore, for example, the first EPS unit 31 sets the target current Ie1 to increase as the absolute value of the steering torque T increases when the vehicle speed Vc is the same, and sets the target current Ie1 to increase as the vehicle speed Vc is low when the absolute value of the steering torque T is the same.

[0028] The first setting unit 30 further includes a first automatic unit 32 that sets the target current Is1 when the steering device 6 performs automatic steering. The first automatic unit 32 sets the target current Is1 based on information sent from other systems such as the vehicle control device 5. The first automatic unit 32 includes a collision avoidance unit 321 that sets a target current Ib for collision avoidance, a skidding suppression unit 322 that sets a target current Ir for suppressing skidding of the vehicle 100, and a parking support unit 323 that sets a target current Ip for assisting the rolling of the front wheels 101 when parking the vehicle 100 in a parking lot or the like.

[0029] The collision avoidance unit 321 sets the target current Ib by having the CPU read and execute the program and various settings for the collision avoidance function stored in the ROM. The lateral slip suppression unit 322 sets the target current Ir by having the CPU read and execute the program and various settings for the lateral slip suppression function stored in the ROM. The parking assistance unit 323 sets the target current Ip by having the CPU read and execute programs and various settings for the parking assistance function that are stored in the ROM.

[0030] Furthermore, the first automatic unit 32 has a first automatic setting unit 324 that outputs a target current Id1 (=Ib+Ir+Ip) obtained by adding the target current Ib set by the collision avoidance unit 321, the target current Ir set by the skid suppression unit 322, and the target current Ip set by the parking support unit 323. Furthermore, the first setting unit 30 has a first total setting unit 325 that outputs a target current Is1 (=Id1+Id2) obtained by adding the target current Id1 output by the first automatic setting unit 324 and the target current Id2 output by the second automatic setting unit 624, which will be described later.

[0031] The first setting unit 30 further includes a first abnormality setting unit 33 that sets a target current If1 for rolling the front wheel 101 in the event of an abnormality in the second control unit 51. In the automatic steering system, even if an abnormality occurs during the execution of automatic steering in response to the automatic driving control or driver assistance control of the vehicle 100, it is necessary to continue minimum operations until the driver returns to steering or until the vehicle 100 comes to a stop. An example of such minimum operations is the correction control of the rolling angle of the front wheels 101. For example, if an abnormality occurs in the second control unit 51 while automatic steering control is being performed and the vehicle 100 is turning a corner, it is necessary to control the rolling angle of the front wheels 101 to an appropriate angle (for example, an angle that prevents the vehicle 100 from going outside the lane) until the turn is completed. The first abnormality setting unit 33 sets a target current If1 for correcting the rolling angle of the front wheels 101 until the vehicle 100 has completed the turn. The first abnormal condition setting unit 33 reads a program and various settings necessary to perform a predetermined minimum operation from the CPU and sets the target current If1.

[0032] The first setting unit 30 further includes a first target setting unit 35 that sets the target current It1 using the target current Ie1 set by the first EPS unit 31, the target current Is1 set by the first automatic unit 32, and the target current If1 set by the first abnormal setting unit 33. The first target setting unit 35 sets the target current It1 as a value obtained by adding the target current Ie1, the target current Is1, and the target current If1 (It1 = Ie1 + Is1 + If1).

[0033] (Second setting section 60) The second setting unit 60 has a second EPS unit 61 that sets a target current Ie2 using the steering torque T detected by the torque sensor 109. The second EPS unit 61 sets the target current Ie2 for the electric motor 110 to generate torque to assist the driver in steering the steering wheel 102. The second EPS unit 61 is the same as the first EPS unit 31, so a detailed explanation is omitted.

[0034] The second setting unit 60 has a second automatic unit 62 that sets the target current Is2 when the steering device 6 performs automatic steering. The second automatic unit 62 sets the target current Is2 based on information sent from other systems such as the vehicle control device 5. The second automatic unit 62 includes a maintenance unit 621 that sets a target current Ik when controlling the rolling angle of the front wheels 101 so that the vehicle 100 maintains its lane, and a change unit 622 that sets a target current Ic when controlling the rolling angle of the front wheels 101 so that the vehicle 100 changes lanes.

[0035] The maintenance unit 621 sets the target current Ik by having the CPU read and execute the program and various settings for the lane keeping assist function stored in the ROM. The modification unit 622 sets the target current Ic by having the CPU read and execute the program for the lane change assistance function and various settings stored in the ROM.

[0036] Furthermore, the second automatic unit 62 has a second automatic setting unit 624 that outputs a target current Id2 (=Ik+Ic) obtained by adding the target current Ik set by the maintenance unit 621 and the target current Ic set by the change unit 622. Furthermore, the second automatic unit 62 has a second total setting unit 625 that outputs a target current Is2 (=Id2+Id1) obtained by adding the target current Id2 output by the second automatic setting unit 624 and the target current Id1 output by the first automatic setting unit 324 of the first setting unit 30.

[0037] The second setting unit 60 further includes a second abnormality setting unit 63 that sets a target current If2 for steering assistance in the event of an abnormality in the first control unit 21. The second abnormality setting unit 63 is the same as the first abnormality setting unit 33, so a detailed explanation is omitted.

[0038] The second setting unit 60 further includes a second target setting unit 65 that sets the target current It2 using the target current Ie2 set by the second EPS unit 61, the target current Is2 set by the second automatic unit 62, and the target current If2 set by the second abnormal setting unit 63. The second target setting unit 65 sets the target current It2 as a value obtained by adding the target current Ie2, the target current Is2, and the target current If2 (It2 = Ie2 + Is2 + If2).

[0039] In the following, the drive control of the electric motor 110 performed by the first control device 20, which sets a target current Ie1 in the first EPS unit 31 and supplies a current corresponding to the target current Ie1 to the first winding assembly 111 as a result of setting the target current Ie1, may be referred to as "first EPS control." Furthermore, the drive control of the electric motor 110 performed by the first control device 20 setting a target current Id1 in the first automatic setting unit 324 and supplying a current corresponding to the target current Id1 to the first winding assembly 111 as a result of setting the target current Id1 may be referred to as "first automatic steering control." Furthermore, the drive control of the electric motor 110 performed by the first control device 20 adding the target current Id2 received from the second automatic setting unit 624 in the first total setting unit 325, and supplying a current corresponding to the target current Id2 to the first winding set 111 as a result of adding the target current Id2, may be referred to as the "second automatic steering control." Furthermore, the drive control of the electric motor 110 performed by the first control device 20, which sets a target current If1 in the first abnormality setting unit 33 and supplies a current corresponding to the target current If1 to the first winding set 111 as a result of setting the target current If1, may be referred to as "first abnormality control."

[0040] Furthermore, the drive control of the electric motor 110 performed by the second control device 50, which sets a target current Ie2 in the second EPS unit 61 and supplies a current corresponding to the target current Ie2 to the second winding assembly 112 as a result of setting the target current Ie2, may be referred to as "second EPS control." Since the target current Ie1 and target current Ie2 are the same, the driving force of the electric motor 110 under the first EPS control and the driving force of the electric motor 110 under the second EPS control are the same. Hereafter, when there is no need to distinguish between the first EPS control and the second EPS control, the first EPS control and the second EPS control may be collectively referred to as "EPS control."

[0041] Furthermore, the drive control of the electric motor 110 performed by the second control device 50, which sets a target current Id2 in the second automatic setting unit 624 and supplies a current corresponding to the target current Id2 to the second winding assembly 112 as a result of setting the target current Id2, may be referred to as "second automatic steering control." In other words, the second automatic steering control is either the drive control of the electric motor 110 performed by the second control device 50, which supplies a current corresponding to the target current Id2 to the second winding assembly 112, or the drive control of the electric motor 110 performed by the first control device 20, which supplies a current corresponding to the target current Id2 to the first winding assembly 111. In either case, since the second automatic steering control is performed using the target current Id2 set by the second control device 50, the second automatic steering control can be considered as a function executed by the second control device 50.

[0042] Furthermore, the drive control of the electric motor 110 performed by the second control device 50, which adds the target current Id1 received from the first automatic setting unit 324 in the second total setting unit 625 and supplies a current corresponding to the target current Id1 to the second winding set 112 as a result of adding the target current Id1, may be referred to as the "first automatic steering control." In other words, the first automatic steering control is either the drive control of the electric motor 110 performed by the second control device 50 supplying a current corresponding to the target current Id1 to the second winding set 112, or the drive control of the electric motor 110 performed by the first control device 20 supplying a current corresponding to the target current Id1 to the first winding set 111. In either case, since the first automatic steering control is performed using the target current Id1 set by the first control device 20, the first automatic steering control can be considered as a function executed by the first control device 20.

[0043] Furthermore, the drive control of the electric motor 110 performed by the second control device 50, which sets a target current If2 in the second abnormal time setting unit 63 and supplies a current corresponding to the target current If2 to the second winding assembly 112 as a result of setting the target current If2, may be referred to as the "second abnormal time control." Since the target current If1 and the target current If2 are the same, the driving force of the electric motor 110 under the first abnormal time control and the driving force of the electric motor 110 under the second abnormal time control are the same. Hereafter, when there is no need to distinguish between the first abnormal time control and the second abnormal time control, the first abnormal time control and the second abnormal time control may be collectively referred to as "abnormal time control."

[0044] (Operation of steering system 1) Figure 4 is a diagram illustrating the operation of the steering device 6. In the following explanation, a situation where there is an abnormality in communication between the first control unit 21 and the second control unit 51 will be referred to as a "communication abnormality," a situation where there is an abnormality in either the first control unit 21 or the second control unit 51 will be referred to as a "control unit abnormality," and a time when there is neither a communication abnormality nor a control unit abnormality will be referred to as a "normal time."

[0045] 《Normal time》 Under normal conditions, the first control device 20 and the second control device 50 of the steering system 6 perform EPS control, first automatic steering control, and second automatic steering control, respectively. Specifically, the first setting unit 30 of the first control unit 21 sets a target current It1 (=Ie1+Id1+Id2) which is the sum of the target current Ie1 set by the first EPS unit 31, the target current Id1 set by the first automatic setting unit 324, and the target current Id2 set by the second automatic setting unit 624. In addition, the second setting unit 60 of the second control unit 51 sets a target current It2 (=Ie2+Id2+Id1) which is the sum of the target current Ie2 set by the second EPS unit 61, the target current Id2 set by the second automatic setting unit 624, and the target current Id1 set by the first automatic setting unit 324. Since the target current Ie1 set by the first EPS unit 31 and the target current Ie2 set by the second EPS unit 61 are the same, the target current It1 set by the first setting unit 30 of the first control unit 21 and the target current It2 set by the second setting unit 60 of the second control unit 51 are the same value. Furthermore, the first abnormality setting unit 33 and the second abnormality setting unit 63 do not set target current If1 and target current If2, respectively, because no abnormality has occurred in the first control unit 21 and the second control unit 51.

[0046] As a result, under normal conditions, the front wheels 101 are moved by a driving force that is the sum of the driving force resulting from the supply of current to the first winding assembly 111 and the driving force resulting from the supply of current to the second winding assembly 112, both based on the same target current value.

[0047] In case of communication failure When there is no abnormality in communication between the first control unit 21 and the second control unit 51, the first setting unit 30 of the first control unit 21 can receive the target current Id2 output by the second automatic setting unit 624 of the second control unit 51, and the second setting unit 60 of the second control unit 51 can receive the target current Id1 output by the first automatic setting unit 324 of the first control unit 21. On the other hand, when there is a communication abnormality, the first setting unit 30 of the first control unit 21 cannot receive the target current Id2 output by the second automatic setting unit 624 of the second control unit 51, and the second setting unit 60 of the second control unit 51 cannot receive the target current Id1 output by the first automatic setting unit 324 of the first control unit 21.

[0048] Therefore, the first control device 20 performs EPS control and the first automatic operation control, and the second control device 50 performs EPS control and the second automatic operation control. In other words, the first setting unit 30 of the first control unit 21 sets a target current It1 (=Ie1+Id1) which is the sum of the target current Ie1 set by the first EPS unit 31 and the target current Id1 set by the first automatic setting unit 324. Also, the second setting unit 60 of the second control unit 51 sets a target current It2 (=Ie2+Id2) which is the sum of the target current Ie2 set by the second EPS unit 61 and the target current Id2 set by the second automatic setting unit 624.

[0049] Thus, in the event of a communication error, the first setting unit 30 does not receive the target current Id2 from the second setting unit 60 of the second control unit 51, so it sets the target current It1 (=Ie1+Id1) which is the sum of the target current Ie1 and the target current Id1. Also, the second setting unit 60 does not receive the target current Id1 from the first setting unit 30 of the first control unit 21, so it sets the target current It2 (=Ie2+Id2) which is the sum of the target current Ie2 and the target current Id2.

[0050] As a result, in the event of a communication error, the front wheels 101 are moved by a driving force that is the sum of the driving force caused by the supply of current to the first winding set 111 and the driving force caused by the supply of current to the second winding set 112. However, the current values ​​supplied to the first winding set 111 and the second winding set 112 are less than or equal to the current values ​​under normal conditions. However, in EPS control, the current values ​​remain the same as under normal conditions even in the event of a communication error.

[0051] 《When the control unit malfunctions》 The first control unit 21 and the second control unit 51 each have a function to diagnose whether or not they are operating normally. If either the first control unit 21 or the second control unit 51 is not operating normally, they transmit that fact to the vehicle control device 5. When the vehicle control device 5 receives a notification from either the first control unit 21 or the second control unit 51 that the control unit is not operating normally, it transmits that fact to the other control unit. As a result, the other control unit understands that there is a malfunction in the other control unit. For example, if the vehicle control device 5 receives a notification from the second control unit 51 that it is not operating normally, it transmits a notification to the first control unit 21 that the second control unit 51 is not operating normally. As a result, the first control unit 21 understands that there is a malfunction in the second control unit 51.

[0052] In the first control unit 21, when a control unit malfunction occurs and the second control unit 51 is not operating normally, the first automatic unit 32 does not set the target current Is1. That is, the collision avoidance unit 321, the skid suppression unit 322, and the parking assistance unit 323 do not set the target currents Ib, Ir, and Ip, respectively. Also, the first automatic setting unit 324 and the first total setting unit 325 do not output the target current Id1 and target current Is1, respectively. However, when a control unit malfunction occurs and the second control unit 51 is not operating normally, the collision avoidance unit 321, the skid suppression unit 322, and the parking assistance unit 323 set the target currents Ib, Ir, and Ip, respectively, but the first automatic setting unit 324 may either not output the target current Id1 or output 0 as the target current Id1. If the second control unit 51 does not operate normally, the first total setting unit 325 does not receive the target current Id2, and therefore either does not output the target current Is1 or outputs 0 as the target current Is1.

[0053] Furthermore, in the first control unit 21, when the second control unit 51 is not operating normally due to a control unit malfunction, the first EPS unit 31 sets the target current Ie1, and the first malfunction setting unit 33 sets the target current If1. The first target setting unit 35 then sets the target current It1 (=Ie1+If1) as the sum of the target current Ie1 set by the first EPS unit 31 and the target current If1 set by the first abnormal condition setting unit 33. Thus, if an abnormality occurs in the second control unit 51, the first control device 20 will perform EPS control and abnormality control without performing automatic steering control.

[0054] On the other hand, in the second control unit 51, if a control unit malfunction occurs and the first control unit 21 is not operating normally, the second automatic unit 62 does not set the target current Is2. In other words, the maintenance unit 621 and the modification unit 622 do not set the target current Ik and target current Ic, respectively. Also, the second automatic setting unit 624 and the second total setting unit 625 do not output the target current Id2 and target current Is2, respectively. However, if a control unit malfunction occurs and the first control unit 21 is not operating normally, the maintenance unit 621 and the modification unit 622 set the target current Ik and target current Ic, respectively, but the second automatic setting unit 624 may either not output the target current Id2 or output 0 as the target current Id2. If the first control unit 21 is not operating normally, the second total setting unit 625 does not receive the target current Id1, so it either does not output the target current Is2 or outputs 0 as the target current Is2.

[0055] Furthermore, in the second control unit 51, when the first control unit 21 is not operating normally due to a control unit malfunction, the second EPS unit 61 sets the target current Ie2, and the second malfunction setting unit 63 sets the target current If2. Then, the second target setting unit 65 sets the target current It2 (=Ie2+If2) as the sum of the target current Ie2 set by the second EPS unit 61 and the target current If2 set by the second abnormal condition setting unit 63. Thus, if an abnormality occurs in the first control unit 21, the second control unit 50 performs EPS control and abnormality control without performing automatic steering control.

[0056] Furthermore, if the vehicle control device 5 receives a notification from either the first control unit 21 or the second control unit 51 that the control unit is not functioning properly, it will notify the driver that automatic steering control cannot be performed. The manner of notification is not particularly limited. For example, the vehicle control device 5 may display a message on the instrument panel or navigation system display of the vehicle 100 stating that an abnormality has occurred and therefore automatic steering control cannot be performed.

[0057] As explained above, in the steering system 1, redundancy is ensured by configuring both the first control unit 20 and the second control unit 50 to perform the same EPS control, so that the control unit 10 can perform EPS control even if an abnormality occurs in either the first control unit 21 or the second control unit 51.

[0058] On the other hand, with respect to automatic steering control that is not required to be executed even if a malfunction occurs in either the first control unit 21 or the second control unit 51, redundancy is not ensured by not configuring both the first control device 20 and the second control device 50 to execute the same automatic steering control. With the steering system 1 configured in this way, the following advantages can be enjoyed.

[0059] For example, in case of a malfunction in one of the control devices, the first control device 20 and the second control device 50 can be configured to perform the same automatic steering control, thereby ensuring redundancy.

[0060] Figure 5 is an example of a block diagram of the first control device 520 and the second control device 550 according to a comparative example. In the comparative example, the first control device 520 and the second control device 550 differ from the first control device 20 and the second control device 50 according to the first embodiment in that the first setting unit 530 corresponds to the first setting unit 30 and the second setting unit 560 corresponds to the second setting unit 60, respectively. The differences from the first control device 20 and the second control device 50 according to the first embodiment will be explained below. Components having the same structure and function in the first control device 20 and the second control device 50 according to the first embodiment and the first control device 520 and the second control device 550 according to the comparative example are denoted by the same reference numerals, and their detailed explanations will be omitted.

[0061] The first setting unit 530 in the comparative example differs from the first setting unit 30 in the first embodiment in that it has a first automatic unit 532 which corresponds to the first automatic unit 32, and does not have a first abnormal setting unit 33. In other words, the first setting unit 530 in the comparative example has a first EPS unit 31 and a first automatic unit 532.

[0062] The first automatic unit 532 comprises the functions of the first automatic unit 32 according to the first embodiment and the functions of the second automatic unit 62 of the second control device 50. For example, the first automatic unit 532 comprises the collision avoidance unit 321, the skid suppression unit 322, and the parking support unit 323 of the first automatic unit 32, and the maintenance unit 621 and the modification unit 622 of the second automatic unit 62. The first automatic setting unit 324 outputs a target current Is1 (=Ib+Ir+Ip+Ik+Ic) obtained by adding the target current Ib set by the collision avoidance unit 321, the target current Ir set by the skid suppression unit 322, the target current Ip set by the parking support unit 323, the target current Ik set by the maintenance unit 621, and the target current Ic set by the modification unit 622.

[0063] Furthermore, the second setting unit 560 in the comparative example differs from the second setting unit 60 in the first embodiment in that it has a second automatic unit 562 which corresponds to the second automatic unit 62, and does not have a second abnormal setting unit 63. In other words, the second setting unit 560 in the comparative example has a second EPS unit 61 and a second automatic unit 562.

[0064] The second automatic unit 562 comprises the functions of the second automatic unit 62 according to the first embodiment and the functions of the first automatic unit 32 of the first control device 20. For example, the second automatic unit 562 comprises the maintenance unit 621 and the modification unit 622 of the second automatic unit 62, and the collision avoidance unit 321, the skid suppression unit 322, and the parking support unit 323 of the first automatic unit 32. The second automatic setting unit 624 outputs a target current Is2 (=Ib+Ir+Ip+Ik+Ic) obtained by adding the target current Ib set by the collision avoidance unit 321, the target current Ir set by the skid suppression unit 322, the target current Ip set by the parking support unit 323, the target current Ik set by the maintenance unit 621, and the target current Ic set by the modification unit 622. In other words, the second automatic unit 562, like the first automatic unit 532, has all the functions of the first automatic unit 32 and the second automatic unit 62 according to the first embodiment.

[0065] The first control device 520, configured as described above, differs from the first control device 20 according to the first embodiment in that the maintenance unit 621 and the modification unit 622 each need to store programs and various settings necessary for setting target currents Ik and Ic in ROM. Furthermore, the second control device 550 differs from the second control device 50 according to the first embodiment in that the collision avoidance unit 321, the skid suppression unit 322, and the parking support unit 323 each need to store programs and various settings necessary for setting target currents Ib, Ir, and Ip in ROM.

[0066] In other words, unlike the first control device 520 according to the comparative example, the first control device 20 according to the first embodiment does not have a maintenance unit 621 and a modification unit 622, so it does not need to store programs and various settings necessary for setting the target current Ik and target current Ic in ROM. On the other hand, the amount of programs and various settings necessary for the first abnormal setting unit 33 to set the target current If1, which the first control device 20 needs to store in ROM, is less than the amount of programs and various settings necessary for setting the target current Ik and target current Ic. As a result, the first control device 20 according to the first embodiment may have less storage space for programs and the like than the first control device 520 according to the comparative example. Also, the load required for the maintenance unit 621 and the modification unit 622 to set the target current Ik and target current Ic, respectively, is higher than the load required for the first abnormal setting unit 33 to set the target current If1. As a result, the first control device 20 according to the first embodiment can be one with inferior performance and memory capacity compared to the first control device 520 according to the comparative example, thus lowering the product cost compared to the first control device 520. Alternatively, if the first control device 20 according to the first embodiment has performance and memory capacity equivalent to the first control device 520 according to the comparative example, it can be equipped with functions necessary for automatic steering in addition to the collision avoidance unit 321, the skid suppression unit 322, and the parking assist unit 323, thus enabling efficient use of valuable resources.

[0067] Furthermore, unlike the comparative example second control device 550, the second control device 50 according to the first embodiment does not include a collision avoidance unit 321, a skid suppression unit 322, and a parking support unit 323. Therefore, it is not necessary to store programs and various settings required to set the target currents Ib, Ir, and Ip in the ROM. On the other hand, the amount of programs and various settings required for the second abnormal setting unit 63 to set the target current If2, which the second control device 50 needs to store in the ROM, is less than the amount of programs and various settings required to set the target currents Ib, Ir, and Ip. As a result, the second control device 50 according to the first embodiment may require less storage space for programs and other data than the second control device 550 according to the comparative example. Also, the load required for the collision avoidance unit 321, the skid suppression unit 322, and the parking support unit 323 to set the target currents Ib, Ir, and Ip, respectively, is higher than the load required for the second abnormal setting unit 63 to set the target current If2. As a result, the second control device 50 according to the first embodiment can be one with inferior performance and memory capacity compared to the second control device 550 according to the comparative example, thus lowering the product cost compared to the second control device 550. Alternatively, if the second control device 50 according to the first embodiment has performance and memory capacity equivalent to the second control device 550 according to the comparative example, it can be equipped with functions necessary for automatic steering in addition to the maintenance unit 621 and the modification unit 622, thus enabling efficient use of valuable resources.

[0068] As described above, the control unit 10 includes a plurality of control devices (for example, a first control device 20 and a second control device 50) that control the drive of an electric motor 110, which is an example of an electric motor. The plurality of control devices have an EPS control function as an example of a general function used to operate the electric motor 110, both in normal operation when all of the control devices are functioning correctly and in abnormal operation when one of the control devices is malfunctioning. In addition, the plurality of control devices have distributed automatic steering control functions as an example of a normal operation function that is used in normal operation but not required in abnormal operation. For example, the first control device 20 sets a target current Id1 used for the first automatic steering control function, and the second control device 50 sets a target current Id2 used for the second automatic steering control function.

[0069] With the control unit 10 configured as described above, the performance of each of the multiple control devices can be reduced. Furthermore, the amount of memory required for programs and other data in each of the multiple control devices can be reduced. As a result, the product cost of each of the multiple control devices can be lowered. Additionally, with the control unit 10, valuable resources can be utilized more efficiently compared to a configuration where the automatic steering control function is not distributed across multiple control devices.

[0070] In the first embodiment, the first setting unit 30 of the first control device 20 has a collision avoidance unit 321, a skid suppression unit 322, and a parking support unit 323, and the second setting unit 60 of the second control device 50 has a maintenance unit 621 and a modification unit 622. However, the number and types of functions distributed to the first setting unit 30 and the second setting unit 60 are not particularly limited.

[0071] Furthermore, while an example is shown where the control device consists of two control devices, a first control device 20 and a second control device 50, it is not limited to two, and may consist of three or more control devices. For example, the electric motor 110 may have three or more winding sets, and three or more control devices may be provided to control the value of the current supplied to each of the three or more winding sets.

[0072] Furthermore, in the control unit 10, each of the multiple control devices has an abnormality control function, which is an example of an abnormality function used to operate the electric motor 110 in the event of an abnormality. This allows, for example, if an abnormality occurs in one of the control devices, it to continue minimum operations such as correcting the rolling angle of the front wheels 101.

[0073] Furthermore, in the control unit 10, the first control unit 20, one of the multiple control devices, sets a target current Id1 as an example of a first control command value for realizing the first automatic steering control function, which is an example of the first function among the normal functions. The second control unit 50 sets a target current Id2 as an example of a second control command value for realizing the second automatic steering control function, which is an example of the second function among the normal functions. The second control unit 50 then transmits the set target current Id2 to the first control unit 20, and the first control unit 20 controls the drive of the electric motor 110 using the set target current Id1 and the target current Id2 received from the second control unit 50. As a result, the control unit 10 can reduce product costs or leave room to include other functions other than the function of setting target current Id2, compared to a configuration in which the first control unit 20 has a function to set target current Id2 in addition to the function of setting target current Id1.

[0074] Furthermore, the first control device 20 transmits the set target current Id1 to the second control device 50, and the second control device 50 controls the drive of the electric motor 110 using the set target current Id2 and the target current Id1 received from the first control device 20. As a result, the control unit 10 can either reduce product costs or leave room to include other functions besides the function of setting target current Id1, compared to a configuration in which the second control device 50 has the function of setting target current Id1 in addition to the function of setting target current Id2, thus enabling efficient use of valuable resources.

[0075] If either the first control device 20 or the second control device 50 is malfunctioning, the control device will not control the drive of the electric motor 110 using the control command value it transmits, which is either the target current Id1 or target current Id2. For example, if the second control device 50 is malfunctioning, the first control device 20 will either not output target current Id1 or output 0. Since automatic steering control is not necessarily a required function when either the first control device 20 or the second control device 50 fails, the load on the normal control device can be reduced, allowing for efficient use of valuable resources.

[0076] However, if either the first control device 20 or the second control device 50 is malfunctioning, the control device may control the drive of the electric motor 110 using a control command value transmitted by itself from among the target currents Id1 or target currents Id2. For example, the first control device 20 may perform first automatic steering control if the second control device 50 is malfunctioning. Also, the second control device 50 may perform second automatic steering control if the first control device 20 is malfunctioning.

[0077] <Second Embodiment> Figure 6 shows an example of a schematic configuration of the control unit 810 according to the second embodiment. Figure 7 is a diagram illustrating the operation of the steering device 86 according to the second embodiment. The steering device 86 according to the second embodiment differs from the steering device 6 according to the first embodiment in that it does not perform automatic steering control even in the event of a communication error. The differences from the steering device 6 according to the first embodiment will be described below, and components having the same functions as the steering device 6 according to the first embodiment will be denoted by the same reference numerals, and their detailed descriptions will be omitted.

[0078] The steering device 86 according to the second embodiment includes a control unit 810 which corresponds to the control unit 10 according to the first embodiment. The control unit 810 includes a first control device 820 corresponding to the first control device 20 according to the first embodiment, and a second control device 850 corresponding to the second control device 50 according to the first embodiment. The first control device 820 includes a first control unit 821 corresponding to the first control unit 21 in the first embodiment, and a first drive unit 22 (see Figure 2). The second control device 850 includes a second control unit 851 corresponding to the second control unit 51 in the first embodiment, and a second drive unit 52 (see Figure 2).

[0079] The first control unit 821 includes a first setting unit 830, which corresponds to the first setting unit 30 in the first embodiment, and a first FB unit 40 (see Figure 2). The first setting unit 830 includes a first EPS unit 31, a first automatic unit 832 corresponding to the first automatic unit 32 in the first embodiment, a first abnormal condition setting unit 33, and a first target setting unit 35. The first automatic unit 832 has a collision avoidance unit 841, a lateral skid suppression unit 842, a parking support unit 843, a first automatic setting unit 844, and a first total setting unit 845, which correspond to the collision avoidance unit 321, a lateral skid suppression unit 322, a parking support unit 323, a first automatic setting unit 324, and a first total setting unit 325, respectively, according to the first embodiment.

[0080] The second control unit 851 includes a second setting unit 860, which corresponds to the second setting unit 60 in the first embodiment, and a second FB unit 70 (see Figure 2). The second setting unit 860 includes a second EPS unit 61, a second automatic unit 862 corresponding to the second automatic unit 62 in the first embodiment, a second abnormal condition setting unit 63, and a second target setting unit 65. The second automatic unit 862 has a maintenance unit 871, a modification unit 872, a second automatic setting unit 874, and a second total setting unit 875, which correspond to the maintenance unit 621, modification unit 622, second automatic setting unit 624, and second total setting unit 625 in the first embodiment.

[0081] In the control unit 810 according to the second embodiment, when a communication error occurs, the first setting unit 830 of the first control unit 821 cannot receive the target current Id2 output by the second automatic setting unit 874 of the second control unit 851, and the second setting unit 860 of the second control unit 851 cannot receive the target current Id1 output by the first automatic setting unit 844 of the first control unit 821. Therefore, the first setting unit 830 and the second setting unit 860 can each recognize that a communication error has occurred.

[0082] Furthermore, if a communication error occurs, the first automatic unit 832 of the first setting unit 830 may choose not to set the target current Is1, similar to the case of a control unit malfunction where the second control unit 851 does not operate normally. Also, if a communication error occurs, the second automatic unit 862 of the second setting unit 860 may choose not to set the target current Is2, similar to the case of a control unit malfunction where the first control unit 821 does not operate normally. As a result, the steering device 86 according to the second embodiment can be configured not to perform automatic steering control in the event of a communication error.

[0083] Furthermore, if at least one of the first control unit 821 or the second control unit 851 detects that a communication error has occurred, it may notify the vehicle control device 5. When the vehicle control device 5 receives notification that a communication error has occurred, it is preferable to inform the driver that automatic steering control cannot be performed.

[0084] <Third Embodiment> Figure 8 shows an example of a schematic configuration of the control unit 910 according to the third embodiment. Figure 9 is a diagram illustrating the operation of the steering device 96 according to the third embodiment. The steering device 96 according to the third embodiment differs from the steering device 6 according to the first embodiment in that it has an electric motor 310 corresponding to the electric motor 110 and a control unit 910 corresponding to the control unit 10. The differences from the steering device 6 according to the first embodiment will be described below, and components having the same functions as the steering device 6 according to the first embodiment will be denoted by the same reference numerals, and their detailed descriptions will be omitted.

[0085] The electric motor 310 differs from the electric motor 110 according to the first embodiment in that it is a three-phase motor having one set of windings (not shown). The control unit 910 includes a first control device 20, a second control device 50, and a switching device 90 that switches between the first control device 20 and the second control device 50 as a control device for controlling the current flowing through the winding assembly of the electric motor 310.

[0086] The switching device 90, under normal conditions and in the event of a communication error, controls the current flowing through the windings of the electric motor 310 using either the first control device 20 or the second control device 50. When the control unit of the first control device malfunctions, the switching device 90 switches to control the current flowing through the windings of the electric motor 310 using the other control device. The switching device 90 can be exemplified by a signal output from the other control device or the vehicle control device 5.

[0087] For example, the switching device 90 controls the current flowing through the windings of the electric motor 310 using the first control device 20 during normal operation and in the event of a communication error. When the control unit of the first control unit 21 malfunctions, the switching device 90 switches to control the current flowing through the windings of the electric motor 310 using the second control device 50. The switching device 90 is preferably switched based on a signal output from the second control unit 51 or the vehicle control device 5.

[0088] In the control unit 910 configured as described above, similar to the control unit 10 according to the first embodiment, the first control device 20 and the second control device 50 can be made of components with inferior performance and memory capacity compared to the first control device 520 and the second control device 550 of the comparative example, thereby reducing product costs. Alternatively, if the first control device 20 and the second control device 50 have performance and memory capacity equivalent to the first control device 520 and the second control device 550 of the comparative example, the entire control unit 910 can be equipped with more functions used for automatic steering, thus efficiently utilizing valuable resources.

[0089] <Fourth Embodiment> Figure 10 shows an example of a schematic configuration of the control unit 410 according to the fourth embodiment. The steering device 46 according to the fourth embodiment differs from the steering device 6 according to the first embodiment, the steering device 86 according to the second embodiment, and the steering device 96 according to the third embodiment in that it has a first setting unit 930 corresponding to the first setting unit 30 and a second setting unit 960 corresponding to the second setting unit 60. The differences from the steering device 6 according to the first embodiment will be described below, and components having the same functions as the steering device 6 according to the first embodiment will be denoted by the same reference numerals, and their detailed descriptions will be omitted.

[0090] The first setting unit 930 differs from the first setting unit 30 in that it has a first EPS unit 940 which corresponds to the first EPS unit 31. The second setting unit 960 differs from the second setting unit 60 in that it has a second EPS unit 970 which corresponds to the second EPS unit 61. Furthermore, in the steering device 46 according to the fourth embodiment, similar to how the steering device 6 according to the first embodiment implements functions related to automatic steering control in a distributed manner, the functions related to EPS control are implemented by distributing them between the first EPS unit 940 and the second EPS unit 970.

[0091] More specifically, the first EPS unit 940 has a first section 941 and a second section 942 that set target currents I1 and I2 for realizing a first function and a second function, respectively, which are some of the functions related to EPS control. The second EPS unit 970 has a third section 971 and a fourth section 972 that set target currents I3 and I4 for realizing a third function and a fourth function, respectively, which are some of the functions related to EPS control other than those realized by the first EPS unit 940.

[0092] Furthermore, the first EPS unit 940 has a first EPS setting unit 944 that outputs a target current Ih1 (=I1+I2) obtained by adding the target current I1 set by the first unit 941 and the target current I2 set by the second unit 942. Furthermore, the second EPS unit 970 has a second EPS setting unit 974 that outputs a target current Ih2 (=I3+I4) obtained by adding the target current I3 set by the third unit 971 and the target current I4 set by the fourth unit 972.

[0093] Furthermore, the first EPS unit 940 has a first EPS totaling unit 945 that outputs the current obtained by adding the target current Ih1 output by the first EPS setting unit 944 and the target current Ih2 output by the second EPS setting unit 974 as the target current Ie1 (=Ih1+Ih2) set by the first EPS unit 940. Furthermore, the second EPS unit 970 has a second EPS totaling unit 975 that outputs the current obtained by adding the target current Ih2 output by the second EPS setting unit 974 and the target current Ih1 output by the first EPS setting unit 944 as the target current Ie2 (=Ih1+Ih2) set by the second EPS unit 970.

[0094] With the steering device 46 according to the fourth embodiment configured as described above, the functions related to EPS control are distributed between the first EPS unit 940 and the second EPS unit 970, which allows for lower product costs and efficient utilization of valuable resources. Although the first EPS unit 940 has a first unit 941 and a second unit 942, and the second EPS unit 970 has a third unit 971 and a fourth unit 972, the number and types of functions distributed to the first EPS unit 940 and the second EPS unit 970 are not particularly limited. [Explanation of Symbols]

[0095] 1...Steering system, 5...Vehicle control device, 6,86,96...Steering device, 10,810,910...Control unit, 20,820...First control device, 50,850...Second control device, 21,821...First control unit, 51,851...Second control unit, 30,830...First setting unit, 60,860...Second setting unit, 32,832...First automatic unit, 62,862...Second automatic unit

Claims

1. A control unit comprising multiple control devices for controlling the drive of an electric motor, The plurality of control devices include a first control device and a second control device, The first control device and the second control device have an abnormality function used to operate the electric motor when any of the control devices among the plurality of control devices is malfunctioning, The first control device has a first function that is used when there is no abnormality but is not necessary when there is an abnormality. The second control device has a second function that is different from the first function, which is used when there is no abnormality but is not necessary when there is an abnormality. Control unit.

2. The first control device sets a first control command value for realizing the first function, The second control device sets a second control command value for realizing the second function, The second control device transmits the set second control command value to the first control device. The first control device controls the drive of the electric motor using the set first control command value and the second control command value received from the second control device. The control unit according to claim 1.

3. The first control device transmits the set first control command value to the second control device, The second control device controls the drive of the electric motor using the set second control command value and the first control command value received from the first control device. The control unit according to claim 2.

4. The control device, either the first control device or the second control device, controls the drive of the electric motor using the control command value it has set from the first control command value or the second control command value when the other control device is malfunctioning. The control unit according to claim 3.

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