JP7740931B2 - Warning device, warning method, and warning program - Google Patents

Description

The present invention relates to a warning device, a warning method, and a warning program.

The technology disclosed in Patent Document 1 calculates a distance conversion coefficient (a coefficient that converts the number of wheel rotations into distance traveled) when a vehicle travels at each point in an identification area set on the road surface on which the vehicle is traveling.The technology then identifies the road surface condition based on the statistical distribution (frequency distribution) of the time-series data of the obtained distance conversion coefficient.

JP 2008-197819 A

The technology disclosed in Patent Document 1 requires the installation of optical beacons and roadside devices on the road surface in addition to the on-board device, which may increase the cost of identifying road surface conditions. Furthermore, road surface conditions cannot be identified using on-board devices alone. Therefore, it is not possible to assess the risk of a vehicle tipping over at low cost.

The present invention was made in consideration of the problems inherent in the prior art. The object of the present invention is to provide a warning device, warning method, and warning program that can assess the risk of a vehicle tipping over at low cost and issue an appropriate warning to the vehicle user or manager.

A warning device according to a first aspect of the present invention includes an input unit to which rotation speed information indicating the rotation speed of each of multiple wheels of a vehicle having a cargo carrying section and the vehicle's position are input, and a controller. The controller determines whether the road surface on which the vehicle is traveling is in a state requiring a warning based on the rotation speed information, and if it determines that the road surface is in a state requiring a warning, outputs status data indicating the state requiring a warning in association with the vehicle position.

A warning method according to a second aspect of the present invention is executed by a computer and acquires rotation speed information indicating the rotation speed of each of multiple wheels of a vehicle having a cargo carrying section, and acquires the vehicle's location. Based on the rotation speed information, it determines whether the road surface on which the vehicle is traveling is in a state requiring a warning, and if it is determined that the road surface is in a state requiring a warning, it associates status data indicating the state requiring a warning with the vehicle location and outputs the data.

A warning program according to a third aspect of the present invention causes a computer to acquire rotation speed information indicating the rotation speed of each of multiple wheels of a vehicle having a cargo carrying section, and to acquire the vehicle's location. Based on the rotation speed information, the computer determines whether the road surface on which the vehicle is traveling is in a state requiring a warning, and if it is determined that the road surface is in a state requiring a warning, causes the computer to output status data indicating the state requiring a warning in association with the vehicle location.

This invention makes it possible to assess the risk of a vehicle tipping over at low cost and issue appropriate warnings to vehicle users or managers.

1 is a side view showing a forklift to which a warning device according to an embodiment of the present invention is applied; 1 is a bottom view showing a forklift to which a warning device according to an embodiment of the present invention is applied; 1 is a block diagram showing an example of the configuration of a warning device according to an embodiment of the present invention; 5 is a flowchart showing a first example of processing by the warning device according to the present embodiment. 10 is a flowchart showing a second example of the processing of the warning device according to the embodiment. 4 is a schematic diagram showing how status data and the like are mapped by the warning device according to the present embodiment. FIG.

Next, the warning device according to this embodiment will be described in detail with reference to the drawings. In the description, identical components will be assigned the same reference numerals and duplicate explanations will be omitted.

[Vehicle configuration example]
A forklift F to which the warning device according to this embodiment is applied will be described with reference to Figures 1 and 2. Figure 1 is a side view of the forklift to which the warning device according to this embodiment is applied. Figure 2 is a bottom view of the forklift to which the warning device according to this embodiment is applied.

The forklift F (vehicle) is equipped with a fork section 51 that moves up and down, a backrest section 52, a mast section 53, front wheels (left front wheel TY1, right front wheel TY2) that serve as running wheels, and rear wheels (left rear wheel TY3, right rear wheel TY4) that serve as drive wheels.

The forklift F may be an engine vehicle powered by an internal combustion engine such as a gasoline engine, or a battery vehicle powered by an electric motor powered by electricity supplied from a secondary battery (battery) that can be charged from a generator or the like.

The fork section 51 and backrest section 52 are attached so as to be able to move up and down relative to a mast section 53 fixed to the body of the forklift F. The fork section 51 and mast section 53 together are referred to as the cargo loading section.

An on-board camera CM1 is provided above the mast 53, which supports the fork 51 and mast 53. The on-board camera CM1 captures images of the road surface in front of the forklift F. An on-board camera CM2 is provided above the rear of the forklift F. The on-board camera CM2 captures images of the road surface behind the forklift F.

The locations at which the vehicle-mounted cameras CM1 and CM2 are installed need only be such that they can capture images of the road surface around the forklift F, and are not limited to the examples given here. Furthermore, the vehicle-mounted cameras CM1 and CM2 may also capture images of the road surface to the sides of the forklift F.

A measurement unit 11 is attached to the body of forklift F to measure the load applied to the front and rear wheels of forklift F and the rotation speed of the front and rear wheels. Figure 2 shows sensors WS1, WS2, WS3, and WS4 as the measurement unit 11. Sensor WS1 measures the load applied to the left front wheel TY1 and its rotation speed. Sensor WS2 measures the load applied to the right front wheel TY2 and its rotation speed. Sensor WS3 measures the load applied to the left rear wheel TY3 and its rotation speed. Sensor WS4 measures the load applied to the right rear wheel TY4 and its rotation speed.

Sensors WS1 and WS2 may measure the load and rotation speed applied to the left front wheel TY1 and the right front wheel TY2, respectively, via axle 61. Sensors WS3 and WS4 may measure the load and rotation speed applied to the left rear wheel TY3 and the right rear wheel TY4, respectively, via axle 62.

In addition, an acceleration sensor (G sensor) that detects acceleration (front-rear G, left-right G, and up-down G) during movement may be attached to the body of the forklift F. The measurement unit 11 may include an acceleration sensor.

A position sensor that acquires position information of the forklift F may also be attached to the body of the forklift F. For example, the position sensor may be a GPS sensor. The GPS sensor receives radio waves from multiple GPS (Global Positioning System) satellites and performs predetermined calculations to acquire latitude and longitude information representing the current position of the forklift F from the received signals. This makes it possible to acquire position information (vehicle position) of the forklift F. The measurement unit 11 may include a position sensor.

Furthermore, a temperature sensor that acquires the temperature around the forklift F may be attached to the body of the forklift F. Also, a humidity sensor that acquires the humidity around the forklift F may be attached to the body of the forklift F. The measurement unit 11 may include a temperature sensor and a humidity sensor.

The operator (driver) of the forklift F operates the steering wheel 71, the gear lever 72, and pedals such as the accelerator pedal and brake pedal (not shown). These operations cause the fork section 51 to rise and fall, and the forklift F to move forward, backward, turn right, turn left, and perform other operations, such as loading and unloading work.

Vehicles to which the warning device according to this embodiment can be applied are not limited to forklifts F. The vehicle may also be a vehicle used for loading and unloading or transporting cargo, products, etc. within the premises of a factory, warehouse, etc.

[Example of warning device configuration]
The configuration of the warning device 1 according to this embodiment will be described with reference to Fig. 3. Fig. 3 is a block diagram showing an example of the configuration of the warning device according to this embodiment. The warning device 1 may be mounted on the forklift F, for example, or may be mounted on a terminal carried by a user or manager of the forklift F.

As shown in FIG. 3, the warning device 1 includes an input unit 21, a controller 100, and an alarm unit 400. Additionally, the warning device 1 may include a measurement unit 11 and a database 15. The measurement unit 11 is mounted on the forklift F, but the database 15 may be mounted on the forklift F or installed externally to the forklift F.

The measurement unit 11 and database 15 are connected to the input unit 21, and the input unit 21 and notification unit 400 are connected to the controller 100. Here, "connection" may refer to either a wired or wireless connection.

The measurement unit 11 measures the load applied to the front and rear wheels of the forklift F, and the rotation speed of the front and rear wheels. Information regarding the load applied to the front and rear wheels acquired by the measurement unit 11 is transmitted to the input unit 21 as load information representing the load on each of the multiple wheels of the forklift F. In addition, information regarding the rotation speed of the front and rear wheels acquired by the measurement unit 11 is transmitted to the input unit 21 as rotation speed information representing the rotation speed of each of the multiple wheels of the forklift F.

The measurement unit 11 may include a temperature sensor and a humidity sensor. Information on the temperature and humidity around the forklift F is sent to the input unit 21 as environmental information. The measurement unit 11 may also include a position sensor that acquires position information of the forklift F. The position information of the forklift F is sent to the input unit 21.

When the controller 100, described below, determines that the road surface on which the forklift F is located is in a state requiring a warning, the database 15 (storage unit) stores status data indicating the state requiring a warning in association with the vehicle position of the forklift F. For example, the status data may be plotted (mapped) on a map of the road surface on which the forklift F is traveling, based on the vehicle position. The database 15 may then store the map on which the status data is plotted. Figure 6 is a schematic diagram showing how status data, etc. are mapped by the warning device according to this embodiment. In Figure 6, danger points determined to be slippery A and caution points determined to be slippery B are plotted on a facility guide map of a factory, etc.

The database 15 may store not only status data generated by the controller 100 of one specific warning device 1, but also status data output from multiple warning devices 1. The status data stored in the database 15 is sent to the input unit 21 as needed. The database 15 may plot the status data on a map of the road surface on which the forklift F is traveling immediately after receiving the status data, thereby updating the map. The database 15 may also send the updated map to one or multiple warning devices 1 each time the map is updated.

When it is determined that the road surface on which the forklift F is traveling is in a state requiring a warning, the database 15 may store environmental information in addition to the state data indicating the state requiring a warning, in association with the vehicle position of the forklift F. The environmental information indicates the temperature or humidity around the forklift F when the forklift F is located on a road surface determined to be in a state requiring a warning. As shown in FIG. 6 , the environmental information may be plotted (mapped) on a map of the road surface on which the forklift F is traveling and stored in the database 15. The database 15 may plot the environmental information on the map of the road surface on which the forklift F is traveling and update the map immediately after receiving the environmental information. The database 15 may also transmit the updated map to one or more warning devices 1 each time the map is updated.

The input unit 21 acquires information transmitted from the measurement unit 11 and the database 15. The various pieces of information acquired by the input unit 21 are transmitted to the controller 100.

The notification unit 400 notifies the user when the controller 100 (described below) determines that the forklift F is in a state requiring a warning.

For example, the notification unit 400 may notify the driver that the road surface on which the forklift F is traveling is a low-mu road (a road surface with a low coefficient of friction), has a step, or has an incline. The notification unit 400 may also notify the driver that caution is required when traveling with the forklift F. The notification unit 400 may be a liquid crystal display, an organic EL display, or the like.

The notification unit 400 is not limited to presenting various types of information visually. The notification unit 400 may present information to the user through auditory information, or may generate vibrations to present information to the user through vibration stimulation. For example, the notification unit 400 may be a sound source, amplifier, speaker, etc. for generating and emitting sound.

The controller 100 is a general-purpose microcomputer equipped with a CPU (central processing unit), memory, and input/output units. A computer program (alert program) that enables the controller 100 to function as part of the alert device 1 is installed in the controller 100. By executing the computer program, the controller 100 functions as multiple information processing circuits (115, 120, 130).

Here, an example is shown in which the multiple information processing circuits (115, 120, 130) provided in the controller 100 are realized by software. However, it is also possible to configure the information processing circuits (115, 120, 130) by preparing dedicated hardware for executing each of the information processes described below. Furthermore, the multiple information processing circuits (115, 120, 130) may also be configured by individual hardware.

The controller 100 includes multiple information processing circuits (115, 120, 130), including a rotational difference calculation unit 115, a position acquisition unit 120, and a determination unit 130.

The rotational speed difference calculation unit 115 calculates rotational speed difference information that represents the difference in rotational speed between multiple wheels of the forklift F based on the rotational speed information. For example, the rotational speed difference calculation unit 115 calculates the difference in rotational speed between the left front wheel TY1 and the right front wheel TY2 of the forklift F as the first difference.

The rotation difference calculation unit 115 may also calculate the difference between the rotation speed of the front wheels and the rotation speed of the rear wheels of the forklift F as the second difference. Here, the rotation speed of the front wheels is given by the average value of the rotation speed of the left front wheel TY1 and the rotation speed of the right front wheel TY2. Furthermore, the rotation speed of the rear wheels is given by the average value of the rotation speed of the left rear wheel TY3 and the rotation speed of the right rear wheel TY4.

The reason why the rotational difference calculation unit 115 calculates the difference for the front wheels above is because the fork section 51, which serves as the cargo loading section, is located on the front wheel side of the forklift F (particularly, forward of the front wheels when viewed from the body of the forklift F). This is because the difference in rotational speed between the front wheels of the forklift F is useful for assessing the risk of the forklift F tipping over. However, the rotational difference calculation unit 115 may also calculate the difference in rotational speed between the left rear wheel TY3 and the right rear wheel TY4 of the forklift F as the third difference.

The position acquisition unit 120 acquires the vehicle position of the forklift F via the input unit 21. For example, the position acquisition unit 120 may acquire the vehicle position of the forklift F based on position information of the forklift F acquired by a position sensor. Alternatively, the position acquisition unit 120 may acquire the vehicle position of the forklift F by odometry based on the number of wheel rotations.

The determination unit 130 determines whether the road surface on which the forklift F is traveling is in a state requiring a warning, based on the rotation speed information or the rotation speed difference information. For example, the determination unit 130 determines that the road surface is in a state requiring a warning when the first difference calculated by the rotation speed difference calculation unit 115 is equal to or greater than a first threshold value. Here, the first threshold value may be determined in advance as a predetermined rotation speed, or may be a rotation speed obtained by multiplying the rotation speed of the front wheels by a predetermined coefficient.

The determination unit 130 may also determine that the road surface is in a state requiring a warning when the second difference calculated by the rotational difference calculation unit 115 is equal to or greater than a second threshold value. Here, the second threshold value may be determined in advance as a predetermined rotational speed, or may be a rotational speed obtained by multiplying the average rotational speed of the front and rear wheels by a predetermined coefficient.

In addition, the determination unit 130 may determine that the road surface is in a state requiring a warning when the third difference calculated by the rotational difference calculation unit 115 is equal to or greater than a third threshold. Here, the third threshold may be determined in advance as a predetermined rotational speed, or may be a rotational speed obtained by multiplying the rotational speed of the rear wheels by a predetermined coefficient.

The predetermined coefficients used to determine the first, second, and third thresholds define the strictness of the determination when determining that the road surface is in a state requiring a warning. For example, the magnitude of the predetermined coefficients may be changed depending on the content of the notification when the road surface is in a state requiring a warning.

For example, when the steering wheel angle is large, the difference in rotation speed between the wheels tends to be large even when wheel spin does not occur. Therefore, the determination unit 130 may obtain the steering wheel angle of the forklift F using a steering wheel angle sensor (not shown) or the like, and set the predetermined coefficient based on the obtained steering wheel angle. More specifically, when the steering wheel angle is large compared to when the steering wheel angle is small and the forklift F is traveling almost straight, the determination unit 130 may set the predetermined coefficient to a large value.

The determination unit 130 may perform a process to determine whether the road surface on which the forklift F is traveling is in a state requiring a warning by combining one or more of the processes described above.

The determination unit 130 may determine that the road surface is in a different warning state depending on the magnitude of the difference in rotation speed. For example, if the difference in rotation speed is small, it may determine that the road surface is in a "weak" warning state, and if the difference in rotation speed is large, it may determine that the road surface is in a "strong" warning state. For example, a "weak" warning state may mean a state in which the user needs to be warned. A "strong" warning state may mean a state in which the user needs to be warned and the forklift F is restricted from traveling.

When it is determined that the road surface on which the forklift F is traveling is in a state requiring a warning, the determination unit 130 may output status data indicating the state requiring a warning and the vehicle position of the forklift F in association with each other. The database 15 may store the status data and vehicle position output from the controller 100 in association with each other.

The determination unit 130 may also acquire status data and vehicle position from the database 15 via the input unit 21. The determination unit 130 may then determine whether the distance between the vehicle position associated with the status data and the current vehicle position of the forklift F is equal to or less than a predetermined distance. If the distance is equal to or less than the predetermined distance, the determination unit 130 may determine that the road surface on which the forklift F is traveling is in a state requiring a warning.

In addition, the determination unit 130 may stop control of the fork unit 51 and backrest unit 52, which are the luggage loading unit, when it determines that the road surface is in a state requiring a warning. For example, the determination unit 130 may stop the lifting and lowering operation of the fork unit 51 when it determines that the road surface is in a state requiring a warning.

The determination unit 130 may stop control of the travel of the forklift F when it determines that the road surface is in a state requiring a warning. For example, the determination unit 130 may stop operations of the forklift F that involve changes in vehicle position and attitude, such as moving forward, backward, turning right, or turning left, when it determines that the road surface is in a state requiring a warning.

[Warning device processing procedure]
Next, the processing procedure of the vehicle operation state detection device according to this embodiment will be described with reference to the flowcharts of FIGS.

The processes shown in the flowcharts of Figures 4 and 5 may start when the ignition of the forklift F is turned on, and may be executed repeatedly while the ignition is on. Furthermore, the processes shown in the flowcharts of Figures 4 and 5 may be executed in parallel, or alternately.

Figure 4 is a flowchart showing a first example of processing by the warning device according to this embodiment. In step S101, the input unit 21 acquires position information. The position acquisition unit 120 calculates the vehicle position of the forklift F based on the position information.

In step S103, the input unit 21 acquires rotation speed information.

In step S105, the rotation difference calculation unit 115 calculates rotation speed difference information based on the rotation speed information.

In step S107, the determination unit 130 determines whether the first difference calculated by the rotational difference calculation unit 115 is equal to or greater than the first threshold. If the first difference is equal to or greater than the first threshold (YES in step S107), the determination unit 130 determines in step S107 that the road surface is in a state that warrants a warning ("one-wheel slippage"). The notification unit 400 also notifies the user that the road surface state is "one-wheel slippage". Then, the process proceeds to step S115.

On the other hand, if the first difference is not greater than or equal to the first threshold (NO in step S107), in step S111, the determination unit 130 determines whether the second difference calculated by the rotation difference calculation unit 115 is greater than or equal to the second threshold.

If the second difference is greater than or equal to the second threshold (YES in step S111), in step S113 the determination unit 130 determines that the road surface is in a state that warrants a warning ("front wheel slippage"). The notification unit 400 also notifies the user that the road surface state is "front wheel slippage." Then, the process proceeds to step S115.

If the second difference is not greater than or equal to the second threshold (NO in step S111), the processing of the flowchart in Figure 4 ends.

In step S115, the determination unit 130 outputs status data indicating the warning-related status in association with the vehicle position of the forklift F. The database 15 stores the status data and vehicle position output from the controller 100 in association with each other.

Next, FIG. 5 is a flowchart showing a second example of processing by the warning device according to this embodiment. In step S201, the input unit 21 acquires position information. The position acquisition unit 120 calculates the current vehicle position of the forklift F based on the position information.

In step S203, the input unit 21 acquires the status data and the vehicle position associated with the status data.

In step S205, the determination unit 130 determines whether the distance between the vehicle position associated with the status data and the current vehicle position of the forklift F is less than or equal to a predetermined distance.

If the distance is less than the predetermined distance (YES in step S205), in step S207, the determination unit 130 determines that the road surface is in a state that warrants a warning, as represented by the state data. The notification unit 400 notifies the user that the road surface state warrants a warning. Then, the processing of the flowchart in Figure 5 ends.

If the distance is not less than the predetermined distance (NO in step S205), the processing of the flowchart in Figure 5 ends.

[Effects of the embodiment]
As described above in detail, the warning device, warning method, and warning program according to this embodiment acquire rotation speed information indicating the rotation speed of each of a plurality of wheels of a vehicle having a cargo loading section, and acquire the vehicle position of the vehicle. Based on the rotation speed information, it is determined whether the road surface on which the vehicle is traveling is in a state requiring a warning, and if it is determined that the road surface is in a state requiring a warning, status data indicating the state requiring a warning is output in association with the vehicle position.

This allows for a low-cost assessment of the risk of a vehicle tipping over and an appropriate warning to be issued to the vehicle's user or manager. In particular, if the vehicle's wheels spin when passing over a low-mu road (a road surface with a low coefficient of friction), a step, or a slope, a warning can be issued indicating that there is a risk of the vehicle tipping over.

Furthermore, according to the warning device, warning method, and warning program of this embodiment, the vehicle may have a luggage carrying section forward of the front wheels of the vehicle. The road surface may be determined to be in a state requiring a warning when the difference between the rotation speed of the right front wheel of the vehicle and the rotation speed of the left front wheel of the vehicle is equal to or greater than a first threshold. This makes it possible to detect "one-wheel skid" on the front wheels, which are more likely to receive load, and determine the risk of the vehicle tipping over. As a result, the accuracy of the determination can be improved.

Furthermore, according to the warning device, warning method, and warning program of this embodiment, the vehicle may have a luggage carrying section forward of the front wheels of the vehicle. The road surface may be determined to be in a state requiring a warning when the difference between the rotation speed of the front wheels and the rotation speed of the rear wheels of the vehicle is equal to or greater than a second threshold. This makes it possible to detect "front wheel slippage" on the front wheels, which are more likely to receive load, and determine the risk of the vehicle tipping over. As a result, the accuracy of the determination can be improved.

Furthermore, the warning device, warning method, and warning program according to this embodiment may stop control of the luggage carrying section when it is determined that the vehicle is in a state requiring a warning. This makes it possible to prevent an increase in the risk of the vehicle tipping over due to the up and down movement of the luggage carrying section when there is a risk of the vehicle tipping over.

Furthermore, the warning device, warning method, and warning program according to this embodiment may be configured so that the storage unit stores the status data in association with the vehicle position. This allows locations with a high risk of vehicle tipping over to be newly registered in a database, etc. Furthermore, a manager can check locations with a high risk of vehicle tipping over after the fact, and use this information to assist in road surface repair work.

Furthermore, the warning device, warning method, and warning program according to this embodiment may be configured so that a memory unit stores a map of the road surface on which the vehicle is traveling, plotting status data. Furthermore, each time the map is updated by receiving status data and vehicle position, the updated map may be output. This allows locations with a high risk of the vehicle tipping over to be managed in a database or the like. Furthermore, a manager can check locations with a high risk of the vehicle tipping over after the fact, and use this information to assist in road surface repair work.

Furthermore, according to the warning device, warning method, and warning program of this embodiment, the notification unit may notify the user when it determines that the road surface is in a state requiring a warning. This allows an appropriate warning to be issued to the vehicle user or manager.

The functions described in the above embodiments may be implemented by one or more processing circuits. Processing circuits include programmed processors, electrical circuits, and even devices such as application specific integrated circuits (ASICs), or circuit components configured to perform the described functions.

The present embodiment has been described above, but it is not limited to this, and various modifications are possible within the scope of the gist of the present embodiment.

1 Warning device 11 Measurement unit 15 Database (storage unit)
21 Input section 51 Fork section (loading section)
52 Backrest section 53 Mast section 100 Controller 115 Rotation difference calculation section 120 Position acquisition section 130 Determination section 400 Notification section F Forklift (vehicle)
TY1 Left front wheel TY2 Right front wheel TY3 Left rear wheel TY4 Right rear wheel

Claims (7)

an input unit for inputting rotation speed information representing the rotation speed of each of a plurality of wheels of a vehicle having a luggage carrying section forward of the front wheels, and a vehicle position of the vehicle;
A controller;
A warning device comprising:
The controller
determining whether the road surface on which the vehicle is traveling is in a state requiring a warning based on the rotation speed information;
When it is determined that the road surface is in the warning condition, outputting the state data indicating the warning condition in association with the vehicle position;
The controller
determining whether a difference between the rotation speed of a right front wheel of the vehicle and the rotation speed of a left front wheel of the vehicle is equal to or greater than a first threshold value based on the rotation speed information ;
When it is determined that the difference is equal to or greater than the first threshold , it is determined that the road surface is in the warning state,
If it is determined that the difference between the rotation speed of the front wheels of the vehicle and the rotation speed of the rear wheels of the vehicle is not equal to or greater than the first threshold value, it is determined whether or not the difference between the rotation speed of the front wheels of the vehicle and the rotation speed of the rear wheels of the vehicle is equal to or greater than a second threshold value, based on the rotation speed information;
When it is determined that the value is equal to or greater than the second threshold , it is determined that the road surface is in the warning state.
Warning device. The warning device described in claim 1, wherein the controller stops control of the luggage loading section when it determines that the vehicle is in the warning state. The warning device of claim 1 or 2, further comprising a storage unit that stores the status data in association with the vehicle position. The warning device described in claim 3, wherein the memory unit stores a map of the road surface on which the condition data is plotted, and outputs the updated map each time the memory unit receives the condition data and the vehicle position and updates the map. The warning device described in any one of claims 1 to 4 further comprises a notification unit that notifies the user when it is determined that the road surface is in the warning condition. 1. A computer-implemented alerting method comprising:
acquire rotation speed information representing the rotation speed of each of a plurality of wheels of a vehicle having a luggage carrying section forward of the front wheels;
Obtaining a vehicle position of the vehicle;
determining whether the road surface on which the vehicle is traveling is in a state requiring a warning based on the rotation speed information;
When it is determined that the road surface is in the warning condition, outputting the state data indicating the warning condition in association with the vehicle position;
determining whether a difference between the rotation speed of a right front wheel of the vehicle and the rotation speed of a left front wheel of the vehicle is equal to or greater than a first threshold value based on the rotation speed information ;
When it is determined that the difference is equal to or greater than the first threshold , it is determined that the road surface is in the warning state,
If it is determined that the difference between the rotation speed of the front wheels of the vehicle and the rotation speed of the rear wheels of the vehicle is not equal to or greater than the first threshold value, it is determined whether or not the difference between the rotation speed of the front wheels of the vehicle and the rotation speed of the rear wheels of the vehicle is equal to or greater than a second threshold value, based on the rotation speed information;
When it is determined that the value is equal to or greater than the second threshold , it is determined that the road surface is in the warning state.
Warning method. acquire rotation speed information representing the rotation speed of each of a plurality of wheels of a vehicle having a luggage carrying section forward of the front wheels;
Obtaining a vehicle position of the vehicle;
determining whether the road surface on which the vehicle is traveling is in a state requiring a warning based on the rotation speed information;
When it is determined that the road surface is in the warning condition, outputting the state data indicating the warning condition in association with the vehicle position;
determining whether a difference between the rotation speed of a right front wheel of the vehicle and the rotation speed of a left front wheel of the vehicle is equal to or greater than a first threshold value based on the rotation speed information ;
When it is determined that the difference is equal to or greater than the first threshold , it is determined that the road surface is in the warning state,
If it is determined that the difference between the rotation speed of the front wheels of the vehicle and the rotation speed of the rear wheels of the vehicle is not equal to or greater than the first threshold value, it is determined whether or not the difference between the rotation speed of the front wheels of the vehicle and the rotation speed of the rear wheels of the vehicle is equal to or greater than a second threshold value, based on the rotation speed information;
When it is determined that the value is equal to or greater than the second threshold , it is determined that the road surface is in the warning state.
A warning program that causes a computer to perform a process.