JP2022083036A - Electronic device and vehicle stop determination method - Google Patents

Abstract

To provide an electronic device with accuracy in determination of a vehicle stop state improved in comparison with conventional ones.SOLUTION: An electronic device of the present invention, mounted on a movable object, has a function to determine a stop state of the movable object. The electronic device includes: an acceleration detection sensor which detects acceleration of the movable object; and determination means which determines the stop state of the movable object based on a value obtained by dividing a difference between a first average value of acceleration of a first detection period and a second average value of acceleration of a second detection period, detected by the acceleration detection sensor, by a standard deviation of the acceleration of the first detection period or the second detection period.SELECTED DRAWING: Figure 2

Description

The present invention relates to an electronic device having a function of determining a stopped state or a stopped state of a moving body.

A navigation device mounted on a moving object (for example, a car or a motorcycle) calculates the position of the own vehicle using a GPS receiver, an angular velocity sensor, an acceleration sensor, etc., and uses this to search for a route to a destination. Provide route guidance. Further, in the navigation device, the mileage and the stop determination of the moving body are determined by using the vehicle speed pulse generated according to the rotation of the wheels. For example, the stop determination device of Patent Document 1 compares the difference between the average value of the accelerations in the period specified this time and the average value of the accelerations in the previously specified period and the threshold value, and when the difference is equal to or less than the threshold value, the moving body moves. It is determined that it is in a stopped state.

Japanese Unexamined Patent Publication No. 2012-163465

The navigation device uses the output of the mounted angular velocity sensor (gyro sensor) to calculate the direction (rotation amount) of the own vehicle, and also uses the vehicle speed pulse to calculate the mileage of the own vehicle. From the results, it is possible to detect the relative position of the own vehicle. However, since the detection of the angular velocity sensor includes an error, if the detection error is accumulated, the detection accuracy of the own vehicle position is lowered. In order to avoid this, when the own vehicle is stopped, the 0 point of the output of the angular velocity sensor is corrected so that the detection error is not accumulated.

Further, the navigation device uses the vehicle speed pulse to determine the stopped state of the own vehicle. That is, when the vehicle speed pulse is not input, it is determined that the vehicle is stopped. However, in this determination method, when the own vehicle is traveling at an extremely low speed, the vehicle speed pulse is not input, and it may be erroneously determined that the vehicle is stopped. In order to avoid such an erroneous determination, as described in Patent Document 1, an acceleration sensor is also used, and when the difference between the average values of accelerations is equal to or less than the threshold value, the vehicle is determined to be in a stopped state.

However, the vehicle stop determination using such an acceleration sensor has the following problems. FIG. 1 is a graph illustrating fluctuations in acceleration detected by an acceleration sensor while the vehicle is stopped. The vertical axis is the output of the acceleration sensor [m / s ² ], and the horizontal axis is the time [seconds]. The acceleration sensor can detect accelerations in the three axes of the X-axis, the Y-axis, and the Z-axis, but here, the acceleration of the X-axis parallel to the straight-ahead direction of the own vehicle is shown.

As shown in the ranges S1, S2, and S3, the detected acceleration fluctuates even when the vehicle is stopped (idling). For example, the acceleration in the range S3 is larger than the acceleration in the ranges S1 and S2. Such fluctuations in acceleration may occur due to vehicle vibration, individual differences in parts, product environment, and the like. When the threshold value for the vehicle stop determination is set to a fixed value, the accuracy of determining the stopped state may decrease due to the fluctuation of the acceleration, and on the other hand, it is difficult to determine the optimum threshold value in advance. Further, even when comparing the difference between the average value of the acceleration in the period specified this time and the average value of the acceleration in the previously specified period and the threshold value as in Patent Document 1, if the acceleration fluctuates, The difference between the average values also varies, making it difficult to accurately determine the stopped state.

An object of the present invention is to solve such a conventional problem and to provide an electronic device and a vehicle stop determination method having improved vehicle stop state determination accuracy as compared with the conventional one.

The electronic device according to the present invention is mounted on a moving body and has a function of determining a stopped state of the moving body, and is detected by a detecting means for detecting the acceleration of the moving body and the detecting means. The difference between the first average value of the acceleration in the first detection period and the second average value of the acceleration in the second detection period detected by the detection means is the difference between the first detection period or the second detection. It has a determination means for determining the stopped state of the moving body based on the value divided by the standard deviation of the acceleration during the period.

In one embodiment, the determination means compares the value with the threshold and determines that the moving object is in a stopped state when the value is equal to or less than the threshold. In one embodiment, the determination means makes a stop determination when the vehicle speed pulse is not input for a certain period of time. In one embodiment, when the first detection period is longer than the second detection period, it is divided by the standard deviation of the acceleration of the first detection period. In one embodiment, the electronic device further comprises a storage means for storing the acceleration detected by the detection means, the determination means storing the accelerations of the first detection period and the second detection period. Get from. In one embodiment, the electronic device further comprises an angular velocity detecting means for detecting the angular velocity of the moving body and a correction means for correcting the output of the angular velocity detecting means when the determination means determines the stopped state of the moving body. include.

The vehicle stop determination method using an acceleration sensor mounted on a moving body according to the present invention has a first average value of accelerations in a first detection period detected by the acceleration sensor and an acceleration in a second detection period. The step includes a step of determining the stopped state of the moving object based on a value obtained by dividing the difference from the second average value by the standard deviation of the acceleration in the first detection period or the second detection period.

According to the present invention, the difference between the first mean value of the acceleration in the first detection period and the second mean value of the acceleration in the second detection period is the difference between the first detection period or the second detection period. By determining the stopped state of the moving object based on the value divided by the standard deviation of the acceleration, it is possible to suppress the influence of fluctuations and fluctuations in the acceleration while the vehicle is stopped, depending on changes in vehicle vibration and individual differences in parts. It is possible to determine the stopped state using the same threshold value. As a result, the accuracy can be improved as compared with the determination of the stopped state using the conventional acceleration sensor.

It is a graph which illustrates the fluctuation of the output value of the acceleration sensor while the vehicle is stopped. It is a block diagram which shows the structure of the vehicle-mounted device which concerns on embodiment of this invention. It is a block diagram which shows the structure of the stop determination function which concerns on embodiment of this invention. It is a figure explaining the setting example of the detection period setting part which concerns on embodiment of this invention. It is a figure explaining the function of the averaging processing part which concerns on embodiment of this invention. It is a graph explaining the effect of the stop determination function which concerns on embodiment of this invention.

Next, an embodiment of the present invention will be described. The electronic device according to the present invention is mounted on a moving body such as an automobile or a motorcycle, and has a stop determination function of the moving body using an acceleration sensor. The electronic device according to the present invention is not particularly limited, but is, for example, an in-vehicle device equipped with a navigation / audio / visual function mounted on a vehicle, a multifunctional mobile phone (smartphone), a portable information terminal (tablet computer, etc.). It can be a laptop computer, a notebook computer), etc.

Next, examples of the present invention will be described with reference to the drawings. FIG. 2 is a block diagram showing a configuration example of the in-vehicle device 100 according to the embodiment of the present invention. The in-vehicle device 100 includes an input unit 110, a position detection unit 120, a navigation unit 130, a communication unit 140, a display unit 150, a voice output unit 160, a storage unit 170, a vehicle state acquisition unit 180, and a control unit 190. .. Although not shown here, the in-vehicle device 100 may include, for example, an audio / visual function, a television / radio broadcast reception function, and the like.

The input unit 110 includes an input key device, a voice input recognition device, a touch panel, and the like, receives an instruction from the user via these devices, and provides the instruction to the control unit 190. The position detection unit 120 detects the position of the own vehicle by using various sensors. In some embodiments, the position detection unit 120 includes a GPS receiver 122, an acceleration sensor 124, an angular velocity sensor (gyro sensor) 126, and the like, and uses the sensor outputs to detect the current position of the own vehicle. In another aspect, the position detection unit 120 may detect the position of the own vehicle by using the vehicle speed pulse 182 acquired from the vehicle state acquisition unit 180 in addition to the sensors 122, 124, and 126 described above. ..

The GPS receiver 122 receives a GPS signal transmitted from a GPS satellite, and detects the absolute position (latitude, longitude, altitude) of the own vehicle based on the received GPS signal. This detection is performed at regular time intervals (eg, detected at 1 second intervals).

The acceleration sensor 124 detects, for example, the acceleration of three axes (X-axis, Y-axis, Z-axis). For example, the X-axis is the straight direction of the own vehicle, the Y-axis is the lateral direction of the own vehicle, and the Z-axis is the vertical direction. The acceleration detected by the acceleration sensor 124 can be used, for example, to calculate the inclination and mileage of the own vehicle. Acceleration detection is performed at regular time intervals (eg, 10 times per second). The acceleration sensor 124 may detect acceleration in the uniaxial or biaxial direction.

The angular velocity sensor 126 detects, for example, an angular velocity (angle / s) indicating the amount of rotation of three axes (yaw, pitch, roll) per unit time. That is, the amount of rotation of the own vehicle in the traveling direction, the amount of rotation before and after the own vehicle, and the amount of left and right rotation of the own vehicle are detected. Angular velocity detection is performed at regular time intervals (eg, 10 times per second). The angular velocity sensor 126 may detect only yaw, or may detect yaw and roll, or yaw and pitch.

The navigation unit 130 displays a road map around the vehicle position on the display unit 150 based on the vehicle position detected by the position detection unit 120, or searches for a route from the vehicle position to the destination, and the searched route. Is displayed on the road map to guide you to your destination. The navigation unit 130 uses the road map data stored in the storage unit 170, or acquires the necessary road map data from the road map server on the network connected via the communication unit 140.

The communication unit 140 enables wired or wireless data communication between the vehicle-mounted device 100 and the outside. For example, it enables data communication with an external server via the Internet. The communication unit 140 may use the communication module built in the vehicle-mounted device 100, or may use the communication function of an electronic device (for example, a smartphone) externally connected to the vehicle-mounted device 100. May be good.

The display unit 150 displays a navigation screen, a menu screen, or the like by the navigation unit 130, and the voice output unit 160 outputs voice guidance or the like by the navigation unit 130. The storage unit 170 is a non-volatile storage medium, and can store data, application software, and the like required for the in-vehicle device 100. Further, the storage unit 170 can store the road map database used by the navigation unit 130. The vehicle state acquisition unit 180 acquires information on the state of the vehicle via, for example, an in-vehicle bus. The information regarding the state of the vehicle is, for example, vehicle speed pulse 182, gear information, side brake information, winker information, and the like. The acquired information is provided to the control unit 190.

The control unit 190 controls the operation of each unit of the vehicle-mounted device 100. In some embodiments, the control unit 190 includes a microprocessor or microcontroller equipped with a ROM / RAM or the like and can execute various programs stored in the ROM / RAM or application software stored in the storage unit 170. Control the operation. In this embodiment, the control unit 190 has a stop determination function using the acceleration sensor 124 in addition to the normal operation control of the in-vehicle device 100.

FIG. 3 is a block diagram showing the configuration of the stop determination function of this embodiment. The vehicle stop determination function 200 includes a vehicle stop determination unit 210, an acceleration storage unit 220, a detection period setting unit 230, an averaging processing unit 240, and a threshold value comparison unit 250.

In one embodiment, the vehicle stop determination unit 210 determines whether or not the vehicle is in the stopped state based on the vehicle speed pulse 182 acquired from the vehicle state acquisition unit 180. The vehicle speed pulse is a pulse waveform generated in response to the rotation of the tire, that is, the number of pulses is proportional to the number of rotations of the tire. The vehicle stop determination unit 210 determines that the vehicle is in the stopped state when the vehicle speed pulse is not input for a certain period of time, but when the vehicle travels at an extremely low speed, the vehicle speed pulse is not input for a certain period and the vehicle is in the stopped state. There is a risk of erroneous judgment. In order to avoid this, the vehicle stop determination unit 210 also uses the acceleration sensor 124 as described later, and uses the detection result of the acceleration sensor 124 for the important matter of the vehicle stop determination. When the vehicle stop determination unit 210 finally determines that the vehicle is stopped, the control unit 190 corrects the rotation amount of the angular velocity sensor 126 to 0 to eliminate the accumulation of detection errors.

The acceleration storage unit 220 sequentially stores the acceleration output from the acceleration sensor 124 at regular time intervals. The acceleration storage unit 220 is not particularly limited, but is configured by using, for example, a memory or a register having a constant storage capacity, and holds the acceleration output from the acceleration sensor 124 for a certain period of time. In one embodiment, the acceleration storage unit 220 stores the acceleration in the X-axis direction (acceleration in the straight direction of the own vehicle) having good sensitivity in the stopped state. However, this is not essential, and the acceleration of the Y-axis or the Z-axis other than the X-axis may be stored.

The detection period setting unit 230 sets the acceleration detection period for determining the stop, and reads the acceleration of the set detection period from the acceleration storage unit 220. The detection period setting unit 230 presets two detection periods having different periods. In one embodiment, as shown in FIG. 4A, the detection periods t1 and t2 with respect to the time ts are set (t1> t2). The time ts is, for example, the timing when the vehicle stop determination unit 210 makes a stop determination using the acceleration sensor without inputting the vehicle speed pulse. The detection period t2 has a relationship that overlaps with the detection period t1, but as shown in FIG. 4B, the detection period t1 and the detection period t2 may have a non-overlapping relationship. In the example of FIG. 4B, the detection period t1 is a period past the offset period tof from the time ts (toff> t1, t1> t2). The setting of the detection period is not limited to the above, and the detection period t1 and the detection period t2 may be partially overlapped, or the lengths of the detection period t1 and the detection period t2 may be equal to each other.

The averaging processing unit 240 calculates the average value of the acceleration of the detection period set by the detection period setting unit 230, then calculates the difference of the average value, and performs the processing of dividing the difference by using the standard deviation. Specifically, as shown in the following equation, the average value of the output of the accelerometer in the past detection period t1 based on the time ts and the output of the accelerometer in the past detection period t2 based on the time ts. The difference from the average value is calculated, and the difference correction value P is calculated by dividing this difference by the standard deviation of the output of the acceleration sensor in the detection period t1.

The variation in acceleration detected by the acceleration sensor in the detection period t1 is equalized by the average, and the variation in acceleration detected by the acceleration sensor in the detection period t2 is also equalized by the average. However, as shown in FIG. 1, even when the vehicle is stopped (idling stop, etc.), when the acceleration detected by the acceleration sensor fluctuates, the difference between the average value of the detection period t1 and the average value of the detection period t2 becomes. However, there are variations (variations), and therefore it is difficult to accurately determine the stopped state by comparing the difference with the threshold value.

This embodiment assumes that the error generated in the accelerometer follows a normal distribution, and utilizes the property that the difference between the mean values of different detection periods is proportional to the standard deviation of the population. That is, when the overall variation in acceleration is large, the variation in the difference between the average value of the detection period t1 and the average value of the detection period t2 is also large, and the standard deviation is proportionally large. On the contrary, when the overall variation of the acceleration is small, the variation of the difference between the average value of the detection period t1 and the average value of the detection period t2 is also small, and the standard deviation is proportionally small. By dividing the difference by the standard deviation, the difference correction value P becomes a value that suppresses the influence of the variation or fluctuation of the acceleration while the vehicle is stopped.

Here, the standard deviation of the accelerometer output of the detection period t1 is used because of the relationship of the detection period t1> the detection period t2, but when the detection period t1 <the detection period t2, the standard deviation of the accelerometer output of the detection period t2 is used. Use deviation. This is because the longer the detection period, that is, the larger the parameter of the accelerometer, the higher the reliability of the standard deviation.

FIG. 5 shows an example of sampling the output of the accelerometer while the vehicle is stopped and correcting it using the standard deviation. FIG. 5A shows an example in which the difference between the average values of accelerations during different periods while the vehicle is stopped is small, and the standard deviation is 40 m / s ² . FIG. 5B is an example in which the difference between the average values of accelerations during different periods while the vehicle is stopped is large, and the standard deviation is 100 m / s ² . The vertical axis of the graph shows the number of differences of the average value, and the horizontal axis shows the range of the difference of the average value [m / s ² ]. Both have a generally normal distribution and are similar in shape, but the magnitude of the difference between the average values is different. In FIG. 5A, the number of differences in the mean value is the largest in the range of −2 to +2, and in FIG. 5B, the number of differences in the mean value is the largest in the range of −5 to +5. Since the magnitude of the difference between the two average values is different, it is difficult to compare the difference with the same threshold value to determine the stop.

5 (C) and 5 (D) are graphs when the difference between the average values of FIGS. 5 (A) and 5 (B) is divided by the standard deviation. In FIG. 5C, by dividing the difference in the mean value by the standard deviation = 40 m / S ² , the number of differences in the mean value is the largest in the range of −0.05 to +0.05, and FIG. 5 (C) In D), by dividing the difference of the mean value by the standard deviation = 100 m / S ² , the number of the difference of the mean value becomes the largest in the range of −0.05 to +0.05. As described above, the magnitude of the difference between the average values is the same in FIGS. 5 (C) and 5 (D) regardless of the variation in acceleration. Therefore, it is possible to make a stop determination using the same threshold value.

The threshold value comparison unit 250 compares the difference correction value P with the threshold value Th. The threshold value Th is a value that can be estimated from the detection periods t1 and t2, and is set in advance. The threshold value comparison unit 250 provides the comparison result to the stop determination unit 210. If the difference correction value P <threshold value Th, the vehicle stop determination unit 210 determines that the vehicle is in a stopped state, and if the difference correction value P ≧ threshold value Th, it is determined that the vehicle is not in the stopped state (running). The determination result of the stopped state is used, for example, for correcting the 0 point of the angular velocity sensor 124, and it becomes possible to improve the accuracy of the correction performed when the vehicle is stopped.

FIG. 6 is a graph illustrating an output example of the accelerometer while the vehicle is running and stopped, and an example of determining the stopped state. The time ts is a timing at which the vehicle speed pulse is not input and the vehicle stop determination unit 210 makes a vehicle stop determination using the acceleration sensor. When traveling, the average value of the accelerations of the detection period A and the detection period B is compared. Since the difference between the average values is large, it is determined that the vehicle is running. That is, the difference correction value P ≧ threshold value Th.

While the vehicle is stopped, the average values of accelerations in the detection period C and the detection period D are compared. Since the difference between the average values is small, it is judged that the vehicle is stopped. That is, the difference correction value P <threshold value Th. Further, in another period while the vehicle is stopped, the average value of the accelerations of the detection period E and the detection period F is compared. The variation in acceleration is larger and the difference in the average value is larger than in the detection periods C and D, but the correction by the standard deviation works and it is determined that the vehicle is stopped. That is, the difference correction value P <threshold value Th.

As described above, according to this embodiment, when the acceleration sensor is used to determine the stopped state of the vehicle, the difference in the average value is corrected by the standard deviation of the acceleration, so that the vibration of the vehicle, the individual difference of parts, or the product environment Therefore, even if the difference in the average value varies, the stopped state can be accurately determined using the same threshold value.

In the above embodiment, an example in which the acceleration sensor is used when making a stop determination by the vehicle speed pulse is shown, but this is an example. For example, the stop determination is made using only the acceleration sensor regardless of the stop determination by the vehicle speed pulse. It may be performed, or the vehicle stop determination may be performed by using an acceleration sensor when performing a stop determination by a method using another sensor or the like (for example, a change in the absolute position due to GPS positioning). .. Further, in the above embodiment, the example of correcting the 0 point of the angular velocity sensor when the vehicle is stopped is shown, but it is also possible to calibrate or correct other sensors or the like.

Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the specific embodiments, and various modifications and variations are made within the scope of the gist of the invention described in the claims. It can be changed.

100: In-vehicle device 110: Input unit 120: Position detection unit 122: GPS receiver 124: Accelerometer 126: Angular velocity sensor 130: Navigation unit 140: Communication unit 150: Display unit 160: Audio output unit 170: Storage unit 180: Vehicle State acquisition unit 182: Vehicle speed pulse 190: Control unit t1, t2, A, B, C, D, E, F: Detection period

Claims (9)

It is an electronic device mounted on a moving body and having a function of determining the stopped state of the moving body.
A detection means that detects the acceleration of a moving object,
The difference between the first average value of the acceleration in the first detection period detected by the detection means and the second average value of the acceleration in the second detection period detected by the detection means is the difference between the first average value and the first average value. A determination means for determining the stopped state of the moving object based on the value divided by the standard deviation of the acceleration in the detection period or the second detection period, and
Electronic device with. The electronic device according to claim 1, wherein the determination means compares the value with a threshold value, and determines that the moving object is in a stopped state when the value is equal to or less than the threshold value. The electronic device according to claim 1, wherein the determination means determines a stop when the vehicle speed pulse is not input for a certain period of time. The stop determination method according to claim 1, wherein when the first detection period is longer than the second detection period, it is divided by the standard deviation of the acceleration in the first detection period. The electronic device further includes a storage means for storing the acceleration detected by the detection means.
The electronic device according to claim 1, wherein the determination means acquires accelerations of the first detection period and the second detection period from the storage means. Electronic devices are also
An angular velocity detecting means for detecting the angular velocity of a moving object,
The electronic device according to any one of claims 1 to 5, further comprising a correction means for correcting the output of the angular velocity detecting means when the stop state of the moving body is determined by the determination means. It is a stop judgment method using an acceleration sensor mounted on a moving body.
The difference between the first average value of the acceleration in the first detection period and the second average value of the acceleration in the second detection period detected by the acceleration sensor is the difference between the first detection period or the second detection. A stop determination method comprising a step of determining a stopped state of a moving object based on a value divided by a standard deviation of acceleration during a period. The stop determination method according to claim 7, wherein when the first detection period is longer than the second detection period, it is divided by the standard deviation of the acceleration in the first detection period. The stop determination method according to claim 7, wherein the determination step determines a stop when the vehicle speed pulse is not input for a certain period of time.

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