JP2013159217A - Failure diagnosis device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a failure diagnosis device for a sensor capable of diagnosing even during vehicle travel without hindering sensing of a physical quantity of an object to be sensed.SOLUTION: A failure diagnosis device 20 for a sensor 100 that outputs a sensing signal used when a control device 200 performs vehicle control, has a state mode information acquisition means 24 that acquires state mode information indicating whether or not the vehicle control can be performed from the control device, and a diagnosis means 25 that gives a diagnosis signal for failure diagnosis to the sensor when the state mode information acquisition means acquires the state mode information indicating that the vehicle control cannot be performed.

Description

  The present invention relates to a sensor failure diagnosis device that outputs a detection signal used by a control device when performing vehicle control.

  A sensor having a movable mechanism formed by micromachining or the like may be mounted on a vehicle. Such a sensor has a structure in which a movable electrode and a fixed electrode are arranged to face each other, and applies a periodic voltage to the fixed electrode to generate an electrostatic attractive force and periodically displace the movable electrode. The magnitude of the external force is detected by utilizing the fact that the amount of displacement changes when an external force is applied to the sensor (or by monitoring the change in voltage to maintain the same amount of displacement).

  However, since the distance between the movable electrode and the fixed electrode is minute, the movable electrode and the fixed electrode may come into contact when the movable electrode is largely displaced by an external force or the like. In the rare case of contact, the continuity or the like occurs, and the movable electrode and the fixed power are welded, and a failure mode called sticking occurs. For example, the zero point of the sensor is adjusted at the time of start-up, so if it is stuck, the sticking state becomes the zero point, and it is detected on the control side whether the zero value is normal (no external force) or sticking occurs. Becomes difficult.

  For this reason, a technique for detecting a failure such as sticking has been conventionally considered (see, for example, Patent Document 1). Patent Document 1 discloses a physical quantity sensor that performs self-diagnosis by determining whether or not the timing at which a diagnostic pulse is output from the control side matches the timing at which the output for self-diagnosis exceeds a threshold for self-diagnosis. It is disclosed.

JP 2009-180638 A

  By the way, the timing immediately after the ignition is turned on is preferable as the timing for performing the self-diagnosis. This is because when the vehicle starts traveling, the control device uses the detection signal of the sensor for control.

  However, if the diagnosis is performed only immediately after the ignition is turned on, if the sensor fails during one trip (between the ignition on and off), there is a problem that the failure cannot be detected.

  In order to solve this problem, it is conceivable that the control device makes a diagnosis periodically, but the detection signal generated by the stimulus (diagnostic signal) applied to the fixed electrode for diagnosis is mistakenly caused by the action of an external force. There is a risk of detection. For this inconvenience, it is conceivable to hold a detection signal before the start of diagnosis during diagnosis. However, even if false detection can be avoided by this, the control device becomes difficult to control using the detection signal of the sensor, and therefore the control performance by the control device is affected, such as a response delay to the action of external force. End up.

  In view of the above problems, an object of the present invention is to provide a sensor failure diagnosis apparatus that can make a diagnosis while a vehicle is running without hindering detection of a physical quantity to be detected.

  The present invention is a sensor failure diagnosis device that outputs a detection signal used when a control device performs vehicle control, and acquires state mode information indicating whether or not the vehicle control is possible from the control device. State mode information acquisition means; and diagnosis means for providing a diagnostic signal for failure diagnosis to the sensor when the state mode information acquisition means acquires the state mode information indicating that the vehicle control is not possible. It is characterized by having.

  It is possible to provide a sensor failure diagnosis device that can perform diagnosis while the vehicle is running without hindering detection of a physical quantity to be detected.

It is an example of the figure explaining the diagnostic method of a sensor. It is a figure which shows an example of the schematic block diagram of a sensor. It is an example of the flowchart figure which shows the procedure in which an abnormality determination part updates CHK based on control state mode. It is an example of the flowchart figure which shows the procedure in which a mode determination part updates ACT. It is an example of the flowchart figure which shows the process in which the monitoring function part monitors the result of an active test.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is an example of a diagram illustrating a sensor diagnosis method according to the present embodiment. Each signal will be described.
・ CHK
This is a flag indicating whether an ECU (Electronic Control Unit) can be controlled using a sensor. CHK: 0 (hereinafter “:” means “=”) means that control is possible, and CHK: 1 means that control is impossible.
・ Detection signal (GX)
This is a (part of) detection signal detected by the sensor. If this detection signal shows a value sufficiently larger than zero, it is determined that the sensor has not failed.
・ ACT
It is a flag indicating whether or not diagnosis can be performed by applying a diagnostic signal to the sensor from the outside. ACT: 0 indicates that a diagnosis cannot be performed, and ACT: 1 indicates that a diagnosis can be performed. The diagnosis by giving a diagnosis signal from the outside is hereinafter referred to as “active test”.
・ FAIL
This flag indicates whether or not a failure is determined as a result of the active test. FAIL: 0 indicates that there is no failure, and FAIL: 1 indicates that there is a failure.

  As shown in the figure, the sensor of the present embodiment performs an active test (ACT becomes “1”) at a timing when the ECU cannot perform control using the sensor (when CHK is 1). In the case of ACT: 1, if the detection signal (GX) is sufficiently large, it is not determined as a failure (FAIL remains “0”). If the detection signal (GX) remains zero, a failure is determined (FAIL becomes “1”).

  As described above, the sensor side determines whether or not the control using the sensor can be performed by the ECU using the CHK, so that it is possible to diagnose the sensor other than immediately after the ignition is turned on.

[Configuration example]
FIG. 2 is a diagram illustrating an example of a schematic configuration diagram of the sensor 100. This sensor 100 is a yaw rate G sensor capable of detecting acceleration in two directions (front-rear direction and left-right direction) and one yaw rate. Such a sensor 100 may be referred to as a 1Y2G type. The type of sensor 100 is merely an example, and the diagnostic method of the present embodiment can be suitably applied to the sensor 100 that detects only the yaw rate or only one acceleration. That is, the sensor 100 according to the present embodiment may be a sensor having a failure mode in which the movable portion has a movable portion and the movable portion is fixed. The yaw rate is a rotation speed when the vehicle axis in the front-rear direction rotates with respect to the road surface around the center of gravity.

  An ECU 200 is connected to the sensor 100. The ECU 200 may be any ECU 200 that controls the vehicle using at least one of the yaw rate and acceleration detected by the sensor 100. For example, there are VSC (Vehicle Stability Control) -ECU, airbag ECU and the like. The VSC-ECU controls the wheel cylinder pressure and engine output of the four wheels and suppresses the side slip when detecting that the vehicle has the rear side skid tendency or the front side skid tendency based on the yaw rate and the front / rear / left / right acceleration. . Further, the airbag ECU deploys the airbag in the direction in which the acceleration is generated based on the longitudinal acceleration and the lateral acceleration.

  Each ECU has predetermined conditions under which control can be executed. As an example of this condition, for example, the vehicle speed is not less than or equal to a threshold value. The ECU 200 determines the control state mode depending on whether the condition is satisfied, and notifies the sensor 100 every time the control state mode changes. The control state mode is either controllable or not.

  The sensor 100 includes an I / F 11, a microcomputer 12, and a sensor module 13. The sensor module 13 includes a sensor unit 14 and a diagnostic unit 20. The sensor 100 and the ECU 200 are connected via the I / F 11 by, for example, a wire harness. The sensor 100 and the ECU 200 communicate according to a predetermined communication protocol (LIN, CAN, etc.). When the control state mode is received from the ECU 200, the I / F 11 notifies the microcomputer 12 and the I / F 11 sends a detection signal (gx, gy, wz) to the ECU 200 and a detection signal (gx, gy, wz) at the time of abnormality (failure). Send.

  The microcomputer 12 includes a CPU, a ROM, a RAM, an A / D conversion circuit, an I / O, and the like. The microcomputer 12 implements the abnormality determination unit 22 and the signal processing unit 23 by the CPU executing a program stored in the ROM and cooperating with hardware (not shown). The abnormality determination unit 22 updates CHK based on the control state mode and outputs the updated CHK to the mode determination unit 24. In the case of FAIL: 1, abnormality determination unit 22 transmits to ECU 200 that abnormality (failure) has been detected.

  The signal processing unit 23 performs filter processing, A / D conversion processing, and the like of the detection signals GX, GY, and ωZ. The detection signals GX, GY, and ωZ after signal processing are set as detection signals (gx, gy, and ωz), respectively. The signal processing unit 23 transmits detection signals (gx, gy, and ωz) to the ECU 200 in response to a request from the ECU 200 or periodically via the I / F 11. When the sensor 100 is abnormal, the detection signals (gx, gy, and ωz) may not be transmitted or may be transmitted.

The sensor unit 14 includes an external force detection unit 28 and a calculation unit 27. The external force detection unit 28 has four movable elements P1 to P4. The calculating unit 27 calculates the yaw rate, the longitudinal acceleration, and the lateral acceleration by calculating the voltage output by the displacement of the movable elements P1 to P4 by a predetermined method. The computing unit 27 computes these voltages as follows, for example.
GX (longitudinal acceleration) = P1 + P2-P3-P4
GY (lateral acceleration) =-P1 + P2-P3 + P4
ωZ (yaw rate: clockwise) = P1-P2 + P3-P4
The arithmetic unit 27 is an electric circuit that generates a desired signal from the four voltages as described above. Since the movable elements P1 to P4 may be fixed, the presence or absence of a failure is determined for each of the detection signals GX, GY, and ωZ. In the present embodiment, only the case where attention is paid to the detection signal (GX) is described.

  The diagnosis unit 20 includes a mode determination unit 24, a monitoring function unit 26, and an active test drive unit 25. The mode determination unit 24 updates the ACT based on the state of CHK, FAIL, and the detection signal (GX), and outputs the updated ACT to the active test drive unit 25 and the monitoring function unit 26.

  In the case of ACT: 1, the active test drive unit 25 outputs a diagnostic signal for an active test to the detection unit 28. The diagnostic signal is a voltage that displaces the movable part so that GX, GY, and ωZ sufficiently larger than zero can be obtained.

  The monitoring function unit 26 reads the detection signals GX, GY, and ωZ from the calculation unit 27 and updates FAIL based on whether the detection signals GX, GY, and ωZ are equal to or greater than a threshold value. Based on the states of ACT, FAIL, and the detection signal (GX), the monitoring function unit 26 updates FAIL and outputs it to the microcomputer 12.

[Processing procedure]
FIG. 3 is an example of a flowchart illustrating a procedure in which the abnormality determination unit 22 updates CHK based on the control state mode. The procedure of FIG. 3 is repeatedly executed periodically regardless of the update of the control state mode when the ignition switch is on (in the case of a hybrid vehicle or an electric vehicle, the main system is on).

  The control state mode is transmitted from the ECU 200 to the microcomputer 12 (S10). As described above, the conditions that enable control of the ECU 200 or the system including the ECU 200 and the sensor 100 are set in the ECU 200 in advance. As an example, the condition that the control is impossible is “vehicle speed ≦ 15 km / h”.

  The abnormality determination unit 22 of the microcomputer 12 determines whether the control state mode is controllable or not (S20).

  When the control state mode is not possible, the abnormality determination unit 22 sets “1” to CHK (S30). When the control state mode is controllable, the abnormality determination unit 22 sets “0” to CHK (S40).

  FIG. 4 is an example of a flowchart illustrating a procedure in which the mode determination unit 24 updates the ACT. The procedure in FIG. 4 is periodically and repeatedly executed with the ignition switch turned on.

  The mode determination unit 24 determines whether or not FAIL: 1 (S110). In the case of FAIL: 1 (Yes in S110), it means that the sensor 100 is out of order, and the process ends. The Timer will be described in S170. In this case, ACT also becomes “0” and the active test is not performed.

  In the case of FAIL: 0 (No in S110), the mode determination unit 24 determines whether or not CHK is 1 in order to determine whether or not the sensor 100 has not failed and an active test can be performed ( S120). If CHK is 0 (No in S120), the control state mode of the ECU 200 is controllable, so the process ends.

  If CHK is 1 (Yes in S120), the control state mode of the ECU 200 is not controllable, so it is determined whether or not the detection signal (GX) is less than the threshold value a (S130). That is, it is detected that the detection signal (GX) is not already increased before the active test. The detection signal (GY) (ωZ) is similarly determined.

  When the detection signal (GX) is less than the threshold value a (Yes in S130), the mode determination unit 24 continues to count up the Timer in order to measure the duration of this state (S140).

  If the detection signal (GX) is not less than the threshold value a (No in S130), it is not preferable to perform an active test. Therefore, Timer is initialized to zero and the process ends (S170). If it is determined in any of steps S110 and S120 that the active test cannot be executed, Timer is initialized to zero.

  Then, the mode determination unit 24 determines whether or not the Timer is equal to or greater than the threshold T (S150).

  When the Timer is equal to or greater than the threshold T (Yes in S150), the mode determination unit 24 sets “1” in ACT and ends the process (S160). That is, since the state where the active test can be executed continues for the threshold value T or more, ACT is set to 1.

  When the Timer is not equal to or greater than the threshold value T (Yes in S180), the mode determination unit 24 sets “0” in ACT and ends the process (S180). That is, the active test is not executed until the state where the active test can be executed continues for the threshold value T or more. If it is determined in any of steps S110 to S130 that the active test cannot be executed, “0” is set in ACT.

  The ACT for which “1” is set is output to the active test drive unit 25 and the monitoring function unit 26. As a result, the active test drive unit 25 starts an active test. In addition, the monitoring function unit 26 outputs detection signals (GX) (GY) (ωZ) generated by the active test.

  According to the procedure of FIG. 4, as shown in FIG. 1, ACT becomes “1” when CHK: 1 and the detection signal (GX) is sufficiently small. If the sensor 100 has not failed, the detection signal (GX) has a large value.

  FIG. 5 is an example of a flowchart illustrating a process in which the monitoring function unit 26 monitors the result of the active test. The procedure of FIG. 5 is repeatedly executed periodically every time ACT is output from the mode determination unit 24 regardless of whether or not the ACT has changed.

The monitoring function unit 26 determines whether or not ACT is 1 (S210).
In the case of ACT: 1 (Yes in S210), first, the monitoring function unit 26 determines whether or not FAIL2: 0 (S220). FAIL2 is a flag for controlling the comparison frequency of the detection signal (GX) and the threshold value a and the state of FAIL. When FAIL2 is “1”, as a result of comparison with the detection signal, if FAIL2 remains “1”, FAIL becomes “1” (S280).

  In the case of FAIL2: 0 (Yes in S220), the monitoring function unit 26 sets “0” in FAIL (S230).

  In the case of FAIL2: 1 (No in S220), the monitoring function unit 26 determines whether or not the detection signal (GX) is greater than or equal to the threshold value b (S240).

  If the detection signal (GX) is greater than or equal to the threshold value b (Yes in S240), it may be determined that the detection signal is not sufficiently large and the monitoring function unit 26 sets “0” in FAIL2 (S250). .

  When ACT is 0 (No in S210), the monitoring function unit 26 determines whether or not ACT is 1 at the time of the previous execution of the process of FIG. 5 (S260). When ACT is 0 at the previous execution of the process of FIG. 5 (No in S260), the process ends.

  When ACT is 1 at the previous execution of the process of FIG. 5 (Yes in S260), the monitoring function unit 26 determines whether FAIL2: 0 is satisfied (S270). In the case of FAIL2: 0 (Yes in S270), the monitoring function unit 26 sets “1” in FAIL2 (S290). Thereby, it determines with No by step S220.

  In the case of FAIL2: 1 (No in S270), since the detection signal (GX) is not equal to or greater than the threshold value b (No in S240), the monitoring function unit 26 sets “1” in FAIL (S280). Thereby, the failure of the sensor 100 can be detected.

  That is, FAIL2 is inverted to “1” when ACT once becomes “1” and ACT acquired from the mode determination unit 24 is “0”. Thereafter, FAIL2 maintains “1” until ACT becomes “1” (No in S260). When ACT becomes “1”, since FAIL2 is “1”, it is determined whether or not the detection signal (GX) is equal to or greater than the threshold value b (S240). Thereby, a failure of the sensor 100 is detected, and when ACT becomes “0”, FAIL becomes “1” (S280).

  Also, once ACT becomes “1”, and FAIL2 becomes “0” as a result of comparison between the detection signal (GX) and the threshold value b, even if the mode determination unit 24 continues to output ACT: 1, Control is performed so that the detection signal (GX) and the threshold value b are not compared (Yes in S220). Therefore, FAIL2 controls the comparison frequency of the detection signal (GX) and the threshold value b.

  As shown in FIG. 1, when ACT is 1 and the detection signal (GX) is equal to or greater than the threshold value b, FAIL remains “0”. If ACT is 1 but the detection signal (GX) is not equal to or greater than the threshold value b, FAIL becomes “1”. Thereby, the abnormality determination part 22 can detect abnormality and can notify ECU200.

  It is assumed that the detection signal (GX) is increased before the active test after ACT becomes “1” based on the comparison result between the control state mode (CHK) and the detection signal (GX) and the threshold value a. Is done. However, also in this case, if the detection signal (GX) is equal to or greater than the threshold value b during the active test, it may be determined that there is no failure.

  Further, although the possibility of fixing by the active test is not zero, in this case, there is no inconvenience because the fixing can be detected by the next active test.

  As described above, the diagnosis method of the present embodiment can diagnose a failure of the sensor 100 not only immediately after the ignition is turned on but also when the ECU 200 does not use the sensor 100 for control even during traveling. Therefore, the ECU 200 does not control based on the detection signal generated by the active test, and does not affect the control performance of the ECU 200.

DESCRIPTION OF SYMBOLS 12 Microcomputer 13 Sensor module 14 Sensor unit 20 Diagnosis part 24 Mode determination part 25 Active test drive part 26 Monitoring function part 100 Sensor 200 ECU

Claims (1)

A sensor failure diagnosis device that outputs a detection signal used when the control device performs vehicle control,
State mode information acquisition means for acquiring state mode information indicating whether or not the vehicle control is possible from the control device;
Diagnostic means for providing a diagnostic signal for failure diagnosis to the sensor when the state mode information acquisition means acquires the state mode information that the vehicle control is not possible;
A fault diagnosis apparatus having

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