JP4678482B2 - Control device and electric power steering device provided with the same - Google Patents

Description

  The present invention relates to a control device that periodically executes an interrupt process, and an electric power steering device including such a control device.

  2. Description of the Related Art Conventionally, an electric power steering device that assists steering by driving an electric motor in accordance with an operation of a steering wheel and transmitting the power of the electric motor to a steering mechanism is mounted on a vehicle and used. The electric power steering apparatus includes, for example, the electric motor and an electric power steering ECU (electronic control unit) that controls the electric motor.

The electric power steering ECU includes, for example, a motor drive circuit that supplies electric power from a battery to the electric motor, a PWM drive pulse generation circuit that supplies a PWM drive pulse to the motor drive circuit, and the PWM drive pulse generation circuit. And a microcomputer for providing a control signal representing the PWM duty.
The microcomputer is composed of a CPU and its peripheral circuits. This peripheral circuit is provided with a timer for giving an interrupt to the microcomputer at every constant control period. The CPU executes a control process for controlling the electric motor in response to the interruption from the timer. As a result, control processing can be performed at regular control cycles.

In order to reset the CPU when it runs away, the microcomputer is provided with a reset circuit composed of a custom IC. The CPU generates a monitoring pulse and supplies it to the reset circuit each time the control process is executed. The reset circuit monitors the period (time interval) of the monitoring pulse, and gives a reset signal to the CPU when the period exceeds a certain time. As a result, if the CPU runs out of control and cannot generate a monitoring pulse or enters an abnormal state in which a monitoring pulse is not generated for a long time, the reset circuit resets the CPU so that it returns to a normal state. It has become.
JP-A-8-6822

However, in the configuration as described above, if the control cycle shifts due to an abnormality of the timer, there is no countermeasure other than resetting the microcomputer, and the electric power steering apparatus immediately enters the system stop state. . As a result, the steering assist is suddenly stopped, which may give the driver a significant discomfort.
In addition, a reset circuit made up of a custom IC is not used with high precision, and the time interval of the monitoring pulses exceeds a fixed time set with a relatively large margin with respect to the control cycle. In addition, the CPU is reset. For this reason, some deviation in the control cycle must be allowed, and control processing in an appropriate control cycle cannot always be guaranteed.

  Accordingly, an object of the present invention is to provide a control device capable of continuing control processing even in the event of an abnormality in which the control cycle is shifted, and capable of executing the control processing with an accurate control cycle, and such a control device. Another object is to provide an electric power steering device.

In order to achieve the above object, the invention according to claim 1 is characterized in that the first time measuring means (21) for generating an interrupt by measuring a predetermined control period, and the period for which the first time measuring means generates an interrupt. A second time measuring means (22) for performing a time measuring operation for monitoring the control, a control means (31) for executing a predetermined control process in response to an interrupt from the first time measuring means, and the first time measuring means. An interrupt period determining means (38) for determining whether or not an interrupt generation period by the first timing means coincides with the control period by referring to a timing result of the second timing means at the time of occurrence of the interrupt; When it is determined by the interrupt cycle determination means that the interrupt generation cycle and the control cycle are inconsistent, the first time counting is performed by an amount corresponding to a deviation between the interrupt generation cycle and the control cycle. in particular to modify the count start timing by means A control device, characterized in that the interrupt generation cycle including the timing correction means (36) to match with the control period. The alphanumeric characters in parentheses indicate corresponding components in the embodiments described later. The same shall apply hereinafter in this section.

According to this configuration, the first time measuring means counts a predetermined control cycle to generate an interrupt, and upon receiving this interrupt, the control means executes a predetermined control process. Thereby, the control means can perform a predetermined control process for every control period. On the other hand, the period at which the first time measuring means generates an interrupt is monitored using the time measurement result of the second time measuring means. That is, it is determined whether or not the interrupt generation period by the first time measuring means coincides with the control period based on the time measurement result of the second time measuring means when the interrupt is generated by the first time measuring means. This is when the mismatch by the amount of the deviation between the interrupt generation period and the control period, the timer starts timing by the first timing means is corrected. As a result, even if the interrupt generation period of the first time measuring means is deviated from the predetermined control period, the control means is given an interrupt for each control period. Thereby, the control means can continue the predetermined control process every control cycle. At the same time, since the deviation of the interrupt generation cycle is corrected, the control process can be performed with an accurate control cycle.

  The first time measuring means may be reset every time the control cycle is timed to restart timekeeping. In this case, it is preferable that the time correction means controls timing (start) timing by the first time measurement means in accordance with a deviation between the interrupt generation period and the control period. According to this configuration, when an abnormality that generates an interrupt occurs before the first time measuring means completes the control cycle time measurement, the time correcting means shifts the time counting start timing of the first time measuring means, thereby interrupting. Make the generation period coincide with the control period. Thus, even when an abnormality occurs in the first time measuring means, an interrupt can be generated with an accurate control cycle.

  Further, the second time measuring means may be reset every time when an abnormality determination period longer than that of the first time measuring means is measured to restart time measurement. In this case, the interrupt cycle determination means calculates the difference between the time measurement result of the second time measurement means at the time of the previous interrupt occurrence and the time measurement result of the second time measurement means at the time of the current interrupt occurrence. It is preferable to include an interrupt period calculating means (33) obtained as an interrupt generation period, and a comparison means (37) for comparing and determining the interrupt generation period calculated by the interrupt period calculating means and the control period. . The comparing means includes a deviation calculating means (34) for obtaining a deviation between the interrupt generation period calculated by the interrupt period calculating means and the control period, and whether the deviation obtained by the deviation calculating means is substantially zero. And determination means (35) for determining whether or not. With such a configuration, it is possible to monitor the abnormality of the interrupt generation cycle by the first time measuring means based on the time measurement result of the second time measuring means.

  According to a second aspect of the present invention, the first timekeeping means is reset every time the control period is timed and restarts timekeeping, and the second timekeeping means is an abnormality determination period longer than the control period. An interrupt determination counter (41) for counting the number of interrupts generated within the abnormality determination cycle by the first time counting means, and the second time counting. In response to an abnormality determination interrupt from the means, it is determined whether or not the number of interrupts counted by the interrupt count counting means has reached a predetermined lower threshold, and the interrupt count is the lower threshold 2. The control device according to claim 1, further comprising: an interrupt stop determination unit (42) that determines that an interrupt stop abnormality has occurred when the error has not been reached.

According to this configuration, when the number of interrupts generated by the first time measuring means does not reach the predetermined lower threshold within the abnormality determination cycle timed by the second time measuring means, an interrupt stop abnormality occurs. It is determined that That is, an abnormality (interruption stop abnormality) is detected in which an interrupt from the first time measuring means is not generated or the generation cycle of this interrupt is longer than normal.
According to a third aspect of the present invention, there is provided monitoring pulse generation means (32) for generating a monitoring pulse every time the control means receives an interrupt from the first time measuring means and executes the predetermined control processing, and the monitoring pulse generating means (32). A reset means (11) for monitoring the generation period of the monitoring pulse generated by the pulse generation means and resetting the control device in response to the generation period of the monitoring pulse reaching a predetermined pulse period abnormality determination time; And pulse generation prohibiting means (44) for prohibiting generation of the monitoring pulse by the monitoring pulse generating means in response to the interrupt stop determining means determining that an interrupt stop abnormality has occurred. The control device according to claim 2, wherein

According to this configuration, when an interrupt stop abnormality occurs, the monitoring pulse is not generated, and as a result, the control device is reset by the reset means. Thus, when the interruption from the first time measuring means has stopped, the control device can be reset.
The invention according to claim 4 is the first timekeeping means (21) for measuring the predetermined control cycle, generating an interrupt, resetting every time the control cycle is timed, and restarting the timekeeping. A second timing means (22) for performing a time measuring operation to monitor a period in which the means generates an interrupt, and generating an abnormality determination interrupt every time an abnormality determination period longer than the control period is measured; The control means (31) which receives an interrupt from the first time measuring means and executes a predetermined control process, and referring to the time measurement result of the second time measuring means at the time of occurrence of the interrupt by the first time measuring means, An interrupt period determining means (38) for determining whether or not the interrupt generation period by the time measuring means coincides with the control period, and the interrupt generation period and the control period are determined by the interrupt period determining means. When it is determined that there is a mismatch, Time correction means (36) for correcting the time measuring operation by the first time measuring means according to the deviation between the generation period and the control period, and the number of interruptions generated by the first time measuring means within the abnormality determination period. In response to an abnormality determination interrupt from the interrupt counting means (41) for counting and the second timing means, the number of interrupts counted by the interrupt count counting means reaches a predetermined lower threshold. Interrupt stop determining means (42) for determining whether or not an interrupt stop abnormality has occurred when the number of interrupts has not reached the lower threshold value, and the control means A monitoring pulse generating means (32) for generating a monitoring pulse every time the predetermined control processing is executed in response to an interrupt from the time measuring means, and a monitoring pulse generation period generated by the monitoring pulse generating means is monitored. And this monitoring pulse The reset means (11) for resetting the control device in response to the occurrence period reaching a predetermined pulse period abnormality determination time, and the interrupt stop determination means determining that an interrupt stop abnormality has occurred And a pulse generation prohibiting means (44) for prohibiting the generation of the monitoring pulse by the monitoring pulse generating means in response to the above.
According to a fifth aspect of the present invention, when the number of interrupts counted by the interrupt number counting means reaches a predetermined upper limit threshold, an abnormality occurs in the occurrence of an abnormality determination interrupt by the second timing means. The control device according to any one of claims 2 to 4, further comprising a time abnormality determination means (42) for determining that the time is present.
According to a sixth aspect of the present invention, the pulse generation prohibiting means further includes the monitoring pulse in response to the timing abnormality determination means determining that an abnormality has occurred in the abnormality determination interrupt generation by the second timing means. 6. The control device according to claim 3, wherein generation of the monitoring pulse by the generating means is prohibited.
The invention according to claim 7 is one in which the first time measuring means is reset every time the control cycle is timed and the time measurement is resumed, and the second time measuring means is an abnormality longer than the first time measuring means. all SANYO for generating an abnormality judgment interrupt every timing the determination period, an interrupt to time the interrupt number of the first counting means is generated between said second time counting means for counting the abnormality determination period When the number of interruptions counted by the number of times counting means (41) and the number of interruption counting means reaches a predetermined upper limit threshold, an abnormality has occurred in the occurrence of an abnormality determination interruption by the second time counting means. The control device according to claim 1 , further comprising a timing abnormality determination means (42) for determining that there is a fault. With this configuration, it is possible to determine that an abnormality has occurred when no abnormality determination interrupt is generated by the second timing means or when the generation period of this abnormality determination interrupt is longer than usual.

According to an eighth aspect of the present invention, there is provided monitoring pulse generation means (32) for generating a monitoring pulse each time the control means receives an interrupt from the first time measuring means and executes the predetermined control processing, and the monitoring pulse generating means (32). A reset means (11) for monitoring the generation period of the monitoring pulse generated by the pulse generation means and resetting the control device in response to the generation period of the monitoring pulse reaching a predetermined pulse period abnormality determination time; The pulse generation prohibiting means (44) for prohibiting the generation of the monitoring pulse by the monitoring pulse generating means in response to the fact that the timing abnormality determining means determines that an abnormality has occurred in the occurrence of the abnormality determination interrupt by the second timing means. The control device according to claim 7, further comprising : Thereby, when an abnormality occurs in the occurrence of the abnormality determination interrupt of the second time measuring means, the control device can be reset.

The invention according to claim 9 is an operation amount detection means (3) for detecting an operation amount of the operation member (1) for steering, and an electric motor for generating power for applying a steering assist force to the steering mechanism (2). A motor (M) and a control device (10) according to any one of claims 1 to 8 for controlling the electric motor, wherein the control means is an operation detected by the operation amount detection means. The electric power steering apparatus is characterized by executing a control process for controlling the driving of the electric motor according to the amount.

  According to this configuration, when a deviation occurs in the interrupt generation cycle by the first time measuring means, by correcting the time measuring operation by the first time measuring means, an interrupt is generated at a predetermined control period. Accordingly, it is possible to continue the state in which the control process for driving and controlling the electric motor is performed. In this way, it is possible to avoid a situation in which the steering assistance by the electric power steering apparatus is suddenly stopped and to give the driver a significant discomfort. At the same time, since the electric motor can be driven and controlled with an accurate control cycle without depending on the deviation of the interrupt generation cycle by the first time measuring means, an excellent steering feeling can be realized.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a block diagram for explaining a configuration example of an electric power steering apparatus according to an embodiment of the present invention. This electric power steering apparatus is used by being mounted on a vehicle, drives an electric motor M in accordance with an operation of a steering wheel 1 as an operation member for steering, and uses the power generated by the electric motor M as a steering mechanism 2. Steering assistance is performed by mechanically transmitting to.

  This electric power steering device includes a torque sensor 3 as an operation amount detecting means for detecting a steering torque applied to the steering wheel 1 as an operation amount, and an electric power steering ECU (electronic control unit) 10 as a control device. I have. The ECU 10 is provided with an output signal of a vehicle speed sensor 4 that detects the speed (vehicle speed) of the vehicle. The ECU 10 controls driving of the electric motor M based on signals from the torque sensor 3 and the vehicle speed sensor 4.

  The ECU 10 includes a microcomputer 20, a PWM (pulse width modulation) pulse generation circuit 15, a motor drive circuit 16, and a current detection circuit 17. The microcomputer 20 generates a control signal for controlling the electric motor M based on the steering torque, the vehicle speed, and the current flowing through the electric motor M, and supplies the control signal to the PWM pulse generation circuit 15. The PWM pulse generation circuit 15 generates a PWM pulse having a duty corresponding to the given control signal and inputs the PWM pulse to the motor drive circuit 16. The motor drive circuit 16 includes a plurality of switching elements that are turned on / off based on the PWM pulse supplied from the PWM pulse generation circuit 15, and supplies a current corresponding to the control signal to the electric motor M. The current (motor current) supplied from the motor drive circuit 16 to the electric motor M is detected by the current detection circuit 17 and the detection result is fed back to the microcomputer 20.

  The microcomputer 20 includes a CPU 30 and its peripheral circuits. The peripheral circuit includes a clock generator 23 that supplies an operation clock to the CPU 30, an A / D converter 24 that converts a signal from the torque sensor 3 into a digital signal, and a signal from the vehicle speed sensor 4 that is converted into a digital signal. An A / D converter 25 and a memory 26 storing an operation program of the CPU 30 and the like are included. Further, the peripheral circuit includes a first timer 21 that counts a predetermined control cycle and generates an interrupt to the CPU 30, and an abnormality determination interrupt to the CPU 30 every time an abnormality determination cycle longer than the control cycle is counted. A second timer 22 is provided.

The first timer 21 is reset every time a predetermined control period (200 μs) is measured, and restarts the time measurement. The second timer 22 is reset every time an abnormality determination period (for example, 5 milliseconds) longer than the control period is measured, and restarts the time measurement.
The CPU 30 executes a control process for controlling the electric motor M based on the operation program stored in the memory 26. This control process is executed each time an interrupt from the first timer 21 is given. As a result, a control process for driving and controlling the electric motor M is repeatedly executed at each control cycle.

  The ECU 10 further includes a reset circuit 11. The CPU 30 gives a monitoring pulse to the reset circuit 11 every time the control process is executed. The reset circuit 11 includes a timer circuit (so-called watchdog timer) that is reset by the monitoring pulse and restarts the time measurement. When the time is measured until a predetermined pulse period abnormality determination time, the reset circuit 11 gives a reset signal to the CPU 30. That is, when the CPU 30 runs out of control and cannot generate a monitoring pulse over the pulse period abnormality determination time, the reset circuit 11 resets the CPU 30 and, as a result, reset processing for initializing the microcomputer 20. Will be done.

  FIG. 2 is a block diagram for explaining a functional configuration of the CPU 30. The CPU 30 substantially functions as a plurality of function processing units by executing the program stored in the memory 26. The plurality of function processing units calculate a target current value to be supplied to the electric motor M based on the steering torque detected by the torque sensor 3 and the vehicle speed detected by the vehicle speed sensor 4, and achieve this target current value. A control unit 31 for supplying the control signal to the PWM pulse generation circuit 15 is included.

  Further, the plurality of function processing units include a monitoring pulse generating unit 32 that generates a monitoring pulse every time the control unit 31 executes the control processing. Further, the plurality of function processing units are provided with an interrupt period calculating unit 33 that obtains an interrupt generation period by referring to a time measurement result of the second timer 22 every time the first timer 21 generates an interrupt. A deviation calculating unit 34 for calculating a deviation between the interrupt generation period and the control period, a determination unit 35 for determining whether the deviation is substantially zero, and a deviation calculation when the deviation is not substantially zero. A timing correction unit 36 that corrects the timing of timing start of the first timer 21 based on the deviation obtained by the unit 34 is included.

  The interrupt cycle calculating unit 33 obtains, as an interrupt generation cycle, the difference between the time measurement result of the second timer when the previous interrupt occurs and the time measurement result of the second timer when the current interrupt occurs. The deviation calculation unit 34 and the determination unit 35 constitute comparison means 37 that compares and determines the interrupt generation cycle calculated by the interrupt cycle calculation unit 33 and the control cycle. The comparison unit 37 and the interrupt cycle calculation unit 33 constitute an interrupt cycle determination unit 38.

The time correction unit 36 corrects the time measurement start (restart) timing of the first timer 21 based on the deviation obtained by the deviation calculation unit 34, and is thereby given from the first timer 21 to the control unit 31. Interrupts are generated accurately at a predetermined control cycle.
The plurality of processing units realized by the program processing of the CPU 30 further serve as interrupt number counting means for counting the number of interrupts generated by the first timer 21 within the abnormality determination period timed by the second timer 22. An interrupt counter 41, an interrupt stop determination unit 42 that compares the interrupt count counted by the interrupt counter 41 with a predetermined lower threshold value, and an interrupt counted by the interrupt counter 41 Monitoring by the monitoring pulse generation unit 32 in response to the determination result by the timer abnormality determination unit 43 as a time abnormality determination unit that compares the number of times with a predetermined upper limit threshold, and the interrupt stop determination unit 42 and the timer abnormality determination unit 43 And a pulse generation prohibiting unit 44 that prohibits the generation of pulses. The interrupt counter 41 is a counter that is incremented every time the first timer 21 generates an interrupt and is reset by an abnormality determination interrupt from the second timer 22.

  The interrupt stop determination unit 42 detects that the interrupt generation from the first timer 21 has stopped when the number of interrupts counted by the interrupt counter 41 has not reached the lower limit threshold (interrupt (Stop abnormality) is determined to occur, and a command for stopping the generation of the monitoring pulse is given to the pulse generation prohibiting unit 44. On the other hand, the timer abnormality determination unit 43 causes the pulse generation prohibition unit 44 to stop generating the monitoring pulse when the number of interrupts counted by the interrupt number counter 41 has reached a predetermined upper limit threshold value. Give instructions for.

  The upper threshold is set larger than the lower threshold. The upper threshold value is equal to or slightly larger than the number of interrupts that can be generated by the normal first timer 21 within the abnormality determination cycle timed by the second timer 22. The value is specified. The case where the timer abnormality determination unit 43 determines that the number of interrupt occurrences has reached the upper limit threshold value is a case where an abnormality has occurred in the second timer 22. In this case, since the count value of the interrupt counter 41 is not reset, the count value reaches the upper limit threshold value.

When a deviation or abnormality occurs in the interrupt generation period from the first timer 21, the timing correction timing of the first timer 21 is shifted by the timing correction unit 36. Thereby, the control part 31 receives an interruption for every said control period irrespective of abnormality of the 1st timer 21. FIG.
FIG. 3 is a time chart for explaining an actual operation example. FIG. 3A shows a time change of the time measured (timer value) of the first timer 21, and FIG. The time change of the time count (timer value) of the timer 22 is shown.

  The second timer 22 is configured to repeatedly operate so as to be reset and restart the time measurement after continuing the time measurement over an abnormality determination period (for example, 5 milliseconds). On the other hand, the first timer 21 is configured to repeatedly operate so as to be reset and restart time measurement after continuing time measurement for a control period (for example, 200 μsec) much shorter than the abnormality determination period.

Therefore, the first timer 21 repeatedly executes time counting for each control cycle within the abnormality determination cycle timed by the second timer 22 and gives an interrupt to the control unit 31 for each control cycle. At each interrupt timing, the timer value of the second timer 22 is acquired, and the interrupt generation period is obtained by the interrupt period calculator 33 (see FIG. 2).
When some abnormality occurs in the first timer 21, as indicated by reference numeral A1, the first timer 21 generates an interrupt in a time shorter than the control period (for example, 100 μsec) from the start of the time measuring operation. Assume that you are in an abnormal state. In this case, it is immediately detected that an abnormality has occurred in the interrupt generation cycle by the functions of the interrupt cycle calculation unit 33, the deviation calculation unit 34, and the determination unit 35.

  At this time, the time correction unit 36 controls the first timer 21 so as to delay the time measurement start timing of the first timer 21 by the deviation (200 μsec-100 μsec) obtained by the deviation calculation unit 34. . As a result, as indicated by reference symbol A2, the first timer 21 starts counting after the stop time of the deviation (100 μsec) and generates an interrupt again after 100 μsec. Therefore, an interrupt is generated every predetermined control cycle (200 μs) and the state given to the control unit 31 is immediately restored. In this way, even when an abnormality occurs in the first timer 21, the control unit 31 can continue the control process for driving and controlling the electric motor M at every predetermined control cycle. It can be carried out.

However, since an abnormality has occurred in the first timer 21, it is inconvenient to perform the control permanently. Therefore, the discomfort given to the driver is reduced by gradually decreasing the steering assist force.
On the other hand, as indicated by reference symbol A3, there may be a case where an abnormality occurs in the first timer 21 and no interrupt is generated. In this case, the number of interrupt occurrences within the abnormality determination cycle timed by the second timer 22 becomes less than the predetermined lower threshold value, and the pulse generation prohibition unit 44 (see FIG. 2) generates a monitoring pulse. It is forbidden. Thereby, the microcomputer 20 is reset and initialized by the action of the reset circuit 11 (see FIG. 1).

  As described above, according to this embodiment, if a deviation occurs in the interrupt generation cycle by the first timer 21, this deviation is corrected by the action of the time correction unit 36 and so on, so-called life extension control is possible. Moreover, it is possible to cause the control unit 31 to execute the control process with an accurate control cycle. As a result, the drive control of the electric motor M is suddenly stopped and the steering assist is stopped, so that it is possible to prevent the driver from feeling uncomfortable, and at the normal time, the electric motor M is controlled by an accurate control cycle. Excellent steering feeling can be realized.

On the other hand, when the generation of an interrupt from the first timer 21 is stopped or when a failure occurs in the second timer 22, the generation of the monitoring pulse from the CPU 30 is prohibited, thereby causing the reset circuit 11 to function. Thus, the microcomputer 20 can be reliably reset.
As mentioned above, although one Embodiment of this invention was described, this invention can also be implemented with another form. For example, in the above-described embodiment, the example in which the present invention is applied to the electric power steering apparatus has been described. However, the control apparatus according to the present invention is similarly applied to a control apparatus other than the electric power steering apparatus. It is something that can be done. In addition, various design changes can be made within the scope of matters described in the claims.

It is a block diagram for demonstrating the structural example of the electric power steering apparatus which concerns on one Embodiment of this invention. It is a block diagram for demonstrating the functional structure of CPU with which ECU as the control apparatus of the said electric power steering device was equipped. It is a time chart for demonstrating an actual operation example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Steering wheel, 20 ... Microcomputer, 37 ... Comparison means, 38 ... Interrupt period determination means

Claims (9)

A first time measuring means for measuring a predetermined control cycle and generating an interrupt;
A second time measuring means for performing a time measuring operation in order to monitor a cycle in which the first time measuring means generates an interrupt;
Control means for executing a predetermined control process in response to an interrupt from the first time measuring means;
An interrupt period for determining whether or not an interrupt generation period by the first time measuring means coincides with the control period by referring to a time measurement result of the second time measuring means when an interrupt is generated by the first time measuring means A determination means;
This interrupt period determination unit, when said interrupt generation period and the control period is determined to be mismatched, by an amount corresponding the first time counting means of the difference between the interrupt generation period and the control period A control device comprising: a time correction means for adjusting the interrupt generation period to match the control period by correcting a time measurement start timing . The first timekeeping means is reset every time the control cycle is timed, and restarts timekeeping,
The second timing means generates an abnormality determination interrupt every time an abnormality determination period longer than the control period is measured,
Interrupt number counting means for counting the number of interrupts generated by the first time counting means within the abnormality determination cycle;
In response to the abnormality determination interrupt from the second time counting means, it is determined whether or not the interrupt count counted by the interrupt count counting means has reached a predetermined lower threshold, and the interrupt count is 2. The control device according to claim 1, further comprising interrupt stop determination means for determining that an interrupt stop abnormality has occurred when the lower limit threshold is not reached. Monitoring pulse generating means for generating a monitoring pulse every time the control means receives an interrupt from the first time measuring means and executes the predetermined control processing;
Resetting means for monitoring the generation period of the monitoring pulse generated by the monitoring pulse generating means and resetting the control device in response to the generation period of the monitoring pulse reaching a predetermined pulse period abnormality determination time;
And further comprising pulse generation prohibiting means for prohibiting generation of a monitoring pulse by the monitoring pulse generating means in response to the interrupt stop determining means determining that an interrupt stop abnormality has occurred. Item 3. The control device according to Item 2.   A first time measuring means for measuring a predetermined control cycle, generating an interrupt, and resetting and restarting the time measurement every time the control cycle is measured;
  A second time measuring means for performing a time measuring operation to monitor a period in which the first time measuring means generates an interrupt, and generating an abnormality determination interrupt each time an abnormality determination period longer than the control period is measured;
  Control means for executing a predetermined control process in response to an interrupt from the first time measuring means;
  An interrupt period for determining whether or not an interrupt generation period by the first time measuring means coincides with the control period by referring to a time measurement result of the second time measuring means when an interrupt is generated by the first time measuring means A determination means;
  When it is determined by the interrupt cycle determination means that the interrupt generation cycle and the control cycle do not coincide with each other, the first time counting unit according to a deviation between the interrupt generation cycle and the control cycle A timing correction means for correcting the timing operation by
  Interrupt number counting means for counting the number of interrupts generated by the first time counting means within the abnormality determination cycle;
  In response to the abnormality determination interrupt from the second time counting means, it is determined whether or not the interrupt count counted by the interrupt count counting means has reached a predetermined lower threshold, and the interrupt count is Interrupt stop determination means for determining that an interrupt stop abnormality has occurred when the lower limit threshold is not reached,
  Monitoring pulse generating means for generating a monitoring pulse every time the control means receives an interrupt from the first time measuring means and executes the predetermined control processing;
  Resetting means for monitoring the generation period of the monitoring pulse generated by the monitoring pulse generating means and resetting the control device in response to the generation period of the monitoring pulse reaching a predetermined pulse period abnormality determination time;
  And a pulse generation prohibiting means for prohibiting generation of a monitoring pulse by the monitoring pulse generating means in response to the interrupt stop determining means determining that an interrupt stop abnormality has occurred. .   Time abnormality determination means for determining that an abnormality has occurred in the abnormality determination interruption by the second time measurement means when the number of interruptions counted by the interruption number counting means has reached a predetermined upper threshold value. The control device according to claim 2, further comprising:   The pulse generation prohibiting means further generates a monitoring pulse by the monitoring pulse generating means in response to the timing abnormality determining means determining that an abnormality has occurred in the abnormality determining interrupt generation by the second timing means. 6. The control device according to claim 3, wherein the control device is prohibited.   The first time measuring means is reset every time the control cycle is timed and restarts time counting;
  The second time measuring means generates an abnormality determination interrupt each time an abnormality determination period longer than the first time measuring means is measured,
  Interrupt number counting means for counting the number of interrupts generated by the first time measuring means while the second time measuring means time the abnormality determination period;
  Timing abnormality determination means for determining that an abnormality has occurred in the occurrence of an abnormality determination interrupt by the second timing means when the number of interruptions counted by the interruption number counting means reaches a predetermined upper threshold value. The control device according to claim 1, further comprising:   Monitoring pulse generating means for generating a monitoring pulse every time the control means receives an interrupt from the first time measuring means and executes the predetermined control processing;
  Resetting means for monitoring the generation period of the monitoring pulse generated by the monitoring pulse generating means and resetting the control device in response to the generation period of the monitoring pulse reaching a predetermined pulse period abnormality determination time;
  Pulse generation prohibiting means for prohibiting generation of a monitoring pulse by the monitoring pulse generating means in response to the fact that the timing abnormality determining means determines that an abnormality has occurred in the occurrence of an abnormality determination interrupt by the second timing means; The control device according to claim 7, further comprising: An operation amount detection means for detecting an operation amount of the operation member for steering;
An electric motor that generates power for applying steering assist force to the steering mechanism;
Including the control device according to any one of claims 1 to 8 for controlling the electric motor,
The electric power steering apparatus characterized in that the control means executes a control process for driving and controlling the electric motor in accordance with an operation amount detected by the operation amount detection means.

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