JP2010184609A - Electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic power steering device for reducing process load of a CPU for steering control and load of an ROM for steering control, and capable of appropriately diagnosing abnormalities of the ROM. <P>SOLUTION: In the electric power steering device including an electric motor for steering assistance, a control means executing steering control to generate a motor driving command for driving and controlling the electric motor for steering assistance based on a steering auxiliary command computed by using the steering torque and vehicle speed, the control means includes a first CPU performing steering control, a first ROM storing data for steering control to be used for the first CPU to perform steering control, a second CPU diagnosing abnormalities of the first ROM, and a second ROM storing the data for diagnosis to be used for the second CPU to perform diagnosis. The second CPU obtains the data for steering control stored in the first ROM to perform diagnosis of abnormalities of the first ROM based on the obtained data for steering control and data for diagnosis stored in the second ROM. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electric power steering apparatus, and more particularly to an electric power steering apparatus that can appropriately perform diagnosis of a ROM for steering control.

  In order to reduce the steering force of vehicles such as passenger cars and trucks, there is a so-called electric power steering (EPS) device that assists steering by a steering assist motor. In the EPS apparatus, the driving force of the steering assist motor is applied (assist control) to the steering shaft or the rack shaft by a transmission mechanism such as a gear or a belt via a speed reducer.

  Since the EPS device plays an important role of vehicle steering, it is particularly necessary to consider safety and reliability among the components that make up an automobile. For this reason, measures such as diagnosis of the control device are taken. Yes.

  In Patent Document 1, in the electric power steering apparatus, the ROM area is a cell composed of a predetermined number of bytes, and data of some cells is added among a plurality of cells for each diagnostic period different from the control cycle, and data addition of all cells is performed. A method for detecting a failure of a ROM based on a comparison with a specified value when a value is obtained is disclosed.

  Regarding the failure detection of the ROM, in addition to the electric power steering device, in Patent Document 2, the high-speed diagnostic means for continuously executing the memory diagnosis over the entire area before using the memory or after using the memory, and the memory being used And a low-speed diagnostic means that intermittently executes memory diagnosis for each divided area by interrupting the memory at a predetermined period, and discloses a method for diagnosing memory by comparing checksum data and the like ing.

  In Patent Document 3, in an electronic control device for an electric motor of an automobile, a host microcomputer calculates a checksum in a predetermined storage area of a ROM and transmits the checksum to a sub-microcomputer, and the sub-microcomputer receives a checksum received from the host microcomputer. A method of diagnosing a ROM abnormality of a host microcomputer by comparing with a checksum determination value stored in advance is disclosed.

JP 2004-133635 A JP 2000-66963 A JP 2006-195739 A

  However, according to the above conventional technique, since the control ROM is diagnosed by the main CPU that performs the control, it is necessary to perform the diagnosis in the normal control processing cycle, and the processing load of the CPU There was a problem that increased. When the processing load on the CPU increases, the assist control may be affected. Further, since a diagnostic program and data necessary for ROM diagnosis are held in the control ROM, there is a problem that the capacity of the control ROM is consumed. When a large amount of ROM capacity for control is consumed by a diagnostic program or the like, there is a possibility that the ROM capacity is insufficient and necessary data cannot be recorded.

  Further, since the ROM diagnosis is a self-diagnosis, there is a possibility that the diagnosis cannot be performed accurately. In other words, since the program and data stored in the ROM to be diagnosed are diagnosed using the diagnostic program stored in the same ROM, the diagnosis can be accurately performed when an abnormality has occurred in the ROM. There was a possibility that it could not be implemented.

  The present invention has been made in view of the above, and is an electric motor capable of appropriately diagnosing an abnormality in a steering control ROM while reducing the processing load of the CPU for steering control and the load of the ROM for steering control. It aims at obtaining a power steering device.

  In order to solve the above-described problems and achieve the object, an electric power steering apparatus according to the present invention is based on a steering assistance command calculated using an electric motor for steering assistance and a steering torque and a vehicle speed. Control means for executing steering control for generating a motor drive command for controlling driving of the electric motor for electric power, wherein the control means includes a first CPU for performing the steering control, A first ROM for storing steering control data used by the first CPU for the steering control, a second CPU for diagnosing abnormality in the first ROM, and the second CPU used for the diagnosis A second ROM for storing diagnostic data; the second CPU acquires the steering control data stored in the first ROM; That on the basis of the steering control data and the second ROM to stored the diagnostic data to diagnose the abnormality of the first ROM, characterized by.

  According to a preferred aspect of the present invention, the diagnostic data is the same data as the steering control data stored in the first ROM, and the second CPU is the first ROM. The steering control data stored in is acquired, the acquired steering control data is compared with the diagnostic data, and based on the identity of the acquired steering control data and the diagnostic data It is desirable to diagnose an abnormality of the first ROM.

  Further, according to a preferred aspect of the present invention, the first calculation result generated by performing the calculation for error detection on the steering control data stored in the first ROM. The second CPU acquires the steering control data stored in the first ROM, performs a calculation for the error detection on the acquired steering control data, 2 calculation result data is generated, the first calculation result data and the second calculation result data are compared, and based on the identity of the first calculation result data and the second calculation result data. It is desirable to diagnose abnormality of the first ROM.

  According to the present invention, since the sub CPU performs diagnosis of the main ROM using the diagnosis data stored in the sub ROM and the steering control data stored in the main ROM, the processing load of the main CPU is increased. In addition, it is possible to appropriately diagnose an abnormality in the main ROM while reducing the load on the main ROM.

FIG. 1 is a diagram illustrating a configuration of an electric power steering (EPS) device according to a first embodiment of the present invention. FIG. 2 is a diagram illustrating a hardware configuration of a control unit of the electric power steering (EPS) device according to the first embodiment of the present invention. FIG. 3 is a schematic diagram for explaining a data flow at the time of diagnosis of the main ROM of the electric power steering (EPS) device according to the first embodiment of the present invention. FIG. 4 is a flowchart for explaining the main ROM diagnosis method in the EPS apparatus according to the first embodiment of the present invention. FIG. 5 is a flowchart for explaining a main ROM diagnosis method in the EPS apparatus according to the second embodiment of the present invention.

  Embodiments of an electric power steering apparatus according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited to the following description, In the range which does not deviate from the summary of this invention, it can change suitably. In the drawings shown below, the scale of each member may be different from the actual scale for easy understanding. The same applies between the drawings.

  FIG. 1 is a diagram illustrating a configuration of an electric power steering (EPS) device 100 according to a first embodiment of the present invention. In FIG. 1, a column shaft 2 of a steering handle 1 is connected to a tie rod 6 of a steering wheel via a reduction gear 3, universal joints 4a and 4b, and a pinion rack mechanism 5. The column shaft 2 is provided with a torque sensor 10 that detects the steering torque T of the steering handle 1, and a steering assist motor 20 that assists the steering force of the steering handle 1 is connected to the column shaft via the reduction gear 3. 2 is connected. Here, the steering assist motor 20 is, for example, a brushless motor or a brush motor. An electronic control unit (ECU) 30 (hereinafter referred to as a control unit 30) that controls the electric power steering device is supplied with electric power from the battery 14 via the built-in power supply relay 13, and is supplied with an ignition signal from the ignition key 11. The Further, the control unit 30 calculates a current command value of the steering assist motor 20 based on the steering torque T detected by the torque sensor 10 and the vehicle speed (vehicle speed) V detected by the vehicle speed sensor 12, and steering assist is performed. Based on the detected current value and the current command value of the motor 20, the steering assist motor 20 is drive-controlled (hereinafter referred to as assist control) so that the detected current value of the steering assist motor 20 follows the current command value.

  FIG. 2 is a diagram showing a hardware configuration of the control unit 30 of FIG. As shown in FIG. 2, the control unit 30 includes a power relay 13, an MCU (micro control unit) 110, an MCU 210, a motor drive circuit 108, a current detection circuit 120, a position detection circuit 130, and the like. .

  The MCU 110 includes a CPU 101, a ROM 102, a RAM 103, an EEPROM (nonvolatile memory) 104, an interface (I / F) 105, an A / D converter 106, a PWM controller 107, and the like, and these are connected by a bus. The CPU 101 executes various programs stored in the ROM 102 and controls the electric power steering apparatus.

  The ROM 102 is steering control data used for assist control, and includes a control program for the steering assist motor 20, a fail-safe function program, and control data used when executing these programs (hereinafter, these programs and control data). Are collectively referred to as ROM data), and the RAM 103 is used as a work memory for operating the program.

  The EEPROM 104 is a non-volatile memory that can retain the stored contents even after the power is cut off. The control data used by the CPU 101 to control the electric power steering device, the failure record data of the failure that has occurred in the electric power steering device, and the failure diagnosis The result etc. are stored. Here, the EEPROM is used as the nonvolatile memory. However, the present invention is not limited to this, and other nonvolatile memories such as a FLASH-ROM and an SDRAM may be used. .

  The A / D converter 106 inputs the steering torque T from the torque sensor 10, the current detection value Im of the steering assist motor 20 from the current detection circuit 120, the motor rotation angle signal θ from the position detection circuit 130, and the like. Convert to digital signal. The interface 105 is connected to a vehicle-mounted network such as CAN, and receives a vehicle speed signal V (vehicle speed pulse) from the vehicle speed sensor 12 and sends a signal indicating a failure to the alarm lamp 60.

  The PWM controller 107 outputs a PWM control signal for each phase of UVW based on the current command value of the steering assist motor 20. The motor drive circuit 108 is configured by an inverter circuit or the like, and drives the steering assist motor 20 based on a signal output from the PWM controller 107. The current detection circuit 120 detects the current value of the steering assist motor 20 and outputs the current detection value Im to the A / D converter 106. The position detection circuit 130 outputs an output signal from the position sensor 25 such as a resolver to the A / D converter 106 as a motor rotation angle signal θ.

  The MCU 210 includes a CPU 201, a ROM 202, a RAM 203, an EEPROM (nonvolatile memory) 204, an interface (I / F) 205, an A / D converter 206, a PWM controller 207, and the like, which are connected by a bus. The CPU 201, ROM 202, RAM 203, EEPROM (nonvolatile memory) 204, interface (I / F) 205, A / D converter 206, and PWM controller 207 are the CPU 101, ROM 102, RAM 103, and EEPROM (nonvolatile memory) of the MCU 110, respectively. ) 104, interface (I / F) 105, A / D converter 106, and PWM controller 107. That is, the MCU 210 can execute the same function as the MCU 110.

  However, here, the MCU 110 described above functions as a main MPU that drives and controls the steering assist motor 20. The MCU 210 monitors the abnormality of the MCU 110 as a basic function, and functions as a sub MCU that performs a predetermined recovery stop process when the abnormality of the MCU 110 occurs. Hereinafter, the ROM 102 is called the main ROM 102, the ROM 202 is called the sub ROM 202, the CPU 101 is called the main CPU 101, and the CPU 201 is called the sub CPU 201.

  Monitoring of abnormality of the MCU 110 is performed by diagnosing the main ROM 102. The MCU 110 and the MCU 210 are connected by serial communication via an interface (I / F) 105 and an interface (I / F) 205, and data communication is possible. When the MCU 110 is stopped, the MCU 210 may execute part of the drive control of the steering assist motor 20 instead.

  A monitoring function (diagnosis function of the main ROM 102) as a sub MPU of the MCU 210 will be described. The sub ROM 202 has the same capacity as the main ROM 102, and the same data as the ROM data recorded in the main ROM 102 is recorded in advance as diagnostic data for the main ROM 102. The sub CPU 201 of the MCU 210 acquires ROM data recorded in the main ROM 102 of the MCU 110 as shown in FIG. FIG. 3 is a schematic diagram for explaining the flow of data when the main ROM 102 is diagnosed.

  The sub CPU 201 diagnoses whether the ROM data recorded in the main ROM 102 is destroyed by directly comparing the ROM data acquired from the main ROM 102 with the ROM data recorded in the sub ROM 202. . That is, the ROM data recorded in the main ROM 102 and the ROM data recorded in the sub ROM 202 are directly compared, and the ROM data recorded in the main ROM 102 based on the identity of these two ROM data. ROM diagnosis is performed to determine whether or not is destroyed.

  When the ROM data acquired from the main ROM 102 and the ROM data recorded in the sub ROM 202 are the same, the sub CPU 201 has not destroyed the ROM data recorded in the main ROM 102, and the main ROM 102 Judge that it is normal. If the ROM data acquired from the main ROM 102 and the ROM data recorded in the sub ROM 202 are different, the sub CPU 201 has destroyed the ROM data recorded in the main ROM 102, and the main ROM 102 is abnormal. It is judged that.

  In the MCU 110 and the MCU 210, while the main CPU 101 performs the assist control, the above-described diagnosis of the main ROM 102 is repeatedly performed at a predetermined period, and the abnormality of the MCU 110 (main ROM 102) is monitored. If the EPS device 100 is being activated, the sub CPU 201 can perform diagnosis of the main ROM 102 even when the main CPU 101 is not performing assist control.

  Hereinafter, a diagnosis method of the main ROM 102 in the EPS apparatus 100 according to the first embodiment will be described with reference to FIG. FIG. 4 is a flowchart for explaining the diagnosis method of the main ROM 102 in the EPS apparatus 100 according to the first embodiment. Here, one cycle of diagnosis of the ROM 102 will be described. First, during execution of assist control, the main CPU 101 transmits ROM data recorded in the main ROM 102 to the sub CPU 201, and the sub CPU 201 receives this ROM data (step S110).

  Next, the sub CPU 201 directly compares the ROM data received from the main ROM 102 with the ROM data recorded in the sub ROM 202 (step S120), and determines whether or not these two ROM data are the same. Judgment is made (step S130).

  If the two ROM data are the same (Yes at step S130), the sub CPU 201 determines that the ROM data recorded in the main ROM 102 has not been destroyed and the main ROM 102 is normal. (Step S140), and a series of diagnosis of the main ROM 102 is completed. If the two ROM data are different (No at step S130), the sub CPU 201 performs "abnormality determination" that the ROM data recorded in the main ROM 102 has been destroyed and the main ROM 102 is abnormal (step S130). S150), a predetermined recovery stop process is executed (step S160).

  As described above, in the EPS apparatus 100 according to the first embodiment, the sub CPU 201 of the MCU 210 obtains the ROM data recorded in the main ROM 102 of the MCU 110, and directly with the ROM data recorded in the sub ROM 202 of the MCU 210. Compare. Based on the identity of these two ROM data, a diagnosis is made as to whether or not the ROM data recorded in the main ROM 102 is destroyed, that is, whether or not the main ROM 102 is normal.

  As described above, the sub CPU 201 of the MCU 210 performs the diagnosis of the main ROM 102, so that the main CPU 101 does not need to perform the diagnosis process of the main ROM 102 during the execution of the assist control in the normal control processing cycle. The load is reduced. In addition, since the diagnostic programs and data necessary for diagnosis of the main ROM 102 are held in the sub ROM 202 of the MCU 210 instead of the main ROM 102, the consumption of the capacity of the main ROM 102 can be reduced, and the main ROM 102 is assisted. It can be effectively used for control. Further, the diagnosis of the main ROM 102 is not self-diagnosis, and the main ROM 102 is diagnosed by the sub CPU 201 of the MCU 210 using the diagnostic program and data stored in the sub ROM 202 of the MCU 210. Even in such a case, the main ROM 102 can be diagnosed appropriately.

  Therefore, the EPS apparatus 100 according to the first embodiment realizes an EPS apparatus that can appropriately diagnose an abnormality in the main ROM 102 while reducing the processing load on the main CPU 101 and the load on the main ROM 102.

  In the first embodiment, the case where the diagnosis of the main ROM 102 is performed based on the identity of the ROM data itself recorded in the main ROM 102 has been described. In the second embodiment, the calculation based on the ROM data recorded in the main ROM 102 is performed. A case in which the diagnosis of the main ROM 102 is performed based on the same result will be described. Since the basic configuration and function of the EPS apparatus according to the second embodiment are the same as those in the first embodiment, detailed description thereof will be omitted, and the diagnostic features of the main ROM 102 in the second embodiment will be described.

  The monitoring function (diagnostic function of the main ROM 102) as the sub MPU of the MCU 210 according to the second embodiment will be described below. The sub ROM 202 has substantially the same capacity as the main ROM 102 or a smaller capacity than the main ROM 102, and calculation result data (hereinafter referred to as first data) obtained by performing calculation for error detection based on the ROM data recorded in the main ROM 102. Called calculation result data). Examples of the first calculation result data include checksum data and a CRC code. In addition, the CPU 201 of the MCU 210 acquires ROM data recorded in the main ROM 102 of the MCU 110.

  The CPU 201 performs an operation for error detection based on the ROM data acquired from the main ROM 102, and generates operation result data (hereinafter referred to as second operation result data). Then, the CPU 201 compares the first calculation result data with the second calculation result data to diagnose whether the ROM data recorded in the main ROM 102 has been destroyed. That is, based on the identity between the first calculation result data and the second calculation result data, a ROM diagnosis is performed to determine whether the ROM data recorded in the main ROM 102 has been destroyed.

  When the first calculation result data and the second calculation result data are the same, the CPU 201 determines that the ROM data recorded in the main ROM 102 is not destroyed and the main ROM 102 is normal. If the first calculation result data is different from the second calculation result data, the CPU 201 determines that the ROM data recorded in the main ROM 102 is destroyed and the main ROM 102 is abnormal.

  In the MCU 110 and the MCU 210, while the main CPU 101 is performing the assist control, the diagnosis of the main ROM 102 described above is repeatedly performed at a predetermined period, and the abnormality of the MCU 210 (main ROM 102) is monitored. If the EPS device 100 is being activated, the sub CPU 201 can perform diagnosis of the main ROM 102 even when the main CPU 101 is not performing assist control.

  Hereinafter, an example of a diagnostic method for the main ROM 102 in the EPS apparatus according to the second embodiment will be described with reference to FIG. FIG. 5 is a flowchart for explaining a diagnosis method of the main ROM 102 in the EPS apparatus according to the second embodiment. Here, one cycle of diagnosis of the ROM 102 will be described by taking as an example a case where a checksum is performed as an operation for error detection.

  In the sub ROM 202, calculation result data (first checksum data) calculated based on the ROM data recorded in the main ROM 102 is recorded in advance. First, during execution of assist control, the main CPU 101 transmits ROM data recorded in the main ROM 102 to the sub CPU 201, and the sub CPU 201 receives this ROM data (step S210).

  Next, the sub CPU 201 performs an operation based on the ROM data received from the main ROM 102, and generates operation result data (second checksum data) (step S220). Then, the sub CPU 201 compares the first checksum data recorded in advance in the main ROM 102 with the second checksum data (step S230), and determines whether these two checksum data are the same. Is determined (step S240).

  If the two checksum data are the same (Yes at step S240), the sub CPU 201 indicates that the ROM data recorded in the main ROM 102 has not been destroyed and the main ROM 102 is normal. Determination "is performed (step S250), and a series of diagnosis of the main ROM 102 is completed. If the two checksum data are different (No at step S240), the CPU 201 performs “abnormality determination” to the effect that the ROM data recorded in the main ROM 102 has been destroyed and the main ROM 102 is abnormal (step S240). S260), a predetermined recovery stop process is executed (step S270).

  As described above, in the EPS apparatus according to the second embodiment, calculation result data (first calculation result data) obtained by performing calculation for error detection based on ROM data recorded in the main ROM 102 is stored in advance in the MCU 210. Are recorded in the sub-ROM 202. When the diagnosis of the main ROM 102 is performed, the sub CPU 201 of the MCU 210 acquires the ROM data recorded in the main ROM 102 of the MCU 110 and performs an operation for error detection based on the ROM data. Result data (second calculation result data) is generated. Thereafter, the CPU 201 compares the first calculation result data with the second calculation result data. Based on the identity of these two calculation result data, a diagnosis is made as to whether or not the ROM data recorded in the main ROM 102 is destroyed, that is, whether or not the main ROM 102 is normal.

  As described above, the sub CPU 201 of the MCU 210 performs the diagnosis of the main ROM 102, so that the main CPU 101 does not need to perform the diagnosis process of the main ROM 102 during the execution of the assist control in the normal control processing cycle. The load is reduced. In addition, since the diagnostic programs and data necessary for diagnosis of the main ROM 102 are held in the sub ROM 202 of the MCU 210 instead of the main ROM 102, the consumption of the capacity of the main ROM 102 can be reduced, and the main ROM 102 is assisted. It can be effectively used for control. In addition, the diagnosis of the main ROM 102 is not self-diagnosis, and the main ROM 102 is diagnosed by the sub CPU 201 of the MCU 210 using the diagnostic program and data stored in the sub ROM 202 of the MCU 210. Therefore, an abnormality occurs in the main ROM 102. Even in such a case, the main ROM 102 can be diagnosed appropriately.

  Therefore, the EPS apparatus 100 according to the second embodiment realizes an EPS apparatus that can appropriately diagnose an abnormality in the main ROM 102 while reducing the processing load on the main CPU 101 and the load on the main ROM 102.

  As described above, the electric power steering apparatus according to the present invention is useful for reducing the load during normal control in the CPU and ROM for steering control and performing appropriate ROM diagnosis.

DESCRIPTION OF SYMBOLS 1 Steering handle 2 Column shaft 3 Reduction gear 4a, 4b Universal joint 5 Pinion rack mechanism 6 Tie rod 10 Torque sensor 11 Ignition key 12 Vehicle speed sensor 13 Power supply relay 14 Battery 20 Steering auxiliary motor 25 Position sensor 30 Control unit 60 Warning lamp 100 EPS Device 101 CPU
102 ROM
103 RAM
104 EEPROM
105 Interface 106 A / D Converter 107 PWM Controller 108 Motor Drive Circuit 110 MCU
120 current detection circuit 130 position detection circuit 201 CPU
202 ROM
203 RAM
204 EEPROM
205 Interface 206 A / D Converter 207 PWM Controller 210 MCU

Claims (3)

A steering assist electric motor, and a control means for executing a steering control for generating a motor drive command for controlling the steering assist electric motor based on a steering assist command calculated using a steering torque and a vehicle speed; In an electric power steering apparatus comprising:
The control means includes
A first CPU for performing the steering control;
A first ROM for storing steering control data used by the first CPU for the steering control;
A second CPU for diagnosing abnormality of the first ROM;
A second ROM for storing diagnostic data used by the second CPU for the diagnosis;
With
The second CPU acquires the steering control data stored in the first ROM, and based on the acquired steering control data and the diagnostic data stored in the second ROM. Diagnosing an abnormality in the first ROM;
An electric power steering device. The diagnostic data is the same data as the steering control data stored in the first ROM;
The second CPU acquires the steering control data stored in the first ROM, compares the acquired steering control data with the diagnostic data, and acquires the acquired steering control data. And diagnosing the abnormality of the first ROM based on the identity of the diagnostic data and
The electric power steering apparatus according to claim 1. The diagnostic data is first calculation result data generated by performing calculation for error detection on the steering control data stored in the first ROM;
The second CPU acquires the steering control data stored in the first ROM, performs a calculation for the error detection on the acquired steering control data, and outputs a second calculation result. Data is generated, the first calculation result data is compared with the second calculation result data, and the first calculation result data is compared with the second calculation result data based on the identity between the first calculation result data and the second calculation result data. Diagnosing abnormalities in ROM,
The electric power steering apparatus according to claim 1.

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