JP2010195220A - Electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric power steering device in which a program is restored when a storage abnormality occurs in a program storage part such as an ROM. <P>SOLUTION: In the electric power steering device having an electronic control device 13 that controls an electric motor 12 generating a steering assistance force for a steering mechanism, the electronic control device 13 includes a main storage part 15c that stores an application program for controlling the electric motor and a storage abnormality detection program for the application program, and a redundant storage part 15d that stores at least the application program. When an abnormality of the application program in the main storage part 15c is detected by the execution of the storage abnormality detection program, the control of the electric motor is continued based on the application program stored in the redundant storage part 15d. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electric power steering apparatus that controls an electric motor that applies a steering assist force to a steering system, and in particular, automatically corrects when a storage abnormality occurs in a storage unit that stores an application program. The present invention relates to an electric power steering apparatus.

  In this type of electric power steering device, the ROM area is composed of a plurality of cells composed of a predetermined number of byte data, and includes a normal control period for controlling the controlled object and a diagnostic period for performing fault diagnosis of the control computer. The control means that performs control in the machine cycle and the addition of data that is partly placed in a plurality of cells for each diagnosis period, and the current diagnosis is performed on the addition value of the data of some cells obtained in the previous diagnosis period Computation means for comparing the sum of the added values with the specified value when the data of all the cells in the ROM area are obtained by adding the data of some other cells to the period of use, and There is known a control computer that performs failure detection based on a comparison between a sum of addition values by means and a prescribed value (see, for example, Patent Document 1).

  In addition, the storage area of the microcomputer RAM provided in the engine control ECU of the automobile is divided into three blocks, a high block, a medium block, and a low block, and the data to be stored in the RAM is also an abnormality of the automobile. It is classified into three types of groups according to the degree of impact on safety, and the blocks are stored in the high block, medium block, and low block in order from the group with the largest impact level. Is a memory diagnosis device and a control device that perform a fail-safe process when an abnormality is detected in a block in which data having a large influence degree is stored, and the block is stored with high frequency (that is, high> medium> low). Is known (see, for example, Patent Document 2).

2004-133635 gazette No. 2003-323353

  As described above, in the conventional examples described in Patent Documents 1 and 2, when a memory failure is detected in the initial memory diagnosis performed before the start of the microcomputer through the assist control, or during the assist control. When a memory failure is detected by the continuous memory diagnosis that is performed, as a fail-safe process, the assist control is stopped, the power to the motor is cut off, or the microcomputer is reset, and the system reaches a serious failure mode. It is preventing.

  However, with the expansion of the adoption of electric power steering devices for medium-sized and large vehicles, a large steering force is required when steering the steering mechanism, and assist control is stopped when the ROM fails or the motor is switched to the motor. If the generation of steering assist force is stopped by shutting off the power to the vehicle or resetting the microcomputer, the driver will be overburdened, and there is an unsolved problem that it is not necessarily a good measure. is there.

  Accordingly, the present invention has been made paying attention to the unsolved problems of the above-described conventional example, and an electric power steering capable of restoring a program when a storage abnormality occurs in a program storage unit such as a ROM. The object is to provide a device.

In order to achieve the above object, an electric power steering apparatus according to claim 1 of the present invention is an electric power steering apparatus including an electronic control unit that controls an electric motor that generates a steering assist force with respect to a steering mechanism. There,
The electronic control device includes an application program for controlling the electric motor, a main storage unit for storing a storage abnormality detection program for the application program, and a redundant storage unit for storing at least the application program, and the storage abnormality detection program When the abnormality of the application program in the main storage unit is detected, the control of the electric motor is continued based on the application program stored in the redundant storage unit.

  With such a configuration, when a storage abnormality of the application program stored in the main storage unit is detected, the corresponding application program is read from the redundant storage unit and the application program in the main storage unit is rewritten, or the RAM is stored in the RAM. By storing the application program, it is possible to repair the application program in which the memory abnormality occurred, and to continue normal steering assist control without interruption.

  In the electric power steering apparatus according to claim 2, the main storage unit stores a first storage area for storing the application program and a storage abnormality detection program, a start program, and the first storage area. A flash ROM having a second storage area for storing a boot program for rewriting and updating the application program in the memory, and when the storage abnormality of the application program is detected by executing the storage abnormality detection program In addition, the application program stored in the redundant storage unit is rewritten and updated in the first storage area by executing the boot program.

  With such a configuration, the main storage unit has a first storage area for storing an application program and a storage abnormality detection program, and a boot program for rewriting and updating the startup program and the application program in the first storage area. By using the flash ROM having the second storage area for storing the application program, it is possible to easily repair the application program in which the storage error has occurred.

  According to a third aspect of the present invention, in the electric power steering apparatus according to the third aspect, the first storage area is a small block that stores at least the specific block that stores the memory abnormality detection program and the application program divided into a plurality of parts. A block in which a storage abnormality is detected by the storage abnormality detection program, and the storage abnormality detection program is configured to detect a storage abnormality for each block of the first storage area. Is detected, the block stored in the redundant storage unit is read corresponding to the corresponding block, and the corresponding block in the first storage area is rewritten and updated.

With this configuration, storage abnormality detection is performed in units of small-capacity blocks, and only the block in which the storage abnormality has occurred is rewritten and updated with the program stored in the corresponding block stored in the redundant storage unit. Update processing can be performed easily.
According to a fourth aspect of the present invention, in the electric power steering apparatus according to the fourth aspect, the main storage unit further includes a RAM, and the storage abnormality detection program eliminates the storage abnormality after rewriting and updating the block in which the storage abnormality has occurred. If not, the corresponding block of the redundant storage unit is written into the RAM, and the boot program stored in the second storage area is the block of the first storage area in which the storage abnormality is detected by the storage abnormality detection program. When accessing, it is configured to access a block stored in the RAM.

  With this configuration, when a block in which a storage abnormality has occurred in the main storage unit is rewritten and updated with a block program stored in the redundant storage unit, if the storage abnormality is not resolved, the corresponding block is written to the RAM, When accessing the block, the application program can be executed by accessing the block stored in the RAM, and the steering assist control can be continued even if the block of the main storage unit becomes abnormal.

  According to a fifth aspect of the present invention, in the electric power steering apparatus according to the fifth aspect, the main memory unit stores at least a specific block that stores the memory abnormality detection program, and a small memory that stores the application program divided into a predetermined number. The redundant storage unit divides at least a specific block for storing the storage abnormality detection program and the application program into a predetermined number in the same manner as the ROM, and includes a ROM having a plurality of blocks having a capacity. The storage abnormality detection program is configured to detect a storage abnormality for each block, and a storage abnormality block is detected by the storage abnormality detection program. The corresponding block is read from the redundant storage unit and written to the RAM. It is seen, in accessing the block became storing abnormality of the main memory unit, is characterized by accessing the blocks on the RAM.

  With this configuration, the storage abnormality detection program and application program are stored in the ROM in the block unit, and by executing the storage abnormality detection program, the storage abnormality can be detected in the block unit, and the storage abnormality is detected. When the block stored in the redundant storage unit is written to the RAM and the corresponding block is accessed, the block stored in the RAM is accessed, so that the steering assist control is performed even if the ROM block becomes abnormal. Can continue.

According to the present invention, when a storage abnormality is detected in the application program stored in the main storage unit, the application program is repaired and updated by rewriting and updating with the application program stored in the redundant storage unit. There is an effect that the steering assist control can be continued without stopping or interrupting the assist control.
In addition to storing application programs in multiple blocks in the main storage unit and storing application programs in multiple blocks in the redundant storage unit as well, rewriting and updating is performed in units of blocks in which storage errors occurred. This makes it possible to easily repair the application program.

It is a schematic block diagram which shows the structure of the electric power steering apparatus by this invention. It is a block diagram which shows the specific structure of a controller. It is explanatory drawing which shows the program structure on a flash memory. It is a flowchart which shows a steering assistance control process. It is a flowchart which shows an example of a memory | storage abnormality detection process sequence. It is a functional block diagram of a controller. It is explanatory drawing which shows embodiment at the time of dividing | segmenting flash ROM and ROM into a some block. It is explanatory drawing which shows embodiment at the time of applying ROM as a main memory part. It is a flowchart which shows an example of the memory | storage abnormality detection process procedure of FIG.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic configuration diagram of an electric power steering apparatus showing an embodiment of the present invention.
In FIG. 1, reference numeral 1 denotes a steering wheel. A steering force applied to the steering wheel 1 from a driver is transmitted to a steering shaft 2 having an input shaft 2a and an output shaft 2b. The steering shaft 2 has one end of the input shaft 2 a connected to the steering wheel 1 and the other end connected to one end of the output shaft 2 b via the torque sensor 3.

  The steering force transmitted to the output shaft 2 b is transmitted to the lower shaft 5 via the universal joint 4 and further transmitted to the pinion shaft 7 via the universal joint 6. The steering force transmitted to the pinion shaft 7 is transmitted to the tie rod 9 via the steering gear 8 to steer a steered wheel (not shown). Here, the steering gear 8 is configured in a rack and pinion type having a pinion 8a connected to the pinion shaft 7 and a rack 8b meshing with the pinion 8a, and the rotational motion transmitted to the pinion 8a is linearly moved by the rack 8b. Has been converted.

A reduction gear 10 that transmits auxiliary steering force to the output shaft 2b is connected to the output shaft 2b of the steering shaft 2, and an output shaft of an electric motor 12 that generates auxiliary steering force is connected to the reduction gear 10. ing.
The torque sensor 3 detects the steering torque applied to the steering wheel 1 and transmitted to the input shaft 2a. For example, the torsion bar (not shown) in which the steering torque is interposed between the input shaft 2a and the output shaft 2b is used. It converts into angular displacement, and it is comprised so that this torsional angular displacement may be detected with a non-contact magnetic sensor.

  The detected torque value T output from the torque sensor 3 is input to the controller 13. In addition to the torque detection value T, the controller 13 also receives a vehicle speed detection value V detected by the vehicle speed sensor 14 and a motor current detection value Imd flowing through the electric motor 12, and the inputted torque detection value T and vehicle speed detection value V are inputted. A steering assist command value Iref that generates the corresponding steering assist force in the electric motor 12 is calculated, and the drive current supplied to the electric motor 12 is feedback-controlled based on the calculated steering assist command value Iref and the motor current detection value Imd.

Next, the configuration of the controller 13 will be described.
FIG. 2 is a block diagram showing the configuration of the controller 13.
As shown in FIG. 3, the controller 13 controls the drive current supplied to the electric motor 12 based on the microcomputer 15 that executes control processing of the electric motor 12 and the motor drive current Imt output from the microcomputer 15. A motor drive circuit 17 and a motor current detection circuit 18 that detects a motor current that is an output current of the electric motor 12 are provided.

A torque detection value T detected by the torque sensor 3 and a motor current detection value Imd detected by the motor current detection circuit 18 are converted into digital values by the A / D converters 21 and 22, respectively, and inputted to the microcomputer 15. The
The microcomputer 15 includes an input interface circuit 15a to which the torque detection value T, the vehicle speed detection value V, and the motor current detection value Imd are input, and the electric motor based on the torque detection value T, the vehicle speed detection value V, and the motor current detection value Imd. The central processing unit 15b that executes steering assist control processing that controls the drive 12 to generate steering assisting force according to the steering torque, and the steering assist control processing program that is executed by the central processing unit 15b, the memory abnormality detection program, and the like A flash ROM 15c as a main storage unit for storing the program, a ROM 15d as a redundant storage unit for storing the same application program as the application program stored in the flash ROM, a torque detection value T and a motor current detection value Detection data such as Imd A motor, a RAM15e for storing data and processing results required during processing of the steering control processing executed by the central processing unit 15b, and an output interface circuit 15f.

  As shown in FIG. 3, the flash ROM 15c includes a steering control processing program as a main program for causing the central processing unit 15b to execute steering control processing, a storage abnormality detection program for detecting abnormality in the storage area of the flash ROM 15c, and the like. The first storage area 21 in which the storage contents for storing the application program can be rewritten, the boot program for causing the central processing unit 15b to boot, and the central processing unit 15b perform the above-described rewriting update of the first storage area. And a second storage area 22 for storing a rewrite update program for generating the program.

In the second storage area 22, the boot program is stored in the first half of the second storage area 22 including the start address in the second storage area 22, and the rewrite program is stored in the second half of the second storage area 22. The second storage area 22 is configured so that it cannot be rewritten.
The central processing unit 15b accesses the start address of the second storage area of the flash ROM 15c when the steering assist control process is booted, and boots the steering assist control process according to the boot program stored in the accessed second storage area 22 To perform steering assist control processing.

  As shown in FIG. 4, in this steering assist control process, first, in step S1, the torque detection value T detected by the torque sensor 3 is read, and then the process proceeds to step S2 where the vehicle speed detection value V is read, and then step The process proceeds to S3, a steering assist current command value Iref is calculated with reference to a steering assist command value calculation map (not shown) based on the detected torque value T and the detected vehicle speed V, and then the process proceeds to step S4.

In this step S4, the motor current detection value Imd detected by the motor current detection circuit 18 is read, and then the process proceeds to step S5, where the current deviation ΔI is calculated by subtracting the motor current detection value Imd from the steering assist current command value Iref. Then, the process proceeds to step S6.
In this step S6, PI control processing is performed based on the calculated current deviation ΔI to calculate the motor drive current Imt, and then the process proceeds to step S7 to output the motor drive current Imt to the motor drive circuit 17. The steering assist control process is terminated.

  Further, when the controller 13 is activated, the central processing unit 15b executes the storage abnormality process shown in FIG. 5 based on the storage abnormality detection program stored in the first storage area 21, and the first processing of the flash ROM 15c by the checksum is performed. The error of the storage area 21 is detected. In this storage abnormality process, first, the process proceeds to step S11 to calculate the addition value SUM0 in the first storage area 21, and then the process proceeds to step S12, where the calculated addition value SUM0 is the second storage area 21. It is determined whether or not it matches with the addition value SUMs of the application program stored in the first storage area 21 stored in.

If the determination result is that the addition value SUM0 matches the set addition value SUMs, it is determined that there is no storage abnormality in the first storage area 21, and the storage abnormality detection process is terminated. The process proceeds to the steering assist control process shown in FIG.
On the other hand, when the addition result SUM0 does not match the preset addition value SUMs as a result of the determination in step S12, the process proceeds to step S13 and is based on the rewrite update program stored in the second storage area 22. Rewrite processing is executed. In this rewriting process, the application program including the steering assist control program and the storage abnormality detection program stored in the storage area 23 of the ROM 15d serving as the redundant storage unit is rewritten and updated to the first storage area arrival 21 of the flash ROM 15c.

  Next, the process proceeds to step S14, where the addition value SUM0 'of the first storage area 21 that has been rewritten and updated is calculated. Then, the process proceeds to step S15, where the calculated addition value SUM0' is added to the updated and stored application program. It is determined whether or not the value SUMs ′ matches, and if both match, it is determined that there is no storage abnormality in the rewritten and updated first storage area, the storage abnormality detection process is terminated, and The process proceeds to the steering assist control process of FIG.

If the calculated addition value SUM0 ′ does not match the set addition value SUMs ′, it is determined that an abnormality has occurred in the first storage area 21 itself, The process proceeds to step S16, the steering assist control process is terminated, and then the memory abnormality detection process is terminated.
A functional block diagram of the controller 15 is represented as shown in FIG.

The torque detection value T detected by the torque sensor 3 and the vehicle speed detection value V detected by the vehicle speed sensor 14 are supplied to the steering auxiliary current command value calculation unit 41, and the torque detection value is calculated by the steering auxiliary current command value calculation unit 41. Based on T and the vehicle speed detection value V, a steering assist current command value Iref is calculated with reference to a steering assist current command value calculation map (not shown).
The steering assist current command value Iref calculated by the steering assist current command value calculation unit 41 and the motor current detection value Imd detected by the motor current detection circuit 18 are supplied to the subtractor 42, and the subtractor 42 assists. The current deviation ΔI is calculated by subtracting the motor current detection value Imd from the current command value Iref, and the calculated current deviation ΔI is supplied to the PI current control unit 43 to execute the PI current control process on the current deviation ΔI. The motor current Imt is calculated, and the calculated motor current Imt is output to the motor drive circuit 17. Further, when the storage abnormality of the flash ROM 15c is detected by the ROM storage abnormality detection unit 44 and an abnormality occurs in the first storage area 21 of the flash ROM 15c, the steering assist control stored in the ROM 15d serving as the redundant storage unit. The application program including the processing program and the storage abnormality detection program is rewritten and updated in the first storage area of the flash ROM 15c. If the checksum result of the rewritten application program is normal, the storage abnormality detection is terminated as it is. However, when the checksum result is abnormal, it is transmitted to the fail-safe processing unit 45 to stop the supply of power to the motor drive circuit 17.

Here, the processing in steps S1 to S3 in FIG. 4 described above corresponds to the current command value calculation unit 41, the processing in steps S4 and S5 corresponds to the subtractor 42, and the processing in step S6 corresponds to the PI current control unit 43. It corresponds. 5 corresponds to the ROM storage abnormality detection unit 44 and the fail safe processing unit 45.
Next, the operation of the above embodiment will be described.

Now, in the normal steering state, the central processing unit 15b of the microcomputer 15 of the controller 13 accesses the boot unit of the second storage area 21 of the flash ROM 15c to boot the steering assist control processing program. The steering assist control process is executed.
In this steering assist control process, the torque detection value T and the vehicle speed detection value V are read (steps S1 and S2), and the steering assist current command value calculation map is calculated based on the torque detection value T and the vehicle speed detection value V. The steering assist current command value Iref is calculated with reference to (step S3).
Next, the motor current detection value Imd is read (step S4), the motor current detection value Imd is subtracted from the steering assist current command value Iref to calculate a current deviation ΔI (step S5), and the calculated current deviation ΔI is PI current controlled. Processing is performed to calculate the motor current Imt (step S6), and the calculated motor current Imt is output to the motor drive circuit 17, so that the electric motor 12 generates a steering assist force according to the torque detection value T. Drive control.

Then, a steering assist force corresponding to the steering torque generated by the electric motor 12 is transmitted to the output shaft 2 b via the reduction gear 10.
At this time, in a so-called stationary state in which the steering wheel 1 is steered while the vehicle is stopped, a large steering with a small torque detection value T is caused by a large gradient of a characteristic line of a steering assist current command value calculation map (not shown). Since the auxiliary current command value Iref is calculated, a large steering assist force can be generated by the electric motor 12 to perform light steering.

On the other hand, when the vehicle starts and reaches a predetermined vehicle speed or more, the gradient of the characteristic line of the steering assist command value calculation map becomes small, so that a small steering assist command value Iref is calculated even with a large torque detection value T. The steering assist force generated at 12 is reduced, and the steering of the steering wheel 1 can be suppressed from becoming too light and optimal steering can be performed.
On the other hand, when the controller 13 is powered on, the central processing unit 15b of the microcomputer 15 boots the storage abnormality detection program stored in the first storage area 21 of the flash ROM 15c, and the storage abnormality is detected. Perform detection processing. In this memory abnormality detection process, an addition value SUM0 of the first storage area 21 storing application programs such as a steering assist control program and a memory abnormality detection program is calculated, and the calculated SUM0 and a preset normal application program are calculated. It is determined whether or not the added value SUMs matches, and if both match, it is determined that the application program stored in the first storage area 21 is normal, and the steering assist control program is read. Then, execution of the steering assist control process described above is started.

However, when the calculated addition value SUM0 of the first storage area 21 does not match the preset addition value SUMs of the normal application program, the rewrite update program is executed and stored in the ROM as the redundant storage unit. The normal application program is rewritten and updated in the first storage area of the flash ROM 15c.
Then, the checksum is executed again on the first storage area 21 in which the new application program is stored after rewriting and updating, and the addition value SUM0 of the first storage area 21 in which the new application program is updated and updated. It is determined whether or not 'and the added value SUMs' of the normal application program match, and when they match, it is determined that normal rewriting has been performed, and execution of the steering assist control process is started.

However, if the calculated addition value SUM0 ′ of the first storage area 21 does not match the addition value SUMs ′ of the normal application program, there is an abnormality in the storage area of the first storage area 21 of the flash ROM 15c. The power supply to the motor drive circuit 17 is stopped because it is determined that it has occurred, and the steering assist control process is terminated.
As described above, in the above embodiment, the checksum is used to diagnose whether application programs such as the steering assist control program and the storage abnormality detection program stored in the first storage area 21 of the flash ROM 15c are normal, When the application program stored in the first storage area 21 is normal, the steering assist control process starts to be executed. When the checksum result in the first storage area 21 is abnormal, the rewrite update program is displayed. Since the normal application program stored in the ROM 15d as the redundant storage unit is executed and rewritten and updated in the first storage area 21 of the flash ROM 15c, the abnormal application program can be repaired and the steering assist control process can be performed. Can continue.

  If the checksum result is abnormal even after the normal application program rewriting / updating process to the first storage area 21 of the flash ROM 15c is completed, an abnormality has occurred in the first storage area 21 of the flash ROM 15c. Therefore, the supply of power to the motor drive control circuit 17 is stopped, and fail-safe processing for stopping the drive control of the electric motor 12 is executed.

  In the above embodiment, the case where the first storage area 21 of the flash ROM 15c is configured by one storage area has been described. However, the present invention is not limited to this, and as shown in FIG. The first storage area 21 of the ROM 15c is divided into a plurality of blocks MB1 to MBn, and application programs including a steering assist control program and a storage abnormality detection program are divided into a plurality of blocks MB1 to MBn and stored in a redundant manner. The ROM 15d as a unit is also divided into blocks MB1 ′ to MBn ′, and application programs including a steering assist control program and a storage abnormality detection program are divided into a plurality of blocks MB1 ′ to MBn ′ and stored. Then, the storage abnormality program performs checksum diagnosis for each block MB1 to MBn to detect whether or not an abnormality has occurred in units of blocks, and for the block MBi (i = 1 to n) where the checksum result is abnormal. Thus, the program data of the corresponding block MBi ′ of the ROM 15d as the redundant storage unit may be rewritten and updated. In this case, since the rewrite update is performed in units of blocks, the rewrite update processing time can be shortened.

  In the above-described embodiment, the case where the flash ROM 15c is applied as the main storage unit has been described. However, the present invention is not limited to this, and the case where the normal ROM 15f is applied as the main storage unit is illustrated in FIG. As described above, the ROM 15d is divided into a plurality of blocks MB0 to MBn, and the application programs including the steering assist control program and the memory abnormality detection program are divided and stored in these blocks MB0 to MBn, and among these, the memory abnormality detection program is divided. Without writing, the data is written from the head address of the first block MB0 as the specific block, and the ROM 15d as the redundant storage unit is divided into blocks MB0 ′ to MBn ′ similar to the ROM 15f, and the first block MB0 as the specific block is divided. Detect memory error at the start address of Storing programs, both by dividing the application program including the remaining steering assist control program stored in each block MB0'~MBn '.

Then, a memory abnormality detection process based on the memory abnormality detection program is executed as shown in FIG. In this memory abnormality detection process, first, in step S21, a checksum diagnosis process is executed for each of the blocks MB0 to MBn. Next, the process proceeds to step S22, and it is determined whether there is an abnormal block MBi (i = 0 to n).
If there is no abnormal block as a result of this determination, the storage abnormality detection process is terminated as it is, and the steering assist control process is executed. If there is an abnormal block MBi, the process proceeds to step S22. The program data of the block MBi ′ of the ROM 15d as the redundant storage unit corresponding to the corresponding block MBi is stored in a predetermined address of the RAM, and then the process proceeds to step S23 where the read address for the block MBi of the ROM 15f is stored in the RAM 15e. After changing to the read address of the block MBi ′, the storage abnormality detection process is repaired, and the process proceeds to the steering assist control process.

In this case, when a checksum abnormality occurs in the block of the ROM 15f, the normal block stored in the redundant storage unit 15d is stored in the RAM 15e, so that the steering assist control can be started or continued.
Further, also in the embodiment of FIG. 7 described above, when the block MBi of the flash ROM 15c is determined to be abnormal, the block MBi ′ of the ROM 15d as the redundant storage unit corresponding to the abnormal block MBi is written to the RAM 15e. Thus, when accessing the block MBi, the block MBi ′ of the RAM 15e may be accessed.

  In the above embodiment, the case where the present invention is applied to a column assist type electric power steering apparatus has been described. However, the present invention is not limited to this, and the rack assist type electric power steering or pinion assist type is not limited thereto. The present invention can also be applied to an electric power steering device.

DESCRIPTION OF SYMBOLS 1 ... Steering wheel, 2 ... Steering shaft, 3 ... Torque sensor, 8 ... Steering gear, 12 ... Electric motor, 13 ... Controller, 14 ... Vehicle speed sensor, 15 ... Microcomputer, 15a ... Input interface circuit, 15b ... Central processing unit 15c ... Flash ROM, 15d ... ROM, 15e ... RAM, 15f ... Output interface circuit, 15g ... ROM, 17 ... Motor drive circuit, 18 ... Motor current detection circuit, 21 ... First storage area, 22 ... Second Storage area, 23 ... Storage area, 41 ... Steering auxiliary current command value calculation section, 42 ... Subtractor, 43 ... PI current control section, 44 ... ROM abnormality detection section, 45 ... Fail safe processing section

Claims (5)

An electric power steering device including an electronic control device that controls an electric motor that generates a steering assist force for a steering mechanism,
The electronic control device includes an application program that controls the electric motor and a main storage unit that stores a storage abnormality detection program of the application program, and a redundant storage unit that stores at least the application program,
When the abnormality of the application program in the main storage unit is detected by executing the storage abnormality detection program, the control of the electric motor is continued by the application program stored in the redundant storage unit. Electric power steering device.   The main storage unit stores a first storage area for storing the application program and a storage abnormality detection program, a second program for storing a boot program for rewriting and updating an activation program and an application program in the first storage area. When the storage abnormality of the application program is detected by executing the storage abnormality detection program, the boot program is executed to store in the redundant storage unit. The electric power steering apparatus according to claim 1, wherein the application program being updated is rewritten and updated in the first storage area. The first storage area includes at least a specific block for storing the storage abnormality detection program, and a plurality of blocks having a small storage capacity for storing the application program divided into a plurality of parts,
The storage abnormality detection program is configured to detect a storage abnormality for each block of the first storage area, and when a block having a storage abnormality is detected by the storage abnormality detection program, The electric power steering apparatus according to claim 2, wherein the block stored in the redundant storage unit is read correspondingly and the corresponding block in the first storage area is rewritten and updated.   The main storage unit further includes a RAM, and the storage abnormality detection program writes the corresponding block of the redundant storage unit to the RAM when the storage abnormality is not solved after rewriting and updating the block in which the storage abnormality has occurred, The boot program stored in the second storage area accesses the block stored in the RAM when accessing the block of the first storage area where the storage abnormality is detected by the storage abnormality detection program. The electric power steering apparatus according to claim 3, wherein the electric power steering apparatus is configured as follows.   The main storage unit is composed of a ROM having at least a specific block for storing the storage abnormality detection program, a plurality of blocks having a small storage capacity for storing the application program by dividing it into a predetermined number, and a RAM, The redundant storage unit has a specific block for storing at least the storage abnormality detection program as in the ROM, and a plurality of blocks having a small storage capacity for storing the application program by dividing it into a predetermined number. The detection program is configured to detect a storage abnormality for each block. When a storage abnormality block is detected by the storage abnormality detection program, the corresponding block is read from the redundant storage unit and written to the RAM. When accessing the block in which the storage error occurred in the main storage unit, The electric power steering apparatus according to claim 1, wherein the accessing the blocks on the serial RAM.

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