JP7534200B2 - Arithmetic device and program - Google Patents

Description

The present invention relates to a computing device and a program.

For example, as shown in Patent Document 1, a technology is known that detects the vibrations of a vehicle traveling on a road and diagnoses the unevenness of the road surface based on the vibration data.

JP 2014-108988 A

However, even if the vehicle is traveling on the same road, if the vehicle type is different and the detection conditions on the vehicle side are different, the vehicle's behavior will be different and there is a risk that the road surface condition cannot be detected properly. Therefore, there is a demand for proper detection of the road surface condition even when the detection conditions on the vehicle side are different.

The present invention has been made in consideration of the above, and aims to provide a calculation device and program that can appropriately detect the condition of the road surface even when the detection conditions on the vehicle side are different.

In order to solve the above-mentioned problems and achieve the objective, the computing device according to the present disclosure includes a vehicle behavior information acquisition unit that acquires vehicle behavior information indicating the behavior of a vehicle detected by a plurality of sensors provided at different positions on the vehicle traveling on a road, and a road surface condition information acquisition unit that acquires road surface condition information indicating the road surface condition of the road by estimating a transfer function indicating the relationship between the road surface condition as an input and the vehicle behavior information as an output based on the plurality of vehicle behavior information.

In order to solve the above-mentioned problems and achieve the objective, the program disclosed herein causes a computer to execute a calculation method including the steps of acquiring vehicle behavior information indicating the behavior of a vehicle traveling on a road, detected by a plurality of sensors provided at different positions on the vehicle, and acquiring road surface condition information indicating the road surface condition of the road by estimating a transfer function indicating the relationship between the road surface condition as an input and the vehicle behavior information as an output based on the plurality of vehicle behavior information.

According to the present invention, it is possible to appropriately check the condition of the road surface even when the detection conditions on the vehicle side are different.

FIG. 1 is a schematic block diagram of a detection system according to the present embodiment. FIG. 2 is a schematic diagram of a vehicle. FIG. 3 is a schematic diagram of a vehicle. FIG. 4 is a schematic block diagram of the computing device. FIG. 5 is a schematic diagram for explaining the calculation of the road surface condition. FIG. 6 is a flowchart illustrating a flow of calculation of the road surface condition according to this embodiment.

Below, a preferred embodiment of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiment described below.

(Detection System)
FIG. 1 is a schematic block diagram of a detection system according to the present embodiment. As shown in FIG. 1, the detection system 1 according to the present embodiment includes a vehicle 10, a measurement data acquisition device 12, and a calculation device 14. The detection system 1 is a system that determines the road surface condition of a road R based on vehicle behavior information of the vehicle 10 traveling on the road R. The vehicle behavior information is information indicating the behavior of the vehicle 10 traveling on the road R, and will be described in detail later. The detection system 1 determines the road surface condition of the road R by calculating the road surface condition of the road R based on the vehicle behavior information using the calculation device 14. In this embodiment, the road surface condition is an index indicating the degree of unevenness of the road surface. Furthermore, in this embodiment, the road surface condition is information indicating the height of the road surface in the vertical direction, and for example, the road surface condition at a certain position on the road R may be the difference in the height of the road surface at that position relative to the height of the road surface at a unit distance before that position along the traveling direction of the vehicle 10. For example, the road surface condition may be at least one of IRI (International Roughness Index), flatness of the road surface, cracks, rutting, and MCI (Maintenance Control Index). For example, the road surface condition may be information indicating the presence or absence of an object that affects the unevenness of the road surface, such as the presence or absence of a manhole or a bridge joint on the road R, or may include the above information (such as IRI) and information indicating the presence or absence of an object that affects the unevenness of the road surface. Furthermore, the road surface condition information is not limited to an index indicating the unevenness of the road surface, as long as it is an index indicating the state of the road surface.

In the detection system 1, the vehicle 10 detects vehicle behavior information while traveling on the road R, and transmits the detected vehicle behavior information to the measurement data acquisition device 12. The measurement data acquisition device 12 is, for example, a device (computer) managed by an entity that manages the road R. The measurement data acquisition device 12 transmits the vehicle behavior information transmitted from the vehicle 10 to the calculation device 14. The calculation device 14 calculates the road surface condition of the road R on which the vehicle 10 traveled based on the vehicle behavior information transmitted from the measurement data acquisition device 12. The calculation device 14 then transmits the calculation result of the road surface condition to the measurement data acquisition device 12. In this way, the calculation device 14 acquires the vehicle behavior information via the measurement data acquisition device 12, but is not limited to this. For example, the detection system 1 may not be provided with the measurement data acquisition device 12, and the calculation device 14 may acquire the vehicle behavior information directly from the vehicle 10.

(vehicle)
2 and 3 are schematic diagrams of a vehicle. The Z direction in FIG. 2 and FIG. 3 indicates the vertical upward direction, FIG. 2 is a schematic diagram of the vehicle 10 viewed from above in the vertical direction, and FIG. 3 is a schematic diagram of the vehicle 10 viewed from the side. As shown in FIG. 2, the vehicle 10 includes a position sensor 10A, a plurality of behavior sensors 10B, and a measuring device 10C. The position sensor 10A is a sensor that acquires position information of the vehicle 10. The position information of the vehicle 10 is information indicating the earth coordinates of the vehicle 10. In this embodiment, the position sensor 10A is a module for a Global Navigation Satellite System (GNSS).

The behavior sensor 10B is a sensor that detects vehicle behavior information that indicates the behavior of the vehicle 10. The vehicle behavior information may be any information that indicates the behavior of the vehicle 10 while traveling on a road. Each behavior sensor 10B may detect different types of vehicle behavior information, but it is preferable that they detect the same type of vehicle behavior information. In this embodiment, it is preferable that the behavior sensor 10B detects the acceleration of the vehicle 10 as the vehicle behavior information. In this case, the behavior sensor 10B is an acceleration sensor that detects acceleration, and more preferably an acceleration sensor that detects acceleration in three axes. In addition, the vehicle behavior information detected by the behavior sensor 10B is not limited to acceleration, and may be, for example, at least one of acceleration, image data captured around the vehicle 10, the speed of the vehicle 10, the angular velocity of the vehicle 10, the steering angle of the vehicle 10, the amount of braking of the vehicle 10, the operation of the wipers of the vehicle 10, and the amount of operation of the suspension of the vehicle 10. Note that the image data around the vehicle 10 changes depending on the movement of the vehicle 10, so it can be said to be information that indicates the behavior of the vehicle 10. The behavior sensor 10B that detects the captured image of the surroundings of the vehicle 10 is, for example, a camera, the behavior sensor 10B that detects the speed of the vehicle 10 is, for example, a speed sensor, the behavior sensor 10B that detects the speed of the vehicle 10 is, for example, a three-axis gyro sensor, the behavior sensor 10B that detects the steering angle of the vehicle 10 is, for example, a steering sensor, the behavior sensor 10B that detects the amount of braking of the vehicle 10 is, for example, a brake sensor, the behavior sensor 10B that detects the operation of the wipers of the vehicle 10 is, for example, a wiper sensor, and the behavior sensor 10B that detects the amount of operation of the suspension of the vehicle 10 is, for example, a suspension sensor.

Each behavior sensor 10B is mounted at a different position on the vehicle 10. As shown in FIG. 3, the behavior sensor 10B is provided on the Z direction side of the suspension SU provided on the tire (wheel) TR of the vehicle 10. That is, the behavior sensor 10B is provided on the opposite side (Z direction side) of the suspension SU of the vehicle 10 from the tire TR. In the example of FIG. 2, the behavior sensor 10B includes a behavior sensor 10B1 provided on the Z direction side of the suspension SU of the tire TR1, which is the left front wheel, a behavior sensor 10B2 provided on the Z direction side of the suspension SU of the tire TR2, which is the right front wheel, a behavior sensor 10B3 provided on the Z direction side of the suspension SU of the tire TR3, which is the left rear wheel, and a behavior sensor 10B4 provided on the Z direction side of the suspension SU of the tire TR4, which is the right rear wheel. However, the position at which the behavior sensor 10B is provided is arbitrary, and is not limited to being provided on the Z direction side of the suspension SU, for example. Furthermore, the number of behavior sensors 10B is not limited to four and may be any number greater than or equal to two. Also, while the number of tires TR is four in the example of FIG. 2, the number may be any number greater than or equal to two.

In this embodiment, the calculation device 14 acquires vehicle behavior information detected by each of these behavior sensors 10B (behavior sensors 10B1 to 10B4 in the example of FIG. 2) and calculates the road surface condition.

The vehicle 10 may be provided with a sensor that detects vehicle behavior information in addition to the behavior sensor 10B described above. For example, a sensor that detects vehicle behavior information may be provided vertically below the suspension SU. In this way, when a sensor that detects vehicle behavior information in addition to the behavior sensor 10B is provided, the calculation device 14 can be said to calculate the road surface condition using the vehicle behavior information detected by the behavior sensor 10B out of the vehicle behavior information detected by these multiple sensors.

The measuring device 10C is a device that controls the position sensor 10A and the behavior sensor 10B to detect the position information and vehicle behavior information of the vehicle 10, and records the detected position information and vehicle behavior information. In other words, the measuring device 10C functions as a data logger that records the position information and vehicle behavior information of the vehicle 10. The measuring device 10C can also be said to be a computer, and includes a control unit 10C1, a memory unit 10C2, and a communication unit 10C3. The control unit 10C1 is a calculation device, i.e., a CPU (Central Processing Unit). The memory unit 10C2 is a memory that stores various information such as the calculation contents and programs of the control unit 10C1, the position information of the vehicle 10, and vehicle behavior information, and includes at least one of a main storage device such as a random access memory (RAM) and a read only memory (ROM), and a non-volatile storage device such as a flash memory or a hard disk drive (HDD). The program for the control unit 10C1 saved in the memory unit 10C2 may be stored in a recording medium that can be read by the measuring device 10C. The communication unit 10C3 is a communication module that communicates with an external device, such as an antenna.

The control unit 10C1 reads out a program stored in the memory unit 10C2 and executes control of the position sensor 10A and the behavior sensor 10B. The control unit 10C1 causes the behavior sensor 10B to detect vehicle behavior information of the vehicle 10 at predetermined time intervals while the vehicle 10 is traveling on a road. The control unit 10C1 also causes the position sensor 10A to detect the position information of the vehicle 10 at the timing when the behavior sensor 10B detects the vehicle behavior information. That is, the control unit 10C1 causes the behavior sensor 10B to detect the vehicle behavior information of the vehicle 10 and the position sensor 10A to detect the position information of the vehicle 10 each time the vehicle 10 travels for a predetermined time. The predetermined time here is preferably a fixed time, such as one minute, but the predetermined time is not limited to a fixed time and may be any length. That is, the predetermined time may change each time, and for example, the current detection may be performed one minute after the previous detection, and the next detection may be performed three minutes after the current detection.

Hereinafter, the position information of the vehicle 10 at the time when the behavior sensor 10B detects the vehicle behavior information will be referred to as vehicle position information, where appropriate. The vehicle position information can also be said to be information (coordinates) of the position where the vehicle behavior information was detected.

The control unit 10C1 acquires the vehicle behavior information and vehicle position information of the vehicle 10 detected at predetermined time intervals, associates the acquired vehicle behavior information and vehicle position information, and stores them in the memory unit 10C2. That is, the vehicle behavior information and vehicle position information detected at the same timing are associated. Therefore, the memory unit 10C2 stores the associated vehicle behavior information and vehicle position information for each detection timing. Note that the vehicle position information and vehicle behavior information associated here are detected at the same timing, but are not limited to being detected at exactly the same timing, and may be detected at different timings. In this case, for example, the vehicle position information and vehicle behavior information whose detection timing difference is equal to or less than a predetermined value are treated as being detected at the same timing and are associated.

The control unit 10C1 transmits the associated vehicle behavior information and vehicle position information to the measurement data acquisition device 12 via the communication unit 10C3. The measurement data acquisition device 12 transmits the vehicle behavior information and vehicle position information received from the vehicle 10 to the calculation device 14. Note that if the measurement data acquisition device 12 is not provided, the control unit 10C1 may transmit the associated vehicle behavior information and vehicle position information directly to the calculation device 14.

(Relationship between vehicle behavior information and road surface conditions)
Here, the road surface condition affects the behavior of the vehicle 10 through the tire TR that contacts the road surface. For example, the tire TR vibrates in response to the unevenness of the road surface (road surface condition), and the vibration is transmitted to the entire vehicle 10, so the acceleration (vehicle behavior information) of the vehicle 10 changes in response to the unevenness of the road surface (road surface condition). Since the vehicle behavior information changes in response to the road surface condition in this way, the road surface condition can be estimated based on the vehicle behavior information. However, when the vehicle is different, the vibration is transmitted in different ways, so that the detected vehicle behavior information may be different even when the vehicle is traveling on a road with the same road surface condition. For example, a lighter vehicle may amplify vibrations and cause a larger change in acceleration. In addition, the vehicle behavior information may also differ depending on the location and type of the sensor that detects the vehicle behavior information.

The relationship between the road surface condition and the vehicle behavior information described above can be expressed as follows. In the vehicle 10, the road surface condition as an input signal is converted into a signal such as vibration and input to the vehicle 10 via the tire TR. Then, the signal (e.g., vibration) is modulated in the vehicle 10 and transmitted to the position where the behavior sensor 10B is installed, and the behavior sensor 10B detects the transmitted signal as an output signal (e.g., acceleration). In this case, the degree of modulation of the signal differs depending on the detection conditions such as the vehicle type, sensor position, and type, so when the detection conditions change, the output signal (vehicle behavior information) detected by the behavior sensor 10B also changes. In other words, since the transfer function when the road surface condition is an input signal and the vehicle behavior information is an output signal differs depending on the detection conditions on the vehicle 10 side, it can be said that the vehicle behavior information changes even if the road surface condition is the same. Note that the transfer function here can be said to be a function that indicates the relationship between the road surface condition, which is an input signal, and the vehicle behavior information, which is an output signal.

In this way, even if the road surface conditions are the same, the transfer function changes depending on the detection conditions on the vehicle 10 side, and as a result, the detected vehicle behavior information differs, so there are cases where the road surface conditions cannot be appropriately estimated based on the vehicle behavior information. Therefore, even if the detection conditions on the vehicle 10 side are different, in other words, it is required to appropriately estimate the road surface conditions regardless of the detection conditions on the vehicle 10 side. In response to this, the calculation device 14 according to this embodiment makes it possible to appropriately detect the road surface conditions regardless of the detection conditions on the vehicle 10 side by estimating a transfer function from multiple pieces of vehicle behavior information. The calculation device 14 will be described in detail below.

(Calculation device)
4 is a schematic block diagram of the arithmetic device. As shown in FIG. 4, the arithmetic device 14 is, for example, a computer, and includes a communication unit 20, a storage unit 22, and a control unit 24. The communication unit 20 is a communication module that communicates with an external device, such as an antenna. The storage unit 22 is a memory that stores various information such as the calculation contents and programs of the control unit 24, and includes at least one of, for example, a RAM, a main storage device such as a ROM, and a non-volatile storage device such as a flash memory or a HDD. The program for the control unit 24 stored in the storage unit 22 may be stored in a recording medium that can be read by the arithmetic device 14.

The control unit 24 is a calculation device, i.e., a CPU. The control unit 24 includes a vehicle behavior information acquisition unit 30 and a road surface condition information acquisition unit 32. The control unit 24 realizes the vehicle behavior information acquisition unit 30 and the road surface condition information acquisition unit 32 by reading and executing a program (software) from the storage unit 22, and executes these processes. The control unit 24 may execute these processes using one CPU, or may be provided with multiple CPUs and execute the processes using the multiple CPUs. Also, at least a portion of the vehicle behavior information acquisition unit 30 and the road surface condition information acquisition unit 32 may be realized by hardware.

(Vehicle behavior information acquisition unit)
The vehicle behavior information acquisition unit 30 acquires vehicle behavior information detected by the multiple behavior sensors 10B. That is, the vehicle behavior information acquisition unit 30 acquires multiple vehicle behavior information detected at different positions in the vehicle 10. In the example of the present embodiment, the vehicle behavior information acquisition unit 30 acquires the vehicle behavior information detected by the behavior sensor 10B1, the vehicle behavior information detected by the behavior sensor 10B2, the vehicle behavior information detected by the behavior sensor 10B3, and the vehicle behavior information detected by the behavior sensor 10B4. More specifically, the vehicle behavior information acquisition unit 30 acquires vehicle position information associated with the vehicle behavior information together with the vehicle behavior information. That is, the vehicle behavior information acquisition unit 32 acquires the vehicle behavior information detected by the multiple behavior sensors 10B and the vehicle position information when the vehicle behavior information is detected. The vehicle behavior information acquisition unit 30 acquires the vehicle behavior information and the vehicle position information sequentially detected by the vehicle 10.

The vehicle behavior information acquisition unit 30 acquires the vehicle behavior information and the vehicle position information from the measurement data acquisition device 12 via the communication unit 20. However, if the measurement data acquisition device 12 is not provided, the vehicle behavior information acquisition unit 30 may acquire the vehicle behavior information and the vehicle position information directly from the measurement device 10C of the vehicle 10.

(Road surface condition information acquisition unit)
The road surface condition information acquisition unit 32 acquires road surface condition information indicating the road surface condition by estimating a transfer function indicating the relationship between the road surface condition as an input signal and the vehicle behavior information as an output signal based on the multiple vehicle behavior information acquired by the vehicle behavior information acquisition unit 30. As described above, the transfer function varies depending on the detection conditions on the vehicle side, and the transfer function for each detection condition is usually unknown, so it is difficult to calculate road surface information using the vehicle behavior information without calculating the transfer function for each detection condition in advance. In contrast, the road surface condition information acquisition unit 32 estimates the transfer function based on the multiple vehicle behavior information, making it possible to calculate the road surface information without calculating the transfer function for each detection condition in advance. Specifically, in this embodiment, the road surface condition information acquisition unit 32 estimates the transfer function based on the multiple vehicle behavior information using the principle of blind signal source separation to calculate the road surface condition. A specific description will be given below.

The road surface condition information acquisition unit 32 assumes that each of the signals (e.g., vibrations) to tires TR1 to TR4 according to the road surface condition affects each of the vehicle behavior information, estimates a transfer function based on the vehicle behavior information, and calculates the road surface condition for each position on the road R where the tire TR is in contact. In other words, the road surface condition information acquisition unit 32 assumes that the signals to each tire TR are transmitted to all of the behavior sensors 10B, estimates a transfer function, and calculates the road surface condition. In this embodiment, the road surface condition information acquisition unit 32 assumes that the signals to the tires TR1, TR2, TR3, and TR4 (vibrations of the tires TR1, TR2, TR3, and TR4) affect the vehicle behavior information detected by the behavior sensor 10B1, the vehicle behavior information detected by the behavior sensor 10B2, the vehicle behavior information detected by the behavior sensor 10B3, and the vehicle behavior information detected by the behavior sensor 10B4, estimates a transfer function, and calculates the road surface condition at the position where the tires TR1, TR2, TR3, and TR4 contact. Note that the tires TR1, TR2, TR3, and TR4 contact the road R at different positions. Therefore, the road surface condition information acquisition unit 32 can be said to estimate a transfer function and calculate the road surface condition, assuming that each of the signals corresponding to the road surface condition input to different positions affects each of the vehicle behavior information.

In addition, the road surface condition information acquisition unit 32 estimates a transfer function for each combination of the signal to the tire TR according to the road surface condition and the vehicle behavior information (for each 1:1 combination of the signal to the tire TR and the vehicle behavior information) to calculate the road surface condition for each position on the road R where the tire TR contacts. In other words, the road surface condition information acquisition unit 32 estimates a transfer function for each combination of the road surface condition at each position on the road R and each vehicle behavior information (for each 1:1 combination of the road surface condition and the vehicle behavior information) to calculate the road surface condition for each position on the road R. That is, the road surface condition information acquisition unit 32 assumes that the degree of modulation when the signal is transmitted to the behavior sensor 10B differs for each combination of the tire TR and the behavior sensor 10B, and estimates a transfer function for each combination of the signal of the tire TR and the vehicle behavior information, in other words, for each combination of the road surface condition at the position on the road R and the vehicle behavior information. In this embodiment, the road surface condition information acquisition unit 32 estimates a total of 16 transfer functions, including the combination of tire TR1 and behavior sensor 10B1, the combination of tire TR1 and behavior sensor 10B2, the combination of tire TR1 and behavior sensor 10B3, the combination of tire TR1 and behavior sensor 10B4, the combination of tire TR2 and behavior sensor 10B1, the combination of tire TR2 and behavior sensor 10B2, the combination of tire TR2 and behavior sensor 10B3, the combination of tire TR2 and behavior sensor 10B4, the combination of tire TR3 and behavior sensor 10B1, the combination of tire TR3 and behavior sensor 10B2, the combination of tire TR3 and behavior sensor 10B3, the combination of tire TR3 and behavior sensor 10B4, the combination of tire TR4 and behavior sensor 10B1, the combination of tire TR4 and behavior sensor 10B2, the combination of tire TR4 and behavior sensor 10B3, and the combination of tire TR4 and behavior sensor 10B4.

More specifically, the road surface condition information acquisition unit 32 calculates the transfer function and the road surface condition by solving the simultaneous equations for each vehicle behavior information, assuming that an equation showing the relationship between the vehicle behavior information, the road surface condition for each position, and the transfer function between the road surface condition and the vehicle behavior information is established for each vehicle behavior information, and that the vehicle behavior information is independent from each other. The vehicle behavior information being independent from each other means that the vehicle behavior information does not affect each other. Figure 5 is a schematic diagram for explaining the calculation of the road surface condition. As shown in FIG. 5, the vehicle behavior information detected by behavior sensor 10B1 is designated as X1, the vehicle behavior information detected by behavior sensor 10B2 is designated as X2, the vehicle behavior information detected by behavior sensor 10B3 is designated as X3, and the vehicle behavior information detected by behavior sensor 10B4 is designated as X4, the road surface condition at a position on road R in contact with tire TR1 is designated as S1, the road surface condition at a position on road R in contact with tire TR2 is designated as S2, the road surface condition at a position on road R in contact with tire TR3 is designated as S3, and the road surface condition at a position on road R in contact with tire TR4 is designated as S4. In addition, a transfer function having the road surface condition S1 as an input signal and the vehicle behavior information X1 as an output signal is denoted as A11, a transfer function having the road surface condition S1 as an input signal and the vehicle behavior information X2 as an output signal is denoted as A12, a transfer function having the road surface condition S1 as an input signal and the vehicle behavior information X3 as an output signal is denoted as A13, a transfer function having the road surface condition S1 as an input signal and the vehicle behavior information X4 as an output signal is denoted as A14, a transfer function having the road surface condition S2 as an input signal and the vehicle behavior information X1 as an output signal is denoted as A21, a transfer function having the road surface condition S2 as an input signal and the vehicle behavior information X2 as an output signal is denoted as A22, a transfer function having the road surface condition S2 as an input signal and the vehicle behavior information X2 as an output signal is denoted as A23, and a transfer function having the road surface condition S2 as an input signal and the vehicle behavior information X3 as an output signal is denoted as A24. A transfer function having the road surface condition S3 as an input signal and the vehicle behavior information X1 as an output signal is denoted as A31, a transfer function having the road surface condition S3 as an input signal and the vehicle behavior information X2 as an output signal is denoted as A32, a transfer function having the road surface condition S3 as an input signal and the vehicle behavior information X3 as an output signal is denoted as A33, a transfer function having the road surface condition S3 as an input signal and the vehicle behavior information X4 as an output signal is denoted as A34, a transfer function having the road surface condition S4 as an input signal and the vehicle behavior information X1 as an output signal is denoted as A41, a transfer function having the road surface condition S4 as an input signal and the vehicle behavior information X2 as an output signal is denoted as A42, a transfer function having the road surface condition S4 as an input signal and the vehicle behavior information X3 as an output signal is denoted as A43, and a transfer function having the road surface condition S4 as an input signal and the vehicle behavior information X4 as an output signal is denoted as A44. In this case, the vehicle behavior information X1 to X4 is known because it is detected by the behavior sensor 10B, and the transfer functions A11 to A44 and the road surface conditions S1 to S4 are unknown, so it can be said that the road surface condition information acquisition unit 32 calculates the transfer functions A11 to A44 and the road surface conditions S1 to S4 based on the vehicle behavior information X1 to X4.

In this case, the road surface condition information acquisition unit 32 calculates the transfer functions A11 to A44 and the road surface conditions S1 to S4 such that all of the following equations (1) to (4) hold. Note that E1, E2, E3, and E4 are coefficients that are set according to the calculation of the transfer functions A11 to A44 and the road surface conditions S1 to S4.

X1=A11・S1+A21・S2+A31・S3+A41・S4+E1...(1)
X2=A12・S1+A22・S2+A32・S3+A42・S4+E2...(2)
X3=A13・S1+A23・S2+A33・S3+A43・S4+E3...(3)
X4=A14・S1+A24・S2+A34・S3+A44・S4+E4...(4)

For example, the road surface condition information acquisition unit 32 calculates the transfer functions A11 to A44 and the road surface conditions S1 to S4 such that the formulas (1) to (4) hold, using a regression calculation in which values are substituted into the transfer functions A11 to A44 and the road surface conditions S1 to S4 while changing the values. Note that the road surface condition information acquisition unit 32 is not limited to determining that the formulas (1) to (4) hold when the left and right sides of the formulas (1) to (4) have exactly the same value, but may determine that the formulas (1) to (4) hold when the difference between the left and right sides of the formulas (1) to (4) falls within a predetermined range, and may calculate the transfer functions A11 to A44 and the road surface conditions S1 to S4 such that the difference between the left and right sides of the formulas (1) to (4) falls within a predetermined range.

A specific example of how the road surface condition information acquisition unit 32 calculates the transfer functions A11 to A44 and the road surface conditions S1 to S4 so that equations (1) to (4) hold is described below.

The road surface condition information acquisition unit 32 performs calculations to calculate the right sides of the formulas (1) to (4) by applying arbitrary values to the transfer functions A11 to A44 and the road surface conditions S1 to S4, and judges whether the difference between the left side (measured value of the vehicle behavior information) and the right side (calculated value of the vehicle behavior information calculated from the transfer function and the road surface condition) is within a predetermined value in all of the formulas (1) to (4). Then, the same calculations are performed while changing the values of the transfer functions A11 to A44 and the road surface conditions S1 to S4, and the transfer functions A11 to A44 and the road surface conditions S1 to S4 when the difference between the left side and the right side is within a predetermined value in all of the formulas (1) to (4) are acquired as the calculation results of the transfer functions A11 to A44 and the road surface conditions S1 to S4. In other words, it can be said that the road surface condition information acquisition unit 32 calculates the transfer functions A11 to A44 and the road surface conditions S1 to S4 using a maximum likelihood estimation method. The coefficients E1 to E4 may be set randomly for each calculation, for example using a probability distribution.

Candidates for road surface conditions S1 to S4 to be used in the calculation may also be extracted as follows. That is, a time waveform, which is the waveform of the measurement values of the vehicle behavior information X1 to X4 that are continuous in time series, and a time waveform of the calculated values of the vehicle behavior information X1 to X4 (i.e., the right-hand sides of equations (1) to (4)) calculated by substituting arbitrary values for the road surface conditions S1 to S4 and the transfer functions A11 to A44, are created, and these time waveforms are compared. Then, if the difference in the shapes of these time waveforms is small, the road surface conditions S1 to S4 used in the time waveforms are set as candidates for the road surface conditions S1 to S4 to be used in the calculation. Any judgment criterion may be used to judge whether the difference in the shapes of the time waveforms is small.

In the above description, the road surface conditions S1 to S4 are unknown, and both the road surface conditions and the transfer functions are calculated. However, the transfer functions A11 to A44 may be calculated in advance using the known road surface conditions S1 to S4. That is, in this case, the vehicle 10 is caused to travel on a road with known road surface conditions to acquire vehicle behavior information X1 to X4. The acquired vehicle information X1 to X4 is then substituted into the left side of the formulas (1) to (4), and the known road surface conditions S1 to S4 are substituted into the right side of the formulas (1) to (4), and the transfer functions A11 to A44 are calculated, for example, using the maximum likelihood estimation method described above. After that, when the vehicle information X1 to X4 is acquired by traveling on a road with unknown road surface conditions, the vehicle information X1 to X4 and the transfer functions A11 to A44 become known, and the road surface conditions S1 to S4 of the road with unknown road surface conditions can be calculated using the formulas (1) to (4). In this way, the calculation load can be reduced by calculating the transfer functions A11 to A44 in advance using the known road surface conditions S1 to S4.

In the above explanation, the case where the number of tires is four has been explained as an example. However, in the general case where the number of tires is n, it can be said that the transfer functions A11 to Ann and the road surface conditions S1 to Sn are calculated so that all of the following equations (A1) to (An) hold true. The calculation method is the same as that explained above. Note that n is an integer of 2 or more, and for example, the transfer function A1n is a transfer function in which the road surface condition S1 is an input signal and the vehicle behavior information Xn is an output signal.

X1=A11・S1+...+An1・Sn+E1...(A1)
...
Xn=A1n・S1+...+Ann・Sn+En...(An)

In the above explanation, an example was given of a case where there are four tires TR and four behavior sensors 10B, but in other words, when there are two or more tires TR and two or more behavior sensors 10B, the road surface condition information acquisition unit 32 calculates the road surface condition as follows. That is, the road surface condition information acquisition unit 32 assumes that the first road surface condition (e.g., road surface condition S1) and the second road surface condition (e.g., road surface condition S2) affect the first vehicle behavior information (e.g., vehicle behavior information X1), and that the first road surface condition and the second road surface condition affect the second vehicle behavior information (e.g., vehicle behavior information X2), and estimates a first transfer function (e.g., transfer function A11) indicating the relationship between the first road surface condition and the first vehicle behavior information, a second transfer function (e.g., transfer function A21) indicating the relationship between the second road surface condition and the first vehicle behavior information, a third transfer function (e.g., transfer function A12) indicating the relationship between the first road surface condition and the second vehicle behavior information, and a fourth transfer function (e.g., transfer function A22) indicating the relationship between the second road surface condition and the second vehicle behavior information, to calculate the first road surface condition and the second road surface condition.

The road surface condition information acquisition unit 32 executes the above-mentioned process for each group of vehicle behavior information detected sequentially by the vehicle 10 to calculate the road surface condition. A group of vehicle behavior information is vehicle behavior information detected at the same timing by multiple behavior sensors 10B, and can be said to be vehicle behavior information associated with the same vehicle position information. That is, in the above example, the vehicle behavior information X1, X2, X3, and X4 are vehicle behavior information detected at the same timing (associated with the same vehicle position information). The road surface condition information acquisition unit 32 can calculate the road surface condition for each position of the road R along the traveling direction of the vehicle 10 by calculating the road surface condition for each group of vehicle behavior information. However, the road surface condition information acquisition unit 32 may calculate the road surface condition using vehicle behavior information detected at different times (using multiple vehicle behavior information associated with different vehicle position information). That is, the vehicle behavior information X1, X2, X3, and X4 may be vehicle behavior information detected at different times (associated with different vehicle position information).

The method of estimating the transfer function and calculating the road surface condition is not limited to the above description, and the road surface condition information acquisition unit 32 may use multiple pieces of vehicle behavior information to estimate the transfer function and calculate the road surface condition in any manner.

(Processing flow)
Next, the flow of the calculation method of the road surface condition described above will be described based on a flowchart. FIG. 6 is a flowchart for explaining the calculation flow of the road surface condition according to this embodiment. As shown in FIG. 6, the calculation device 14 acquires the vehicle behavior information detected by the multiple behavior sensors 10B by the vehicle behavior information acquisition unit 30 (step S10). Then, the calculation device 14 estimates a transfer function indicating the relationship between the vehicle behavior information and the road surface condition based on the multiple vehicle behavior information acquired by the vehicle behavior information acquisition unit 30, and calculates the road surface condition (step S12). The calculation device 14 executes these processes for each group of vehicle behavior information to calculate the road surface condition for each position on the road R along the traveling direction of the vehicle 10.

(effect)
As described above, the arithmetic device 14 according to the present embodiment includes a vehicle behavior information acquisition unit 30 and a road surface condition information acquisition unit 32. The vehicle behavior information acquisition unit 30 acquires vehicle behavior information indicating the behavior of the vehicle 10 detected by a plurality of behavior sensors 10B (sensors) provided at different positions of the vehicle 10 traveling on the road R. The road surface condition information acquisition unit 32 acquires road surface condition information indicating the road surface condition of the road R by estimating a transfer function indicating the relationship between the road surface condition of the road R as an input and the vehicle behavior information as an output based on the plurality of vehicle behavior information. Here, even when traveling on a road with the same road surface condition, if the detection conditions on the vehicle 10 side are different, the transfer function is different, and the vehicle behavior information changes. Therefore, it is difficult to detect the road surface condition based on the vehicle behavior information regardless of the detection conditions on the vehicle 10 side. In contrast, the arithmetic device 14 according to the present embodiment estimates a transfer function based on a plurality of vehicle behavior information, so that even when the detection conditions on the vehicle 10 side are different, the road surface condition can be appropriately detected using the estimated transfer function. In other words, the calculation device 14 according to this embodiment estimates the transfer function based on multiple vehicle behavior information, and therefore, even if the transfer function is not known in advance, it is possible to appropriately detect the road surface condition regardless of the detection conditions on the vehicle 10 side.

The road surface condition information acquisition unit 32 also estimates a transfer function by assuming that the road surface conditions at different positions on the road R affect each vehicle behavior information, thereby acquiring road surface condition information for each position on the road R. By making this assumption, the road surface condition information acquisition unit 32 calculates the transfer function and road surface information under the condition that signals (such as vibrations) based on the road surface conditions at each position are transmitted to all behavior sensors 10B. This enables the calculation device 14 to estimate the transfer function with higher accuracy and detect the road surface conditions with higher accuracy, regardless of the detection conditions on the vehicle 10 side.

The road surface condition information acquisition unit 32 also estimates a transfer function for each combination of the road surface condition at each position on the road R and the vehicle behavior information, and acquires road surface condition information for each position on the road R. By estimating a transfer function for each combination, the road surface condition information acquisition unit 32 is able to individually set the degree of modulation of the signal when the signal based on the road surface condition is transmitted to the behavior sensor 10B. Therefore, the calculation device 14 is able to estimate the transfer function with higher accuracy, and detect the road surface condition with higher accuracy, regardless of the detection conditions on the vehicle 10 side.

In addition, when the vehicle behavior information detected by the different behavior sensors 10B is defined as the first vehicle behavior information and the second vehicle behavior information, and the road surface conditions at different positions are defined as the first road surface condition and the second road surface condition, the road surface condition information acquisition unit 32 determines that the first road surface condition (e.g., road surface condition S1) and the second road surface condition (e.g., road surface condition S2) affect the first vehicle behavior information (e.g., vehicle behavior information X1), and that the first road surface condition and the second road surface condition affect the second vehicle behavior information (e.g., vehicle behavior information X2). By assuming the above, the first transfer function (e.g., transfer function A11) showing the relationship between the first road surface condition and the first vehicle behavior information, the second transfer function (e.g., transfer function A21) showing the relationship between the second road surface condition and the first vehicle behavior information, the third transfer function (e.g., transfer function A12) showing the relationship between the first road surface condition and the second vehicle behavior information, and the fourth transfer function (e.g., transfer function A22) showing the relationship between the second road surface condition and the second vehicle behavior information are estimated, and the first road surface condition and the second road surface condition are obtained as road surface condition information. By calculating the road surface condition in this way, the calculation device 14 can estimate the transfer function with higher accuracy, and detect the road surface condition with high accuracy regardless of the detection conditions on the vehicle 10 side.

The vehicle behavior information acquisition unit 30 also acquires vehicle behavior information detected by a behavior sensor 10B provided on the opposite side (Z direction side) of the suspension SU of the vehicle 10 from the tires TR of the vehicle 10. By using the vehicle behavior information detected by the sensor on the Z direction side of the suspension SU, the calculation device 14 can estimate the transfer function with higher accuracy and detect the road surface condition with higher accuracy, regardless of the detection conditions on the vehicle 10 side.

The vehicle behavior information acquisition unit 30 also acquires at least information on the acceleration of the vehicle 10 as the vehicle behavior information. By using the acceleration as the vehicle behavior information, it becomes possible to estimate the transfer function with higher accuracy and detect the road surface condition with higher accuracy, regardless of the detection conditions on the vehicle 10 side.

The road surface condition is an index that indicates the degree of unevenness of the road surface of road R. By using an index that indicates the degree of unevenness of the road surface as the road surface condition, it is possible to appropriately determine the condition of the road surface.

Although the embodiments and examples of the present invention have been described above, the embodiments are not limited to the contents of these embodiments. The above-mentioned components include those that a person skilled in the art can easily imagine, those that are substantially the same, and those that are within the so-called equivalent range. Furthermore, the above-mentioned components can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the spirit of the above-mentioned embodiments.

1 Detection system 10 Vehicle 10B Behavior sensor (sensor)
12 Measurement data acquisition device 14 Calculation device 30 Vehicle behavior information acquisition unit 32 Road surface condition information acquisition unit R Road TR Tire

Claims (6)

a vehicle behavior information acquisition unit that acquires vehicle behavior information indicating a behavior of the vehicle detected by a plurality of sensors provided at different positions of the vehicle traveling on a road;
a road surface condition information acquisition unit that acquires road surface condition information indicating the road surface condition of the road by estimating a transfer function indicating a relationship between the road surface condition of the road as an input and the vehicle behavior information as an output based on a plurality of the vehicle behavior information;
Including,
The road surface condition is at least one of IRI (International Roughness Index), road surface flatness, cracks, rutting, MCI (Maintenance Control Index), the presence or absence of manholes, and the presence or absence of bridge joints.
Calculation device. a vehicle behavior information acquisition unit that acquires vehicle behavior information indicating a behavior of the vehicle detected by a plurality of sensors provided at different positions of the vehicle traveling on a road;
a road surface condition information acquisition unit that acquires road surface condition information indicating the road surface condition of the road by estimating a transfer function indicating a relationship between the road surface condition of the road as an input and the vehicle behavior information as an output based on a plurality of the vehicle behavior information;
Including,
the road surface condition information acquisition unit estimates the transfer function by assuming that road surface conditions at different positions on the road affect the respective vehicle behavior information, thereby acquiring road surface condition information for each position on the road .
Calculation device. 3. The calculation device according to claim 1, wherein the road surface condition information acquisition unit estimates the transfer function for each combination of the road surface condition at each position on the road and each of the vehicle behavior information, and acquires road surface condition information for each position on the road. When the vehicle behavior information detected by different sensors is X1, X2, X3, and X4, and the road surface conditions at different positions are S1, S2, S3, and S4,
The road surface condition information acquisition unit calculates the road surface condition information by calculating transfer functions A11 to A44 and vehicle behavior information S1 to S4 such that all of the following equations (1) to (4) are satisfied. The calculation device according to claim 3.
X1=A11・S1+A21・S2+A31・S3+A41・S4+E1...(1)
X2=A12・S1+A22・S2+A32・S3+A42・S4+E2...(2)
X3=A13・S1+A23・S2+A33・S3+A43・S4+E3...(3)
X4=A14・S1+A24・S2+A34・S3+A44・S4+E4...(4)
Here, the transfer function with S1 as an input signal and X1 as an output signal is A11, the transfer function with S1 as an input signal and X2 as an output signal is A12, the transfer function with S1 as an input signal and X3 as an output signal is A13, the transfer function with S1 as an input signal and X4 as an output signal is A14, the transfer function with S2 as an input signal and X1 as an output signal is A21, the transfer function with S2 as an input signal and X2 as an output signal is A22, the transfer function with S2 as an input signal and X3 as an output signal is A23, the transfer function with S2 as an input signal and X4 as an output signal is A24, and the transfer function with S3 as an input signal and X1 as an output signal is A25. A31 is a transfer function having a force signal and X1 as an output signal, A32 is a transfer function having S3 as an input signal and X2 as an output signal, A33 is a transfer function having S3 as an input signal and X3 as an output signal, A34 is a transfer function having S3 as an input signal and X4 as an output signal, A41 is a transfer function having S4 as an input signal and X1 as an output signal, A42 is a transfer function having S4 as an input signal and X2 as an output signal, A43 is a transfer function having S4 as an input signal and X3 as an output signal, A44 is a transfer function having S4 as an input signal and X4 as an output signal, and E1 to E4 are coefficients. acquiring vehicle behavior information indicating a behavior of a vehicle traveling on a road, the vehicle behavior information being detected by a plurality of sensors provided at different positions of the vehicle;
A step of estimating a transfer function indicating a relationship between a road surface condition of the road as an input and the vehicle behavior information as an output, based on a plurality of the vehicle behavior information, thereby acquiring road surface condition information indicating a road surface condition of the road;
A method for calculating a number of parameters, comprising :
The road surface condition is at least one of IRI (International Roughness Index), road surface flatness, cracks, rutting, MCI (Maintenance Control Index), the presence or absence of manholes, and the presence or absence of bridge joints.
program. acquiring vehicle behavior information indicating a behavior of a vehicle traveling on a road, the vehicle behavior information being detected by a plurality of sensors provided at different positions of the vehicle;
A step of estimating a transfer function indicating a relationship between a road surface condition of the road as an input and the vehicle behavior information as an output, based on a plurality of the vehicle behavior information, thereby acquiring road surface condition information indicating a road surface condition of the road;
A method for calculating a number of parameters, comprising:
In the step of acquiring road surface condition information, the transfer function is estimated by assuming that road surface conditions at different positions on the road affect each of the vehicle behavior information, thereby acquiring road surface condition information for each position on the road.
Program.

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