JP2020194467A - 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 even when a combination of sensors generally installed in many vehicles is used and a data sampling interval is set long.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 rear wheels of the vehicle are determined to have passed over the bump within a given period of time after the front wheels of the vehicle are determined to have passed over the bump based on a rate of change in the front-rear acceleration and the front-rear wheel speed difference.SELECTED DRAWING: Figure 8

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.

On the other hand, as a method of increasing the detection accuracy, it is effective to shorten the data sampling cycle by the sensor, but if the sampling cycle is shortened, there is a problem that the amount of data to be processed increases and the processing load increases.

The present invention has been made to solve the above-mentioned problems in the prior art, and even when a large number of sensors mounted on a vehicle are used in combination and a long data sampling cycle is set. 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 that can accurately determine the passage of a step of a vehicle.

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. Front and rear wheel speed difference acquisition means for acquiring the front and rear wheel speed difference, and front wheel step passage for determining whether or not the front wheel of the vehicle has passed the step based on the rate of change of the front and rear acceleration and the front and rear wheel speed difference. By the determination means, the rear wheel step passage determination means for determining whether or not the rear wheel of the vehicle has passed the step based on the rate of change of the front-rear acceleration and the front-rear wheel speed difference, and the front wheel step passage determination means. When the rear wheel of the vehicle is determined to have passed the step within a predetermined time from the time when the front wheel of the vehicle is determined to have passed the step, the vehicle has passed the step. It has a step passage specifying means for specifying.

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. Front and rear wheel speed difference acquisition means for acquiring the speed difference, front wheel step passage determination means for determining whether or not the front wheel of the vehicle has passed the step based on the rate of change of the front and rear acceleration and the front and rear wheel speed difference. Based on the rate of change of the front-rear acceleration and the speed difference between the front and rear wheels, the rear wheel step passage determining means for determining whether or not the rear wheels of the vehicle have passed the step, and the front wheel step passing determination means for the front wheels of the vehicle. When it is determined by the rear wheel step passage determining means that the rear wheel of the vehicle has passed the step within a predetermined time from the time when it is determined that the vehicle has passed the step, the step passage that specifies that the vehicle has passed the step It has a specific means.

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. Front and rear wheel speed difference acquisition means, front wheel step passage determining means for determining whether or not the front wheels of the vehicle have passed the step based on the rate of change of the front and rear acceleration and the front and rear wheel speed difference, and the front and rear acceleration. The front wheel of the vehicle has passed the step by the rear wheel step passing determination means for determining whether or not the rear wheel of the vehicle has passed the step based on the rate of change and the front and rear wheel speed difference, and the front wheel step passing determination means. When it is determined by the rear wheel step passing determination means that the rear wheel of the vehicle has passed the step within a predetermined time from the time when the determination is made, the step passing specifying means for specifying that the vehicle has passed the step, and the step passing specifying means. To make it work.

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, when sensors generally mounted on many vehicles are used in combination and the data sampling cycle is set long. Even in the case of, it is 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.

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 the front wheel of a vehicle starts passing a step. 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 rotation speed (wheel speed) of a front wheel and a rear wheel when a vehicle passes a step. It is a figure which showed the difference (front wheel-rear wheel) of the rotation speed of a front wheel and a rear wheel when a vehicle passes a step. It is a figure which showed the acceleration in the front-rear direction which occurs at the time when the rear wheel of a vehicle starts passing 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 front wheel step passage determining means determines whether or not the front wheels of the vehicle have passed the step based on the rate of change in the front-rear acceleration and the speed difference between the front and rear wheels. The rear wheel step passage determining means determines whether or not the rear wheels of the vehicle have passed the step based on the rate of change in the front-rear acceleration and the speed difference between the front and rear wheels. The step passage specifying means determines that the rear wheel of the vehicle has passed the step by the rear wheel step passage determination means within a predetermined time from the time when the front wheel of the vehicle is determined to have passed the step by the front wheel step passage determination means. If so, identify that the vehicle has passed a step.

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. The rotation speed of each wheel is detected by the wheel speed sensor 40 at predetermined time intervals (for example, 200 msec), and is cumulatively stored in the flash memory 54 or the like.

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, 200 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, 200 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 satisfies at least one of (1) and (2) among the following conditions (1) to (4) as a determination of passing the step of the front wheel, and Whether or not at least one of (3) and (4) is satisfied within a predetermined period (for example, within 1 second, but also at the same time), and the "step passage determination flag" is set to "OFF". Is determined. In the following description, the acceleration generated in the front-rear direction with respect to the vehicle (hereinafter referred to as front-rear G) is defined as the positive direction from the rear to the front of the vehicle (that is, when the vehicle is moving forward, acceleration is performed. Positive, negative when decelerating). Further, the difference in the rotational speeds of the front and rear wheels is based on the front wheels (that is, positive if the rotational speeds of the front wheels are faster, negative if the rotational speeds of the rear wheels are faster).
(1) Current front-rear G increases in the negative direction (2) Current front-rear G change rate is above the threshold in the negative direction (3) Difference in rotation speed between front and rear wheels is above the threshold in the positive direction (4) Before and after The rate of change of the difference in wheel rotation speed is above the threshold in the positive direction

The conditions (1) and (2) above are the conditions of front and rear G indicating that the front wheels have passed the step, and the threshold value of (2) is, for example, 0.1 G / s. Here, as shown in FIG. 7, when the vehicle 4 passes through the step 60 on the road surface, the front wheels first collide with the step. Then, as a result of the front wheels colliding with the step, the front and rear G changes from 0 or a value close to 0 to a large negative value. That is, the front-rear G increases in the negative direction, and the rate of change of the front-rear G becomes equal to or higher than the threshold value in the negative direction. FIG. 8 is a diagram showing changes in the front-rear G when the vehicle 4 passes the step. As shown in FIG. 8, the front and rear G change significantly negative when the front wheels collide with the step at first, but then the front and rear G gradually approach 0 as the front wheels overcome the step. Then, the front and rear wheels completely ride on the step (when the front wheel is located near the top of the step), and the front and rear G returns to 0 or a value close to 0.

On the other hand, the above conditions (3) and (4) are the conditions of the rotation speed of the wheels indicating that the front wheels have passed the step, the threshold value of (3) is, for example, 30 rpm, and the threshold value of (4) is, for example, 50 rpm / s. And. Here, FIG. 9 is a diagram showing changes in the rotational speeds (wheel speeds) of the front wheels and the rear wheels when the vehicle 4 passes the step, and FIG. 10 shows the front wheels and the rear when the vehicle 4 passes the step. It is a figure which showed the difference (front wheel-rear wheel) of the rotation speed of a wheel. As shown in FIG. 9, when the vehicle 4 passes through the step 60 on the road surface, the rotation speed of the front wheels temporarily increases when the front wheels get over the step. On the other hand, since the rear wheels of the vehicle 4 are not affected by the step during that period, basically a constant rotation speed is maintained. That is, when the front wheels get over the step, the difference in the rotation speeds of the front and rear wheels becomes equal to or more than the threshold value in the positive direction (the front wheels are faster) as shown in FIG. Is above the threshold in the positive direction. As shown in FIG. 9, 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 initial rotation speed is reached. And back.

In this embodiment, the data sampling cycle by the sensor is set to a relatively long interval (for example, 200 msec). Therefore, if both (1) and (2) are satisfied, before and after shown in FIG. Even though G is generated for the vehicle 4, it may be determined that the condition (1) or (2) is not satisfied. Therefore, in this embodiment, it is a condition that at least one of (1) and (2) is satisfied. Similarly, if both (3) and (4) are satisfied, the condition of (3) or (4) is satisfied even though the wheel speed difference shown in FIG. 10 occurs with respect to the vehicle 4. May be determined not to meet. Therefore, in this embodiment, it is a condition that at least one of (3) and (4) is satisfied.

Then, with respect to the above conditions (1) to (4), at least one of (1) and (2) is satisfied, and within a predetermined period from that, at least one of (3) and (4) is also satisfied. When it is determined that the "step passage determination flag" is set to "OFF" (S1: YES), it is estimated that the front wheels of the vehicle may have passed the step, and the process proceeds to S2. On the other hand, when it is determined that both (1) and (2), or both (3) and (4) are not satisfied, or that the "step passage determination flag" is set to "ON" ( In S1: NO), the process proceeds to S3.

The "step passage determination flag" is set to "ON" when the navigation device 5 determines that the vehicle has passed the step as described later (S8), and until a predetermined time (for example, 3 sec) elapses thereafter. It is continuously set to "ON". That is, the case where the "step passage determination flag" is set to "ON" indicates that the vehicle has passed the step within the latest predetermined time.

In S2, the CPU 51 estimates that the front wheels of the vehicle may have passed the step, and sets the parameter "front wheel step passage determination flag" to "ON". The "front wheel step passage determination flag" is set to "OFF" when the ACC power supply (accessory power supply) of the vehicle is turned on (initial state), and is stored in the flash memory 54 or the like.

Next, in S3, the CPU 51 reads the "front wheel step passage determination flag" from the flash memory 54, and determines whether or not the "front wheel step passage determination flag" is set to "ON".

Then, when it is determined that the "front wheel step passage determination flag" is set to "ON" (S3: YES), that is, when it is estimated that the front wheel of the vehicle may have passed the step. , S4. On the other hand, when it is determined that the "front wheel step passage determination flag" is set to "OFF" (S3: NO), that is, when it is estimated that there is no possibility that the front wheel of the vehicle has passed the step. The step passage detection processing program is terminated.

In S4, the CPU 51 sets a predetermined margin (for example, 0.2 sec) in consideration of an error in the "estimated rear wheel passing time" for the elapsed time from the setting of the "front wheel step passing determination flag" to "ON" to the present. Determine if it is less than or equal to the added total time. Here, the "estimated rear wheel passing time" is the time required from that time until the rear wheels are expected to pass the step when the front wheel passes the step. Specifically, the following equation (5) Is calculated by.
Estimated rear wheel transit time = wheelbase length / current vehicle speed ... (5)

It is desirable that the wheelbase length of the vehicle is acquired in advance from the vehicle control ECU or the like and stored in the flash memory 54. Further, the current vehicle speed is acquired by using the vehicle speed sensor 39. Further, it is desirable that the margin added to the "estimated rear wheel passing time" is set according to the current vehicle speed of the vehicle. Specifically, the slower the current vehicle speed of the vehicle, the more likely it is that an error will occur, so it is desirable to set the time longer.

Further, in S4, the lower limit condition may be set. For example, the elapsed time from the setting of the "front wheel step passage determination flag" to "ON" is equal to or greater than the time obtained by subtracting a predetermined margin from the "estimated rear wheel passage time" and the "estimated rear wheel passage time". It may be determined whether it is less than or equal to the time obtained by adding a predetermined margin to "".

Then, when it is determined that the elapsed time from the setting of the "front wheel step passage determination flag" to "ON" to the present is equal to or less than the total time obtained by adding the margin to the "estimated rear wheel passage time" (S4: YES). Will shift to S6.

On the other hand, when it is determined that the elapsed time from the setting of the "front wheel step passage determination flag" to "ON" exceeds the total time obtained by adding the margin to the "estimated rear wheel passage time" (S4: NO). ), It is finally determined that the vehicle has not passed the step. After that, in S5, the CPU 51 reads the "front wheel step passage determination flag" from the flash memory 54 and sets the "front wheel step passage determination flag" to "OFF". After that, the step passage detection processing program is terminated.

On the other hand, in S6, the CPU 51 determines whether at least one of the following conditions (6) to (9) is satisfied as the passage determination of the step of the rear wheel.
(6) Current front-rear G increases in the negative direction (7) Current front-rear G change rate is above the threshold in the negative direction (8) Difference in rotation speed between front and rear wheels is above the threshold in the negative direction (9) Before and after The rate of change of the difference in wheel rotation speed is above the threshold in the negative direction

The conditions (6) and (7) above are the conditions of front and rear G indicating that the rear wheels have passed the step, and the threshold value of (7) is, for example, 0.1 G / s. Here, as shown in FIG. 11, when the vehicle 4 passes through the step 60 on the road surface, the rear wheels collide with the step after the front wheels pass. Then, as a result of the rear wheels colliding with the step, the front and rear G changes from 0 or a value close to 0 to a large negative value. That is, the front-rear G increases in the negative direction, and the rate of change of the front-rear G becomes equal to or higher than the threshold value in the negative direction. As shown in FIG. 8, the front-rear G changes significantly negative when the rear wheels collide with the step, but then the front-rear G gradually approaches 0 as the rear wheels get over the step. Then, the front and rear wheels G completely ride on the step (when the rear wheel is located near the top of the step) return to 0 or a value close to 0.

On the other hand, the above conditions (8) and (9) are the conditions of the rotation speed of the wheels indicating that the rear wheels have passed the step, the threshold value of (8) is set to, for example, 30 rpm, and the threshold value of (9) is set to, for example, 50 rpm / Let s. Here, as shown in FIG. 9, when the vehicle 4 passes through the step 60 on the road surface, the rotation speed of the rear wheels temporarily increases when the rear wheels get over the step. On the other hand, since the front wheels of the vehicle 4 are not affected by the step during that period, basically a constant rotation speed is maintained. That is, when the rear wheels get over the step, as shown in FIG. 10, the difference in the rotational speeds of the front and rear wheels becomes equal to or greater than the threshold value in the negative direction (the rear wheels are faster), and the difference in the rotational speeds of the front and rear wheels changes. The rate also falls below the threshold in the negative direction. As shown in FIG. 9, when the rear 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 rear wheels completely overcome the step, the first rotation Return to speed.

In this embodiment, the data sampling cycle by the sensor is set to a relatively long interval (for example, 200 msec). Therefore, if both (6) and (7) are satisfied, before and after shown in FIG. Even though G is generated for the vehicle 4, it may be determined that the condition (6) or (7) is not satisfied. Therefore, in this embodiment, it is a condition that at least one of (6) and (7) is satisfied. Similarly, if both (7) and (8) are satisfied, the condition of (7) or (8) is satisfied even though the wheel speed difference shown in FIG. 10 occurs with respect to the vehicle 4. May be determined not to meet. Therefore, in this embodiment, it is a condition that at least one of (7) and (8) is satisfied. Further, when the rear wheels pass through a step as compared with the front wheels, it tends to be difficult to obtain ideal detection results as shown in FIGS. 8 and 10. Therefore, the condition (S6) for determining the step passage of the rear wheels is looser than the condition (S1) for determining the step passage of the front wheels, and the rear wheels of the vehicle can be used as long as at least one of the conditions (6) to (9) is satisfied. It is presumed that it may have passed a step.

Then, when it is determined that at least one of the above conditions (6) to (9) is satisfied (S6: YES), it is presumed that the rear wheels may have passed the step following the front wheels of the vehicle. , S7. On the other hand, when it is determined that none of (6) to (9) is satisfied (S6: NO), the process proceeds to S8.

In S7, the CPU 51 finally determined that the vehicle passed the step because it was detected that the front wheels of the vehicle passed the step and the rear wheels also passed the step within the time corresponding to the wheelbase length of the vehicle. Determine. Then, the CPU 51 "ONs" the parameter "step passage determination flag" and shifts to S8. 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 S8, the CPU 51 determines whether or not a predetermined time (for example, 3 sec) or more has elapsed since the parameter “step passage determination flag” was “ON”.

Then, when it is determined that a predetermined time or more has passed since the "step passage determination flag" was "ON" (S8: YES), the "step passage determination flag" is "OFF" (S9). On the other hand, when it is determined that a predetermined time or more has not passed since the "step passage determination flag" was "ON" (S8: NO), the step passage detection processing program is temporarily terminated and a predetermined time is determined. After the execution cycle elapses, the processing after S1 is started again.

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 difference in front and rear wheel speed, which is the difference in rotational speed between the front and rear wheels of the vehicle, is acquired, and when it is determined that the front wheel of the vehicle has passed the step based on the rate of change in front and rear acceleration and the difference in speed between front and rear wheels. If it is determined that the rear wheels of the vehicle have also passed the step within a predetermined time, it is specified that the vehicle has passed the step (S7). Therefore, in combination with sensors that are generally installed in many vehicles. Even when the vehicle is used and the data sampling cycle is set to be long, it is possible to accurately determine the passage of the 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 at least one of the above (1) and (2) is satisfied for the determination of passing the step of the front wheel, and at least one of (3) and (4) is satisfied within a predetermined period from that. , It is determined that the front wheels of the vehicle have passed the step. For example, when all the conditions (1) to (4) above are satisfied, or only one of the conditions (1) to (4) is satisfied. When the above conditions are satisfied, it may be determined that the front wheels of the vehicle have passed the step. Further, regarding the determination of passing the step of the rear wheel, it is determined that the rear wheel of the vehicle has passed the step when at least one of the above conditions (6) to (9) is satisfied. For example, the above (6). ) To (9), or when at least one of (6) and (7) is satisfied and at least one of (8) and (9) is satisfied, the rear wheel of the vehicle It may be determined that the vehicle has passed the step.

Further, the threshold value used for the above conditions (1) to (4) may be different from the threshold value used for the above conditions (6) to (9). For example, the threshold values of (6) to (9), which are the conditions for determining the step passage of the rear wheels, are looser than the threshold values of (1) to (4), which are the conditions for determining the step passage of the front wheels (the conditions are easily satisfied). Value) may be used. Further, regarding (1) and (6), the condition that "the current front-rear G increases in the negative direction" is set, but the condition that "the current front-rear G increases in the negative direction by a threshold value (for example, 0.1 G) or more". May be.

Further, in the present embodiment, basically, 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.
Before and after acquiring the front-rear acceleration acquisition means (51) that acquires the front-rear acceleration, which is the acceleration generated in the front-rear direction with respect to the vehicle (4), and the front-rear wheel speed difference, which is the difference between the rotational speeds of the front and rear wheels of the vehicle. The wheel speed difference acquisition means (51), the front wheel step passage determination means (51) that determines whether or not the front wheels of the vehicle have passed the step based on the rate of change of the front-rear acceleration and the front-rear wheel speed difference. Based on the rate of change of the front-rear acceleration and the difference in speed between the front and rear wheels, the rear wheel step passage determination means (51) for determining whether or not the rear wheels of the vehicle have passed the step, and the front wheel step passage determination means for the vehicle When it is determined by the rear wheel step passage determination means that the rear wheel of the vehicle has passed the step within a predetermined time from the time when the front wheel of the vehicle is determined to have passed the step, it is specified that the vehicle has passed the step. It has a step passage specifying means (51) and the like.
According to the road surface condition identification system having the above configuration, even when a combination of sensors generally installed in a vehicle is used in combination and a long data sampling cycle is set, the level difference of the vehicle can be accurately measured. It becomes possible to determine the passage. 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.
The predetermined time is set based on the wheelbase length of the vehicle (4).
According to the road surface condition identification system having the above configuration, the difference between the timing when the front wheel of the vehicle is determined to have passed the step and the timing when the rear wheel of the vehicle is determined to have passed the step is the wheelbase length of the vehicle. By considering whether or not it corresponds, it becomes possible to more accurately determine the passage of the step of the vehicle.

The third configuration is as follows.
It has a vehicle speed acquisition means (51) for acquiring the vehicle speed of the vehicle (4), and the predetermined time is set to a longer time as the vehicle speed of the vehicle is slower.
According to the road surface condition identification system having the above configuration, in a situation where an error is likely to occur in the difference between the timing when it is determined that the front wheels have passed the step and the timing when it is determined that the rear wheels of the vehicle have passed the step. By providing a large margin at a predetermined time as a determination standard, it is possible to more accurately determine the passage of a vehicle step.

The fourth configuration is as follows.
In the front wheel step passage determination means (51), the front-rear wheel speed difference is within a predetermined period from the time when the front-rear acceleration increases by the first threshold value or more or the change rate of the front-rear acceleration becomes the second threshold value or more. When the change rate of the front / rear wheel speed difference is equal to or higher than the third threshold value or the fourth threshold value or higher, it is determined that the front wheels of the vehicle have passed the step, and the rear wheel step passage determination means (51) determines that the front and rear wheels have passed the step. The acceleration increased by the fifth threshold value or more, the change rate of the front-rear acceleration became the sixth threshold value or more, the front-rear wheel speed difference became the seventh threshold value or more, and the change rate of the front-rear wheel speed difference became. When at least one of the conditions that the eighth threshold value or more is satisfied is satisfied, it is determined that the rear wheel of the vehicle has passed the step.
According to the road surface condition identification system having the above configuration, it is possible to accurately determine the passage of a step of a vehicle even when a combination of sensors generally mounted on the vehicle is used in combination. .. Further, regarding the passing condition of the step of the rear wheel, which is more likely to have an error in the detection value than that of the front wheel, it is possible to more accurately determine the passing of the step of the vehicle by making it looser than that of the front wheel. The first threshold value and the sixth threshold value may be set as the minimum detection unit of the front-back acceleration. In that case, "the time when the front-back acceleration increases by the first threshold value or more" is substantially "the time when the front-back acceleration increases", and "the time when the front-back acceleration increases by the fifth threshold value or more" is substantially ". The front-back acceleration has increased. "

The fifth 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 sixth 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 seventh 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 (9)

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,
A front wheel step passage determining means for determining whether or not the front wheels of the vehicle have passed the step based on the rate of change of the front-rear acceleration and the front-rear wheel speed difference.
A rear wheel step passage determining means for determining whether or not the rear wheels of the vehicle have passed the step based on the rate of change of the front-rear acceleration and the front-rear wheel speed difference.
When it is determined by the rear wheel step passing determination means that the rear wheel of the vehicle has passed the step within a predetermined time from the time when the front wheel of the vehicle is determined to have passed the step by the front wheel step passing determination means. A road surface condition identification system having a step passage identification means for identifying a vehicle that has passed a step. The road surface condition specifying system according to claim 1, wherein the predetermined time is set based on the wheelbase length of the vehicle. It has a vehicle speed acquisition means to acquire the vehicle speed of the vehicle,
The road surface condition specifying system according to claim 1 or 2, wherein the predetermined time is set to a longer time as the vehicle speed is slower. In the front wheel step passage determination means, the front-rear wheel speed difference becomes the third threshold value within a predetermined period from the time when the front-rear acceleration increases by the first threshold value or more or the change rate of the front-rear acceleration becomes the second threshold value or more. When the rate of change of the front / rear wheel speed difference is equal to or greater than the fourth threshold value, it is determined that the front wheels of the vehicle have passed the step.
In the rear wheel step passage determination means, the front-rear acceleration has increased by the fifth threshold value or more, the rate of change of the front-rear acceleration has become the sixth threshold value or more, and the front-rear wheel speed difference has become the seventh threshold value or more. Claims 1 to claim that it is determined that the rear wheels of the vehicle have passed the step when at least one of the conditions that the rate of change of the front and rear wheel speed difference is equal to or more than the eighth threshold value is satisfied. The road surface condition identification system according to any one of Item 3. 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 4, 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 5, 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 5 or 6, 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,
A front wheel step passage determining means for determining whether or not the front wheels of the vehicle have passed the step based on the rate of change of the front-rear acceleration and the front-rear wheel speed difference.
A rear wheel step passage determining means for determining whether or not the rear wheels of the vehicle have passed the step based on the rate of change of the front-rear acceleration and the front-rear wheel speed difference.
When it is determined by the rear wheel step passing determination means that the rear wheel of the vehicle has passed the step within a predetermined time from the time when the front wheel of the vehicle is determined to have passed the step by the front wheel step passing determination means. A road surface condition identifying device having a step passage identifying means for identifying a vehicle that has passed a step. 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,
A front wheel step passage determining means for determining whether or not the front wheels of the vehicle have passed the step based on the rate of change of the front-rear acceleration and the front-rear wheel speed difference.
A rear wheel step passage determining means for determining whether or not the rear wheels of the vehicle have passed the step based on the rate of change of the front-rear acceleration and the front-rear wheel speed difference.
When it is determined by the rear wheel step passing determination means that the rear wheel of the vehicle has passed the step within a predetermined time from the time when the front wheel of the vehicle is determined to have passed the step by the front wheel step passing determination means. A step-passing identification means that identifies a vehicle as having passed a step,
A computer program to make it work.