JP6545225B2 - Steering wheel unit - Google Patents

Description

  The present invention relates to a steering wheel unit that detects a human body's contact with a steering wheel of a vehicle by a sensor.

  There are vehicles capable of switching between manual steering performed mainly by a driver and automatic steering performed mainly by a system. Such a vehicle detects whether or not the driver is in contact (grasp) with the steering wheel at a predetermined timing, for example, when returning from automatic steering to manual steering. A capacitance sensor is used to detect the grip of the steering wheel. Specifically, the detection value of the capacitance sensor is compared with a predetermined threshold to detect contact / non-contact of the driver (human body) with the steering wheel.

  Although Patent Documents 1 and 2 do not compare the detection value of a capacitance sensor with a predetermined threshold, a device for detecting contact / non-contact of a driver with a steering wheel using a capacitance sensor is shown. Be This device sets the detection value of the capacitance sensor when the ignition switch is operated, that is, when the driver does not contact the steering wheel, as a reference value. Then, when the vehicle is traveling, the reference value is subtracted from the detection value of the capacitance sensor, and the driver's contact / non-contact with the steering wheel is detected based on the subtraction value.

Patent No. 5816827 gazette Unexamined-Japanese-Patent No. 2015-231829

  Disturbances such as deterioration occur in the capacitance sensor. When a disturbance occurs, an error occurs in the comparison result between the detection value of the capacitance sensor and the predetermined threshold value, and the detection accuracy of contact / non-contact of the human body with the steering wheel decreases.

  The present invention has been made in consideration of such problems, and provides a steering wheel unit capable of suppressing a decrease in detection accuracy of contact / non-contact of a human body with a steering wheel even if a disturbance occurs. The purpose is

The present invention
A steering wheel unit for detecting a contact of a human body with a steering wheel of a vehicle by a sensor,
A capacitance sensor provided on the steering wheel for detecting the magnitude of capacitance changing in accordance with contact and non-contact of a human body with the steering wheel;
A storage device for storing a contact determination threshold and a correction determination threshold;
A contact detection unit that detects contact and non-contact of the human body with the steering wheel based on the comparison result of the detection value of the capacitance sensor and the contact determination threshold;
The average value of the detection values for the most recent predetermined number of times including the current detection value is calculated, and the detection value is obtained when the human body is not in contact with the steering wheel and the average value is larger than the correction determination threshold. And a correction unit configured to correct an error generated by comparing the contact determination threshold value with the contact determination threshold value.

  In the above configuration, an error occurs in the comparison between the detection value of the capacitance sensor and the contact determination threshold at the timing when the human body does not contact the steering wheel and the timing when the average value becomes larger than the correction determination threshold. Correct the For this reason, the detection value of the capacitance sensor and the contact determination threshold value are always properly compared, and even if a disturbance occurs, the decrease in the detection accuracy of human contact / non-contact with the steering wheel is suppressed. can do.

In the present invention,
The correction unit performs an operation of correcting the detection value as the correction of the error when the average value is larger than the correction determination threshold.
The contact detection unit may compare the detection value after calculation with the contact determination threshold.

  When a disturbance occurs, the detected value of the capacitance sensor deviates from the normal value as compared with the case where there is no disturbance. The amount of displacement is manifested when the human body is not in contact with the steering wheel. In the above configuration, even if the detection value of the capacitance sensor deviates from the normal value due to the disturbance, the calculation for correcting the detection value is performed. And since the detection value after calculation and a contact determination threshold value are compared, the fall of the detection precision of the contact / non-contact of the human body with respect to a steering wheel can be suppressed.

In the present invention,
When the average value is larger than the correction determination threshold value, the correction unit performs an operation of correcting the contact determination threshold value as the correction of the error.
The contact detection unit may compare the detected value with the contact determination threshold after calculation.

  When a disturbance occurs, the detected value of the capacitance sensor deviates from the normal value as compared with the case where there is no disturbance. The amount of displacement is manifested when the human body is not in contact with the steering wheel. In the above configuration, even if the detected value of the electrostatic capacity sensor deviates from the normal value due to the disturbance, the operation of correcting the contact determination threshold value is performed. And since a detected value and the contact determination threshold value after calculation are compared, the fall of the detection precision of the contact / non-contact of the human body with respect to a steering wheel can be suppressed.

In the present invention,
The storage device further stores a failure determination threshold indicating a magnitude of capacitance when the capacitance sensor fails.
The correction unit may perform an operation to correct the failure determination threshold simultaneously with the correction of the error.

  According to the above configuration, since the failure determination threshold is corrected along with other corrections, it is possible to suppress a decrease in the accuracy of the failure determination.

In the present invention,
The storage device further stores failure information indicating the magnitude of capacitance when the capacitance sensor fails.
The correction unit may calculate a moving average value of the detection values for n times as the average value, and compare the moving average value with the failure information to perform failure determination.

  The capacitance sensor in which a disturbance such as deterioration has occurred can detect a contact by correction, but a faulty capacitance sensor can not detect a contact. According to the above configuration, the failure of the capacitance sensor is detected by comparing the moving average value with the failure information indicating the size of the capacitance when the capacitance sensor is broken. be able to.

In the present invention,
A steering angle sensor and / or an angular velocity sensor that detects a turning state when the vehicle turns;
If the turning state is detected by the steering angle sensor and / or the angular velocity sensor, and no contact of the human body with the steering wheel is detected by the contact detection unit, it is estimated that a failure occurs in the capacitance sensor And a failure estimation unit.

  The driver is operating the steering wheel when the vehicle is turning. In other words, the driver is in contact with the steering wheel. If the detection value of the capacitance sensor in this state is the detection value at the time of contact, the capacitance sensor is normal. On the other hand, when the detection value of the capacitance sensor is the detection value at the time of non-contact, the capacitance sensor is estimated to be faulty. According to the above configuration, the failure determination of the electrostatic capacity sensor is performed using the detection result of the steering angle sensor and / or the angular velocity sensor, so that the accuracy of the failure determination is improved.

  According to the present invention, even when the steering wheel is provided with a plurality of contact sensors, the contact state of the occupant with the steering wheel can be properly determined.

FIG. 1 is a block diagram of a steering wheel unit according to the present embodiment. FIG. 2 is a flowchart of the first correction process. FIG. 3 is a diagram showing a time change of the detected value corresponding to the size of the capacitance. FIG. 4 is a flowchart of the second correction process. FIG. 5 is a diagram showing the time change of the detected value corresponding to the size of the capacitance. FIG. 6 is a flowchart of the failure estimation process.

  Hereinafter, a preferred embodiment of the steering wheel unit according to the present invention will be described in detail with reference to the attached drawings.

[1 Configuration of Vehicle 10]
As shown in FIG. 1, a steering wheel unit 12 according to the present embodiment is provided in a vehicle 10. The vehicle 10 can be switched as appropriate between manual steering in which steering is performed mainly by the driver and automatic steering in which steering is performed mainly by the system (the automatic driving device 14). In the present embodiment, it is assumed that the vehicle 10 is an autonomous driving vehicle capable of mainly performing driving and braking operations in addition to steering. In addition to the steering wheel unit 12, the vehicle 10 includes an automatic driving device 14, a traveling device 16, and a notification device 18.

  The automatic driving device 14 is constituted by an ECU, and includes an arithmetic device such as a processor and a storage device such as a ROM and a RAM. The automatic driving device 14 realizes various functions by executing a program stored in the storage device by the arithmetic device. The automatic driving device 14 acquires information necessary for automatic driving, such as information on the outside world (detection results of cameras and radars), traveling state information (traveling speed, acceleration / deceleration) of the vehicle 10, navigation information, etc. from various sensors and devices. Control instruction for automatically performing driving, steering, and braking operations.

  The traveling device 16 includes a driving force device 20, a steering device 22, and a braking device 24. The driving force device 20 has a driving force ECU and a driving source including an engine and a driving motor. The driving force device 20 generates a driving force in response to an operation of an accelerator pedal performed by the driver or a control instruction for driving output from the automatic driving device 14. The steering device 22 has an electric power steering system (EPS) ECU and an EPS actuator. The steering device 22 generates a steering force in response to an operation of the steering wheel 26 performed by the driver or a steering control instruction output from the automatic driving device 14. The braking device 24 has a brake ECU and a brake actuator. The braking device 24 generates a braking force in accordance with a brake pedal operation performed by the driver or a braking control instruction output from the automatic driving device 14.

  The notification device 18 includes a notification ECU, a display device, an acoustic device, and a tactile device. The notification device 18 notifies the driver according to a notification instruction output from the automatic driving device 14 or a contact determination device 34 described later.

[2 Configuration of steering wheel unit 12]
The steering wheel unit 12 includes a steering wheel 26 and a contact determination device 34. The steering wheel unit 12 further includes a capacitance sensor 28, a steering angle sensor 30, and an angular velocity sensor 32 as sensors.

  The rim of the steering wheel 26 is a laminated structure including a plurality of layers in cross section (cross section parallel to the central axis of the steering wheel 26). In the rim, the resin covers the whole core metal corresponding to the skeleton, the capacitance sensor 28 covers a part or the whole of the resin, the elastic member covers the remaining portion of the resin, and the capacitance sensor 28 and the elastic member Leather covers.

  The capacitance sensor 28 corresponds to an electrode made of a conductive member and is insulated from surrounding members. The capacitance sensor 28 is formed of a paint or a conductive sheet of a conductive material. The capacitance sensor 28 is provided along the circumferential direction of the rim. In the present embodiment, one capacitance sensor 28 is provided to go around the rim at the lower end of the rim. Both ends of the capacitance sensor 28 are insulated at the bottom of the rim. Capacitance sensor 28 forms a capacitor between steering wheel 26 and / or a human body in contact with steering wheel 26, and has a capacitance which changes in accordance with the contact and non-contact of human body with steering wheel 26. Detect the size. In the present specification, a value corresponding to the magnitude of the capacitance is referred to as a detected value C.

  The steering angle sensor 30 detects a turning angle of the steering wheel 26, and outputs a signal indicating the turning angle to the contact determination device 34. The angular velocity sensor 32 detects the amount of angular movement of the vehicle 10, and outputs an electrical signal indicating the amount of angular movement to the contact determination device 34. Note that both the steering angle sensor 30 and the angular velocity sensor 32 may be provided, or either one may be provided.

  The contact determination device 34 is constituted by an ECU, and includes a sensor circuit 36, an arithmetic device 38 such as a processor, and a storage device 40 such as a ROM or a RAM.

  The sensor circuit 36 includes a power supply that energizes the electrostatic capacitance sensor 28, a measuring device (for example, a current sensor) that measures a detection value C corresponding to the magnitude of the electrostatic capacitance, and a power on of the electrostatic capacitance sensor 28. And a switch for switching on / off.

  Arithmetic unit 38 implements various functions by executing a program stored in storage unit 40. In the present embodiment, the arithmetic device 38 functions as the general control unit 42, the contact detection unit 44, the correction unit 46, the failure estimation unit 48, and the notification instruction unit 50.

  The general control unit 42 controls the processing performed by the arithmetic device 38 and performs processing excluding the processing performed by the contact detection unit 44, the correction unit 46, the failure estimation unit 48, and the notification instruction unit 50. For example, the general control unit 42 controls the switch operation of the sensor circuit 36 to switch on / off of the capacitance sensor 28.

  The contact detection unit 44 recognizes the detection value C measured by the measurement device of the sensor circuit 36 and detects whether the human body is in contact with the steering wheel 26 according to the detection value C. In the present embodiment, the contact detection unit 44 detects the contact and non-contact of the human body with the steering wheel 26 based on the comparison result of the detection value C and the contact determination threshold Cth1.

The correction unit 46 calculates the average value Cav of the detection values C for the latest predetermined number of times including the current detection value C, and the non-contact state of the human body with the steering wheel 26 is obtained. When the value is also large, the error generated by the comparison between the detection value C and the contact determination threshold Cth1 is corrected. In the present embodiment, the correction unit 46 calculates a moving average value SMA _M of n detected values C as the average value Cav. The correction unit 46 stores the moving average value SMA _M in the storage device 40 for each calculation.

  When the turning state is detected by the steering angle sensor 30 and / or the angular velocity sensor 32 and the contact detection unit 44 does not detect the contact of the human body with the steering wheel 26, the failure estimation unit 48 fails in the capacitance sensor 28. It is estimated that

  The notification instruction unit 50 outputs a notification instruction to the notification device 18 when the driver needs to be notified.

  The storage device 40 determines, in addition to various programs, a contact determination threshold Cth1 for the contact detection unit 44 to determine whether the human body is in contact or non-contact with the steering wheel 26, and whether the correction unit 46 performs correction. The threshold value Cth2 for correction and various threshold values such as the failure determination threshold Cth3 for determining whether or not the capacitance sensor 28 has a failure are stored and predetermined values. Further, failure information indicating the magnitude of capacitance when the capacitance sensor 28 fails is stored.

[3 Operation of steering wheel unit 12]
[3.1 Contact detection process]
The contact detection unit 44 performs contact determination when the vehicle power is on. At the timing when the vehicle power is turned on, the general control unit 42 switches the sensor circuit 36 to the on state to start energization of the capacitance sensor 28. The contact detection unit 44 determines that the contact is detected if the detection value C of the capacitance sensor 28 is equal to or greater than the contact determination threshold Cth1 stored in the storage device 40, and the detection value C is smaller than the contact determination threshold Cth1. Determined as non-contact. If it is determined that the driver does not touch the vehicle even though the driver needs to grip the steering wheel 26, the notification instructing unit 50 outputs a notification instruction to the notification device 18.

  Furthermore, when the detection value C of the capacitance sensor 28 is equal to or greater than the failure determination threshold Cth3 stored in the storage device 40, the contact detection unit 44 determines that a failure occurs. In this case, the notification instruction unit 50 outputs a notification instruction to the notification device 18.

[3.2 First correction process]
The first correction process performed by the steering wheel unit 12 will be described with reference to FIG. A series of processing described below is repeatedly performed at predetermined time intervals. The first correction processing corrects the detection value C of the capacitance sensor 28 itself when the disturbance such as deterioration occurs in the capacitance sensor 28, and the contact detection processing described in the above [3.1] is performed. It is something to do.

  In step S1, the contact detection unit 44 compares the detection value C of the capacitance sensor 28 with the contact determination threshold Cth1 to detect contact / non-contact of the driver with the steering wheel 26. If the driver is not in contact with the steering wheel 26, that is, if the detection value C <the contact determination threshold Cth1 (step S1: YES), the process proceeds to step S2. On the other hand, when the driver is in contact with the steering wheel 26, that is, when the detection value C ≧ the contact determination threshold Cth1 (step S1: NO), the series of processes is ended, and the next series of processes are started stand by.

When the process proceeds from step S1 to step S2, the correction unit 46 compares the change amount of the moving average value SMA _M with a predetermined value to determine the stable state of the moving average value SMA _M. For example, the correction unit 46 may determine whether the difference (absolute value) between the latest moving average value SMA _M and the previous moving average value SMA _M-1 is less than or equal to a predetermined value, or the latest with respect to the previous moving average value SMA _M-1 . It is determined whether the rate of change of the moving average value SMA _M is equal to or less than a predetermined rate of change. If the change amount ≦ the predetermined value (step S2: YES), the process proceeds to step S3. On the other hand, if the change amount> the predetermined value (step S2: NO), the series of processes is ended, and the process waits until the next series of processes is started.

When the process proceeds from step S2 to step S3, the correction unit 46 compares the moving average value SMA _M with the correction determination threshold Cth2 to determine whether the correction is necessary. If the moving average value SMA _M <correction determination threshold Cth2 (step S3: YES), the process proceeds to step S4. On the other hand, if the moving average value SMA _M補正 the correction determination threshold Cth2 (step S3: NO), the process proceeds to step S5.

  When the process proceeds from step S3 to step S4, the correction unit 46 performs the contact detection process described in the above [3.1] without correcting the detection value C of the capacitance sensor 28.

When the process proceeds from step S3 to step S5, the correction unit 46 calculates a correction value A for correcting the detection value C of the capacitance sensor 28. Here, (moving average value SMA _M -present correction determination threshold Cth2) is set as the correction value A. The correction unit 46 stores the correction value A in the storage device 40. Thereafter, the contact detection unit 44 subtracts the correction value A from the detection value C, and then performs the contact detection process described in the above [3.1]. Further, the notification instruction unit 50 may output a notification instruction to the notification device 18 to notify the driver that the capacitance sensor 28 is generating disturbance such as deterioration.

In addition, the correction unit 46 compares the moving average value SMA _M with the failure information stored in the storage device 40 to perform failure determination.

  Note that the notification instruction unit 50 outputs an notification instruction to the notification device 18 together with the calculation of the correction value A in step S5, and the disturbance such as deterioration is generated in the capacitance sensor 28 to the driver. You may make it alert | report.

The first correction process shown in FIG. 2 will be described in comparison with the change in the detection value C of the capacitance sensor 28 shown in FIG. In FIG. 3, the contact detection process of the steering wheel 26 is started from time t0, and at the same time, the first correction process is started. When the driver contacts the steering wheel 26, the detection value C starts to increase, and when the detection value C 接触 contact determination threshold Cth1 at time t1, the contact detection unit 44 detects that the driver is in contact with the steering wheel 26. To detect. When the detected values C for n times are aligned at time t2, the correction unit 46 starts calculating the moving average value SMA _M. At this time point, the detected value C 接触 the contact determination threshold value Cth1, the determination in step S1 of FIG. 2 is NO. The NO determination of step S1 continues to time t3.

When the detected value C <contact determination threshold Cth1 at time t3, the contact detection unit 44 detects that the driver is not in contact with the steering wheel 26. At this time, the determination in step S1 of FIG. 2 is YES. At time t4, the correction unit 46 detects that the moving average value SMA _M has become stable. At this point of time, the determination in step S2 of FIG. 2 is YES. Since the moving average value SMA _M at time t4 is larger than the correction determination threshold Cth2, the determination in step S3 of FIG. 2 is NO. At this time, the correction unit 46 calculates the correction value A, and subtracts the correction value A from the detection value C, as shown in FIG.

  As shown after time point t4, the contact detection unit 44 performs the contact determination with the value obtained by subtracting the correction value A from the detection value C as the detection value C. Note that when no disturbance such as deterioration occurs in the capacitance sensor 28, the detection value C after time t3 becomes equal to or less than the correction determination threshold Cth2, the determination in step S1 of FIG. No correction is made.

[3.3 Second correction processing]
The second correction process performed by the steering wheel unit 12 will be described using FIG. 4. A series of processing described below is repeatedly performed at predetermined time intervals. In the second correction processing, when a disturbance such as deterioration occurs in the capacitance sensor 28, the contact determination threshold Cth1 is corrected, and the contact detection processing described in the above [3.1] is performed. is there. In addition, since the process of step S11-step S14 shown by FIG. 4 is the same as the process of step S1-step S4 shown by FIG. 2, the description is abbreviate | omitted.

When the process proceeds from step S13 to step S15, the correction unit 46 performs an operation to correct the contact determination threshold Cth1. Here, {current touch determination threshold Cth1 + (moving average value SMA _M −current corrected determination threshold Cth2)} is calculated to be a new touch determination threshold Cth1. The correction unit 46 stores the touch determination threshold Cth1 in the storage device 40.

In step S16, the correction unit 46 performs an operation to correct the failure determination threshold Cth3. Here, {current failure determination threshold Cth3 + (moving average value SMA _M −current corrected determination threshold Cth2)} is calculated to be a new failure determination threshold Cth3. The correction unit 46 stores the failure determination threshold Cth3 in the storage device 40.

Furthermore, in step S17, the correction unit 46 corrects the correction determination threshold Cth2. Here, the current moving average value SMA _M is set as a new correction determination threshold Cth2. The correction unit 46 stores the correction determination threshold Cth2 in the storage device 40. Further, the notification instruction unit 50 may output a notification instruction to the notification device 18 to notify the driver that the capacitance sensor 28 is generating disturbance such as deterioration.

In addition, the correction unit 46 compares the moving average value SMA _M with the failure information stored in the storage device 40 to perform failure determination.

The second correction process shown in FIG. 4 will be described in comparison with the change of the detection value C of the capacitance sensor 28 shown in FIG. The flow of processing from time point t0 to time point t4 is the same as in the first correction process. Since the moving average value SMA _M at time t4 is larger than the correction determination threshold Cth2, the determination in step S13 of FIG. 4 is NO. At this time, as shown in FIG. 5, the correction unit 46 corrects the contact determination threshold Cth1, the correction determination threshold Cth2, and the failure determination threshold Cth3.

  As shown after time t4, the contact detection unit 44 performs the contact determination using the corrected contact determination threshold Cth1. In the case where no disturbance such as deterioration occurs in the capacitance sensor 28, the detection value C after time t3 becomes equal to or less than the correction determination threshold Cth2, the determination in step S11 of FIG. The correction of Cth1, the correction determination threshold Cth2, and the failure determination threshold Cth3 is not performed.

[3.4 Failure estimation processing]
The failure estimation processing performed by the steering wheel unit 12 will be described with reference to FIG. A series of processing described below is repeatedly performed at predetermined time intervals. A series of processing described below is executed when automatic steering by the automatic driving device 14 is not performed, that is, during manual steering.

  In step S21, the failure estimation unit 48 determines whether the vehicle 10 is in a turning state based on the detection results of the steering angle sensor 30 and / or the angular velocity sensor 32. If the vehicle 10 is in a turning state (step S21: YES), the process proceeds to step S22. On the other hand, when the vehicle 10 is not in the turning state (step S21: NO), the series of processing ends, and the process waits until the next series of processing is started.

  In step S <b> 22, the failure estimation unit 48 determines, based on the detection result of the contact detection unit 44, whether non-contact of the driver with respect to the steering wheel 26 is detected. When a disturbance such as deterioration occurs in the capacitance sensor 28, the contact detection unit 44 detects the contact state of the driver with respect to the steering wheel 26 after performing the correction by the first correction process or the second correction process. . When non-contact is detected (step S22: YES), the process proceeds to step S23. On the other hand, when the contact is detected (step S22: NO), the series of processes is ended, and the process waits until the next series of processes is started.

  In step S23, the failure estimation unit 48 estimates that a failure has occurred in the capacitance sensor 28. The driver operates the steering wheel 26 while the vehicle 10 is turning. The fact that non-contact with the steering wheel 26 is detected at this time means that it is not possible to detect that the driver is in contact with the steering wheel 26, that is, it is estimated that the capacitance sensor 28 is broken. The failure estimation unit 48 subsequently outputs an instruction to the automatic driving device 14 to prohibit automatic steering. Further, the notification instruction unit 50 outputs a notification instruction to the notification device 18, and notifies the driver that the capacitance sensor 28 has a failure. At this time, the failure estimation unit 48 stores the detected value C in the storage device 40 as failure information.

[4 Summary of the embodiment]
The steering wheel unit 12 is provided on the steering wheel 26. The capacitance sensor 28 detects the magnitude of capacitance that changes according to the contact and non-contact of the human body with the steering wheel 26, and the touch determination threshold Cth1 and correction A storage unit 40 for storing the determination threshold Cth2 and a contact detection unit 44 for detecting contact and non-contact of the human body with the steering wheel 26 based on the comparison result of the detection value C of the capacitance sensor 28 and the contact determination threshold Cth1. The average value Cav (moving average value SMA _M ) of the detection values C for the latest predetermined number of times including the current detection value C is calculated, and the human body is not in contact with the steering wheel 26. An error that occurs when the detected value C is compared with the contact determination threshold Cth1 when it is larger than Cth2 It includes a correction unit 46 for correcting, the.

  In the above configuration, the detection value C of the capacitance sensor 28 and the contact determination threshold Cth1 are at the timing when the human body is not in contact with the steering wheel 26 and when the average value Cav becomes larger than the correction determination threshold Cth2. Correct the error that occurs in the comparison of Therefore, the detection value C of the capacitance sensor 28 and the contact determination threshold Cth1 are always properly compared, and even if a disturbance occurs, the detection accuracy of the contact / non-contact of the human body with the steering wheel 26 Can be suppressed.

In the first correction process of the above embodiment, the correction unit 46 performs an operation of correcting the detection value C as an error correction when the average value Cav (moving average value SMA _M ) is larger than the correction determination threshold Cth2. . The contact detection unit 44 compares the detection value C after the calculation with the contact determination threshold Cth1.

  When a disturbance occurs, the detection value C of the capacitance sensor 28 deviates from the normal value as compared with the case where there is no disturbance. The amount of deviation is manifested when the steering wheel 26 is not in contact with the human body. In the above configuration, even if the detected value C of the capacitance sensor 28 deviates from the normal value due to the disturbance, an operation for correcting the detected value C is performed. And since the detection value C after calculation and the contact determination threshold value Cth1 are compared, it is possible to suppress the decrease in the detection accuracy of the contact / non-contact of the human body with the steering wheel 26.

In the second correction process of the above embodiment, the correction unit 46 performs an operation to correct the contact determination threshold Cth1 as an error correction when the average value Cav (moving average value SMA _M ) is larger than the correction determination threshold Cth2. Do. The contact detection unit 44 compares the detection value C with the contact determination threshold Cth1 after the calculation.

  In the above configuration, even if the detection value C of the capacitance sensor 28 deviates from the normal value due to the disturbance, an operation is performed to correct the contact determination threshold Cth1. Then, since the detection value C is compared with the contact determination threshold value Cth1 after the calculation, it is possible to suppress the decrease in the detection accuracy of the contact / non-contact of the human body with the steering wheel 26.

  The storage device 40 further stores a failure determination threshold Cth3 indicating the size of the capacitance when the capacitance sensor 28 fails. The correction unit 46 performs an operation of correcting the failure determination threshold Cth3 as well as correcting the error.

  According to the above configuration, since the failure determination threshold Cth3 is corrected along with other corrections, it is possible to suppress a decrease in the accuracy of the failure determination.

The storage device 40 further stores failure information indicating the size of the capacitance when the capacitance sensor 28 fails. The correction unit 46 performs failure determination by comparing the moving average value SMA _M with the failure information.

The capacitance sensor 28 in which disturbance such as deterioration has occurred can detect a contact by correction, but the faulty capacitance sensor 28 can not detect a contact. According to the above configuration, the moving average value SMA _M is compared with the failure information indicating the size of the capacitance when the capacitance sensor 28 fails, and the failure determination is performed. Failure can be detected.

  The steering wheel unit 12 detects the turning state by the steering angle sensor 30 and / or the angular velocity sensor 32, which detects the turning state when the vehicle 10 turns, and the steering angle sensor 30 and / or the angular velocity sensor 32, and contacts And a failure estimation unit that estimates that a failure has occurred in the capacitance sensor when the detection unit does not detect the contact of the human body with the steering wheel.

  The driver operates the steering wheel 26 when the vehicle 10 is in a turning state. That is, the driver is in contact with the steering wheel 26. When the contact state is detected by the capacitance sensor 28 in this state, the capacitance sensor 28 is normal. On the other hand, when the non-contact state is detected by the capacitance sensor 28, it is estimated that the capacitance sensor 28 is broken. According to the above configuration, since the failure determination of the capacitance sensor 28 is performed using the detection result of the steering angle sensor 30 and / or the angular velocity sensor 32, the accuracy of the failure determination is improved.

DESCRIPTION OF SYMBOLS 10 Vehicle 12 steering wheel unit 26 steering wheel 28 capacitance sensor 30 steering angle sensor 32 angular velocity sensor 40 storage device 44 contact detection unit 46 correction unit 48 failure estimation unit

Claims (6)

A steering wheel unit for detecting a contact of a human body with a steering wheel of a vehicle by a sensor,
A capacitance sensor provided on the steering wheel for detecting the magnitude of capacitance changing in accordance with contact and non-contact of a human body with the steering wheel;
A storage device for storing a contact determination threshold and a correction determination threshold;
A contact detection unit that detects contact and non-contact of the human body with the steering wheel based on the comparison result of the detection value of the capacitance sensor and the contact determination threshold;
The average value of the detection values for the latest predetermined number of times including the current detection value is calculated at predetermined time intervals, and the non-contact state of the human body with respect to the steering wheel and the latest average value and the previous average value And a correction unit that corrects an error that occurs in comparison between the detection value and the contact determination threshold when the absolute value of the difference is smaller than a predetermined value and the average value is larger than the correction determination threshold. Steering wheel unit characterized by In the steering wheel unit according to claim 1,
The correction unit performs an operation of correcting the detection value as the correction of the error when the average value is larger than the correction determination threshold.
The steering wheel unit, wherein the contact detection unit compares the calculated detection value with the contact determination threshold. In the steering wheel unit according to claim 1,
The correction unit is configured to correct the contact determination threshold by adding the difference between the average value and the correction determination threshold to the current contact determination threshold when the average value is larger than the correction determination threshold. Do,
The steering wheel unit, wherein the contact detection unit compares the detected value with the contact determination threshold after calculation. In the steering wheel unit according to claim 3,
The storage device further stores a failure determination threshold indicating a magnitude of capacitance when the capacitance sensor fails.
The said correction | amendment part performs calculation which correct | amends the said failure determination threshold value with the correction | amendment of the said error. The steering wheel unit characterized by the above-mentioned. The steering wheel unit according to any one of claims 1 to 4.
The storage device further stores failure information indicating the magnitude of capacitance when the capacitance sensor fails.
The steering wheel unit, wherein the correction unit calculates a moving average value of the detection values for n times as the average value, and compares the moving average value with the failure information to perform failure determination. The steering wheel unit according to any one of claims 1 to 5.
A steering angle sensor and / or an angular velocity sensor that detects a turning state when the vehicle turns;
If the turning state is detected by the steering angle sensor and / or the angular velocity sensor, and no contact of the human body with the steering wheel is detected by the contact detection unit, it is estimated that a failure occurs in the capacitance sensor And a failure estimation unit.

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