JP2005337828A - Method for diagnosing malfunction of angular velocity sensor and occupant protection system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To precisely detect the malfunction in which the output of an angular velocity sensor varies like the AC, in a method for diagnosing the malfunction of the angular velocity sensor and an occupant protection system. <P>SOLUTION: A turnover determination part 24 directly monitors the output voltage of the roll angular velocity sensor 1. It is judged that the angular velocity sensor 1 has failed, when: (1) the output voltage difference during a prescribed time interval (corresponding to the difference between the maximum value and the minimum value of the roll angular velocity) exceeds a preset threshold of 0.6; or (2) the output voltage of the roll angular velocity sensor 1 continuously exceeds the threshold of 2.8 for a specific time (e.g., 100 [msec]), or the output voltage of the roll angular velocity sensor 1 is continuously below the threshold of 2.2 for the specific time (e.g., 100 [msec]). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an angular velocity sensor failure diagnosis method and an occupant protection system that implements the failure diagnosis method.

  Conventionally, when a vehicle rolls over, a passenger airbag system such as a curtain airbag, a seat belt pretensioner device, an active rollover device, etc. is activated to roll the vehicle over. There is known an occupant protection system for protecting an occupant from an impact caused by the accident (Patent Document 1).

  This vehicle occupant protection system determines the behavior of a vehicle according to a two-dimensional value defined by the roll angle and roll angular velocity of the vehicle, and controls the operation of the occupant protection device based on the determined behavior. It is.

  Here, the roll angle and roll angular velocity of the vehicle are calculated by the control unit of the occupant protection system based on the output of the angular velocity sensor installed in the vehicle. That is, the roll angular velocity is subjected to band limitation processing or the like on the output of the angular velocity sensor, converted into a digital signal, and calculated based on the digital signal. On the other hand, the roll angle is converted into the digital signal. It is calculated by time integration processing of the sensor output.

  Thus, since the output of the angular velocity sensor directly affects the operation of the occupant protection system, whether or not the angular velocity sensor is operating properly is an important issue.

Therefore, a technique for diagnosing whether the angular velocity sensor is healthy or malfunctioning has been proposed. That is, the angular velocity sensor has a substantially constant output value when the behavior of the vehicle is in a normal behavior state (normal state). It is determined that the angular velocity sensor has failed when it has been continuously exceeded for a certain period of time or when the output value of the angular velocity sensor has been continuously below a preset lower limit value for a certain period of time (Patent Document 2). ).
JP-A-5-170037 JP-A-9-281138

  By the way, the above-described failure diagnosis technique according to Patent Document 2 detects a so-called DC (direct current component) change in which the output value of the angular velocity sensor is offset with respect to a reference value, and determines the presence or absence of a failure. However, the failure of the angular velocity sensor includes not only a change in output in a DC manner but also a change in output in an AC (alternating current component).

  Such a fault whose output changes in an AC manner cannot be detected by the fault diagnosis technique according to Patent Document 2 described above. That is, when the output changes in an AC manner, exceeding the upper limit value or falling below the lower limit value is only instantaneous and does not continue for a certain period of time. Therefore, it is impossible to detect a fault in which the output changes in an AC manner by a technique for detecting that the upper limit value is continuously exceeded for a certain period of time or that the lower limit value is continuously decreased for a certain period of time.

  Here, the roll angle in the occupant protection system is calculated by integrating the change (absolute value) with respect to the output value (reference output value) of the angular velocity sensor in the normal state of the vehicle. When the output value changes in an AC manner with the amplitude as the center, the angle calculated by integrating the change (absolute value) on both the upper and lower sides across the reference output value, even though the behavior of the actual vehicle is normal Is monotonously increased with time, and it is erroneously determined that the vehicle is in a state of rollover, and the occupant protection device of the occupant protection system may cause an unexpected operation.

  The present invention has been made in view of the above circumstances, and a failure diagnosis method for an angular velocity sensor capable of accurately detecting a failure in which the output of the angular velocity sensor changes in an AC manner, and an occupant protection device that implements this failure diagnosis method An object of the present invention is to provide an occupant protection system with improved operational reliability.

  The failure diagnosis method for an angular velocity sensor according to the present invention detects an AC output fluctuation failure by determining the presence or absence of failure based on the difference between the maximum value and the minimum value of the output of the angular velocity sensor. .

  That is, in the first angular velocity sensor failure diagnosis method according to the present invention, the output of the angular velocity sensor is monitored for a predetermined time, and the difference between the maximum value and the minimum value of the angular velocity sensor output during the monitoring period is determined in advance. Whether or not the angular velocity sensor has failed is determined depending on whether or not a set threshold value is exceeded.

  Here, as the threshold value, for example, a value larger than the width of the output fluctuation that may occur even when the vehicle on which the angular velocity sensor is mounted is in a normal state may be set. Can be sought.

  According to the failure diagnosing method of the angular velocity sensor according to the present invention configured as described above, when the fluctuation range of the output within a predetermined time exceeds a preset threshold value, for example, the output of the angular velocity sensor is Even if the time exceeding the upper limit of the normal output is extremely short, or the time below the lower limit is extremely short, it is determined as a failure.

  Therefore, it is possible to reliably detect a failure of the angular velocity sensor that outputs a value that changes in an AC manner (the output changes periodically).

Also, the second of the angular velocity sensor failure diagnosis method according to the present invention is to monitor the output of the angular velocity sensor for a predetermined time,
(1) when the difference between the maximum value and the minimum value of the output of the angular velocity sensor during the monitoring period exceeds a preset threshold; and (2) the output of the angular velocity sensor during the monitoring period. When the preset upper limit value is continuously exceeded for a certain period of time, or when the output of the angular velocity sensor is continuously lower than the preset lower limit value for a certain period of time during the monitoring period,
When at least one of them is satisfied, it is determined that the angular velocity sensor has failed.

  Here, the upper limit value may be set to a value larger than the output upper limit value that can occur even when the vehicle on which the angular velocity sensor is mounted is in a normal state, and the lower limit value may be generated even when the vehicle is in a normal state. A value smaller than the output lower limit value may be set, and these upper limit value and lower limit value can be obtained in advance experimentally or empirically.

  According to the failure diagnosing method of the angular velocity sensor according to the present invention configured as described above, when the fluctuation range of the output within a predetermined time exceeds the preset threshold value according to (1), for example, the angular velocity Even if the time when the output of the sensor exceeds the upper limit of the normal output for a very short time or the time when the output of the sensor falls below the lower limit is a very short time, it is determined as a failure. Therefore, it is possible to reliably detect a failure of the angular velocity sensor that outputs a value that changes in an AC manner (the output changes periodically).

  On the other hand, from (2), it is possible to determine the presence or absence of a failure by detecting a so-called DC (direct current component) change in which the output value of the angular velocity sensor is offset with respect to the reference value.

  The occupant protection system according to the present invention detects an AC output fluctuation failure by determining the presence or absence of a failure based on the difference between the maximum value and the minimum value of the output of the angular velocity sensor, and determines that there is a failure. Is to prevent the occupant protection device from operating.

  That is, the first occupant protection system according to the present invention includes an occupant protection device mounted on a vehicle, an angular velocity sensor that detects the behavior of the vehicle, and an operation of the occupant protection device according to an output of the angular velocity sensor. In a vehicle occupant protection system comprising at least a control unit that performs control, the control unit monitors the output of the angular velocity sensor for a predetermined time, and the maximum value and the minimum value of the output of the angular velocity sensor during the monitoring period Whether or not the angular velocity sensor has failed is determined according to whether or not the difference between the two exceeds a preset threshold value.

  According to the occupant protection system according to the present invention configured as described above, when the fluctuation range of the output within a predetermined time exceeds a preset threshold value, for example, the output of the angular velocity sensor is the normal output. Even if the time exceeding the upper limit value is extremely short or the time falling below the lower limit value is extremely short, the control unit determines that the angular velocity sensor has failed.

  Therefore, it is possible to reliably detect a failure of the angular velocity sensor that outputs a value that changes in an AC manner (the output changes periodically).

  When the control unit detects such a malfunction of the angular velocity sensor, the control unit does not perform the process of calculating the roll angle based on the output of the malfunctioning angular velocity sensor, or based on the calculated roll angle. By not performing the operation control of the occupant protection device, it is possible to prevent the occupant protection device of the occupant protection system from operating unexpectedly, and to improve the reliability.

A second aspect of the occupant protection system according to the present invention is an occupant protection device mounted on a vehicle, an angular velocity sensor that detects the behavior of the vehicle, and an operation of the occupant protection device according to an output of the angular velocity sensor. In a vehicle occupant protection system comprising at least a control unit that performs control, the control unit monitors the output of the angular velocity sensor for a predetermined time,
(1) when the difference between the maximum value and the minimum value of the output of the angular velocity sensor during the monitoring period exceeds a preset threshold; and (2) the output of the angular velocity sensor during the monitoring period. When the preset upper limit value is continuously exceeded for a certain period of time, or when the output of the angular velocity sensor is continuously lower than the preset lower limit value for a certain period of time during the monitoring period,
When at least one of them is satisfied, it is determined that the angular velocity sensor has failed.

  According to the occupant protection system of the present invention configured as described above, when the fluctuation range of the output within a predetermined time exceeds a preset threshold value according to (1), for example, the output of the angular velocity sensor However, even if the time exceeding the upper limit value of the normal output is extremely short or the time falling below the lower limit value is extremely short, the control unit determines that there is a failure. Therefore, it is possible to reliably detect a failure of the angular velocity sensor that outputs a value that changes in an AC manner (the output changes periodically).

  On the other hand, from (2), the control unit can determine the presence or absence of a failure by detecting a so-called DC (direct current component) change in which the output value of the angular velocity sensor is offset with respect to the reference value.

  When the control unit detects the failure of the angular velocity sensor, the control unit does not perform the process of calculating the roll angle based on the output of the malfunctioning angular velocity sensor, or the occupant based on the calculated roll angle. By not performing the operation control of the protection device, the occupant protection device of the occupant protection system can be prevented from causing an unexpected operation, and the reliability can be improved.

  The occupant protection system according to the present invention further includes a warning lamp that turns on and off, and a storage unit that stores a failure history. When the control unit determines that there is a failure, the warning lamp is turned on or blinked. It is preferable to control the operation of the warning lamp and store the failure history in the storage unit.

  According to the occupant protection system according to the present invention configured as described above, when the control unit detects that the angular velocity sensor has failed, the warning lamp is turned on or blinking, so that the user such as the driver of the automobile can recognize the user. be able to. In addition, since the control unit stores the failure of the angular velocity sensor as a failure history in the storage unit, for example, the failure of the angular velocity sensor is temporary. Even if the failure state cannot be reproduced, it is possible to easily confirm the occurrence of the failure by reading the failure history stored in the storage unit. It is also possible to prevent the occurrence of a malfunction.

  According to the failure diagnosing method of the angular velocity sensor according to the present invention, when the fluctuation range of the output within a predetermined time exceeds a preset threshold value, for example, the output of the angular velocity sensor is the upper limit value of the normal output. The value of the angular velocity sensor that changes AC (the output changes periodically) in order to determine a failure even if the time exceeding the time is extremely short or the time falling below the lower limit is extremely short Can be reliably detected.

  According to the occupant protection system of the present invention, when the fluctuation range of the output within a predetermined time exceeds a preset threshold value, for example, the time when the output of the angular velocity sensor exceeds the upper limit of the normal output Even if is extremely short or when the time below the lower limit is extremely short, the control unit determines that the angular velocity sensor is faulty, so the angular velocity sensor changes AC (the output changes periodically). A fault that outputs a value can be reliably detected.

  When the control unit detects such a malfunction of the angular velocity sensor, the control unit does not perform the process of calculating the roll angle based on the output of the malfunctioning angular velocity sensor, or based on the calculated roll angle. By not performing the operation control of the occupant protection device, it is possible to prevent the occupant protection device of the occupant protection system from operating unexpectedly, and to improve the reliability.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a best mode for carrying out an occupant protection system for carrying out an angular velocity sensor failure diagnosis method of the invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an occupant protection system 50 according to an embodiment of the present invention. The occupant protection system 50 is mounted on a vehicle (not shown) and detects a signal corresponding to the roll angular velocity of the vehicle. A roll angular velocity sensor 1 (angular velocity sensor), a low-pass filter (hereinafter referred to as LPF) 2 for band-limiting the analog output signal of the roll angular velocity sensor 1, and a signal obtained by band-limiting the LPF 2 with a predetermined sampling period ( For example, the A / D converter 3 that converts the signal into a digital signal at 5 [msec]), the occupant protection device 40 mounted on the vehicle, and the signals detected by the roll angular velocity sensor 1 control the operation of the occupant protection device 40. The control unit 20, a warning lamp 30 installed in the passenger compartment of the automobile and turned on and off, and a predetermined threshold value are stored in advance. Together they are, failure history later and a EEPROM 10 (storage unit) stored.

  Here, the occupant protection device 40 is, for example, an airbag system such as a curtain airbag, a seat belt pretensioner device, or the like.

  The control unit 20 includes a noise cut digital filter 21 that performs noise cut processing on the digital output value of the A / D converter 3, and a roll angle calculation unit 22 that calculates a roll angle based on the signal subjected to the noise removal processing. A roll angular velocity calculating unit 23 that calculates a roll angular velocity, and a rollover determining unit 24 that determines whether the vehicle rolls over based on the calculated roll angle and roll angular velocity.

  The roll angle calculation unit 22 calculates the roll angle by performing time integration processing on the roll angular velocity signal that has been subjected to noise removal processing.

  Further, the EEPROM 10 stores a two-dimensional threshold value (for example, a two-dimensional threshold value as a function) of a roll angle and a roll angular velocity that are to be compared when the rollover determination unit 24 determines the rollover of the vehicle. The unit 24 compares the two-dimensional value composed of the roll angle calculated by the roll angle calculation unit 22 and the roll angular velocity calculated by the roll angular velocity calculation unit 23 with the two-dimensional threshold value of the roll angle and roll angular velocity stored in the EEPROM 10. By contrasting, whether or not the vehicle body rolls over is determined. When it is determined that there is a rollover, the occupant protection device 40 is operated, and when it is determined that there is no rollover, the occupant protection device 40 is not operated.

  Further, the EEPROM 10 stores three failure determination thresholds for determining failure of the roll angular velocity sensor 1 described later.

  Here, in the roll angular velocity sensor 1, when the roll angular velocity is 0 [deg / sec], the output voltage is set to 2.5 [V], and the roll angular velocity in the downwardly inclined direction increases (left The output voltage increases when the roll angular velocity in the downward slope direction decreases), and the output voltage decreases when the roll angular velocity in the downward slope direction increases (the roll angular velocity decreases in the downward slope direction). It is set to be.

  And the output voltage (upper limit value) corresponding to the assumed maximum value of the roll angular velocity in the downward slope direction is, for example, 2.8 [V], and corresponds to the assumed maximum value of the roll angular velocity in the downward direction. The output voltage (lower limit value) is set to 2.2 [V], for example.

  Here, one of the three failure determination threshold values stored in the EEPROM 10 is 2.8 corresponding to the upper limit value of the output voltage, and the other is 2.2 corresponding to the lower limit value of the output voltage. Is set to The remaining one of the three failure determination thresholds is set to 0.6 corresponding to the difference 0.6 [V] between the output voltage 2.8 [V] and the output voltage 2.2 [V]. ing.

Then, the rollover judging unit 24 directly monitors the output voltage of the roll angular velocity sensor 1, and hereinafter, when at least one of the conditions (1) and (2) is satisfied, the angular velocity sensor 1 is broken. judge.
(1) When the difference in output voltage (corresponding to the difference between the maximum value and the minimum value of the roll angular velocity) during a predetermined time interval exceeds a preset threshold value 0.6 (2) Roll angular velocity sensor When the output voltage of 1 exceeds the threshold value 2.8 for a certain time (for example, 100 [msec]) continuously, or the output voltage of the roll angular velocity sensor 1 exceeds the threshold value 2.2 for a certain time (for example, 100 [msec]). Here, the condition (1) is to monitor the fluctuation range of the output voltage, and the angular velocity sensor 1 is used to determine whether or not there is a failure that outputs a voltage that fluctuates in an AC manner. It is a condition.

  On the other hand, the condition (2) is for monitoring whether or not the output voltage is in a normal range between the upper limit value and the lower limit value, and the angular velocity sensor 1 outputs a voltage that is offset in a DC manner. This is a condition for determining the presence or absence of a failure.

  Next, the operation of the occupant protection system 50 according to the present embodiment will be described.

  First, the roll angular velocity sensor 1 continuously detects an output signal (output voltage) corresponding to the roll angular velocity of the vehicle, and the detected output signal is input to the LPF 2 and the rollover judging unit 24.

  The LPF 2 performs band limiting processing on the input output signal and outputs it to the A / D converter 3. The A / D converter 3 converts the input signal into a digital signal at a sampling interval of 5 [msec], for example. And input to the noise cut digital filter 21 of the control unit 20.

  The noise cut digital filter 21 performs noise cut processing on the input digital signal, and inputs the signal from which the noise has been removed to the roll angle calculation unit 22 and the roll angular velocity calculation unit 23.

  The roll angle calculation unit 22 performs an integration process on the input signal to calculate a roll angle, while the roll angular velocity calculation unit 23 calculates a roll angular velocity at a time interval of 5 [msec] based on the input signal. Is calculated.

  The roll angle and roll angular velocity calculated by the above-described operation are input to the rollover determination unit 24, and the rollover determination unit 24 stores the two-dimensional values including the input roll angle and roll angular velocity in the EEPROM 10. In comparison with the dimension threshold value, whether or not the vehicle rolls over is determined, and when it is determined that there is a rollover (including a state where it is clear that the vehicle rolls over), the occupant protection device 40 is When the control for starting the operation is performed and it is determined that there is no rollover, the control for starting the operation for the occupant protection device 40 is not performed.

  On the other hand, the rollover judging unit 24 constantly monitors the output voltage directly input from the roll angular velocity sensor 1 and responds to the difference in output voltage (the difference between the maximum value and the minimum value of the roll angular velocity) during a predetermined time interval. ) Exceeds a preset threshold value 0.6, it is determined that the roll angular velocity sensor 1 is a fault that outputs a voltage that varies in an AC manner, regardless of the above-described rollover determination based on the two-dimensional threshold value. The operation start control for the occupant protection device 40 is not performed, and the history of the failure is stored in the EEPROM 10 and the warning lamp 30 is turned on or blinked so that the driver or the like recognizes the failure of the roll angular velocity sensor 1.

  Further, the rollover judging unit 24 detects that the output voltage of the roll angular velocity sensor 1 continuously exceeds the threshold value 2.8 for a certain time (for example, 100 [msec]) or the output voltage of the roll angular velocity sensor 1 is the threshold value 2.2. When the roll angular velocity sensor 1 has fallen continuously for a certain time (for example, 100 [msec]), it is determined that the roll angular velocity sensor 1 has output a voltage that fluctuates in offset in a DC manner, and the rollover determination based on the two-dimensional threshold described above. Regardless of the above, the control of starting the operation for the occupant protection device 40 is not performed, and the history of the failure is stored in the EEPROM 10, and the warning lamp 30 is lit or blinked, so that the driver or the like is informed Recognize.

  As a result, it is possible to prevent the occupant protection device 40 from causing an unexpected operation when the roll angular velocity sensor 1 has a fault that outputs a voltage that varies in an AC manner or a fault that outputs a voltage that varies in a DC manner. And the reliability of operation can be improved.

  Further, since the failure history of the roll angular velocity sensor 1 is stored in the EEPROM 10, for example, the failure of the roll angular velocity sensor 1 is temporary, and the failure state cannot be reproduced at the time of subsequent maintenance of the automobile. Even in such a case, the occurrence of the failure can be confirmed by reading the failure history stored in the EEPROM 10, and future malfunction of the occupant protection device 40 can be prevented by replacing or repairing the roll angular velocity sensor 1. It can be prevented in advance.

  Furthermore, since the warning lamp 30 is lit or blinking, the driver of the automobile can easily recognize the occurrence of the failure, and the driver can be alerted.

  The failure determination operation of the roll angular velocity sensor 1 in the operation of the occupant protection system 50 described above is an embodiment of the failure diagnosis method for the angular velocity sensor according to the present invention.

  In the present embodiment, the rollover judging unit 24 directly monitors the output voltage of the roll angular velocity sensor 1. However, the present invention is not limited to this configuration. For example, an input signal from the roll angular velocity calculating unit 23 is input. It is possible to make a failure determination by monitoring, and even with such a failure determination method, it is possible to achieve the same effects as the above-described embodiment.

  Further, in the present embodiment, as the failure determination of the roll angular velocity sensor 1, both detection of AC output fluctuation based on the condition (1) and detection of DC output fluctuation based on the condition (2) are detected. However, the failure diagnosis method and occupant protection system of the angular velocity sensor according to the present invention are not limited to this embodiment, and the failure determination is performed only by detecting the AC output fluctuation under the condition (1). It may be.

1 is a block diagram showing an occupant protection system according to an embodiment of the present invention.

Explanation of symbols

1 Roll angular velocity sensor (angular velocity sensor)
2 LPF (low pass filter)
3 A / D converter 10 EEPROM (storage unit)
20 control unit 21 noise cut digital filter 22 roll angle calculation unit 23 roll angular velocity calculation unit 24 rollover judging unit 30 warning lamp 40 occupant protection device 50 occupant protection system

Claims (5)

  The output of the angular velocity sensor is monitored for a predetermined time, and depending on whether or not the difference between the maximum value and the minimum value of the angular velocity sensor output during the monitoring period exceeds a preset threshold, A method for diagnosing a failure of an angular velocity sensor, wherein the presence or absence of a failure is determined.   Monitoring the output of the angular velocity sensor for a predetermined time; (1) when the difference between the maximum value and the minimum value of the output of the angular velocity sensor during the monitoring period exceeds a preset threshold; and (2) When the output of the angular velocity sensor continuously exceeds a preset upper limit value for a certain period of time during the monitoring period, or the lower limit value of the angular velocity sensor continues for a certain period of time during the monitoring period. The angular velocity sensor failure diagnosing method is characterized by determining that the angular velocity sensor is defective when at least one of them is satisfied. Vehicle occupant protection comprising at least an occupant protection device mounted on a vehicle, an angular velocity sensor that detects the behavior of the vehicle, and a control unit that controls operation of the occupant protection device according to an output of the angular velocity sensor. In the system,
The control unit monitors the output of the angular velocity sensor for a predetermined time, and depends on whether the difference between the maximum value and the minimum value of the angular velocity sensor output during the monitoring period exceeds a preset threshold value. The occupant protection system is characterized in that the presence or absence of a failure of the angular velocity sensor is determined, and when it is determined that there is a failure, the occupant protection device is not operated regardless of the output of the angular velocity sensor. Vehicle occupant protection comprising at least an occupant protection device mounted on a vehicle, an angular velocity sensor that detects the behavior of the vehicle, and a control unit that controls operation of the occupant protection device according to an output of the angular velocity sensor. In the system,
The control unit monitors the output of the angular velocity sensor for a predetermined time. (1) When the difference between the maximum value and the minimum value of the angular velocity sensor output during the monitoring period exceeds a preset threshold value. And (2) when the output of the angular velocity sensor has continuously exceeded a preset upper limit value for a certain period of time during the monitoring period, or when the output of the angular velocity sensor has been preset during the monitoring period. When the value is continuously below a certain time, when at least one of the values is satisfied, it is determined that the angular velocity sensor has failed. An occupant protection system characterized by not operating a protective device. A warning lamp that turns on and off, and a storage unit that stores a failure history;
When the control unit determines that there is a failure, the control unit controls the operation of the warning lamp so that the warning lamp is turned on or blinks, and the history of the failure is stored in the storage unit. Item 5. An occupant protection system according to item 3 or 4.

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