JP2007253766A - Electric power steering system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric power steering system capable of previously correcting a control data concerning decision of detected steering auxiliary force by a correction data corresponding to characteristics of a detection device and maintaining a fail safe function by avoiding occurrence of serious failure. <P>SOLUTION: Abnormality is judged by previously correcting a control data concerning decision of the detected steering auxiliary force, for example, a torque detection value, a motor electric current value, a battery voltage value, etc. by the first correction data corresponding to the characteristics of the detection device at a torque correction part 20, an electric current correction part 30, a battery voltage judgement part 40, etc., and using a first abnormality judgement threshold value. When determined as abnormal, the control data is corrected by using a second correction data and the abnormality is determined by using a second abnormality judgement threshold value wider in tolerance than the first abnormality judgement threshold value. When it is within the range of the threshold value, control is continued using the control data, and when it is out of the range of the threshold, an abnormal signal is output to an output limiting unit 25 to suppress or stop the output. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electric power steering apparatus, and more particularly to an electric power steering apparatus provided with processing means when an abnormality in reading of its characteristic correction value occurs.

  An electric power steering device for a vehicle detects a steering torque and a vehicle speed generated in a steering shaft by operating a steering handle, and drives a motor based on the detection signal to assist a steering force of the steering handle. is there. Such control of the electric power steering device is executed by the control device, and the outline of the control is based on the steering torque detected by the torque sensor and the current supplied to the motor based on the vehicle speed detected by the vehicle speed sensor. The magnitude is calculated, and the current supplied to the motor is controlled based on the calculation result.

  That is, when the steering wheel is operated and steering torque is generated, the control device supplies a large steering assist force when the detected vehicle speed is zero or low, and when the detected vehicle speed is high. By controlling the current supplied to the motor in accordance with the steering torque of the steering wheel and the vehicle speed so as to supply a small steering assist force, an optimum steering assist force according to the traveling state can be provided.

  In this type of control device, for example, feedback control is performed so that the current that actually flows through the motor matches the control target value of the motor current calculated based on the steering torque and the vehicle speed. A motor current detector that detects a flowing current is provided, and a predetermined characteristic correction, that is, an offset value, a gain correction, and the like is performed on the motor current detection value (see Patent Document 1).

  Besides, in the control device, it is common to obtain the control data for controlling the control device by correcting the calculation value calculated based on the detection value and the detection value by performing various calculations and other calculations. A characteristic correction value (correction data) for this purpose is stored in a nonvolatile memory such as an EEPROM, and is configured to be read out as necessary.

  However, when reading correction data from the non-volatile memory, if the correction data cannot be read correctly from the memory due to the influence of external noise or the like, the above-described detection values and calculation values cannot be corrected, and correction errors may occur. As a result, the apparatus is controlled by the included control data, and the electric power steering apparatus adversely affects the steering performance and fail-safe performance.

As a countermeasure, it is verified whether the correction data read from the non-volatile memory is garbled due to the influence of external noise or the like. If garbled data is generated, it is stored in another memory. A control device configured to use an alternative value as correction data has been proposed (see Patent Document 2).
JP 2002-234457 A JP-A-7-77102

  However, the substitute value is not the original correction data set finely according to the control state at the time of detection, but corrects the detection value or detection value to the extent that it can be used for predetermined control even if it is incomplete. It is possible alternative data.

  For this reason, for example, when detecting a failure in the motor current detector, the motor current detection value is corrected using the characteristic correction data in order to correct the characteristic of the motor current detector, but the characteristic correction data can be read correctly. If the current detection value is corrected using the alternative data without being able to do this, there will be inconveniences such as excessive steering assistance and too little steering assistance, and the fail-safe function will not function normally. This results in inconvenience.

  In addition, the use of alternative data may cause inconveniences such as detecting a non-failure as a failure, misdetection that a failure has occurred but cannot be detected as a failure, and allowing operation outside the guaranteed operating voltage. There is concern about the occurrence.

  Since the conventional electric power steering device is intended for small vehicles, it has not been a problem even if output fluctuations due to some correction errors as described above occur, but recently it can be used for large vehicles as well. The output of the electric power steering system has increased, and even if a slight correction error occurs, it has a significant effect on the steering performance and the fail-safe function. Therefore, it is required to reduce the correction error as much as possible. Yes. The present invention aims to solve the above-mentioned problems.

  The present invention solves the above-mentioned problems, and the invention of claim 1 calculates a current command value based on a detection device for detecting control data related to the determination of the steering assist force and the detected control data, In the electric power steering apparatus comprising: a control device that controls an output of a motor that applies a steering assist force to the steering mechanism based on the calculated current command value, the control device transmits the detected control data to the detection device. The control data that has been corrected based on the first characteristic correction data corresponding to the characteristic is compared with a first abnormality determination threshold value to determine whether or not the detection apparatus is abnormal. The corrected control data obtained by correcting the characteristics of the control data based on the second correction data corresponding to the characteristics of the detection device has a wider allowable range than the first abnormality determination threshold value. An electric power steering apparatus characterized by determining the abnormality of the detection device in comparison with the second abnormality determination threshold.

  According to a second aspect of the present invention, there is provided a detection device for detecting control data related to the determination of the steering assist force, a current command value based on the detected control data, and a steering mechanism based on the calculated current command value. An electric power steering apparatus comprising: a control device that controls an output of a motor that applies a steering assist force to the control device, wherein the control device receives the detected control data as an input, and is corrected according to the characteristics of the detection device A characteristic corrector that outputs corrected control data, a characteristic correction data storage device that stores first characteristic correction data and second characteristic correction data corresponding to the characteristic of the detection device, and the first characteristic Threshold value in which a first abnormality determination threshold value corresponding to correction data and a second abnormality determination threshold value corresponding to second characteristic correction data different from the first abnormality determination threshold value are stored. A storage device, and compares the first corrected characteristic control data output when the first characteristic correction data is set in the characteristic corrector with the first abnormality determination threshold value to determine abnormality of the detection device, When it is determined that there is an abnormality, the second characteristic correction data is further set, and the characteristic-corrected control data that is output is compared with the second abnormality determination threshold value to determine an abnormality of the detection device. This is an electric power steering device.

  The second abnormality determination threshold value is assumed to have a larger allowable range that is determined to be normal than the first abnormality determination threshold value.

  The control device further includes an output limiting device, and as a result of comparison between the characteristic-corrected control data and the second abnormality determination threshold, the characteristic-corrected control data is defined by the second abnormality determination threshold. When it is determined that it is out of the allowable range, an abnormal signal is output to the output limiting device to limit or stop the output of the motor.

  Further, the motor output is limited or stopped by the output limiting device when the first characteristic correction data set in the characteristic corrector cannot be read correctly and the second characteristic correction data is set.

  The control data related to the determination of the steering assist force detected by the detection device is any one or more of steering torque, motor current, battery voltage, motor power supply voltage, motor terminal voltage, and other control data. It shall be.

  As described above, according to the present invention, when the control data related to the determination of the detected steering assist force is corrected with the correction data determined in advance according to the characteristics of the detection device, the first correction data is When it is found from the comparison between the control data and the abnormality determination threshold value that the control data cannot be corrected correctly because the data is not read correctly, the control data is corrected using the second correction data. Thus, even when the first correction data cannot be read correctly, the control data can be corrected using the second correction data, and the control of the control device can be safely continued.

  Embodiments of the present invention will be described below. FIG. 1 is a diagram for explaining an outline of the configuration of an electric power steering apparatus suitable for carrying out the present invention. A shaft 2 of a steering handle 1 passes through a reduction gear 4, universal joints 5a and 5b, and a pinion rack mechanism 7. Coupled to the steering wheel tyrod 8. A torque sensor 3 that detects the steering torque of the steering handle 1 is provided on the shaft 2, and a motor 9 that assists the steering force is coupled to the shaft 2 via a reduction gear 4.

  The control device 10 for controlling the power steering device is supplied with an ignition key signal from the battery 14 via the ignition key 11 and is supplied with power from a parallel power supply line. The control device 10 calculates a current command value based on the steering torque detected by the torque sensor 3 and the vehicle speed detected by the vehicle speed sensor 12, and supplies a current to be supplied to the motor 9 based on the calculated current command value. Control.

  FIG. 2 is a block diagram for explaining the configuration of the control device 10 constituting the control means. In this embodiment, the control device 10 is mainly composed of a CPU. Here, functions executed by a program in the CPU are shown. For example, the characteristic corrector 21 of the torque correction unit 20 does not indicate the characteristic corrector 21 as independent hardware, but indicates a characteristic correction function executed by the CPU. Needless to say, these functional elements can be configured by independent hardware (electronic circuits) without configuring the control device 10 by a CPU.

  Hereinafter, functions and operations of the control device 10 will be described. The steering torque signal input from the torque sensor 3 is input to the current command value calculator 23 via the torque correction unit 20 described later. A vehicle speed signal detected by the vehicle speed sensor 12 is also input to the current command value calculator 23.

  The current command value calculator 23 calculates a current command value Ir that is a control target value of the current supplied to the motor 9 by a predetermined calculation formula based on the input steering torque, vehicle speed, and other parameters. The adder 24 adds (including positive and negative signs) a current control value by adding the current command value Ir and the motor current detection value id detected by the motor current detector 27 and corrected through a current correction unit 30 described later. E is calculated and input to the motor drive circuit 26 via the output limiter 25 described later, and the motor 9 is driven. Here, the detected steering torque, vehicle speed, motor current detection value, and the like are control data related to the determination of the steering assist force.

  The motor drive circuit 26 is supplied with power from the battery 14, and it is determined by a battery voltage determination unit 40 described later whether or not the battery voltage is within a predetermined operating voltage range.

  The motor current detector 27 detects the motor current that actually flows through the motor 9. The detected motor current detection value is corrected through a current correction unit 30 described later, and the corrected motor current detection value id is input to the adder 24 to perform current feedback control.

  The motor current estimator 28 calculates a motor current estimated value Ie based on the current command value Ir calculated by the current command value calculator 23.

  Next, the torque correction unit 20, the current correction unit 30, the battery voltage determination unit 40, and the output limiter 25, which are the features of the present invention, will be described with reference to FIG.

[Torque correction part]
The torque correction unit 20 will be described. The torque correction unit 20 corrects the characteristic characteristic of the torque sensor and outputs the steering torque detected by the torque sensor 3. The torque correction unit 20 includes a characteristic corrector 21, a characteristic correction value memory 21a that stores a correction value for correcting the characteristic of the torque sensor, a torque abnormality determination unit 22, and a failure-safe abnormality determination threshold memory 22a.

  The characteristic correction value memory 21a stores first torque correction data and second torque correction data. The fail-safe abnormality determination threshold memory 22a corresponds to the first torque correction data. The first abnormality determination threshold value and the second abnormality determination threshold value corresponding to the second torque correction data are stored.

  Normally, the first torque correction data is read from the torque correction value memory 21a and predetermined characteristic correction is performed on the detected steering torque. However, when reading of the first torque correction data fails, for example, the following inconvenience may occur.

  That is, since the main torque signal and the sub torque signal are not corrected by the first torque correction data, the torque abnormality determination unit 22 that monitors the allowable error between the main torque signal and the sub torque signal causes a failure in the torque sensor. However, it may be erroneously detected that a failure has occurred, or the occurrence of a torque sensor failure may not be detected.

  Therefore, a sufficient margin is provided for the threshold for determining the allowable error between the main torque signal and the sub torque signal executed by the torque abnormality determination unit 22, and the range of the allowable error between the main torque signal and the sub torque signal is expanded. Avoid troubles due to false detection of abnormal conditions.

  In this embodiment, the main torque signal Vmt and the sub torque signal Vst output from the torque sensor 3 sampled at a predetermined sampling period are input to the characteristic corrector 21, and the input main torque signal Vmt and sub torque are input. The signal Vst is corrected by the first torque correction data stored in the torque correction value memory 21a in the characteristic corrector 21.

  At this time, the torque abnormality determination unit 22 determines whether or not the first torque correction data is correctly read from the torque correction value memory 21a and corrected. That is, in the torque abnormality determiner 22, the difference (| Vmt−Vst |) between the main torque signal Vmt and the sub torque signal Vst is a first abnormality determination for a predetermined failsafe stored in the abnormality determination threshold memory 22a. It is determined whether the threshold value and the range of the fixed time are exceeded.

  When it is determined that the first torque correction data is correctly read and corrected, the corrected main torque signal Vmt is output to the current command value calculator 23.

  When it is determined that the first correction data is not read correctly, the input main torque signal Vmt and sub torque signal Vst are stored in the torque correction value memory 21a in the characteristic corrector 21. Is corrected by the torque correction data.

  At this time, the torque abnormality determination unit 22 determines whether or not predetermined second torque correction data is correctly read from the torque correction value memory 21a and corrected. That is, in the torque abnormality determiner 22, the difference (| Vmt−Vst |) between the main torque signal Vmt and the sub torque signal Vst is the second abnormality determination for a predetermined fail-safe stored in the abnormality determination threshold memory 22a. It is determined whether the threshold value and the range of the fixed time are exceeded.

  When it is determined that the second torque correction data is correctly read and corrected, the corrected main torque signal Vmt is output to the current command value calculator 23.

  The second torque correction data may be the same as the first torque correction data, or may be the same as different correction data. However, the second abnormality determination threshold value and the fixed time range stored in the abnormality determination threshold value memory 22a have an allowable error range larger than that of the first abnormality determination threshold value and the fixed time range, resulting in erroneous detection of an abnormal state. Set to avoid problems.

  When the torque abnormality determination unit 22 determines that an abnormality has occurred based on the second abnormality determination threshold and the range of the determination time, the torque abnormality is determined and a fail-safe process described later is performed. Specifically, torque abnormality is determined based on the following order, threshold value, and fixed time. Note that the threshold values and determination times described below are examples for explanation, and are not limited to these numerical values. Moreover, in the following illustration, although the abnormality determination threshold is the same for the second determination, the second determination (1) and the second determination (2) with different confirmation times are shown, but either one may be used.

* First judgment *
First abnormality determination threshold: 0.3 V, determination time: 14 ms
In this determination, | Vmt−Vst−5V | ≧ 0.3V between the absolute value of the value obtained by subtracting 5V from the difference between the main torque signal Vmt and the sub torque signal Vst and the first abnormality determination threshold value 0.3V. Is established during the determination time of 14 ms, it is determined that the main torque signal Vmt exceeds the allowable error range defined by the threshold and is abnormal.

* Second judgment (1) *
When it is determined as abnormal in the first determination, it is determined under the following conditions.

Second abnormality determination threshold: 0.25 V Determination time: 14 ms
In this determination, | Vmt−Vst−5V | ≧ 0.25 V between the absolute value of the value obtained by subtracting 5 V from the difference between the main torque signal Vmt and the sub torque signal Vst and the second abnormality determination threshold value 0.25 V. When the relationship is established during the determination time of 14 ms, it is determined that the main torque signal Vmt exceeds the allowable error range defined by the threshold, and the detected torque is determined to be abnormal. This is a case where a gradual change function for gradually decreasing the detected torque is provided. In the case of a torque abnormality, the steering assist function is gradually reduced by the gradual change function to ensure safety, so the above threshold value is narrower than the first determination threshold value.

* Second judgment (2) *
When it is determined that there is an abnormality in the second determination (1), the abnormality determination threshold is the same, but the determination is made under the following conditions in which the determination time is further shortened.

Second abnormality determination threshold: 0.25 V Determination time: 7 ms
In this determination, a relationship of | Vmt−Vst−5V | ≧ 0.25 V is established between the absolute value of a value obtained by subtracting 5 V from the difference between the main torque signal Vmt and the sub torque signal Vst and the second threshold value 0.25 V. Is determined during the determination time of 7 ms, it is determined that the main torque signal Vmt exceeds the allowable error range defined by the threshold value. When the detected torque is determined to be abnormal, the detected torque This is a case in which a gradual change function for gradually decreasing is not provided.

  In the case of a torque abnormality, the abnormal operation of the steering assist function becomes large, so the second abnormality determination threshold is narrower than the first abnormality determination threshold, the determination time is shortened, and the abnormality is determined early.

  If it is not determined to be abnormal in the first determination described above, it is determined that the torque correction value has been correctly read and processed normally. Even if it is determined to be abnormal in the first determination, if it is not determined to be abnormal in the second determination (1) or the second determination (2), it is processed as being processed normally. Further, when it is determined that there is an abnormality in the second determination (1) or the second determination (2), a signal indicating the abnormality is output to an output limiter 25 described later, and a failure such as limiting or stopping the driving of the motor is performed. Activate the safe function.

  Note that the numerical values described here such as the first and second determination threshold values, the determination time, and the difference between the main torque signal Vmt and the sub torque signal Vst are examples described for explanation, and It is not limited.

[Current correction section]
The current correction unit 30 will be described. The current correction unit 30 corrects the characteristic of the motor current detector and outputs the detected current value detected by the motor current detector 27. The current correction unit 30 includes a characteristic correction unit 31, a characteristic correction value memory 31 a storing a characteristic correction value of the motor current detector, a monitoring timer 33 and a fail counter 34, a fail-safe threshold memory 35, and a fail determination unit 36. Composed.

  The characteristic correction value memory 31a stores first characteristic correction data and second characteristic correction data, and the threshold value memory 35 determines the current change rate corresponding to the first characteristic correction data. A determination threshold value and a second determination threshold value corresponding to the second characteristic correction data are stored.

  First, predetermined characteristic correction is performed on the current detection value detected by reading the first current correction data from the characteristic correction value memory 31a. However, when the reading of the first current correction data fails, the current change rate which is the difference between the previous current detection value i0 and the current detection value i1 of the current detection value i sampled at a predetermined sampling period. There is a possibility that the motor current detector 27 is erroneously detected as having failed, or that the motor current detector has failed.

  Therefore, a sufficient margin is provided for the threshold for determining the allowable error of the current change rate, and the allowable error range of the current change rate is expanded to avoid troubles due to erroneous detection of abnormal conditions.

  In this embodiment, the detected current value i detected by the motor current detector 27 is input to the characteristic corrector 31. In the characteristic corrector 31, the input current detection value i is corrected by the first characteristic correction data stored in the current correction value memory 31a. Then, the absolute value (detection current change rate) of the difference between the corrected current detection value of the previous sampling and the corrected current detection value of the current sampling is stored in the abnormality determination threshold memory 35 in the first determination. When the detected current change rate is equal to or lower than the first determination threshold value, the monitoring timer 33 starts measuring time.

  When a predetermined time has elapsed from the time measured by the monitoring timer 33, the motor current estimator 28 estimates the motor current estimated value Ie0 estimated based on the current command value Ir0 of the previous sampling and the current command value Ir1 of the current sampling. The difference (estimated current change rate) from the estimated motor current value Ie1 is calculated, and it is determined whether or not it is equal to or less than the first determination threshold stored in the abnormality determination threshold memory 29, and the estimated current change rate is the first If it is equal to or greater than the determination threshold value, the fail counter 34 starts to time.

  Specifically, the monitoring timer 33 and the fail counter 34 are timed under the following conditions. In addition, the conditions described below are examples described for explanation, and are not limited thereto.

* Monitoring timer start condition *
(1) When the first characteristic correction data is normally read, when the detected current change rate is equal to or higher than the first determination threshold value (1A), the monitoring timer starts counting.

  (2) When the first characteristic correction data is not read normally, the second characteristic correction data is read. When the detected current change rate is equal to or higher than the second determination threshold value (2A), the monitoring timer starts counting.

  When the first and second determination conditions are not satisfied, that is, when the absolute value of the rate of change of the current detection value is equal to or less than a predetermined threshold, the monitoring timer is reset.

* Fail counter timing start condition *
(1) When the first characteristic correction data is normally read, when the count value of the monitoring timer is 5 ms or more and the absolute value of the current estimated value change rate is the predetermined threshold value 10A or more, the fail counter is timed. Start.

  (2) When the first characteristic correction data is not read normally, the second characteristic correction data is read. When the count value of the monitoring timer is 5 ms or more and the absolute value of the current estimated value change rate is the predetermined threshold value 15A or more, the time measurement of the fail counter is started.

  When the first and second determination conditions are not satisfied, that is, when the absolute value of the rate of change of the current detection value is equal to or less than a predetermined threshold, the monitoring timer is reset.

* Fail judgment condition *
The fail counter 34 accumulates the count value of the past 180 ms every 20 ms, and calculates a cumulative value for 200 ms.

  In this determination, when the cumulative value of the fail counter for the past 200 ms does not exceed the threshold value 10, it is determined that the motor current detector is normal and not in an abnormal state. When the cumulative value of the fail counter for the past 200 ms exceeds 10, it is determined that the motor current is an abnormal vibration current and the current detector has failed, and an abnormal signal is output to the output limiter 25. A fail-safe function such as limiting or stopping the driving of the motor is activated.

  In addition, the numerical values described here, such as the first and second determination threshold values and the determination time, the numerical values of the detected current change rate and the current estimated value change rate, the count value of the monitoring timer, the fail counter count time and the cumulative value, etc. Is an example described for illustrative purposes, and is not limited thereto.

[Battery voltage determination unit]
The battery voltage determination unit 40 will be described. The battery 14 supplies power to the motor 9 via the motor drive circuit 26. In addition, since the battery 14 also supplies power to the control device, an abnormality in the battery voltage may cause the control device to malfunction. When it is determined that an abnormality has occurred, an abnormal signal is output to stop the control operation.

  The battery voltage determination unit 40 includes a battery voltage detector 41, a characteristic corrector 42 that corrects the characteristics of the battery voltage detector, a characteristic correction value memory 42a that stores correction values for correcting the characteristics of the battery voltage detector, a battery A voltage abnormality determination unit 43 that determines abnormality of voltage and an abnormality determination threshold value memory 43a that determines abnormality of battery voltage are provided. The characteristic correction value memory 42a includes a first characteristic correction value and a second characteristic correction value. And are stored. The abnormality determination threshold value memory 41a stores a first determination threshold value corresponding to the first characteristic correction value and a second determination threshold value corresponding to the second characteristic correction value. The determination threshold is a threshold obtained by adding or subtracting a predetermined fail-safe threshold to the first determination threshold to expand the determination margin to the safe side.

  The characteristic corrector 42 corrects the characteristic of the battery voltage detector 41, and usually reads the first characteristic correction value from the characteristic correction value memory 42a and corrects the detected battery voltage detection value. However, when the reading of the first characteristic correction value fails, the detected battery voltage abnormality cannot be recognized, and there is a concern that the control operation may be performed outside the operating range voltage.

  Therefore, when reading of the first characteristic correction value fails, the second characteristic correction value determination is read to correct the detected battery voltage detection value.

  Then, it is determined by the first determination threshold whether or not the battery voltage detection value corrected by the first characteristic correction value is in an appropriate range, and it is determined that the corrected battery voltage detection value is in an appropriate range. When it is done, the control is continued as it is.

  When it is determined that the battery voltage detection value corrected by the first characteristic correction value is not within the proper range, it is estimated that the reading of the first characteristic correction value has failed, and the second characteristic correction is performed. The battery voltage detection value is corrected by the value, and whether or not the corrected battery voltage detection value is in an appropriate range is determined by the second determination threshold value (threshold value obtained by expanding the determination margin to the safe side) and corrected. When it is determined that the battery voltage detection value is within the second determination threshold range, the control is continued as it is.

  When it is determined that the battery voltage detection value corrected by the second characteristic correction value is still outside the range of the second determination threshold value, an abnormal signal is output to the output limiter 25 and the driving of the motor is stopped. Activate the fail-safe function.

  For example, when the first determination threshold value is VS1 (= 15V ± 0.5V), the second determination threshold value VS2 is a value obtained by subtracting 0.5V from the threshold value on the voltage increase side, and 0 on the threshold value on the voltage decrease side. .5V is added value.

  As a result, even when it is determined that the battery voltage detection value corrected by the first characteristic correction value is not in the proper range, the battery voltage detection value corrected by the second characteristic correction value ensures a safe determination margin. When it is within the range of the second determination threshold value that is enlarged to the side, it can be determined that the battery voltage is not abnormal, and the control operation can be continued.

  The numerical values described here, such as the first and second determination threshold values and the battery voltage detection value described above, are examples given for explanation, and are not limited thereto.

[Output limiter]
The output limiter 25 will be described. When a signal indicating an abnormal state is output from the torque correction unit 20, the current correction unit 30, and the battery voltage determination unit 40, the output limiter 25 is output before the steering assist force is generated, that is, from the adder 24. The current control value E output to the motor drive circuit 26 is limited to perform a fail-safe function for reducing or stopping the unstable steering assist operation in the abnormal state described above.

  Thereby, even if the above-described abnormal state occurs, the steering assist force is limited or stopped, so that the driver is not put in danger.

  The control data related to the determination of the detected steering assist force is corrected with the first correction data corresponding to the characteristics of the detection device, the abnormality is determined using the first abnormality determination threshold, and the abnormality is determined. In such a case, the control data is corrected with the second correction data, and the abnormality is determined using the second abnormality determination threshold having a wider allowable range than the first abnormality determination threshold. Provided is an electric power steering device capable of avoiding a serious failure and maintaining a fail-safe function.

The figure explaining the structure of the electric power steering apparatus suitable for implementing this invention. The block diagram explaining the structure of an electronic controller.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steering handle 2 Axis 3 Torque sensor 4 Reduction gear 5a, 5b Universal joint 7 Pinion rack mechanism 8 Tyrode 9 Motor 10 Control device 11 Ignition key 12 Vehicle speed sensor 14 Battery 20 Torque correction part 21 Characteristic corrector 21a Characteristic correction value memory DESCRIPTION OF SYMBOLS 22 Torque abnormality determination device 22a Abnormality determination threshold memory 23 Current command value calculator 24 Adder 25 Output limiter 26 Motor drive circuit 27 Motor current detector 28 Motor current estimator 29 Abnormality determination threshold memory 30 Current correction unit 31 Characteristic correction unit 31a Characteristic correction value memory 33 Monitoring timer 34 Fail counter 35 Threshold memory 36 Fail determination device 40 Battery voltage determination unit 41 Battery voltage detector 42 Characteristic correction device 43 Voltage abnormality determination device 43a Abnormality determination threshold memory

Claims (6)

A detection device that detects control data related to the determination of steering assist force, and a motor that calculates a current command value based on the detected control data and applies a steering assist force to the steering mechanism based on the calculated current command value In an electric power steering apparatus provided with a control device for controlling the output of
The control device detects the control data that has been corrected for the detected control data based on the first characteristic correction data corresponding to the characteristics of the detection device, and compares the control data with a first abnormality determination threshold value. An abnormality of the apparatus is determined, and when the abnormality is determined, the control data after the characteristic correction is performed by correcting the detected control data based on the second correction data corresponding to the characteristic of the detection apparatus. An electric power steering apparatus characterized by determining an abnormality of the detection device in comparison with a second abnormality determination threshold having a wider allowable range than the abnormality determination threshold. A detection device that detects control data related to the determination of steering assist force, and a motor that calculates a current command value based on the detected control data and applies a steering assist force to the steering mechanism based on the calculated current command value In an electric power steering apparatus provided with a control device for controlling the output of
The control device receives the detected control data, and outputs a characteristic-corrected control data corrected according to the characteristics of the detection device.
A characteristic correction data storage device storing first characteristic correction data and second characteristic correction data corresponding to the characteristic of the detection device;
A threshold value storing a first abnormality determination threshold value corresponding to the first characteristic correction data and a second abnormality determination threshold value corresponding to second characteristic correction data different from the first abnormality determination threshold value. A storage device,
When the first characteristic correction data is set in the characteristic corrector, the characteristic-corrected control data output is compared with the first abnormality determination threshold to determine abnormality of the detection device, and when it is determined as abnormal Further sets second characteristic correction data, and compares the output characteristic-corrected control data with the second abnormality determination threshold value to determine abnormality of the detection device. . The electric power steering apparatus according to claim 2, wherein the second abnormality determination threshold has a larger allowable range in which it is determined to be normal than the first abnormality determination threshold. The control device further includes an output limiting device, and as a result of comparison between the characteristic-corrected control data and the second abnormality determination threshold, an allowable range in which the characteristic-corrected control data is defined by the second abnormality determination threshold. 3. The electric power steering apparatus according to claim 1, wherein when the output is determined to be outside, an abnormal signal is output to the output limiting device to limit or stop the output of the motor. Limiting or stopping the output of the motor by the output limiting device is a case where the first characteristic correction data set in the characteristic corrector cannot be read correctly and the second characteristic correction data is set. The electric power steering apparatus according to claim 4. The control data related to the determination of the steering assist force detected by the detection device is one or more of steering torque, motor current, battery voltage, motor power supply voltage, motor terminal voltage, and other control data. The electric power steering apparatus according to any one of claims 1 to 5.

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