JP2020194468A - Road surface condition identification system, road surface condition identification device, and computer program - Google Patents

Abstract

To provide a road surface condition identification system, road surface condition identification device, and computer program, which allow for accurately identifying passage of a vehicle over bumps by utilizing a combination of sensors generally installed in many vehicles.SOLUTION: A road surface condition identification system provided herein is configured to: acquire front-rear acceleration being acceleration in a front-rear direction of a vehicle, and acquire a front-rear wheel speed difference being a difference in rotational speed between front wheels and rear wheels of the vehicle; and identify that the vehicle has passed over a bump when the front-rear wheel speed difference becomes equal to or greater than a second threshold within a given period of time after a rate of change in the front-rear acceleration becomes equal to or greater than a first threshold.SELECTED DRAWING: Figure 9

Description

The present invention relates to a road surface condition identification system, a road surface condition identification device, and a computer program for determining the passage of a step on the road surface of a vehicle.

Conventionally, road information obtained from map data of navigation devices, traffic information acquired from the center, various information related to the driving of the vehicle such as the current position specified by GPS, etc. have been acquired to notify the driver. , Driving assistance, and various techniques for making proper driving by intervening in driving have been proposed. Here, the existence of a step on the road surface is one of the events that the driver must pay attention to when the vehicle travels on the road. Some of the steps on the road surface are caused by deterioration of the road surface, and some are artificial steps such as speed bumps.

Then, when the vehicle passes through the step, for example, the user can be guided to the step in advance, or the suspension can be controlled at the time of passing so that the vehicle can run without causing discomfort to the user. However, in order to perform such guidance and control, it is necessary to accurately grasp the position of the step existing on the road on the device side in advance. Therefore, conventionally, there is known a means of detecting that a vehicle has passed a step from the detection results of various sensors mounted on the vehicle and specifying the position of the step based on the detection result of the step passage. For example, Japanese Patent Application Laid-Open No. 2015-204097 states that the rate of change in wheel rotation speed input from the wheel speed sensor is equal to or greater than the threshold value, or the rate of change in vehicle height input from the vehicle height sensor is greater than or equal to the threshold value. , Detects that a disturbance has occurred on the front and rear wheels, and calculates the distance traveled from the occurrence of the disturbance on the front wheels to the occurrence of the disturbance on the rear wheels from the vehicle speed, and corresponds to the wheelbase of the vehicle. A technique for detecting that a speed bump has been passed has been proposed.

Japanese Unexamined Patent Publication No. 2015-204097 (page 6)

In Patent Document 1, speed bumps are detected by using three sensors, a wheel speed (wheel speed) sensor, a vehicle height sensor, and a vehicle speed sensor. However, the vehicle height sensor is not a general sensor and is usually installed in only a small number of vehicles. On the other hand, the rotation speed of a wheel is an element that easily changes due to various factors other than passing through a step (for example, acceleration / deceleration of a vehicle), and speed is achieved by using only a wheel speed sensor and a vehicle speed sensor without using a vehicle height sensor. There is a problem that the detection accuracy is lowered when the passage of the bump is detected.

The present invention has been made to solve the above-mentioned conventional problems, and it is possible to accurately determine the passage of a step of a vehicle by using a combination of sensors generally mounted on a vehicle. It is an object of the present invention to provide a road surface condition identification system, a road surface condition identification device, and a computer program.

In order to achieve the above object, the road surface condition specifying system according to the present invention has a front-rear acceleration acquisition means for acquiring front-rear acceleration, which is an acceleration generated in the front-rear direction with respect to the vehicle, and a difference in rotational speed between the front and rear wheels of the vehicle. The front-rear wheel speed difference acquisition means for acquiring the front-rear wheel speed difference, and the front-rear wheel speed difference becomes the second threshold value or more within a predetermined period from the time when the change rate of the front-rear acceleration becomes the first threshold value or more. In this case, the vehicle has a step passage specifying means for identifying that the vehicle has passed the step.

Further, the road surface condition specifying device according to the present invention includes a front-rear acceleration acquisition means for acquiring front-rear acceleration, which is an acceleration generated in the front-rear direction with respect to the vehicle, and front-rear wheels, which is the difference between the rotational speeds of the front and rear wheels of the vehicle. When the front-rear wheel speed difference acquisition means for acquiring the speed difference and the front-rear wheel speed difference become the second threshold value or more within a predetermined period from the time when the change rate of the front-rear acceleration becomes the first threshold value or more. It has a step passage specifying means for specifying that the vehicle has passed the step.

Further, the computer program according to the present invention is a program for detecting the state of the road surface on which the vehicle travels. Specifically, the computer acquires the front-rear acceleration acquisition means for acquiring the front-rear acceleration, which is the acceleration generated in the front-rear direction with respect to the vehicle, and the front-rear wheel speed difference, which is the difference between the rotational speeds of the front and rear wheels of the vehicle. When the front-rear wheel speed difference acquisition means and the front-rear wheel speed difference become the second threshold value or more within a predetermined period from the time when the change rate of the front-rear acceleration becomes the first threshold value or more, the vehicle makes a step. It functions as a step passage identification means for identifying that the vehicle has passed.

According to the road surface condition identification system, the road surface condition identification device, and the computer program according to the present invention having the above-described configuration, a sensor that detects acceleration generated in the front-rear direction of the vehicle, which is a sensor generally mounted on many vehicles. By using it in combination with a sensor that detects the wheel speed, it is possible to accurately determine the passage of a step of the vehicle. Then, if the position of the step existing on the road surface can be accurately specified on the device side, for example, the user is guided to the step in advance before the vehicle passes the step, or the suspension is controlled when the step is passed. By doing this, it is possible to drive the vehicle without causing discomfort to the user.

It is a schematic block diagram which showed the road surface condition identification system which concerns on this embodiment. It is a block diagram which showed the structure of the road surface condition identification system which concerns on this embodiment. It is a figure which showed an example of the probe information stored in the probe information DB. It is a figure which showed an example of the step information stored in the probe statistical information DB. It is a block diagram which shows typically the control system of the navigation device which concerns on this embodiment. It is a flowchart of the step passage detection processing program which concerns on this embodiment. It is a figure which showed the acceleration in the front-rear direction which occurs at the time when a vehicle starts passing a step. It is a figure which showed an example of the step on the road surface of a road. It is a figure which showed the change of the acceleration in the front-rear direction which occurs in the vehicle when the vehicle passes a step. It is a figure which showed the change of the rotational speed (wheel speed) of a front wheel and a rear wheel when the front wheel of a vehicle passes a step. It is a figure which showed the difference (front wheel-rear wheel) of the rotation speed of the front wheel and the rear wheel when the front wheel of a vehicle passes a step.

Hereinafter, the road surface condition specifying system according to the present invention will be described in detail with reference to the drawings based on a specific embodiment. First, the schematic configuration of the road surface condition specifying system 1 according to the present embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic configuration diagram showing a road surface condition specifying system 1 according to the present embodiment. FIG. 2 is a block diagram showing the configuration of the road surface condition specifying system 1 according to the present embodiment.

As shown in FIG. 1, the road surface condition identification system 1 according to the present embodiment includes a server device 3 included in the probe center 2 and a navigation device (road surface condition identification device) which is a communication (guidance) terminal mounted on the vehicle 4. It basically has 5. Further, the server device 3 and the navigation device 5 are configured to be able to send and receive electronic data to and from each other via the communication network 6. Instead of the navigation device 5, for example, another vehicle-mounted device included in the vehicle 4 or a vehicle control ECU that controls the vehicle 4 may be used.

Here, the road surface condition specifying system 1 according to the present embodiment constitutes a so-called probe car system. Here, the probe car system is a system that collects information using the vehicle 4 as a sensor. Specifically, the vehicle 4 transmits the operation status of each system such as the steering operation and the shift position together with the GPS position information to the probe center 2 via the communication device mounted on the vehicle 4 in advance, including the speed data. A system that reuses the collected data as various information on the center side.

Then, the server device 3 provided in the probe center 2 appropriately collects and accumulates probe information (material information) including the current time and traveling information from each vehicle 4 traveling nationwide, and also collects and accumulates probe information (material information) from the accumulated probe information on the road. Various support information (for example, traffic jam information, position information of steps such as speed bumps, accident information, travel time, etc.) is generated, and the generated support information is distributed to the navigation device 5 or the support information is used. An information management server that performs various processes. In particular, in the present embodiment, the server device 3 collects from each vehicle 4 the position information of the point where the vehicle 4 is detected to have passed the step and the information for specifying the passing direction (the traveling direction of the vehicle when passing the step). By statistically collecting the collected information, step information that specifies the position of the step existing on the road surface of the road in the whole country is created and distributed to the vehicle 4. The "steps existing on the road surface" basically correspond to speed bumps, but also include steps caused by factors such as deterioration of the road surface in addition to speed bumps.

On the other hand, the navigation device 5 is mounted on the vehicle 4 and displays a map around the position of the own vehicle based on the stored map data, displays the current position of the vehicle on the map image, and sets a guide route. It is an in-vehicle device that provides movement guidance along the route. Further, the navigation device 5 also uses the detection results of various sensors installed on the vehicle 4 as described later to detect the passage of the step when the vehicle 4 passes the step on the road surface. Further, the traffic information received from the server device 3 and the information about the step are also guided to the user. The details of the navigation device 5 will be described later.

In addition, the communication network 6 includes a large number of base stations located all over the country and a communication company that manages and controls each base station, and the base stations and communication companies are connected to each other by wire (optical fiber, ISDN, etc.) or wirelessly. It is configured by connecting. Here, the base station has a transceiver (transmitter / receiver) and an antenna for communicating with the navigation device 5. Then, while the base station performs wireless communication between the communication companies, it becomes the terminal of the communication network 6 and relays the communication of the navigation device 5 within the range (cell) of the radio wave of the base station with the server device 3. Has a role to play.

Subsequently, the configuration of the server device 3 constituting the road surface condition specifying system 1 will be described in more detail with reference to FIG.

As shown in FIG. 2, the server device 3 basically includes a server control ECU 11, a probe information DB 12 as information recording means connected to the server control ECU 11, a probe statistical information DB 13, and a center communication device 14. ..

The server control ECU 11 (electronic control unit) is an electronic control unit that controls the entire server device 3, and is used as a computing device, a CPU 21 as a control device, and a working memory when the CPU 21 performs various arithmetic processes. It is provided with an internal storage device such as a RAM 22, a ROM 23 in which a control program or the like is recorded, and a flash memory 24 for storing a program read from the ROM 23.

Further, the probe information DB 12 is a storage means for cumulatively storing probe information collected from each vehicle 4 traveling nationwide. In the present embodiment, the probe information collected from the vehicle 4 includes (a) the date and time, (b) the link where the vehicle detects the passage of the step, and (c) the point where the vehicle detects the passage of the step. The position coordinates and (d) the traveling direction (forward or reverse direction) of the vehicle when the step passage is detected are included. However, the probe information does not necessarily include all the information related to the above (a) to (d), and the information other than the information (a) to (d) (for example, the vehicle speed when passing the step, the type of the step passed (for example) The configuration may include speed bumps, etc.) and the shape of the step that has passed through.

FIG. 3 is a diagram showing an example of probe information stored in the probe information DB 12. As shown in FIG. 3, the probe information includes a vehicle ID that identifies the source vehicle, information related to the above (a) to (d), and the like. For example, the probe information shown in FIG. 3 remembers that the vehicle with ID "A" detected the passage of the step at the point (x1, y1) in the forward direction of the link with ID "100001". Similarly, other probe information is also stored.

On the other hand, the probe statistical information DB 13 is a storage means for cumulatively storing the probe statistical information generated by statisticizing the probe information stored in the probe information DB 12. In particular, in the present embodiment, by performing statistics on probe information, information that identifies steps existing on the road surface of roads nationwide is generated. For example, it may be recognized that a step exists at a point where the passage of the step is detected at least once in the collected probe information, or when the passage of the step is detected at the same point more than once, the step is detected at the point. May be accredited to exist. Further, if the type and shape of the step (speed bump, etc.) and the shape can be specified, it is desirable to include the type and shape of the step in the probe statistical information DB 13.

FIG. 4 is a diagram showing an example of probe statistical information stored in the probe statistical information DB 13. As shown in FIG. 4, the probe statistical information is information indicating a step existing on the road surface of the road. Specifically, it includes a link and a traveling direction in which a step is recognized to exist on the road surface, and a position coordinate of the step.

For example, the probe statistical information shown in FIG. 4 stores that a step exists at a point (X1, Y1) in the forward direction of the link with ID “100001”. Then, the probe statistical information is generated for each link included in the roads nationwide.

Further, the server device 3 distributes the probe statistical information stored in the probe statistical information DB 13 to the navigation device 5 in response to a request from the navigation device 5. On the other hand, the navigation device 5 to which the probe statistical information is distributed executes various guidance and vehicle control using the distributed probe statistical information. For example, it is possible to guide the user to the step before the vehicle passes the step, or to control the suspension when the vehicle passes the step so that the vehicle can run without causing discomfort to the user.

Further, the center communication device 14 is a communication device for communicating with an external traffic information center such as a vehicle 4 or a VICS (registered trademark: Vehicle Information and Communication System) center via a network 15. In the present embodiment, probe information and distribution information are transmitted and received to and from each vehicle 4 via the center communication device 14.

Next, a schematic configuration of the navigation device 5 mounted on the vehicle 4 will be described with reference to FIG. FIG. 5 is a block diagram showing a navigation device 5 according to the present embodiment.

As shown in FIG. 5, the navigation device 5 according to the present embodiment includes a current position detection unit 31 that detects the current position of the vehicle 4 on which the navigation device 5 is mounted, and a data recording unit 32 that records various data. , A navigation ECU 33 that performs various arithmetic processes based on the input information, an operation unit 34 that receives operations from the user, a liquid crystal display 35 that displays a map around the vehicle, traffic information, etc. to the user. It has a speaker 36 that outputs voice guidance regarding route guidance, a DVD drive 37 that reads a DVD as a storage medium, and a communication module 38 that communicates between an information center such as a probe center 2 or a VICS center. The navigation device 5 is also connected to various sensors mounted on the vehicle 4 via an in-vehicle network such as CAN. The sensors mounted on the vehicle 4 include a vehicle speed sensor 39, a wheel speed sensor 40, and a front-rear acceleration sensor 41.

Hereinafter, each component of the navigation device 5 will be described in order.
The current position detection unit 31 includes a GPS 42, a gyro sensor 43, and the like, and can detect the current position, direction, and the like of the vehicle. In addition, by acquiring the detection results of the vehicle speed sensor 39, the wheel speed sensor 40, the front-rear acceleration sensor 41, and other various sensors installed in the vehicle, it is possible to detect the current vehicle position, orientation, etc. with higher accuracy. It is possible.

Further, the data recording unit 32 reads a hard disk (not shown) as an external storage device and a recording medium, a map information DB 45, a distribution information DB 46, a predetermined program, etc. recorded on the hard disk, and outputs predetermined data to the hard disk. It is equipped with a recording head (not shown) that is a driver for writing. The data recording unit 32 may be configured by a flash memory, a memory card, or an optical disk such as a CD or DVD instead of the hard disk. Further, the map information DB 45 and the distribution information DB 46 may be stored in an external server and acquired by the navigation device 5 by communication.

Here, the map information DB 45 is, for example, link data related to a road (link), node data related to a node point, search data used for processing related to route search or change, facility data related to a facility, and a map for displaying a map. It is a storage means that stores display data, intersection data for each intersection, search data for searching a point, and the like.

Further, the distribution information DB 46 is a storage means for storing distribution information (probe statistical information) distributed from the server device 3.

On the other hand, the navigation ECU (electronic control unit) 33 is an electronic control unit that controls the entire navigation device 5, and is a computing device, a CPU 51 as a control device, and a working memory when the CPU 51 performs various arithmetic processes. From the ROM 53 and ROM 53 in which the RAM 52 for storing the route data and the like when the route is searched, the control program, and the step passage detection processing program (see FIG. 6) described later are recorded. It is provided with an internal storage device such as a flash memory 54 for storing the read program. The navigation ECU 33 has various means as a processing algorithm together with the server control ECU 11. For example, the front-rear acceleration acquisition means acquires the front-rear acceleration, which is the acceleration generated in the front-rear direction with respect to the vehicle. The front / rear wheel speed difference acquisition means acquires the front / rear wheel speed difference, which is the difference in rotational speed between the front wheels and the rear wheels of the vehicle. The step passage identifying means identifies that the vehicle has passed the step when the front / rear wheel speed difference becomes the second threshold value or more within a predetermined period from the time when the rate of change of the front-rear acceleration becomes the first threshold value or more. ..

The operation unit 34 is operated when inputting a starting point as a traveling start point and a destination as a traveling end point, and is composed of a plurality of operation switches (not shown) such as various keys and buttons. Then, the navigation ECU 33 controls to execute the corresponding various operations based on the switch signals output by pressing each switch or the like. The operation unit 34 can also be configured by a touch panel provided on the front surface of the liquid crystal display 35. It can also be configured by a microphone and a voice recognition device.

In addition, the liquid crystal display 35 has a map image including roads, traffic information, operation guidance, operation menus, key guidance, guidance information along the guidance route (scheduled travel route), news, weather forecast, time, mail, and television. Programs etc. are displayed. In particular, in the present embodiment, the information regarding the step existing on the road surface of the road distributed from the server device 3 is also displayed. A HUD or HMD may be used instead of the liquid crystal display 35.

Further, the speaker 36 outputs voice guidance for guiding the traveling along the guiding route (scheduled traveling route) and traffic information guidance based on the instruction from the navigation ECU 33. In particular, in the present embodiment, the information regarding the step existing on the road surface of the road delivered from the server device 3 is also output.

The DVD drive 37 is a drive capable of reading data recorded on a recording medium such as a DVD or a CD. Then, based on the read data, music and video are reproduced, the map information DB 45 is updated, and the like. A card slot for reading and writing a memory card may be provided instead of the DVD drive 37.

Further, the communication module 38 is a communication device for receiving traffic information or the like transmitted from a probe center 2, a VICS center, another external center, or the like, and corresponds to, for example, a mobile phone or a DCM. It also includes a vehicle-to-vehicle communication device that communicates between vehicles and a road-to-vehicle communication device that communicates with a roadside unit. It is also used to send and receive probe information and distribution information to and from the server device 3.

Further, the vehicle speed sensor 39 is a sensor for detecting the moving distance and the vehicle speed of the vehicle, generates a pulse according to the rotation of the driving wheel of the vehicle, and outputs the pulse signal to the navigation ECU 33. Then, the navigation ECU 33 calculates the vehicle speed and the moving distance of the vehicle by counting the generated pulses.

Further, the wheel speed sensor 40 is a sensor used for ABS, TRC control, etc. of the vehicle, and is installed on each of the four wheels in the front, rear, left, and right sides of the vehicle, and is a sensor for detecting the rotation speed of each wheel. Is.

Further, the front-rear acceleration sensor 41 is a sensor for detecting acceleration generated in the front-rear direction of the vehicle (direction parallel to the traveling direction of the vehicle), and for example, a capacitance type sensor is used. Further, the acceleration generated in the left-right direction (the direction intersecting the traveling direction of the vehicle) in addition to the front-rear direction of the vehicle may be included in the detection target. The acceleration generated in the front-rear direction of the vehicle is detected by the front-rear acceleration sensor 41 at predetermined time intervals (for example, 100 msec), and is cumulatively stored in the flash memory 54 or the like.

Subsequently, a step passage detection processing program executed by the navigation device 5 included in the road surface condition specifying system 1 having the above configuration will be described with reference to FIG. FIG. 6 is a flowchart of the step passage detection processing program according to the present embodiment. Here, the step passage detection processing program is executed at predetermined time intervals (for example, 100 msec) after the ACC power supply (accessory power supply) of the vehicle is turned on, and the detection results of various sensors installed in the vehicle 4 are used. This is a program that detects the passage of a step when the vehicle 4 passes the step on the road surface. The program shown in the flowchart in FIG. 6 below is stored in a RAM 52, a ROM 53, or the like included in the navigation device 5, and is executed by the CPU 51.

In step 1 (hereinafter abbreviated as S) 1, the CPU 51 acquires the history of the detection result of the front-rear acceleration sensor 41, and obtains the absolute value of the rate of change of the acceleration (hereinafter, referred to as front-rear G) generated in the front-rear direction with respect to the vehicle. , It is determined whether or not the state below the threshold value continues for a predetermined time (for example, 5 sec) or more. The threshold value serving as the determination criterion of S1 is an upper limit of the absolute value of the rate of change of the front-rear G indicating that the vehicle is in a state where there is no possibility of passing through the step, and is set to, for example, 0.1 G / s.

Then, when it is determined that the state of the absolute value of the rate of change of the front-rear G below the threshold value continues for a predetermined time or more, that is, there is no possibility that the vehicle has passed the step within the latest predetermined time (S1). : YES), the process proceeds to S2. On the other hand, when it is determined that the absolute value of the rate of change of the front-rear G is equal to or higher than the threshold value within a predetermined time, that is, the vehicle may have passed the step within the latest predetermined time (S1: NO) shifts to S3.

In S2, the CPU 51 initializes various parameters used for detecting the passage of a step in the vehicle. Specifically, "0" is substituted for "t_ΔG" and "count", and "OFF" is set for the "step passage determination flag". Each parameter is stored in the flash memory 54 or the like.

Subsequently, in S3, the CPU 51 determines whether or not all of the following conditions (1) to (3) are satisfied. In the following description, the front and rear G are defined as the positive direction from the rear to the front of the vehicle (that is, when the vehicle is moving forward, acceleration is positive and deceleration is negative).
(1) The rate of change of front and rear G at the present time is greater than or equal to the threshold in the negative direction. (2) The difference in rotational speed between the left and right wheels (both left and right of the front wheels and left and right of the rear wheels) is less than the threshold. (3) count = 0

The condition (1) above is a condition indicating that the wheel has collided with a step, and the threshold value is, for example, 0.1 G / s. Here, as shown in FIG. 7, when the wheels of the vehicle 4 pass through the step 60 on the road surface, the wheels first collide with the step. Then, as a result of the wheels colliding with the step, the front-rear G changes from 0 or a value close to 0 to a large negative value. That is, the rate of change of the front-rear G becomes equal to or higher than the threshold value in the negative direction. Note that FIG. 7 shows an example in which the front wheels collide with the step 60, but the same applies to the case where the rear wheels collide with the step 60.

Further, the condition of (2) above is that, as shown in FIG. 8, the step 60 through which the vehicle 4 passes is a step in the road width direction, and the vehicle 4 enters in the direction perpendicular to the direction of the step. The condition is set to 20 rpm, for example. The threshold value may be changed according to the current vehicle speed of the vehicle. In the present embodiment, the passage of a step in the road width direction such as a speed bump is targeted for detection, but the passage of other steps may also be a detection target. In that case, the condition (2) may be deleted.

Then, when it is determined that all the conditions (1) to (3) above are satisfied (S3: YES), it is presumed that the vehicle may have started passing the step, and the process proceeds to S4. .. On the other hand, when it is determined that all or any of the above conditions (1) to (3) is not satisfied (S3: NO), the process proceeds to S5.

In S4, the CPU 51 reads the parameter “t_ΔG” from the flash memory 54 and substitutes the value of the rate of change of the front and rear G at the present time. The front-rear G generated in the vehicle is detected by the front-rear acceleration sensor 41 at a predetermined time interval (for example, 100 msec) at any time, and is cumulatively stored in the flash memory 54 or the like. Further, the CPU 51 adds "1" to the parameter "count".

Next, in S5, the CPU 51 reads the parameter “count” from the flash memory 54, and determines whether or not the numerical value range is within the range of “0 <count ≦ upper limit value”. The upper limit value is set to a different value depending on the execution interval of the step passage detection processing program (FIG. 6). For example, if the step passage detection processing program is executed at intervals of 100 msec, the upper limit value is set to "10". That is, the S5 is a process for determining whether or not 1 sec or more has elapsed after it is estimated that the vehicle may have started passing the step in the S3. However, the upper limit value does not necessarily have to be "10", and may be, for example, "20" or "30".

Then, it was determined that "0 <count ≤ upper limit value" is satisfied, that is, after it is estimated that the vehicle may have started passing the step in S3, and 1 sec or more has not passed since then. In the case (S5: YES), the process proceeds to S7.

On the other hand, if "0 <count ≤ upper limit value" is not satisfied, that is, it is not estimated that the vehicle may have started passing the step in S3, or the vehicle may have started passing the step. Even if it is estimated that the vehicle has passed 1 sec or more without being confirmed after that (S5: NO), it is finally determined that the vehicle has not passed the step. After that, in S6, the CPU 51 initializes the parameter “count” and ends the step passage detection processing program. If it is presumed that the vehicle may have started passing the step in S3, but the passage is not confirmed after that and 1 sec or more elapses, for example, the vehicle suddenly decelerates. The case where the condition of S3 is satisfied is applicable.

Further, in S7, the CPU 51 determines whether or not all of the following conditions (4) and (5) are satisfied.
(4) t_ΔG × (current rate of change of G before and after) <0
(5) The rate of change of G before and after at the present time is above the threshold in the positive direction.

The condition (4) above is one of the conditions indicating that the wheel has overcome the step. Here, FIG. 9 is a diagram showing changes in the front-rear G when the vehicle 4 passes the step. As shown in FIG. 9, when the wheels of the vehicle 4 pass through the step 60 on the road surface, the front and rear G change significantly negatively due to the wheels colliding with the step at first, but then the wheels make a step. As it gets over, the front and rear G gradually approaches 0. Then, the front and rear G when the wheel completely rides on the step (when the wheel is located near the top of the step) returns to 0 or a value close to 0. That is, when the vehicle gets over the step, the rate of change of the front-rear G changes from negative to positive, and the above condition (4) is satisfied. Note that FIG. 9 shows an example in which the front wheels get over the step 60, but the same applies to the case where the rear wheels get over the step 60.

Further, the condition (5) is one of the conditions indicating that the wheel has overcome the step together with the above (4). The threshold value is, for example, 0.1 G / s. As described above, when the wheel gets over the step, the front and rear G once change to a large negative value, and then approach 0. The rate of change of the front-rear G when the front-rear G approaches 0 becomes equal to or higher than the threshold value in the positive direction.

Then, when it is determined that all the conditions (4) and (5) above are satisfied (S7: YES), it is presumed that the vehicle may have started passing the step and may have overcome the step. , S8. On the other hand, when it is determined that all or any of the above conditions (4) and (5) is not satisfied (S7: NO), the process proceeds to S10.

Subsequently, in S8, the CPU 51 determines whether or not all of the following conditions (6) and (7) are satisfied.
(6) The difference in the rotational speeds of the front and rear wheels is greater than or equal to the threshold value. (7) The difference in the rotational speeds of the left and right wheels (both the left and right front wheels and the left and right rear wheels) is less than the threshold value.

The condition (6) above is one of the conditions indicating that the wheel has overcome the step. The threshold value is, for example, 50 rpm. Here, FIG. 10 is a diagram showing changes in the rotational speeds (wheel speeds) of the front wheels and the rear wheels when the front wheels of the vehicle 4 pass through the step, and FIG. 11 is a diagram showing changes in the rotational speeds (wheel speeds) of the front wheels of the vehicle 4 when the front wheels of the vehicle 4 pass through the steps. It is the figure which showed the difference (front wheel-rear wheel) of the rotation speed of the front wheel and the rear wheel of. As shown in FIG. 10, since the rear wheels of the vehicle 4 are not affected by the step, the rotation speed is basically maintained constant. On the other hand, when the front wheels of the vehicle 4 get over the step, the rotation speed temporarily increases. Then, when the front wheels completely ride on the step (the front wheels are located near the top of the step), the rotation speed gradually decreases, and when the front wheels completely overcome the step, the rotation speed returns to the initial speed. That is, when the vehicle gets over the step, as shown in FIG. 11, the difference in the rotational speeds of the front and rear wheels increases from 0 or a value close to 0 to a threshold value or more, and the above condition (6) is satisfied. Note that FIG. 10 shows an example in which the front wheels get over the step 60, but when the rear wheels get over the step 60, the rotation speed of the front wheels and the rotation speed of the rear wheels are opposite.

Further, the condition of (7) above is the same as that of (2), the step 60 through which the vehicle 4 passes is a step in the road width direction, and the vehicle 4 is perpendicular to the direction of the step. The condition for indicating entry is set to, for example, 20 rpm. The threshold value may be changed according to the current vehicle speed of the vehicle. In the present embodiment, the passage of a step in the road width direction such as a speed bump is targeted for detection, but the passage of other steps may also be a detection target. In that case, the condition (7) may be deleted.

Then, when it is determined that all the conditions (6) and (7) above are satisfied (S8: YES), the CPU 51 finally determines that the vehicle has passed the step. Then, in S9, the CPU 51 "ONs" the parameter "step passage determination flag" and shifts to S10. When the "step passage determination flag" is turned on, the CPU 51 determines the link at which the vehicle detects the passage of the step, the position coordinates of the point where the vehicle detects the passage of the step, and the traveling direction of the vehicle when the vehicle detects the passage of the step. (Forward or reverse direction) is acquired respectively. After that, each acquired information (step passage history information) is transmitted to the server device 3 as probe information.

On the other hand, the server device 3 to which the probe information is transmitted periodically performs statistics on the probe information to generate probe statistical information (FIG. 4) that identifies steps existing on the road surface of roads nationwide. For example, it may be recognized that a step exists at a point where the passage of the step is detected at least once in the collected probe information, or when the passage of the step is detected at the same point more than once, the step is detected at the point. May be accredited to exist.

Further, the server device 3 distributes the generated probe statistical information to the navigation device 5 in response to a request from the navigation device 5. On the other hand, the navigation device 5 to which the probe statistical information is distributed executes various guidance and vehicle control using the distributed probe statistical information. For example, it is possible to guide the user to the step before the vehicle passes the step, or to control the suspension when the vehicle passes the step so that the vehicle can run without causing discomfort to the user.

As guidance for the step, for example, when the step is located in front of the vehicle in the traveling direction, the speaker 36 outputs a voice saying "There is a step in the future". It is also possible to display an icon at a position where a step exists on the map image displayed on the liquid crystal display 35.

On the other hand, in S10, the CPU 51 reads the parameter "count" from the flash memory 54 and adds "1". After that, the step passage detection processing program is temporarily terminated, and after a predetermined execution cycle has elapsed, the processing after S1 is started again.

The above-mentioned step passage detection processing program (FIG. 6) may be implemented only when the front wheels of the vehicle pass through the steps, or may be implemented only when the rear wheels of the vehicle pass through the steps. You may. Further, it may be carried out for both the case where the front wheel of the vehicle passes the step and the case where the rear wheel of the vehicle passes the step. When the implementation is carried out for both the case where the front wheel of the vehicle passes the step and the case where the rear wheel of the vehicle passes the step, the case where the front wheel of the vehicle passes the step and the case where the rear wheel of the vehicle passes the step In both cases, it may be determined that the vehicle has passed the step when the "step passage determination flag" is "ON", or at least on the other hand, the vehicle is "ON" when the "step passage determination flag" is "ON". May be determined to have passed the step.

As described in detail above, in the computer program executed by the road surface condition specifying system 1, the navigation device 5, and the navigation device 5 according to the present embodiment, the front-rear acceleration, which is the acceleration generated in the front-rear direction with respect to the vehicle, is acquired. At the same time, the front-rear wheel speed difference, which is the difference between the rotation speeds of the front and rear wheels of the vehicle, is acquired, and the front-rear wheel speed difference becomes the second within a predetermined period from the time when the rate of change of the front-rear acceleration becomes equal to or higher than the first threshold value. When the value exceeds the threshold value, it is specified that the vehicle has passed the step (S9). Therefore, a sensor that detects acceleration generated in the front-rear direction of the vehicle, which is a sensor that is generally mounted on the vehicle, and a wheel speed. By using it in combination with a sensor that detects the above, it is possible to accurately determine the passage of a step of the vehicle. Then, if the position of the step existing on the road surface can be accurately specified on the device side, for example, the user is guided to the step in advance before the vehicle passes the step, or the suspension is controlled when the step is passed. By doing this, it is possible to drive the vehicle without causing discomfort to the user.

It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that various improvements and modifications can be made without departing from the gist of the present invention.
For example, in the present embodiment, the server device 3 collects the step passage detection results from a plurality of vehicles 4, and uses the collected information to identify the position of the step on the road surface, but the navigation device 5 May be configured to specify the position of the step on the road surface based only on the passing detection result of the step of the own vehicle. In that case, the configuration for acquiring the passage detection result of the step of the server device 3 or another vehicle becomes unnecessary.

Further, in the present embodiment, when all the conditions (1) to (7) above are satisfied, it is determined that the vehicle finally passes the step, but the above (1) to (7) Even when only some conditions are satisfied, it may be determined that the vehicle has passed the step. For example, it may be determined that the vehicle has passed the step if only (1) and (6) are satisfied. Alternatively, it may be determined that the vehicle has passed the step if only (1), (4), and (6) are satisfied.

Further, in the present embodiment, the passage of a step in the road width direction such as a speed bump is targeted for detection, but the passage of other steps may also be detected. Further, for example, the type and shape of the step passed by the vehicle may be specified from the numerical values of the front-rear G and the rotation speed of the wheels when passing the step, or the image of the camera. In that case, for example, it is possible to detect only a specific type of step (for example, speed bump) as a passage detection target.

Further, in the present embodiment, the execution subject of the step passage detection processing program shown in FIG. 6 is the navigation device 5, but the server device 3 may be configured to execute a part or the whole. For example, the server device 3 may collect the detection results of the wheel speed sensor 40 and the front-rear acceleration sensor 41 from the vehicle 4 and perform the processing after S1 for each vehicle.

Further, although the embodiment in which the road surface condition identification system, the road surface condition identification device and the computer program according to the present invention are embodied has been described above, the road surface condition identification system can also have the following configurations, in which case. Has the following effects.

For example, the first configuration is as follows.
Front-rear acceleration acquisition means (51) that acquires front-rear acceleration, which is the acceleration generated in the front-rear direction with respect to the vehicle (4), and front-rear wheel speed difference, which is the difference between the rotational speeds of the front and rear wheels of the vehicle. When the wheel speed difference acquisition means (51) and the front-rear wheel speed difference become the second threshold value or more within a predetermined period from the time when the change rate of the front-rear acceleration becomes the first threshold value or more, the vehicle steps. It has a step passage specifying means (51) for specifying that the vehicle has passed.
According to the road surface condition identification system having the above configuration, a sensor that detects acceleration generated in the front-rear direction of the vehicle, which is a sensor that is generally mounted on many vehicles, and a sensor that detects wheel speed are used in combination. This makes it possible to accurately determine the passage of a vehicle step. Then, if the position of the step existing on the road surface can be accurately specified on the device side, for example, the user is guided to the step in advance before the vehicle passes the step, or the suspension is controlled when the step is passed. By doing this, it is possible to drive the vehicle without causing discomfort to the user.

The second configuration is as follows.
When the direction from the rear to the front of the vehicle (4) is the positive direction of the front-rear acceleration, the step passage identifying means (51) is predetermined from the time when the rate of change of the front-rear acceleration becomes equal to or higher than the first threshold value in the negative direction. When the rate of change of the front-rear acceleration changes from the negative direction to the positive direction within the period and the front-rear wheel speed difference becomes equal to or more than the second threshold value, it is specified that the vehicle has passed the step.
According to the road surface condition specifying system having the above configuration, it is possible to more accurately determine the passage of a step of the vehicle by considering the change mode of the rate of change of the acceleration occurring in the front-rear direction of the vehicle.

The third configuration is as follows.
The left and right wheel speed difference acquisition means (51) for acquiring the left and right wheel speed difference, which is the difference in rotational speed between the right wheel and the left wheel of the vehicle (4), is provided, and the step passage specifying means (51) is the left and right wheel. When the speed difference is less than the third threshold and the front-rear wheel speed difference becomes the second threshold or more within a predetermined period from the time when the rate of change of the front-rear acceleration becomes the first threshold or more, the vehicle Identify that you have passed a step.
According to the road surface condition identification system having the above configuration, the passage of the step is determined on the condition that the step existing in the width direction of the road is targeted and the vehicle enters in the direction perpendicular to the direction of the step. Therefore, it is possible to more accurately determine the passage of a vehicle step.

The fourth configuration is as follows.
With the step passage history collecting means (21), which collects information on the step passage history of each vehicle specified by the step passage identification means (51) for a plurality of vehicles (4) traveling on the road as the step passage history information. It also has a step position specifying means (21) for identifying a position where there is a step on the road surface by statisticizing the step passing history information of each vehicle collected by the step passing history collecting means.
According to the road surface condition identification system having the above configuration, it is possible to identify the position of a step on a road nationwide based on the information on the passage history of the step collected from a plurality of vehicles traveling on the road. ..

The fifth configuration is as follows.
The step position specifying means (21) identifies a position where a speed bump is particularly present as a step.
According to the road surface condition identification system having the above configuration, it is possible to specify the position of the speed bump on the roads nationwide for the speed bump which is a step intentionally provided by the road administrator.

The sixth configuration is as follows.
The step position specifying means (21) also specifies the traveling direction of a road having a step based on the traveling direction of the vehicle (4) identified as having passed the step.
According to the road surface condition specifying system having the above configuration, it is possible to specify the traveling direction with a step for the road passing in the round-trip direction.

1 Road surface condition identification system 2 Probe center 3 Server device 4 Vehicle 5 Navigation device 33 Navigation ECU
39 Vehicle speed sensor 40 Wheel speed sensor 41 Front-rear acceleration sensor 51 CPU
52 RAM
53 ROM
54 Flash memory 60 Steps

Claims (8)

A front-rear acceleration acquisition means for acquiring front-rear acceleration, which is an acceleration generated in the front-rear direction with respect to the vehicle,
Front and rear wheel speed difference acquisition means for acquiring the front and rear wheel speed difference, which is the difference in rotational speed between the front and rear wheels of the vehicle,
Step passage identifying means for specifying that the vehicle has passed the step when the front / rear wheel speed difference becomes the second threshold value or more within a predetermined period from the time when the rate of change of the front-rear acceleration becomes the first threshold value or more. And, a road surface condition identification system having. When the direction from the rear to the front of the vehicle is the positive direction of the front-rear acceleration,
In the step passage specifying means, the rate of change of the front-rear acceleration changes from the negative direction to the positive direction within a predetermined period from the time when the rate of change of the front-rear acceleration becomes equal to or higher than the first threshold value in the negative direction, and the front-back / rear acceleration changes. The road surface condition specifying system according to claim 1, wherein the vehicle has passed a step when the wheel speed difference becomes equal to or larger than the second threshold value. It has a left-right wheel speed difference acquisition means for acquiring the left-right wheel speed difference, which is the difference in rotational speed between the right wheel and the left wheel of the vehicle.
The step passage specifying means has a second front-rear wheel speed difference within a predetermined period from the time when the change rate of the front-rear acceleration becomes equal to or more than the first threshold value in a state where the left-right wheel speed difference is less than the third threshold value. The road surface condition specifying system according to claim 1 or 2, wherein the vehicle has passed a step when the threshold value is exceeded. A step passage history collecting means that collects information on the step passage history of each vehicle specified by the step passage identification means for a plurality of vehicles traveling on the road as step passage history information.
Any of claims 1 to 3, wherein the step position specifying means for specifying the position where there is a step on the road surface by statisticizing the step passing history information of each vehicle collected by the step passing history collecting means. Road surface condition identification system described in Crab. The road surface condition specifying system according to claim 4, wherein the step position specifying means specifies a position where a speed bump is particularly present as a step. The road surface condition specifying system according to claim 4 or 5, wherein the step position specifying means also specifies the traveling direction of a road having a step based on the traveling direction of a vehicle identified as having passed the step. A front-rear acceleration acquisition means for acquiring front-rear acceleration, which is an acceleration generated in the front-rear direction with respect to the vehicle,
Front and rear wheel speed difference acquisition means for acquiring the front and rear wheel speed difference, which is the difference in rotational speed between the front and rear wheels of the vehicle,
Step passage identifying means for specifying that the vehicle has passed the step when the front / rear wheel speed difference becomes the second threshold value or more within a predetermined period from the time when the rate of change of the front-rear acceleration becomes the first threshold value or more. And, a road surface condition identification device having. Computer,
A front-rear acceleration acquisition means for acquiring front-rear acceleration, which is an acceleration generated in the front-rear direction with respect to the vehicle,
Front and rear wheel speed difference acquisition means for acquiring the front and rear wheel speed difference, which is the difference in rotational speed between the front and rear wheels of the vehicle,
Step passage identifying means for specifying that the vehicle has passed the step when the front-rear wheel speed difference becomes the second threshold value or more within a predetermined period from the time when the rate of change of the front-rear acceleration becomes the first threshold value or more. And a computer program to make it work.