Abnormality determination apparatus for yaw rate sensor

Abstract

To provide a technique for avoiding a situation in which an abnormality of a yaw rate sensor due to the influence of rotation by a turntable is determined.SOLUTION: A correction-amount holding part 18 holds a zero-point correction amount YRz of a yaw rate sensor 4. A drift-amount calculation unit 14 calculates a drift amount YRd from the zero point of the yaw rate sensor 4 during a predetermined period. A processing unit 16 includes the function of determining an abnormality of the yaw rate sensor 4 on the basis of the drift amount YRd. The processing unit 16 does not determine that the yaw rate sensor 4 is abnormal when the signs of the zero-point correction amount YRz and the drift amount YRd are opposite.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technique for determining an abnormality in a yaw rate sensor mounted on a vehicle. [Background technology]

[0002] In a yaw rate sensor mounted on a vehicle, a discrepancy may occur between the detected yaw rate and the actual yaw rate, and this discrepancy is generally referred to as drift. When the vehicle is stopped, the actual yaw rate of the vehicle is zero, so the detected value of the yaw rate sensor when the vehicle is stopped corresponds to the amount of drift of the yaw rate sensor. A conventional technique is known in which the amount of drift of the yaw rate sensor is calculated based on the detected value of the yaw rate sensor when the vehicle is stopped, and the amount of drift is subtracted from the detected value of the yaw rate sensor to perform zero point correction of the yaw rate sensor.

[0003] When a vehicle is placed on a turntable installed in a multi-story parking lot or the like and the turntable rotates, a yaw rate is generated in the vehicle, and a yaw rate sensor detects the yaw rate even when the vehicle is stopped. Patent Document 1 discloses a technique for calculating an average value of the yaw rate detection value when the vehicle is stopped, and determining that the yaw rate sensor is abnormal if this average value exceeds a threshold value set based on the maximum value of the yaw rate detection value detected when the vehicle is placed on the rotating turntable. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-292435 Summary of the Invention [Problem to be solved by the invention]

[0005] In a multi-story parking garage equipped with an elevator, a vehicle may be rotated in one direction by a turntable when entering the garage, then parked for a period of time, and then rotated in the opposite direction by the turntable when leaving. For example, when entering a multi-story parking garage, a driver places the vehicle on the turntable inside the elevator, and the elevator takes the vehicle to the destination floor where it is rotated counterclockwise by the turntable. When the elevator doors open, the driver drives the vehicle through the flat parking garage at the destination floor and parks the vehicle. When leaving the garage, the driver places the vehicle on the turntable inside the elevator, and the elevator takes the vehicle to the exit floor (e.g., the ground floor) where it is rotated clockwise by the turntable. When the elevator doors open, the driver drives the vehicle out of the multi-story parking garage.

[0006] In the yaw rate sensor abnormality detection process, by setting the abnormality detection threshold A to a value greater than the expected maximum angular velocity M of the turntable, it is possible to avoid a situation in which the yaw rate sensor is detected as abnormal when the vehicle is being rotated by the turntable. However, if the yaw rate sensor's zero-point correction process is also performed, if the yaw rate sensor outputs a detection value (+M) when the turntable rotates the vehicle counterclockwise, the absolute value of the detection value M is smaller than the abnormality detection threshold A, so the yaw rate sensor is not detected as abnormal. However, the zero-point correction process corrects the detection value by a negative value (-M). Note that counterclockwise rotation is considered a positive rotation in this example. Therefore, when the turntable next rotates the vehicle clockwise, the yaw rate sensor outputs a detection value (-2M) that is the sum of the angular velocity (-M) of the right rotation (negative rotation) and the over-corrected angular velocity (-M). If the absolute value of this detection value (-2M) exceeds the abnormality detection threshold A, the yaw rate sensor will be detected as abnormal even if it is not.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a technique for avoiding a situation in which an abnormality in the yaw rate sensor is determined due to the influence of rotation by the turntable. [Means for solving the problem]

[0008] An abnormality determination device according to one aspect of the present invention is an abnormality determination device for determining an abnormality in a yaw rate sensor, and includes a storage unit that stores a zero point correction amount YRz of the yaw rate sensor, a drift amount calculation unit that calculates a drift amount YRd from the zero point of the yaw rate sensor over a predetermined period of time, and a processing unit that determines an abnormality in the yaw rate sensor based on the drift amount YRd. The processing unit does not determine that the yaw rate sensor is abnormal if the zero point correction amount YRz and the drift amount YRd have opposite signs. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a diagram illustrating a functional configuration of a system for determining an abnormality in a yaw rate sensor. [Figure 2] FIG. 10 is a diagram illustrating an example of transition of the detected value of the yaw rate sensor from when the vehicle enters a multi-story parking garage until when the vehicle leaves the parking garage. [Figure 3] FIG. 10 is a diagram illustrating an example of a flowchart for processing a detection value of a yaw rate sensor. [Figure 4] FIG. 10 is a diagram showing another example of a flowchart for processing a detection value of a yaw rate sensor. DETAILED DESCRIPTION OF THE INVENTION

[0010] 1 shows the functional configuration of a yaw rate sensor abnormality determination system 1 according to an embodiment. The abnormality determination system 1 includes a wheel speed sensor 2 that detects the wheel speed, a yaw rate sensor 4 that detects the yaw rate generated in the vehicle, and an abnormality determination device 10 that determines an abnormality in the yaw rate sensor 4. The abnormality determination device 10 is mounted on the vehicle and includes a vehicle state determination unit 12, a drift amount calculation unit 14, a processing unit 16, and a correction amount holding unit 18.

[0011] The vehicle may be a vehicle that uses only an internal combustion engine as a driving force source, or may be an electrically powered vehicle that uses an electric motor as a driving force source. Electrically powered vehicles include, for example, battery electric vehicles (BEVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and fuel cell electric vehicles (FCEVs). The vehicle may be a vehicle driven by a driver or an autonomous vehicle.

[0012] The wheel speed sensors 2 are provided on each wheel of the vehicle, periodically detect the rotational speeds of the wheels (wheel speeds), and output the detected wheel speeds to the vehicle state determination unit 12. The vehicle state determination unit 12 derives the vehicle speed V from the received wheel speeds, and determines at least whether the vehicle is stopped or moving based on the vehicle speed V. The vehicle state determination unit 12 has a function of determining whether the vehicle speed V exceeds a predetermined threshold Vth, and may determine that the vehicle has started moving when the vehicle speed V exceeds the threshold Vth from a stopped state. The vehicle state determination unit 12 outputs the result of its determination based on the vehicle speed V (i.e., the state of the vehicle) to the processing unit 16.

[0013] The yaw rate sensor 4 periodically detects the yaw rate generated in the vehicle and outputs the detected yaw rate value YR to the drift amount calculation unit 14. The drift amount calculation unit 14 acquires the detected value YR output from the yaw rate sensor 4 over a predetermined period T2 and calculates a drift amount YRd from the zero point of the yaw rate sensor 4 during the predetermined period T2. The drift amount calculation unit 14 calculates the drift amount YRd for each predetermined period T2 and outputs the calculated drift amount YRd to the processing unit 16.

[0014] The processing unit 16 performs an abnormality determination process and a zero point correction process for the yaw rate sensor 4 based on the vehicle state output from the wheel speed sensor 2 and the drift amount YRd output from the yaw rate sensor 4. In this embodiment, the processing unit 16 performs an abnormality determination process and a zero point correction process for the yaw rate sensor 4 when the vehicle starts moving after being stopped. After being notified by the vehicle state determination unit 12 that the vehicle has started moving, the processing unit 16 performs an abnormality determination process and a zero point correction process for the yaw rate sensor 4 when predetermined conditions are satisfied.

[0015] In the abnormality determination process, the processing unit 16 determines that the yaw rate sensor 4 is abnormal if the absolute value of the drift amount YRd immediately before start is equal to or greater than the abnormality determination threshold A. Here, the abnormality determination threshold A is set to be greater than the maximum angular velocity M of the turntable. When the processing unit 16 determines that the yaw rate sensor 4 is abnormal, it may notify a control device that performs skid prevention control of the vehicle that the yaw rate sensor 4 is abnormal, and may stop the skid prevention control.

[0016] The zero point correction process is not performed if the abnormality determination process determines that the yaw rate sensor 4 is abnormal. The zero point correction process is performed if the abnormality determination process does not determine that the yaw rate sensor 4 is abnormal.

[0017] In the zero point correction process, the processing unit 16 supplies the drift amount YRd immediately before start-up as the zero point correction amount YRz to the drift amount calculation unit 14. As a result, the drift amount calculation unit 14 treats the value obtained by subtracting the zero point correction amount YRz from the detection value YR of the yaw rate sensor 4 as the detection value YR of the yaw rate sensor 4. After performing the zero point correction process, the processing unit 16 causes the correction amount holding unit 18 to hold the zero point correction amount YRz.

[0018] FIG. 2 shows an example of the transition of the detection value of the yaw rate sensor from when a vehicle enters a multi-story parking garage until when it leaves. Here, the sensor detection value is shown from when the vehicle enters a multi-story parking garage equipped with a turntable until when it leaves. In this example, the maximum angular velocity M of the turntable installed in the elevator is 3 [deg / sec], and taking this angular velocity M into consideration, the abnormality determination threshold A of the yaw rate sensor 4 is set to 5 [deg / sec]. Note that the values ​​of the maximum angular velocity M and the abnormality determination threshold A are merely examples, and the abnormality determination threshold A must be set to at least be greater than the maximum angular velocity M of the turntable. Note that if the abnormality determination threshold A is too large, the abnormality determination process may not be performed appropriately. Therefore, it is preferable that the abnormality determination threshold A be less than twice the maximum angular velocity M. In other words, it is preferable that the abnormality determination threshold A be set to a value within the range shown below. Maximum angular velocity M<Abnormality threshold A<Maximum angular velocity M×2

[0019] When entering a multi-story parking garage, the driver places the vehicle on the turntable inside the elevator, and the elevator takes the vehicle to the destination floor, where it rotates counterclockwise on the turntable. When the elevator doors open, the driver drives the vehicle through the flat parking lot at the destination floor and parks the vehicle in the desired location. In the example shown in Figure 2, during the "period in which the vehicle is rotating counterclockwise," the turntable rotates counterclockwise at 3 deg / sec, and the yaw rate sensor 4 mounted on the vehicle detects a yaw rate of 3 deg / sec while the turntable is rotating counterclockwise.

[0020] In this example, when the elevator transports the vehicle to the destination floor and the elevator doors open, the turntable's left rotation has not yet stopped, and the driver starts the vehicle before the turntable's left rotation has stopped. At this time, the processing unit 16 determines that no abnormality has occurred in the yaw rate sensor 4 because the yaw rate detected immediately before the vehicle starts is 3 [deg / sec], which is smaller than the abnormality determination threshold of 5 [deg / sec]. The processing unit 16 also notifies the drift amount calculation unit 14 of the yaw rate detected immediately before the vehicle starts (3 [deg / sec]) as the zero point correction amount YRz. As a result, the drift amount calculation unit 14 treats the value obtained by subtracting the zero point correction amount YRz from the detection value YR of the yaw rate sensor 4 as the detection value YR of the yaw rate sensor 4. After performing the zero point correction process, the processing unit 16 causes the correction amount holding unit 18 to hold the zero point correction amount YRz.

[0021] 2, it is assumed that, after the vehicle is parked, and before it starts moving again and enters the elevator, the zero point correction process of the yaw rate sensor 4 is not performed for some reason. Therefore, during the "period when the vehicle is not on the rotating turntable," the yaw rate sensor 4 outputs an angular velocity (-3 [deg / sec]) that is over-corrected to the negative side.

[0022] 3 shows an example of a flowchart for processing the detection value of the yaw rate sensor 4. In the embodiment, the processing described below is performed during a "period in which the vehicle is rotating clockwise." As shown in FIG. 2, the zero point correction amount YRz in the most recent (previous) zero point correction processing is 3 [deg / sec], and the correction amount holding unit 18 holds 3 [deg / sec] as the zero point correction amount YRz of the yaw rate sensor 4.

[0023] The vehicle state determination unit 12 determines whether the vehicle has been stopped for a time T1 or more (S10). The time T1 is set to a time during which the vehicle can be considered to be stationary, and may be, for example, about 10 seconds. The vehicle state determination unit 12 measures the vehicle's stopped time until the vehicle's stopped time reaches the time T1 (N in S10), and when the vehicle's stopped time reaches or exceeds the time T1 (Y in S10), it notifies the drift amount calculation unit 14 that the vehicle is in a stationary state.

[0024] Upon receiving the notification that the vehicle has stopped, the drift amount calculation unit 14 activates a count-up timer to start measuring time T2 (S12). The drift amount calculation unit 14 increments the count value of the timer (S14) until time T2 exceeds a predetermined time Tth (N in S12), and accumulates the detected yaw rate value YR during this time (S16). Here, time Tth is the time required to calculate the average value of the detected values ​​YR of the yaw rate sensor 4 while the vehicle is stopped, and may be, for example, about 5 seconds. Therefore, the drift amount calculation unit 14 repeats the calculation of adding the current detected value YR to the accumulated value YRs until time T2 exceeds time Tth.

[0025] When the time T2 during which the detection value YR has been accumulated exceeds the time Tth (Y in S12), the drift amount calculation unit 14 calculates the drift amount YRd from the zero point at time T2 (S18). The calculated drift amount YRd is the average value of the detection value YR of the yaw rate sensor 4 at time T2, and is calculated by dividing the accumulated value YRs obtained by accumulating the detection value YR by the number of times it has been accumulated. As shown in FIG. 2, the drift amount calculation unit 14 calculates the drift amount YRd as -6 [deg / sec]. This drift amount YRd is derived as the result of adding the angular velocity (-3 [deg / sec]) of the right rotation (negative rotation) to the angular velocity (-3 [deg / sec]) that was over-corrected to the negative side by the previous zero point correction process. After calculating the drift amount YRd, the drift amount calculation unit 14 resets the count value of the timer to zero and also resets the integrated value YRs to zero (S20).

[0026] At this time, the vehicle state determination unit 12 determines whether the vehicle has started moving (S22). The vehicle state determination unit 12 may determine whether the vehicle has started moving by comparing the vehicle speed V with a predetermined speed Vth. For example, the predetermined speed Vth may be approximately 5 to 10 km / h, and the vehicle state determination unit 12 uses the predetermined speed Vth to determine whether the vehicle has started moving from a stopped state. If the vehicle speed V does not exceed the predetermined speed Vth (N in S22), the abnormality determination process and the zero point correction process for the yaw rate sensor 4 are not performed. On the other hand, if the vehicle speed V exceeds the predetermined speed Vth (Y in S22), the vehicle state determination unit 12 notifies the processing unit 16 that the vehicle has started moving.

[0027] In this embodiment, the drift amount YRd immediately before the vehicle starts is calculated to be −6 [deg / sec], and the absolute value of the drift amount YRd is greater than the abnormality determination threshold A, which is 5 [deg / sec]. Therefore, simply comparing the absolute value of the drift amount YRd with the abnormality determination threshold A would result in a determination that the yaw rate sensor 4 is abnormal. However, the calculated drift amount YRd appears to be large because it includes the angular velocity that was over-corrected to the negative side in the previous zero point correction process and the angular velocity detected this time because the vehicle has rotated in the opposite direction. Therefore, it is not desirable to determine that the yaw rate sensor 4 is abnormal in such a situation.

[0028] Therefore, in this embodiment, the processing unit 16 is configured not to determine that the yaw rate sensor 4 is abnormal when the signs of the previous zero point correction amount YRz and the drift amount YRd are opposite to each other. The processing unit 16 uses a positive / negative determination threshold YRth to determine whether the zero point correction amount YRz and the drift amount YRd have opposite signs. The positive / negative determination threshold YRth is set to a value smaller than the angular velocity M of the turntable. For example, the positive / negative determination threshold YRth may be a value greater than 0.1 times the angular velocity M and less than 0.5 times the angular velocity M. Since minute zero point drifts often occur in the yaw rate sensor 4, it is preferable that the positive / negative determination threshold YRth be set to a value greater than this minute drift amount. In this embodiment, the positive / negative determination threshold YRth may be set to 0.5 [deg / sec].

[0029] The processing unit 16 determines whether or not either of the following relational expressions (a) and (b) holds (S24). (a) YRz>YRth & YRd<-YRth (b) YRz<-YRth & YRd>YRth If either of the relational expressions (a) and (b) is satisfied, it means that the zero point correction amount YRz and the drift amount YRd have opposite signs.

[0030] If either of the relational expressions (a) and (b) is satisfied (Y in S24), the processing unit 16 does not perform the abnormality determination process. Zero point correction amount YRz = 3[deg / sec] Drift amount YRd = -6[deg / sec] Positive / negative judgment threshold YRth = 0.5 [deg / sec] Therefore, (a) 3>0.5 & -6<-0.5 is established, and therefore the processing unit 16 does not perform the abnormality determination process.

[0031] In this way, when the zero point correction amount YRz and the drift amount YRd have opposite signs, the processing unit 16 does not determine that there is an abnormality in the yaw rate sensor 4. This allows the processing unit 16 to realize control that does not determine that there is an abnormality in the yaw rate sensor 4 in which an apparently large drift amount YRd occurs due to rotation by the turntable.

[0032] On the other hand, if neither of the relational expressions (a) nor (b) holds (N in S24), the processing unit 16 compares the absolute value of (YRz-YRd) with the abnormality determination threshold value A (S26). If the absolute value of (YRz-YRd) is equal to or greater than the abnormality determination threshold value A (N in S26), the processing unit 16 determines that the yaw rate sensor 4 is abnormal (S28).

[0033] If the absolute value of (YRz-YRd) is less than the abnormality determination threshold A (Y in S26), the processing unit 16 supplies the drift amount YRd as a new zero point correction amount YRz to the drift amount calculation unit 14. As a result, the drift amount calculation unit 14 obtains the value obtained by subtracting the zero point correction amount YRz from the detection value YR of the yaw rate sensor 4 as the detection value YR of the yaw rate sensor 4 (S30).

[0034] The present invention has been described above based on the embodiments. The embodiments are merely examples, and those skilled in the art will understand that various modifications are possible in the combination of each component and each treatment process, and that such modifications are also within the scope of the present invention. In the embodiments, in S26, processing unit 16 compares the absolute value of (YRz-YRd) with abnormality determination threshold A, but the absolute value of drift amount YR may also be compared with abnormality determination threshold A.

[0035] Fig. 4 shows another example of a flowchart for processing the detection value of the yaw rate sensor 4. Compared to the flowchart shown in Fig. 3, the processing in each step from S10 to S28 is the same, so a description of these steps will be omitted.

[0036] In the processing example shown in FIG. 4, if either of the relational expressions (a) or (b) is satisfied in S24 (Y in S24), the processing unit 16 does not perform the abnormality determination processing, which is the same as the processing example shown in FIG. 3. However, the drift amount calculation unit 14 obtains the value obtained by subtracting the zero point correction amount YRz from the detection value YR of the yaw rate sensor 4 as the yaw rate sensor value YRc after zero point correction (S34).

[0037] 4, if the absolute value of (YRz-YRd) is less than the abnormality determination threshold A in S26 (Y in S26), the processing unit 16 supplies the drift amount YRd to the drift amount calculation unit 14 as a new zero point correction amount YRz (S32). As a result, the drift amount calculation unit 14 acquires a value obtained by subtracting the zero point correction amount YRz from the detection value YR of the yaw rate sensor 4 as the detection value YRc of the yaw rate sensor 4 after zero point correction (S34). This example differs from the example shown in FIG. 3 in that the yaw rate sensor value YR is not directly zero-point corrected, but the yaw rate sensor value YRc used in calculating the vehicle state quantity is updated. [Explanation of symbols]

[0038] 1···Abnormality determination system, 2···Wheel speed sensor, 4···Yaw rate sensor, 10···Abnormality determination device, 12···Vehicle state determination unit, 14···Drift amount calculation unit, 16···Processing unit, 18···Correction amount holding unit.

Claims

1. An abnormality determination device for determining an abnormality in a yaw rate sensor, a holding unit that holds a zero point correction amount YRz of the yaw rate sensor; a drift amount calculation unit that calculates a drift amount YRd from the zero point of the yaw rate sensor during a predetermined period; a processing unit that determines whether the yaw rate sensor is abnormal based on the drift amount YRd, The processing unit does not determine that the yaw rate sensor is abnormal when the zero point correction amount YRz and the drift amount YRd have opposite signs. An abnormality determination device characterized by:

2. the processing unit uses a positive / negative determination threshold YRth for determining whether the zero point correction amount YRz and the drift amount YRd are positive or negative when determining whether the zero point correction amount YRz and the drift amount YRd have opposite signs.

2. The abnormality determination device according to claim 1.

3. the processing unit does not perform an abnormality determination process for the yaw rate sensor when the signs of the zero point correction amount YRz and the drift amount YRd are opposite to each other; 2. The abnormality determination device according to claim 1.

4. When the maximum angular velocity of the turntable is M, the abnormality determination threshold for determining an abnormality in the yaw rate sensor is set to a value greater than M and smaller than 2M.

2. The abnormality determination device according to claim 1.

Images